Preserve original formatting in Unmarshaler by using raw byte ranges

Instead of reconstructing key-value lines from parsed components, now
uses the original raw bytes from the document. This preserves:
- Whitespace around '=' (e.g., "key   =   value")
- String quoting style (basic vs literal)
- Number formats (hex, octal, binary)
- Inline table formatting

Changes:
- Add Raw range tracking to KeyValue expressions in parseKeyval
- Update handleKeyValuesUnmarshaler to use expr.Raw directly
- Remove keyNeedsQuoting helper (no longer needed)
- Add TestIssue873_FormattingPreservation test
- Update expected output in ExampleParser_comments

.dockerignore

@@ -0,0 +1,2 @@
+cmd/tomll/tomll
+cmd/tomljson/tomljson

.gitattributes

@@ -0,0 +1,4 @@
+* text=auto
+
+benchmark/benchmark.toml text eol=lf
+testdata/** text eol=lf

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,22 @@
+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior. Including TOML files.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen, if other than "should work".
+
+**Versions**
+ - go-toml: version (git sha)
+ - go: version
+ - operating system: e.g. macOS, Windows, Linux
+
+**Additional context**
+Add any other context about the problem here that you think may help to diagnose.

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,19 @@
+<!--
+
+Thank you for your pull request!
+
+Please read the Code changes section of the CONTRIBUTING.md file,
+and make sure you have followed the instructions.
+
+https://github.com/pelletier/go-toml/blob/v2/CONTRIBUTING.md#code-changes
+
+-->
+
+Explanation of what this pull request does.
+
+More detailed description of the decisions being made and the reasons why (if
+the patch is non-trivial).
+
+---
+
+Paste `benchstat` results here

.github/dependabot.yml

@@ -0,0 +1,17 @@
+version: 2
+updates:
+- package-ecosystem: gomod
+  directory: /
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10
+- package-ecosystem: github-actions
+  directory: /
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10
+- package-ecosystem: docker
+  directory: /
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10

.github/release.yml

@@ -0,0 +1,21 @@
+changelog:
+  exclude:
+    labels:
+      - build
+      - testing
+  categories:
+    - title: What's new
+      labels:
+        - feature
+    - title: Performance
+      labels:
+        - performance
+    - title: Fixed bugs
+      labels:
+        - bug
+    - title: Documentation
+      labels:
+        - doc
+    - title: Other changes
+      labels:
+        - "*"

.github/workflows/cifuzz.yml

@@ -0,0 +1,26 @@
+name: CIFuzz
+on: [pull_request]
+jobs:
+  Fuzzing:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Build Fuzzers
+      id: build
+      uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'go-toml'
+        dry-run: false
+        language: go
+    - name: Run Fuzzers
+      uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'go-toml'
+        fuzz-seconds: 300
+        dry-run: false
+        language: go
+    - name: Upload Crash
+      uses: actions/upload-artifact@v6
+      if: failure() && steps.build.outcome == 'success'
+      with:
+        name: artifacts
+        path: ./out/artifacts

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,67 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ master, v2 ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ master ]
+  schedule:
+    - cron: '26 19 * * 0'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python' ]
+        # Learn more:
+        # https://docs.github.com/en/free-pro-team@latest/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#changing-the-languages-that-are-analyzed
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v6
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v4
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+    # Autobuild attempts to build any compiled languages (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v4
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v4

.github/workflows/coverage.yml

@@ -0,0 +1,20 @@
+name: coverage
+on:
+  pull_request:
+    branches:
+      - v2
+
+jobs:
+  report:
+    runs-on: "ubuntu-latest"
+    name: report
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Setup go
+        uses: actions/setup-go@v6
+        with:
+          go-version: "1.25"
+      - name: Run tests with coverage
+        run: ./ci.sh coverage -d "${GITHUB_BASE_REF-HEAD}"

.github/workflows/go-versions-test.yml

@@ -0,0 +1,36 @@
+name: Go Versions Compatibility Test
+
+on:
+  workflow_dispatch:
+    inputs:
+      go_versions:
+        description: 'Go versions to test (space-separated, e.g., "1.21 1.22 1.23")'
+        required: false
+        default: ''
+        type: string
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Run Go versions compatibility test
+        run: |
+          VERSIONS="${{ github.event.inputs.go_versions }}"
+          ./test-go-versions.sh --output ./test-results $VERSIONS
+
+      - name: Upload test results
+        uses: actions/upload-artifact@v6
+        with:
+          name: go-versions-test-results
+          path: |
+            test-results/
+          retention-days: 30

.github/workflows/lint.yml

@@ -0,0 +1,22 @@
+name: lint
+on:
+  pull_request:
+    branches:
+      - v2
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Setup go
+        uses: actions/setup-go@v6
+        with:
+          go-version: "1.24"
+      - name: Run golangci-lint
+        uses: golangci/golangci-lint-action@v9
+        with:
+          version: v2.8.0

.github/workflows/release.yml

@@ -0,0 +1,39 @@
+name: release
+on:
+  push:
+    tags:
+      - "v2.*"
+  workflow_call:
+    inputs:
+      args:
+        description: "Extra arguments to pass goreleaser"
+        default: ""
+        required: false
+        type: string
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Set up Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: "1.25"
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Run GoReleaser
+        uses: goreleaser/goreleaser-action@v6
+        with:
+          distribution: goreleaser
+          version: '~> v2'
+          args: release ${{ inputs.args }} --clean
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/workflow.yml

@@ -0,0 +1,32 @@
+name: test
+on:
+  push:
+    branches:
+      - v2
+  pull_request:
+    branches:
+      - v2
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ 'ubuntu-latest', 'windows-latest', 'macos-latest', 'macos-14' ]
+        go: [ '1.24', '1.25' ]
+    runs-on: ${{ matrix.os }}
+    name: ${{ matrix.go }}/${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Setup go ${{ matrix.go }}
+        uses: actions/setup-go@v6
+        with:
+          go-version: ${{ matrix.go }}
+      - name: Run unit tests
+        run: go test -race ./...
+  release-check:
+    if: ${{ github.ref != 'refs/heads/v2' }}
+    uses: ./.github/workflows/release.yml
+    with:
+      args: --snapshot

.gitignore

@@ -1 +1,8 @@
 test_program/test_program_bin
+fuzz/
+cmd/tomll/tomll
+cmd/tomljson/tomljson
+cmd/tomltestgen/tomltestgen
+dist
+tests/
+test-results

.golangci.toml

@@ -0,0 +1,76 @@
+version = "2"
+
+[linters]
+default = "none"
+enable = [
+    "asciicheck",
+    "bodyclose",
+    "dogsled",
+    "dupl",
+    "durationcheck",
+    "errcheck",
+    "errorlint",
+    "exhaustive",
+    "forbidigo",
+    "gochecknoinits",
+    "goconst",
+    "gocritic",
+    "godoclint",
+    "goheader",
+    "gomodguard",
+    "goprintffuncname",
+    "gosec",
+    "govet",
+    "importas",
+    "ineffassign",
+    "lll",
+    "makezero",
+    "mirror",
+    "misspell",
+    "nakedret",
+    "nilerr",
+    "noctx",
+    "nolintlint",
+    "perfsprint",
+    "prealloc",
+    "predeclared",
+    "revive",
+    "rowserrcheck",
+    "sqlclosecheck",
+    "staticcheck",
+    "thelper",
+    "tparallel",
+    "unconvert",
+    "unparam",
+    "unused",
+    "usetesting",
+    "wastedassign",
+    "whitespace",
+]
+
+[linters.settings.exhaustive]
+default-signifies-exhaustive = true
+
+[linters.settings.lll]
+line-length = 150
+
+[[linters.exclusions.rules]]
+path = ".test.go"
+linters = ["goconst", "gosec"]
+
+[[linters.exclusions.rules]]
+path = "main.go"
+linters = ["forbidigo"]
+
+[[linters.exclusions.rules]]
+path = "internal"
+linters = ["revive"]
+text = "(exported|indent-error-flow): "
+
+[formatters]
+enable = [
+    "gci",
+    "gofmt",
+    "gofumpt",
+    "goimports",
+]

.goreleaser.yaml

@@ -0,0 +1,127 @@
+version: 2
+before:
+  hooks:
+    - go mod tidy
+    - go fmt ./...
+    - go test ./...
+builds:
+  - id: tomll
+    main: ./cmd/tomll
+    binary: tomll
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -X main.version={{.Version}} -X main.commit={{.Commit}} -X main.date={{.CommitDate}}
+    mod_timestamp: '{{ .CommitTimestamp }}'
+    targets:
+      - linux_amd64
+      - linux_arm64
+      - linux_arm
+      - linux_riscv64
+      - windows_amd64
+      - windows_arm64
+      - windows_arm
+      - darwin_amd64
+      - darwin_arm64
+  - id: tomljson
+    main: ./cmd/tomljson
+    binary: tomljson
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -X main.version={{.Version}} -X main.commit={{.Commit}} -X main.date={{.CommitDate}}
+    mod_timestamp: '{{ .CommitTimestamp }}'
+    targets:
+      - linux_amd64
+      - linux_arm64
+      - linux_arm
+      - linux_riscv64
+      - windows_amd64
+      - windows_arm64
+      - windows_arm
+      - darwin_amd64
+      - darwin_arm64
+  - id: jsontoml
+    main: ./cmd/jsontoml
+    binary: jsontoml
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -X main.version={{.Version}} -X main.commit={{.Commit}} -X main.date={{.CommitDate}}
+    mod_timestamp: '{{ .CommitTimestamp }}'
+    targets:
+      - linux_amd64
+      - linux_arm64
+      - linux_riscv64
+      - linux_arm
+      - windows_amd64
+      - windows_arm64
+      - windows_arm
+      - darwin_amd64
+      - darwin_arm64
+universal_binaries:
+  - id: tomll
+    replace: true
+    name_template: tomll
+  - id: tomljson
+    replace: true
+    name_template: tomljson
+  - id: jsontoml
+    replace: true
+    name_template: jsontoml
+archives:
+- id: jsontoml
+  format: tar.xz
+  builds:
+    - jsontoml
+  files:
+  - none*
+  name_template: "{{ .Binary }}_{{.Version}}_{{ .Os }}_{{ .Arch }}"
+- id: tomljson
+  format: tar.xz
+  builds:
+    - tomljson
+  files:
+  - none*
+  name_template: "{{ .Binary }}_{{.Version}}_{{ .Os }}_{{ .Arch }}"
+- id: tomll
+  format: tar.xz
+  builds:
+    - tomll
+  files:
+  - none*
+  name_template: "{{ .Binary }}_{{.Version}}_{{ .Os }}_{{ .Arch }}"
+dockers:
+  - id: tools
+    goos: linux
+    goarch: amd64
+    ids:
+      - jsontoml
+      - tomljson
+      - tomll
+    image_templates:
+      - "ghcr.io/pelletier/go-toml:latest"
+      - "ghcr.io/pelletier/go-toml:{{ .Tag }}"
+      - "ghcr.io/pelletier/go-toml:v{{ .Major }}"
+    skip_push: false
+checksum:
+  name_template: 'sha256sums.txt'
+snapshot:
+  version_template: "{{ incpatch .Version }}-next"
+release:
+  github:
+    owner: pelletier
+    name: go-toml
+  draft: true
+  prerelease: auto
+  mode: replace
+changelog:
+  use: github-native
+announce:
+  skip: true

.travis.yml

@@ -1,6 +0,0 @@
-language: go
-script: "./test.sh"
-go:
-    - 1.1
-    - 1.2
-    - tip

AGENTS.md

@@ -0,0 +1,64 @@
+# Agent Guidelines for go-toml
+
+This file provides guidelines for AI agents contributing to go-toml. All agents must follow these rules derived from [CONTRIBUTING.md](./CONTRIBUTING.md).
+
+## Project Overview
+
+go-toml is a TOML library for Go. The goal is to provide an easy-to-use and efficient TOML implementation that gets the job done without getting in the way.
+
+## Code Change Rules
+
+### Backward Compatibility
+
+- **No backward-incompatible changes** unless explicitly discussed and approved
+- Avoid breaking people's programs unless absolutely necessary
+
+### Testing Requirements
+
+- **All bug fixes must include regression tests**
+- **All new code must be tested**
+- Run tests before submitting: `go test -race ./...`
+- Test coverage must not decrease. Check with:
+  ```bash
+  go test -covermode=atomic -coverprofile=coverage.out
+  go tool cover -func=coverage.out
+  ```
+- All lines of code touched by changes should be covered by tests
+
+### Performance Requirements
+
+- go-toml aims to stay efficient; avoid performance regressions
+- Run benchmarks to verify: `go test ./... -bench=. -count=10`
+- Compare results using [benchstat](https://pkg.go.dev/golang.org/x/perf/cmd/benchstat)
+
+### Documentation
+
+- New features or feature extensions must include documentation
+- Documentation lives in [README.md](./README.md) and throughout source code
+
+### Code Style
+
+- Follow existing code format and structure
+- Code must pass `go fmt`
+- Code must pass linting with the same golangci-lint version as CI (see version in `.github/workflows/lint.yml`):
+  ```bash
+  # Install specific version (check lint.yml for current version)
+  curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/HEAD/install.sh | sh -s -- -b $(go env GOPATH)/bin <version>
+  # Run linter
+  golangci-lint run ./...
+  ```
+
+### Commit Messages
+
+- Commit messages must explain **why** the change is needed
+- Keep messages clear and informative even if details are in the PR description
+
+## Pull Request Checklist
+
+Before submitting:
+
+1. Tests pass (`go test -race ./...`)
+2. No backward-incompatible changes (unless discussed)
+3. Relevant documentation added/updated
+4. No performance regression (verify with benchmarks)
+5. Title is clear and understandable for changelog

CONTRIBUTING.md

@@ -0,0 +1,235 @@
+# Contributing
+
+Thank you for your interest in go-toml! We appreciate you considering
+contributing to go-toml!
+
+The main goal is the project is to provide an easy-to-use and efficient TOML
+implementation for Go that gets the job done and gets out of your way – dealing
+with TOML is probably not the central piece of your project.
+
+As the single maintainer of go-toml, time is scarce. All help, big or small, is
+more than welcomed!
+
+## Ask questions
+
+Any question you may have, somebody else might have it too. Always feel free to
+ask them on the [discussion board][discussions]. We will try to answer them as
+clearly and quickly as possible, time permitting.
+
+Asking questions also helps us identify areas where the documentation needs
+improvement, or new features that weren't envisioned before. Sometimes, a
+seemingly innocent question leads to the fix of a bug. Don't hesitate and ask
+away!
+
+[discussions]: https://github.com/pelletier/go-toml/discussions
+
+## Improve the documentation
+
+The best way to share your knowledge and experience with go-toml is to improve
+the documentation. Fix a typo, clarify an interface, add an example, anything
+goes!
+
+The documentation is present in the [README][readme] and thorough the source
+code. On release, it gets updated on [pkg.go.dev][pkg.go.dev]. To make a change
+to the documentation, create a pull request with your proposed changes. For
+simple changes like that, the easiest way to go is probably the "Fork this
+project and edit the file" button on GitHub, displayed at the top right of the
+file. Unless it's a trivial change (for example a typo), provide a little bit of
+context in your pull request description or commit message.
+
+## Report a bug
+
+Found a bug! Sorry to hear that :(. Help us and other track them down and fix by
+reporting it. [File a new bug report][bug-report] on the [issues
+tracker][issues-tracker]. The template should provide enough guidance on what to
+include. When in doubt: add more details! By reducing ambiguity and providing
+more information, it decreases back and forth and saves everyone time.
+
+## Code changes
+
+Want to contribute a patch? Very happy to hear that!
+
+First, some high-level rules:
+
+- A short proposal with some POC code is better than a lengthy piece of text
+  with no code. Code speaks louder than words. That being said, bigger changes
+  should probably start with a [discussion][discussions].
+- No backward-incompatible patch will be accepted unless discussed. Sometimes
+  it's hard, but we try not to break people's programs unless we absolutely have
+  to.
+- If you are writing a new feature or extending an existing one, make sure to
+  write some documentation.
+- Bug fixes need to be accompanied with regression tests.
+- New code needs to be tested.
+- Your commit messages need to explain why the change is needed, even if already
+  included in the PR description.
+
+It does sound like a lot, but those best practices are here to save time overall
+and continuously improve the quality of the project, which is something everyone
+benefits from.
+
+### Get started
+
+The fairly standard code contribution process looks like that:
+
+1. [Fork the project][fork].
+2. Make your changes, commit on any branch you like.
+3. [Open up a pull request][pull-request]
+4. Review, potential ask for changes.
+5. Merge.
+
+Feel free to ask for help! You can create draft pull requests to gather
+some early feedback!
+
+### Run the tests
+
+You can run tests for go-toml using Go's test tool: `go test -race ./...`.
+
+During the pull request process, all tests will be ran on Linux, Windows, and
+MacOS on the last two versions of Go.
+
+However, given GitHub's new policy to _not_ run Actions on pull requests until a
+maintainer clicks on button, it is highly recommended that you run them locally
+as you make changes.
+
+### Test across Go versions
+
+The repository includes tooling to test go-toml across multiple Go versions
+(1.11 through 1.25) both locally and in GitHub Actions.
+
+#### Local testing with Docker
+
+Prerequisites: Docker installed and running, Bash shell, `rsync` command.
+
+```bash
+# Test all Go versions in parallel (default)
+./test-go-versions.sh
+
+# Test specific versions
+./test-go-versions.sh 1.21 1.22 1.23
+
+# Test sequentially (slower but uses less resources)
+./test-go-versions.sh --sequential
+
+# Verbose output with custom results directory
+./test-go-versions.sh --verbose --output ./my-results 1.24 1.25
+
+# Show all options
+./test-go-versions.sh --help
+```
+
+The script creates Docker containers for each Go version and runs the full test
+suite. Results are saved to a `test-results/` directory with individual logs and
+a comprehensive summary report.
+
+The script only exits with a non-zero status code if either of the two most
+recent Go versions fail.
+
+#### GitHub Actions testing (maintainers)
+
+1. Go to the **Actions** tab in the GitHub repository
+2. Select **"Go Versions Compatibility Test"** from the workflow list
+3. Click **"Run workflow"**
+4. Optionally customize:
+   - **Go versions**: Space-separated list (e.g., `1.21 1.22 1.23`)
+   - **Execution mode**: Parallel (faster) or sequential (more stable)
+
+### Check coverage
+
+We use `go tool cover` to compute test coverage. Most code editors have a way to
+run and display code coverage, but at the end of the day, we do this:
+
+```
+go test -covermode=atomic -coverprofile=coverage.out
+go tool cover -func=coverage.out
+```
+
+and verify that the overall percentage of tested code does not go down. This is
+a requirement. As a rule of thumb, all lines of code touched by your changes
+should be covered. On Unix you can use `./ci.sh coverage -d v2` to check if your
+code lowers the coverage.
+
+### Verify performance
+
+Go-toml aims to stay efficient. We rely on a set of scenarios executed with Go's
+builtin benchmark systems. Because of their noisy nature, containers provided by
+GitHub Actions cannot be reliably used for benchmarking. As a result, you are
+responsible for checking that your changes do not incur a performance penalty.
+You can run their following to execute benchmarks:
+
+```
+go test ./... -bench=. -count=10
+```
+
+Benchmark results should be compared against each other with
+[benchstat][benchstat]. Typical flow looks like this:
+
+1. On the `v2` branch, run `go test ./... -bench=. -count 10` and save output to
+   a file (for example `old.txt`).
+2. Make some code changes.
+3. Run `go test ....` again, and save the output to an other file (for example
+   `new.txt`).
+4. Run `benchstat old.txt new.txt` to check that time/op does not go up in any
+   test.
+
+On Unix you can use `./ci.sh benchmark -d v2` to verify how your code impacts
+performance.
+
+It is highly encouraged to add the benchstat results to your pull request
+description. Pull requests that lower performance will receive more scrutiny.
+
+[benchstat]: https://pkg.go.dev/golang.org/x/perf/cmd/benchstat
+
+### Style
+
+Try to look around and follow the same format and structure as the rest of the
+code. We enforce using `go fmt` on the whole code base.
+
+---
+
+## Maintainers-only
+
+### Merge pull request
+
+Checklist:
+
+- Passing CI.
+- Does not introduce backward-incompatible changes (unless discussed).
+- Has relevant doc changes.
+- Benchstat does not show performance regression.
+- Pull request is [labeled appropriately][pr-labels].
+- Title will be understandable in the changelog.
+
+1. Merge using "squash and merge".
+2. Make sure to edit the commit message to keep all the useful information
+   nice and clean.
+3. Make sure the commit title is clear and contains the PR number (#123).
+
+### New release
+
+1. Decide on the next version number. Use semver. Review commits since last
+   version to assess.
+2. Tag release. For example:
+   ```
+   git checkout v2
+   git pull
+   git tag v2.2.0
+   git push --tags
+   ```
+3. CI automatically builds a draft GitHub release. Review it and edit as
+   necessary. Look for "Other changes". That would indicate a pull request not
+   labeled properly. Tweak labels and pull request titles until changelog looks
+   good for users.
+4. Check "create discussion" box, in the "Releases" category.
+5. If new version is an alpha or beta only, check pre-release box.
+
+
+[issues-tracker]: https://github.com/pelletier/go-toml/issues
+[bug-report]: https://github.com/pelletier/go-toml/issues/new?template=bug_report.md
+[pkg.go.dev]: https://pkg.go.dev/github.com/pelletier/go-toml
+[readme]: ./README.md
+[fork]: https://help.github.com/articles/fork-a-repo
+[pull-request]: https://help.github.com/en/articles/creating-a-pull-request
+[new-release]: https://github.com/pelletier/go-toml/releases/new
+[gh]: https://github.com/cli/cli
+[pr-labels]: https://github.com/pelletier/go-toml/blob/v2/.github/release.yml

Dockerfile

@@ -0,0 +1,5 @@
+FROM scratch
+ENV PATH "$PATH:/bin"
+COPY tomll /bin/tomll
+COPY tomljson /bin/tomljson
+COPY jsontoml /bin/jsontoml

LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+go-toml v2
+Copyright (c) 2021 - 2023 Thomas Pelletier
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,88 +1,636 @@
-# go-toml
+# go-toml v2
 
-Go library for the [TOML](https://github.com/mojombo/toml) format.
+Go library for the [TOML](https://toml.io/en/) format.
 
-This library supports TOML version
-[v0.1.0](https://github.com/mojombo/toml/blob/master/versions/toml-v0.1.0.md)
+This library supports [TOML v1.0.0](https://toml.io/en/v1.0.0).
 
-[![Build Status](https://travis-ci.org/pelletier/go-toml.png?branch=master)](https://travis-ci.org/pelletier/go-toml)
+[🐞 Bug Reports](https://github.com/pelletier/go-toml/issues)
 
-## Import
-
-    import "github.com/pelletier/go-toml"
-
-## Usage
-
-Say you have a TOML file that looks like this:
-
-```toml
-[postgres]
-user = "pelletier"
-password = "mypassword"
-```
-
-Read the username and password like this:
-
-```go
-import (
-    "fmt"
-    "github.com/pelletier/go-toml"
-)
-
-config, err := toml.LoadFile("config.toml")
-if err != nil {
-    fmt.Println("Error ", err.Error())
-} else {
-    // retrieve data directly
-    user := config.Get("postgres.user").(string)
-    password := config.Get("postgres.password").(string)
-
-    // or using an intermediate object
-    configTree := config.Get("postgres").(*toml.TomlTree)
-    user = configTree.Get("user").(string)
-    password = configTree.Get("password").(string)
-    fmt.Println("User is ", user, ". Password is ", password)
-}
-```
+[💬 Anything else](https://github.com/pelletier/go-toml/discussions)
 
 ## Documentation
 
-The documentation is available at
-[godoc.org](http://godoc.org/github.com/pelletier/go-toml).
+Full API, examples, and implementation notes are available in the Go
+documentation.
 
-## Contribute
+[![Go Reference](https://pkg.go.dev/badge/github.com/pelletier/go-toml/v2.svg)](https://pkg.go.dev/github.com/pelletier/go-toml/v2)
 
-Feel free to report bugs and patches using GitHub's pull requests system on
-[pelletier/go-toml](https://github.com/pelletier/go-toml). Any feedback would be
-much appreciated!
+## Import
 
-### Run tests
+```go
+import "github.com/pelletier/go-toml/v2"
+```
 
-You have to make sure two kind of tests run:
+See [Modules](#Modules).
 
-1. The Go unit tests: `go test`
-2. The TOML examples base: `./test_program/go-test.sh`
+## Features
 
-You can run both of them using `./test.sh`.
+### Stdlib behavior
+
+As much as possible, this library is designed to behave similarly as the
+standard library's `encoding/json`.
+
+### Performance
+
+While go-toml favors usability, it is written with performance in mind. Most
+operations should not be shockingly slow. See [benchmarks](#benchmarks).
+
+### Strict mode
+
+`Decoder` can be set to "strict mode", which makes it error when some parts of
+the TOML document was not present in the target structure. This is a great way
+to check for typos. [See example in the documentation][strict].
+
+[strict]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#example-Decoder.DisallowUnknownFields
+
+### Contextualized errors
+
+When most decoding errors occur, go-toml returns [`DecodeError`][decode-err],
+which contains a human readable contextualized version of the error. For
+example:
+
+```
+1| [server]
+2| path = 100
+ |        ~~~ cannot decode TOML integer into struct field toml_test.Server.Path of type string
+3| port = 50
+```
+
+[decode-err]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#DecodeError
+
+### Local date and time support
+
+TOML supports native [local date/times][ldt]. It allows to represent a given
+date, time, or date-time without relation to a timezone or offset. To support
+this use-case, go-toml provides [`LocalDate`][tld], [`LocalTime`][tlt], and
+[`LocalDateTime`][tldt]. Those types can be transformed to and from `time.Time`,
+making them convenient yet unambiguous structures for their respective TOML
+representation.
+
+[ldt]: https://toml.io/en/v1.0.0#local-date-time
+[tld]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalDate
+[tlt]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalTime
+[tldt]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#LocalDateTime
+
+### Commented config
+
+Since TOML is often used for configuration files, go-toml can emit documents
+annotated with [comments and commented-out values][comments-example]. For
+example, it can generate the following file:
+
+```toml
+# Host IP to connect to.
+host = '127.0.0.1'
+# Port of the remote server.
+port = 4242
+
+# Encryption parameters (optional)
+# [TLS]
+# cipher = 'AEAD-AES128-GCM-SHA256'
+# version = 'TLS 1.3'
+```
+
+[comments-example]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#example-Marshal-Commented
+
+## Getting started
+
+Given the following struct, let's see how to read it and write it as TOML:
+
+```go
+type MyConfig struct {
+	Version int
+	Name    string
+	Tags    []string
+}
+```
+
+### Unmarshaling
+
+[`Unmarshal`][unmarshal] reads a TOML document and fills a Go structure with its
+content. 
+
+Note that the struct variable names are _capitalized_, while the variables in the toml document are _lowercase_.
+
+For example:
+
+```go
+doc := `
+version = 2
+name = "go-toml"
+tags = ["go", "toml"]
+`
+
+var cfg MyConfig
+err := toml.Unmarshal([]byte(doc), &cfg)
+if err != nil {
+	panic(err)
+}
+fmt.Println("version:", cfg.Version)
+fmt.Println("name:", cfg.Name)
+fmt.Println("tags:", cfg.Tags)
+
+// Output:
+// version: 2
+// name: go-toml
+// tags: [go toml]
+```
+
+[unmarshal]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Unmarshal
+
+
+Here is an example using tables with some simple nesting:
+
+```go
+doc := `
+age = 45
+fruits = ["apple", "pear"]
+
+# these are very important!
+[my-variables]
+first = 1
+second = 0.2
+third = "abc"
+
+# this is not so important.
+[my-variables.b]
+bfirst = 123
+`
+
+var Document struct {
+	Age int
+	Fruits []string
+
+	Myvariables struct {
+		First  int
+		Second float64
+		Third  string
+
+		B struct {
+			Bfirst int
+		}
+	} `toml:"my-variables"`
+}
+
+err := toml.Unmarshal([]byte(doc), &Document)
+if err != nil {
+	panic(err)
+}
+
+fmt.Println("age:", Document.Age)
+fmt.Println("fruits:", Document.Fruits)
+fmt.Println("my-variables.first:", Document.Myvariables.First)
+fmt.Println("my-variables.second:", Document.Myvariables.Second)
+fmt.Println("my-variables.third:", Document.Myvariables.Third)
+fmt.Println("my-variables.B.Bfirst:", Document.Myvariables.B.Bfirst)
+
+// Output:
+// age: 45
+// fruits: [apple pear]
+// my-variables.first: 1
+// my-variables.second: 0.2
+// my-variables.third: abc
+// my-variables.B.Bfirst: 123
+```
+
+
+### Marshaling
+
+[`Marshal`][marshal] is the opposite of Unmarshal: it represents a Go structure
+as a TOML document:
+
+```go
+cfg := MyConfig{
+	Version: 2,
+	Name:    "go-toml",
+	Tags:    []string{"go", "toml"},
+}
+
+b, err := toml.Marshal(cfg)
+if err != nil {
+	panic(err)
+}
+fmt.Println(string(b))
+
+// Output:
+// Version = 2
+// Name = 'go-toml'
+// Tags = ['go', 'toml']
+```
+
+[marshal]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Marshal
+
+## Unstable API
+
+This API does not yet follow the backward compatibility guarantees of this
+library. They provide early access to features that may have rough edges or an
+API subject to change.
+
+### Parser
+
+Parser is the unstable API that allows iterative parsing of a TOML document at
+the AST level. See https://pkg.go.dev/github.com/pelletier/go-toml/v2/unstable.
+
+## Benchmarks
+
+Execution time speedup compared to other Go TOML libraries:
+
+<table>
+	<thead>
+		<tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
+	</thead>
+	<tbody>
+		<tr><td>Marshal/HugoFrontMatter-2</td><td>1.9x</td><td>2.2x</td></tr>
+		<tr><td>Marshal/ReferenceFile/map-2</td><td>1.7x</td><td>2.1x</td></tr>
+		<tr><td>Marshal/ReferenceFile/struct-2</td><td>2.2x</td><td>3.0x</td></tr>
+		<tr><td>Unmarshal/HugoFrontMatter-2</td><td>2.9x</td><td>2.7x</td></tr>
+		<tr><td>Unmarshal/ReferenceFile/map-2</td><td>2.6x</td><td>2.7x</td></tr>
+		<tr><td>Unmarshal/ReferenceFile/struct-2</td><td>4.6x</td><td>5.1x</td></tr>
+	 </tbody>
+</table>
+<details><summary>See more</summary>
+<p>The table above has the results of the most common use-cases. The table below
+contains the results of all benchmarks, including unrealistic ones. It is
+provided for completeness.</p>
+
+<table>
+	<thead>
+		<tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
+	</thead>
+	<tbody>
+		<tr><td>Marshal/SimpleDocument/map-2</td><td>1.8x</td><td>2.7x</td></tr>
+		<tr><td>Marshal/SimpleDocument/struct-2</td><td>2.7x</td><td>3.8x</td></tr>
+		<tr><td>Unmarshal/SimpleDocument/map-2</td><td>3.8x</td><td>3.0x</td></tr>
+		<tr><td>Unmarshal/SimpleDocument/struct-2</td><td>5.6x</td><td>4.1x</td></tr>
+		<tr><td>UnmarshalDataset/example-2</td><td>3.0x</td><td>3.2x</td></tr>
+		<tr><td>UnmarshalDataset/code-2</td><td>2.3x</td><td>2.9x</td></tr>
+		<tr><td>UnmarshalDataset/twitter-2</td><td>2.6x</td><td>2.7x</td></tr>
+		<tr><td>UnmarshalDataset/citm_catalog-2</td><td>2.2x</td><td>2.3x</td></tr>
+		<tr><td>UnmarshalDataset/canada-2</td><td>1.8x</td><td>1.5x</td></tr>
+		<tr><td>UnmarshalDataset/config-2</td><td>4.1x</td><td>2.9x</td></tr>
+		<tr><td>geomean</td><td>2.7x</td><td>2.8x</td></tr>
+	 </tbody>
+</table>
+<p>This table can be generated with <code>./ci.sh benchmark -a -html</code>.</p>
+</details>
+
+## Modules
+
+go-toml uses Go's standard modules system.
+
+Installation instructions:
+
+- Go ≥ 1.16: Nothing to do. Use the import in your code. The `go` command deals
+  with it automatically.
+- Go ≥ 1.13: `GO111MODULE=on go get github.com/pelletier/go-toml/v2`.
+
+In case of trouble: [Go Modules FAQ][mod-faq].
+
+[mod-faq]: https://github.com/golang/go/wiki/Modules#why-does-installing-a-tool-via-go-get-fail-with-error-cannot-find-main-module
+
+## Tools
+
+Go-toml provides three handy command line tools:
+
+ * `tomljson`: Reads a TOML file and outputs its JSON representation.
+
+	```
+	$ go install github.com/pelletier/go-toml/v2/cmd/tomljson@latest
+	$ tomljson --help
+	```
+
+ * `jsontoml`: Reads a JSON file and outputs a TOML representation.
+
+	```
+	$ go install github.com/pelletier/go-toml/v2/cmd/jsontoml@latest
+	$ jsontoml --help
+	```
+
+ * `tomll`: Lints and reformats a TOML file.
+
+	```
+	$ go install github.com/pelletier/go-toml/v2/cmd/tomll@latest
+	$ tomll --help
+	```
+
+### Docker image
+
+Those tools are also available as a [Docker image][docker]. For example, to use
+`tomljson`:
+
+```
+docker run -i ghcr.io/pelletier/go-toml:v2 tomljson < example.toml
+```
+
+Multiple versions are available on [ghcr.io][docker].
+
+[docker]: https://github.com/pelletier/go-toml/pkgs/container/go-toml
+
+## Migrating from v1
+
+This section describes the differences between v1 and v2, with some pointers on
+how to get the original behavior when possible.
+
+### Decoding / Unmarshal
+
+#### Automatic field name guessing
+
+When unmarshaling to a struct, if a key in the TOML document does not exactly
+match the name of a struct field or any of the `toml`-tagged field, v1 tries
+multiple variations of the key ([code][v1-keys]).
+
+V2 instead does a case-insensitive matching, like `encoding/json`.
+
+This could impact you if you are relying on casing to differentiate two fields,
+and one of them is a not using the `toml` struct tag. The recommended solution
+is to be specific about tag names for those fields using the `toml` struct tag.
+
+[v1-keys]: https://github.com/pelletier/go-toml/blob/a2e52561804c6cd9392ebf0048ca64fe4af67a43/marshal.go#L775-L781
+
+#### Ignore preexisting value in interface
+
+When decoding into a non-nil `interface{}`, go-toml v1 uses the type of the
+element in the interface to decode the object. For example:
+
+```go
+type inner struct {
+	B interface{}
+}
+type doc struct {
+	A interface{}
+}
+
+d := doc{
+	A: inner{
+		B: "Before",
+	},
+}
+
+data := `
+[A]
+B = "After"
+`
+
+toml.Unmarshal([]byte(data), &d)
+fmt.Printf("toml v1: %#v\n", d)
+
+// toml v1: main.doc{A:main.inner{B:"After"}}
+```
+
+In this case, field `A` is of type `interface{}`, containing a `inner` struct.
+V1 sees that type and uses it when decoding the object.
+
+When decoding an object into an `interface{}`, V2 instead disregards whatever
+value the `interface{}` may contain and replaces it with a
+`map[string]interface{}`. With the same data structure as above, here is what
+the result looks like:
+
+```go
+toml.Unmarshal([]byte(data), &d)
+fmt.Printf("toml v2: %#v\n", d)
+
+// toml v2: main.doc{A:map[string]interface {}{"B":"After"}}
+```
+
+This is to match `encoding/json`'s behavior. There is no way to make the v2
+decoder behave like v1.
+
+#### Values out of array bounds ignored
+
+When decoding into an array, v1 returns an error when the number of elements
+contained in the doc is superior to the capacity of the array. For example:
+
+```go
+type doc struct {
+	A [2]string
+}
+d := doc{}
+err := toml.Unmarshal([]byte(`A = ["one", "two", "many"]`), &d)
+fmt.Println(err)
+
+// (1, 1): unmarshal: TOML array length (3) exceeds destination array length (2)
+```
+
+In the same situation, v2 ignores the last value:
+
+```go
+err := toml.Unmarshal([]byte(`A = ["one", "two", "many"]`), &d)
+fmt.Println("err:", err, "d:", d)
+// err: <nil> d: {[one two]}
+```
+
+This is to match `encoding/json`'s behavior. There is no way to make the v2
+decoder behave like v1.
+
+#### Support for `toml.Unmarshaler` has been dropped
+
+This method was not widely used, poorly defined, and added a lot of complexity.
+A similar effect can be achieved by implementing the `encoding.TextUnmarshaler`
+interface and use strings.
+
+#### Support for `default` struct tag has been dropped
+
+This feature adds complexity and a poorly defined API for an effect that can be
+accomplished outside of the library.
+
+It does not seem like other format parsers in Go support that feature (the
+project referenced in the original ticket #202 has not been updated since 2017).
+Given that go-toml v2 should not touch values not in the document, the same
+effect can be achieved by pre-filling the struct with defaults (libraries like
+[go-defaults][go-defaults] can help). Also, string representation is not well
+defined for all types: it creates issues like #278.
+
+The recommended replacement is pre-filling the struct before unmarshaling.
+
+[go-defaults]: https://github.com/mcuadros/go-defaults
+
+#### `toml.Tree` replacement
+
+This structure was the initial attempt at providing a document model for
+go-toml. It allows manipulating the structure of any document, encoding and
+decoding from their TOML representation. While a more robust feature was
+initially planned in go-toml v2, this has been ultimately [removed from
+scope][nodoc] of this library, with no plan to add it back at the moment. The
+closest equivalent at the moment would be to unmarshal into an `interface{}` and
+use type assertions and/or reflection to manipulate the arbitrary
+structure. However this would fall short of providing all of the TOML features
+such as adding comments and be specific about whitespace.
+
+
+#### `toml.Position` are not retrievable anymore
+
+The API for retrieving the position (line, column) of a specific TOML element do
+not exist anymore. This was done to minimize the amount of concepts introduced
+by the library (query path), and avoid the performance hit related to storing
+positions in the absence of a document model, for a feature that seemed to have
+little use. Errors however have gained more detailed position
+information. Position retrieval seems better fitted for a document model, which
+has been [removed from the scope][nodoc] of go-toml v2 at the moment.
+
+### Encoding / Marshal
+
+#### Default struct fields order
+
+V1 emits struct fields order alphabetically by default. V2 struct fields are
+emitted in order they are defined. For example:
+
+```go
+type S struct {
+	B string
+	A string
+}
+
+data := S{
+	B: "B",
+	A: "A",
+}
+
+b, _ := tomlv1.Marshal(data)
+fmt.Println("v1:\n" + string(b))
+
+b, _ = tomlv2.Marshal(data)
+fmt.Println("v2:\n" + string(b))
+
+// Output:
+// v1:
+// A = "A"
+// B = "B"
+
+// v2:
+// B = 'B'
+// A = 'A'
+```
+
+There is no way to make v2 encoder behave like v1. A workaround could be to
+manually sort the fields alphabetically in the struct definition, or generate
+struct types using `reflect.StructOf`.
+
+#### No indentation by default
+
+V1 automatically indents content of tables by default. V2 does not. However the
+same behavior can be obtained using [`Encoder.SetIndentTables`][sit]. For example:
+
+```go
+data := map[string]interface{}{
+	"table": map[string]string{
+		"key": "value",
+	},
+}
+
+b, _ := tomlv1.Marshal(data)
+fmt.Println("v1:\n" + string(b))
+
+b, _ = tomlv2.Marshal(data)
+fmt.Println("v2:\n" + string(b))
+
+buf := bytes.Buffer{}
+enc := tomlv2.NewEncoder(&buf)
+enc.SetIndentTables(true)
+enc.Encode(data)
+fmt.Println("v2 Encoder:\n" + string(buf.Bytes()))
+
+// Output:
+// v1:
+//
+// [table]
+//   key = "value"
+//
+// v2:
+// [table]
+// key = 'value'
+//
+//
+// v2 Encoder:
+// [table]
+//   key = 'value'
+```
+
+[sit]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Encoder.SetIndentTables
+
+#### Keys and strings are single quoted
+
+V1 always uses double quotes (`"`) around strings and keys that cannot be
+represented bare (unquoted). V2 uses single quotes instead by default (`'`),
+unless a character cannot be represented, then falls back to double quotes. As a
+result of this change, `Encoder.QuoteMapKeys` has been removed, as it is not
+useful anymore.
+
+There is no way to make v2 encoder behave like v1.
+
+#### `TextMarshaler` emits as a string, not TOML
+
+Types that implement [`encoding.TextMarshaler`][tm] can emit arbitrary TOML in
+v1. The encoder would append the result to the output directly. In v2 the result
+is wrapped in a string. As a result, this interface cannot be implemented by the
+root object.
+
+There is no way to make v2 encoder behave like v1.
+
+[tm]: https://golang.org/pkg/encoding/#TextMarshaler
+
+#### `Encoder.CompactComments` has been removed
+
+Emitting compact comments is now the default behavior of go-toml. This option
+is not necessary anymore.
+
+#### Struct tags have been merged
+
+V1 used to provide multiple struct tags: `comment`, `commented`, `multiline`,
+`toml`, and `omitempty`. To behave more like the standard library, v2 has merged
+`toml`, `multiline`, `commented`, and `omitempty`. For example:
+
+```go
+type doc struct {
+	// v1
+	F string `toml:"field" multiline:"true" omitempty:"true" commented:"true"`
+	// v2
+	F string `toml:"field,multiline,omitempty,commented"`
+}
+```
+
+Has a result, the `Encoder.SetTag*` methods have been removed, as there is just
+one tag now.
+
+#### `Encoder.ArraysWithOneElementPerLine` has been renamed
+
+The new name is `Encoder.SetArraysMultiline`. The behavior should be the same.
+
+#### `Encoder.Indentation` has been renamed
+
+The new name is `Encoder.SetIndentSymbol`. The behavior should be the same.
+
+
+#### Embedded structs behave like stdlib
+
+V1 defaults to merging embedded struct fields into the embedding struct. This
+behavior was unexpected because it does not follow the standard library. To
+avoid breaking backward compatibility, the `Encoder.PromoteAnonymous` method was
+added to make the encoder behave correctly. Given backward compatibility is not
+a problem anymore, v2 does the right thing by default: it follows the behavior
+of `encoding/json`. `Encoder.PromoteAnonymous` has been removed.
+
+[nodoc]: https://github.com/pelletier/go-toml/discussions/506#discussioncomment-1526038
+
+### `query`
+
+go-toml v1 provided the [`go-toml/query`][query] package. It allowed to run
+JSONPath-style queries on TOML files. This feature is not available in v2. For a
+replacement, check out [dasel][dasel].
+
+This package has been removed because it was essentially not supported anymore
+(last commit May 2020), increased the complexity of the code base, and more
+complete solutions exist out there.
+
+[query]: https://github.com/pelletier/go-toml/tree/f99d6bbca119636aeafcf351ee52b3d202782627/query
+[dasel]: https://github.com/TomWright/dasel
+
+## Versioning
+
+Expect for parts explicitly marked otherwise, go-toml follows [Semantic
+Versioning](https://semver.org). The supported version of
+[TOML](https://github.com/toml-lang/toml) is indicated at the beginning of this
+document. The last two major versions of Go are supported (see [Go Release
+Policy](https://golang.org/doc/devel/release.html#policy)).
 
 ## License
 
-Copyright (c) 2013, 2014 Thomas Pelletier, Eric Anderton
-
-Permission is hereby granted, free of charge, to any person obtaining a copy of
-this software and associated documentation files (the "Software"), to deal in
-the Software without restriction, including without limitation the rights to
-use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
-of the Software, and to permit persons to whom the Software is furnished to do
-so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+The MIT License (MIT). Read [LICENSE](LICENSE).

SECURITY.md

@@ -0,0 +1,16 @@
+# Security Policy
+
+## Supported Versions
+
+| Version    | Supported          |
+| ---------- | ------------------ |
+| Latest 2.x | :white_check_mark: |
+| All 1.x    | :x:                |
+| All 0.x    | :x:                |
+
+## Reporting a Vulnerability
+
+Email a vulnerability report to `security@pelletier.codes`. Make sure to include
+as many details as possible to reproduce the vulnerability. This is a
+side-project: I will try to get back to you as quickly as possible, time
+permitting in my personal life. Providing a working patch helps very much!

benchmark/bench_datasets_test.go

@@ -0,0 +1,80 @@
+package benchmark_test
+
+import (
+	"compress/gzip"
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+var benchInputs = []struct {
+	name    string
+	jsonLen int
+}{
+	// from https://gist.githubusercontent.com/feeeper/2197d6d734729625a037af1df14cf2aa/raw/2f22b120e476d897179be3c1e2483d18067aa7df/config.toml
+	{"config", 806507},
+
+	// converted from https://github.com/miloyip/nativejson-benchmark
+	{"canada", 2090234},
+	{"citm_catalog", 479897},
+	{"twitter", 428778},
+	{"code", 1940472},
+
+	// converted from https://raw.githubusercontent.com/mailru/easyjson/master/benchmark/example.json
+	{"example", 7779},
+}
+
+func TestUnmarshalDatasetCode(t *testing.T) {
+	for _, tc := range benchInputs {
+		t.Run(tc.name, func(t *testing.T) {
+			buf := fixture(t, tc.name)
+
+			var v interface{}
+			assert.NoError(t, toml.Unmarshal(buf, &v))
+
+			b, err := json.Marshal(v)
+			assert.NoError(t, err)
+			assert.Equal(t, len(b), tc.jsonLen)
+		})
+	}
+}
+
+func BenchmarkUnmarshalDataset(b *testing.B) {
+	for _, tc := range benchInputs {
+		b.Run(tc.name, func(b *testing.B) {
+			buf := fixture(b, tc.name)
+			b.SetBytes(int64(len(buf)))
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				var v interface{}
+				assert.NoError(b, toml.Unmarshal(buf, &v))
+			}
+		})
+	}
+}
+
+// fixture returns the uncompressed contents of path.
+func fixture(tb testing.TB, path string) []byte {
+	tb.Helper()
+
+	file := path + ".toml.gz"
+	f, err := os.Open(filepath.Join("testdata", file))
+	if os.IsNotExist(err) {
+		tb.Skip("benchmark fixture not found:", file)
+	}
+	assert.NoError(tb, err)
+	defer func() { _ = f.Close() }()
+
+	gz, err := gzip.NewReader(f)
+	assert.NoError(tb, err)
+
+	buf, err := io.ReadAll(gz)
+	assert.NoError(tb, err)
+	return buf
+}

benchmark/benchmark.toml

@@ -0,0 +1,244 @@
+################################################################################
+## Comment
+
+# Speak your mind with the hash symbol. They go from the symbol to the end of
+# the line.
+
+
+################################################################################
+## Table
+
+# Tables (also known as hash tables or dictionaries) are collections of
+# key/value pairs. They appear in square brackets on a line by themselves.
+
+[table]
+
+key = "value" # Yeah, you can do this.
+
+# Nested tables are denoted by table names with dots in them. Name your tables
+# whatever crap you please, just don't use #, ., [ or ].
+
+[table.subtable]
+
+key = "another value"
+
+# You don't need to specify all the super-tables if you don't want to. TOML
+# knows how to do it for you.
+
+# [x] you
+# [x.y] don't
+# [x.y.z] need these
+[x.y.z.w] # for this to work
+
+
+################################################################################
+## Inline Table
+
+# Inline tables provide a more compact syntax for expressing tables. They are
+# especially useful for grouped data that can otherwise quickly become verbose.
+# Inline tables are enclosed in curly braces `{` and `}`. No newlines are
+# allowed between the curly braces unless they are valid within a value.
+
+[table.inline]
+
+name = { first = "Tom", last = "Preston-Werner" }
+point = { x = 1, y = 2 }
+
+
+################################################################################
+## String
+
+# There are four ways to express strings: basic, multi-line basic, literal, and
+# multi-line literal. All strings must contain only valid UTF-8 characters.
+
+[string.basic]
+
+basic = "I'm a string. \"You can quote me\". Name\tJos\u00E9\nLocation\tSF."
+
+[string.multiline]
+
+# The following strings are byte-for-byte equivalent:
+key1 = "One\nTwo"
+key2 = """One\nTwo"""
+key3 = """
+One
+Two"""
+
+[string.multiline.continued]
+
+# The following strings are byte-for-byte equivalent:
+key1 = "The quick brown fox jumps over the lazy dog."
+
+key2 = """
+The quick brown \
+
+
+  fox jumps over \
+    the lazy dog."""
+
+key3 = """\
+       The quick brown \
+       fox jumps over \
+       the lazy dog.\
+       """
+
+[string.literal]
+
+# What you see is what you get.
+winpath  = 'C:\Users\nodejs\templates'
+winpath2 = '\\ServerX\admin$\system32\'
+quoted   = 'Tom "Dubs" Preston-Werner'
+regex    = '<\i\c*\s*>'
+
+
+[string.literal.multiline]
+
+regex2 = '''I [dw]on't need \d{2} apples'''
+lines  = '''
+The first newline is
+trimmed in raw strings.
+   All other whitespace
+   is preserved.
+'''
+
+
+################################################################################
+## Integer
+
+# Integers are whole numbers. Positive numbers may be prefixed with a plus sign.
+# Negative numbers are prefixed with a minus sign.
+
+[integer]
+
+key1 = +99
+key2 = 42
+key3 = 0
+key4 = -17
+
+[integer.underscores]
+
+# For large numbers, you may use underscores to enhance readability. Each
+# underscore must be surrounded by at least one digit.
+key1 = 1_000
+key2 = 5_349_221
+key3 = 1_2_3_4_5     # valid but inadvisable
+
+
+################################################################################
+## Float
+
+# A float consists of an integer part (which may be prefixed with a plus or
+# minus sign) followed by a fractional part and/or an exponent part.
+
+[float.fractional]
+
+key1 = +1.0
+key2 = 3.1415
+key3 = -0.01
+
+[float.exponent]
+
+key1 = 5e+22
+key2 = 1e6
+key3 = -2E-2
+
+[float.both]
+
+key = 6.626e-34
+
+[float.underscores]
+
+key1 = 9_224_617.445_991_228_313
+key2 = 1e1_00
+
+
+################################################################################
+## Boolean
+
+# Booleans are just the tokens you're used to. Always lowercase.
+
+[boolean]
+
+True = true
+False = false
+
+
+################################################################################
+## Datetime
+
+# Datetimes are RFC 3339 dates.
+
+[datetime]
+
+key1 = 1979-05-27T07:32:00Z
+key2 = 1979-05-27T00:32:00-07:00
+key3 = 1979-05-27T00:32:00.999999-07:00
+
+
+################################################################################
+## Array
+
+# Arrays are square brackets with other primitives inside. Whitespace is
+# ignored. Elements are separated by commas. Data types may not be mixed.
+
+[array]
+
+key1 = [ 1, 2, 3 ]
+key2 = [ "red", "yellow", "green" ]
+key3 = [ [ 1, 2 ], [3, 4, 5] ]
+key4 = [ [ 1, 2 ], ["a", "b", "c"] ] # this is ok
+
+# Arrays can also be multiline. So in addition to ignoring whitespace, arrays
+# also ignore newlines between the brackets.  Terminating commas are ok before
+# the closing bracket.
+
+key5 = [
+  1, 2, 3
+]
+key6 = [
+  1,
+  2, # this is ok
+]
+
+
+################################################################################
+## Array of Tables
+
+# These can be expressed by using a table name in double brackets. Each table
+# with the same double bracketed name will be an element in the array. The
+# tables are inserted in the order encountered.
+
+[[products]]
+
+name = "Hammer"
+sku = 738594937
+
+[[products]]
+
+[[products]]
+
+name = "Nail"
+sku = 284758393
+color = "gray"
+
+
+# You can create nested arrays of tables as well.
+
+[[fruit]]
+  name = "apple"
+
+  [fruit.physical]
+    color = "red"
+    shape = "round"
+
+  [[fruit.variety]]
+    name = "red delicious"
+
+  [[fruit.variety]]
+    name = "granny smith"
+
+[[fruit]]
+  name = "banana"
+
+  [[fruit.variety]]
+    name = "plantain"

benchmark/benchmark_test.go

@@ -0,0 +1,654 @@
+package benchmark_test
+
+import (
+	"bytes"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestUnmarshalSimple(t *testing.T) {
+	doc := []byte(`A = "hello"`)
+	d := struct {
+		A string
+	}{}
+
+	err := toml.Unmarshal(doc, &d)
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func BenchmarkUnmarshal(b *testing.B) {
+	b.Run("SimpleDocument", func(b *testing.B) {
+		doc := []byte(`A = "hello"`)
+
+		b.Run("struct", func(b *testing.B) {
+			b.SetBytes(int64(len(doc)))
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			for i := 0; i < b.N; i++ {
+				d := struct {
+					A string
+				}{}
+
+				err := toml.Unmarshal(doc, &d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+		})
+
+		b.Run("map", func(b *testing.B) {
+			b.SetBytes(int64(len(doc)))
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			for i := 0; i < b.N; i++ {
+				d := map[string]interface{}{}
+				err := toml.Unmarshal(doc, &d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+		})
+	})
+
+	b.Run("ReferenceFile", func(b *testing.B) {
+		bytes, err := os.ReadFile("benchmark.toml")
+		if err != nil {
+			b.Fatal(err)
+		}
+
+		b.Run("struct", func(b *testing.B) {
+			b.SetBytes(int64(len(bytes)))
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				d := benchmarkDoc{}
+				err := toml.Unmarshal(bytes, &d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+		})
+
+		b.Run("map", func(b *testing.B) {
+			b.SetBytes(int64(len(bytes)))
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				d := map[string]interface{}{}
+				err := toml.Unmarshal(bytes, &d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+		})
+	})
+
+	b.Run("HugoFrontMatter", func(b *testing.B) {
+		b.SetBytes(int64(len(hugoFrontMatterbytes)))
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			d := map[string]interface{}{}
+			err := toml.Unmarshal(hugoFrontMatterbytes, &d)
+			if err != nil {
+				b.Error(err)
+			}
+		}
+	})
+}
+
+func marshal(v interface{}) ([]byte, error) {
+	var b bytes.Buffer
+	enc := toml.NewEncoder(&b)
+	err := enc.Encode(v)
+	return b.Bytes(), err
+}
+
+func BenchmarkMarshal(b *testing.B) {
+	b.Run("SimpleDocument", func(b *testing.B) {
+		doc := []byte(`A = "hello"`)
+
+		b.Run("struct", func(b *testing.B) {
+			d := struct {
+				A string
+			}{}
+
+			err := toml.Unmarshal(doc, &d)
+			if err != nil {
+				b.Error(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+
+			b.SetBytes(int64(len(out)))
+		})
+
+		b.Run("map", func(b *testing.B) {
+			d := map[string]interface{}{}
+			err := toml.Unmarshal(doc, &d)
+			if err != nil {
+				b.Error(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+
+			b.SetBytes(int64(len(out)))
+		})
+	})
+
+	b.Run("ReferenceFile", func(b *testing.B) {
+		bytes, err := os.ReadFile("benchmark.toml")
+		if err != nil {
+			b.Fatal(err)
+		}
+
+		b.Run("struct", func(b *testing.B) {
+			d := benchmarkDoc{}
+			err := toml.Unmarshal(bytes, &d)
+			if err != nil {
+				b.Error(err)
+			}
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+
+			b.SetBytes(int64(len(out)))
+		})
+
+		b.Run("map", func(b *testing.B) {
+			d := map[string]interface{}{}
+			err := toml.Unmarshal(bytes, &d)
+			if err != nil {
+				b.Error(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					b.Error(err)
+				}
+			}
+
+			b.SetBytes(int64(len(out)))
+		})
+	})
+
+	b.Run("HugoFrontMatter", func(b *testing.B) {
+		d := map[string]interface{}{}
+		err := toml.Unmarshal(hugoFrontMatterbytes, &d)
+		if err != nil {
+			b.Error(err)
+		}
+
+		b.ReportAllocs()
+		b.ResetTimer()
+
+		var out []byte
+
+		for i := 0; i < b.N; i++ {
+			out, err = marshal(d)
+			if err != nil {
+				b.Error(err)
+			}
+		}
+
+		b.SetBytes(int64(len(out)))
+	})
+}
+
+type benchmarkDoc struct {
+	Table struct {
+		Key      string
+		Subtable struct {
+			Key string
+		}
+		Inline struct {
+			Name struct {
+				First string
+				Last  string
+			}
+			Point struct {
+				X int64
+				Y int64
+			}
+		}
+	}
+	String struct {
+		Basic struct {
+			Basic string
+		}
+		Multiline struct {
+			Key1      string
+			Key2      string
+			Key3      string
+			Continued struct {
+				Key1 string
+				Key2 string
+				Key3 string
+			}
+		}
+		Literal struct {
+			Winpath   string
+			Winpath2  string
+			Quoted    string
+			Regex     string
+			Multiline struct {
+				Regex2 string
+				Lines  string
+			}
+		}
+	}
+	Integer struct {
+		Key1        int64
+		Key2        int64
+		Key3        int64
+		Key4        int64
+		Underscores struct {
+			Key1 int64
+			Key2 int64
+			Key3 int64
+		}
+	}
+	Float struct {
+		Fractional struct {
+			Key1 float64
+			Key2 float64
+			Key3 float64
+		}
+		Exponent struct {
+			Key1 float64
+			Key2 float64
+			Key3 float64
+		}
+		Both struct {
+			Key float64
+		}
+		Underscores struct {
+			Key1 float64
+			Key2 float64
+		}
+	}
+	Boolean struct {
+		True  bool
+		False bool
+	}
+	Datetime struct {
+		Key1 time.Time
+		Key2 time.Time
+		Key3 time.Time
+	}
+	Array struct {
+		Key1 []int64
+		Key2 []string
+		Key3 [][]int64
+		// TODO: Key4 not supported by go-toml's Unmarshal
+		Key4 []interface{}
+		Key5 []int64
+		Key6 []int64
+	}
+	Products []struct {
+		Name  string
+		Sku   int64
+		Color string
+	}
+	Fruit []struct {
+		Name     string
+		Physical struct {
+			Color string
+			Shape string
+		}
+		Variety []struct {
+			Name string
+		}
+	}
+}
+
+func TestUnmarshalReferenceFile(t *testing.T) {
+	bytes, err := os.ReadFile("benchmark.toml")
+	assert.NoError(t, err)
+	d := benchmarkDoc{}
+	err = toml.Unmarshal(bytes, &d)
+	assert.NoError(t, err)
+
+	expected := benchmarkDoc{
+		Table: struct {
+			Key      string
+			Subtable struct{ Key string }
+			Inline   struct {
+				Name struct {
+					First string
+					Last  string
+				}
+				Point struct {
+					X int64
+					Y int64
+				}
+			}
+		}{
+			Key: "value",
+			Subtable: struct{ Key string }{
+				Key: "another value",
+			},
+			// note: x.y.z.w is purposefully missing
+			Inline: struct {
+				Name struct {
+					First string
+					Last  string
+				}
+				Point struct {
+					X int64
+					Y int64
+				}
+			}{
+				Name: struct {
+					First string
+					Last  string
+				}{
+					First: "Tom",
+					Last:  "Preston-Werner",
+				},
+				Point: struct {
+					X int64
+					Y int64
+				}{
+					X: 1,
+					Y: 2,
+				},
+			},
+		},
+		String: struct {
+			Basic     struct{ Basic string }
+			Multiline struct {
+				Key1      string
+				Key2      string
+				Key3      string
+				Continued struct {
+					Key1 string
+					Key2 string
+					Key3 string
+				}
+			}
+			Literal struct {
+				Winpath   string
+				Winpath2  string
+				Quoted    string
+				Regex     string
+				Multiline struct {
+					Regex2 string
+					Lines  string
+				}
+			}
+		}{
+			Basic: struct{ Basic string }{
+				Basic: "I'm a string. \"You can quote me\". Name\tJos\u00E9\nLocation\tSF.",
+			},
+			Multiline: struct {
+				Key1      string
+				Key2      string
+				Key3      string
+				Continued struct {
+					Key1 string
+					Key2 string
+					Key3 string
+				}
+			}{
+				Key1: "One\nTwo",
+				Key2: "One\nTwo",
+				Key3: "One\nTwo",
+
+				Continued: struct {
+					Key1 string
+					Key2 string
+					Key3 string
+				}{
+					Key1: `The quick brown fox jumps over the lazy dog.`,
+					Key2: `The quick brown fox jumps over the lazy dog.`,
+					Key3: `The quick brown fox jumps over the lazy dog.`,
+				},
+			},
+			Literal: struct {
+				Winpath   string
+				Winpath2  string
+				Quoted    string
+				Regex     string
+				Multiline struct {
+					Regex2 string
+					Lines  string
+				}
+			}{
+				Winpath:  `C:\Users\nodejs\templates`,
+				Winpath2: `\\ServerX\admin$\system32\`,
+				Quoted:   `Tom "Dubs" Preston-Werner`,
+				Regex:    `<\i\c*\s*>`,
+
+				Multiline: struct {
+					Regex2 string
+					Lines  string
+				}{
+					Regex2: `I [dw]on't need \d{2} apples`,
+					Lines: `The first newline is
+trimmed in raw strings.
+   All other whitespace
+   is preserved.
+`,
+				},
+			},
+		},
+		Integer: struct {
+			Key1        int64
+			Key2        int64
+			Key3        int64
+			Key4        int64
+			Underscores struct {
+				Key1 int64
+				Key2 int64
+				Key3 int64
+			}
+		}{
+			Key1: 99,
+			Key2: 42,
+			Key3: 0,
+			Key4: -17,
+
+			Underscores: struct {
+				Key1 int64
+				Key2 int64
+				Key3 int64
+			}{
+				Key1: 1000,
+				Key2: 5349221,
+				Key3: 12345,
+			},
+		},
+		Float: struct {
+			Fractional struct {
+				Key1 float64
+				Key2 float64
+				Key3 float64
+			}
+			Exponent struct {
+				Key1 float64
+				Key2 float64
+				Key3 float64
+			}
+			Both        struct{ Key float64 }
+			Underscores struct {
+				Key1 float64
+				Key2 float64
+			}
+		}{
+			Fractional: struct {
+				Key1 float64
+				Key2 float64
+				Key3 float64
+			}{
+				Key1: 1.0,
+				Key2: 3.1415,
+				Key3: -0.01,
+			},
+			Exponent: struct {
+				Key1 float64
+				Key2 float64
+				Key3 float64
+			}{
+				Key1: 5e+22,
+				Key2: 1e6,
+				Key3: -2e-2,
+			},
+			Both: struct{ Key float64 }{
+				Key: 6.626e-34,
+			},
+			Underscores: struct {
+				Key1 float64
+				Key2 float64
+			}{
+				Key1: 9224617.445991228313,
+				Key2: 1e100,
+			},
+		},
+		Boolean: struct {
+			True  bool
+			False bool
+		}{
+			True:  true,
+			False: false,
+		},
+		Datetime: struct {
+			Key1 time.Time
+			Key2 time.Time
+			Key3 time.Time
+		}{
+			Key1: time.Date(1979, 5, 27, 7, 32, 0, 0, time.UTC),
+			Key2: time.Date(1979, 5, 27, 0, 32, 0, 0, time.FixedZone("", -7*3600)),
+			Key3: time.Date(1979, 5, 27, 0, 32, 0, 999999000, time.FixedZone("", -7*3600)),
+		},
+		Array: struct {
+			Key1 []int64
+			Key2 []string
+			Key3 [][]int64
+			Key4 []interface{}
+			Key5 []int64
+			Key6 []int64
+		}{
+			Key1: []int64{1, 2, 3},
+			Key2: []string{"red", "yellow", "green"},
+			Key3: [][]int64{{1, 2}, {3, 4, 5}},
+			Key4: []interface{}{
+				[]interface{}{int64(1), int64(2)},
+				[]interface{}{"a", "b", "c"},
+			},
+			Key5: []int64{1, 2, 3},
+			Key6: []int64{1, 2},
+		},
+		Products: []struct {
+			Name  string
+			Sku   int64
+			Color string
+		}{
+			{
+				Name: "Hammer",
+				Sku:  738594937,
+			},
+			{},
+			{
+				Name:  "Nail",
+				Sku:   284758393,
+				Color: "gray",
+			},
+		},
+		Fruit: []struct {
+			Name     string
+			Physical struct {
+				Color string
+				Shape string
+			}
+			Variety []struct{ Name string }
+		}{
+			{
+				Name: "apple",
+				Physical: struct {
+					Color string
+					Shape string
+				}{
+					Color: "red",
+					Shape: "round",
+				},
+				Variety: []struct{ Name string }{
+					{Name: "red delicious"},
+					{Name: "granny smith"},
+				},
+			},
+			{
+				Name: "banana",
+				Variety: []struct{ Name string }{
+					{Name: "plantain"},
+				},
+			},
+		},
+	}
+
+	assert.Equal(t, expected, d)
+}
+
+var hugoFrontMatterbytes = []byte(`
+categories = ["Development", "VIM"]
+date = "2012-04-06"
+description = "spf13-vim is a cross platform distribution of vim plugins and resources for Vim."
+slug = "spf13-vim-3-0-release-and-new-website"
+tags = [".vimrc", "plugins", "spf13-vim", "vim"]
+title = "spf13-vim 3.0 release and new website"
+include_toc = true
+show_comments = false
+
+[[cascade]]
+  background = "yosemite.jpg"
+  [cascade._target]
+    kind = "page"
+    lang = "en"
+    path = "/blog/**"
+
+[[cascade]]
+  background = "goldenbridge.jpg"
+  [cascade._target]
+    kind = "section"
+`)

ci.sh

@@ -0,0 +1,284 @@
+#!/usr/bin/env bash
+
+
+stderr() {
+    echo "$@" 1>&2
+}
+
+usage() {
+    b=$(basename "$0")
+    echo $b: ERROR: "$@" 1>&2
+
+    cat 1>&2 <<EOF
+
+DESCRIPTION
+
+    $(basename "$0") is the script to run continuous integration commands for
+    go-toml on unix.
+
+    Requires Go and Git to be available in the PATH. Expects to be ran from the
+    root of go-toml's Git repository.
+
+USAGE
+
+    $b COMMAND [OPTIONS...]
+
+COMMANDS
+
+benchmark [OPTIONS...] [BRANCH]
+
+    Run benchmarks.
+
+    ARGUMENTS
+
+        BRANCH Optional. Defines which Git branch to use when running
+               benchmarks.
+
+    OPTIONS
+
+        -d      Compare benchmarks of HEAD with BRANCH using benchstats. In
+                this form the BRANCH argument is required.
+
+        -a      Compare benchmarks of HEAD against go-toml v1 and
+                BurntSushi/toml.
+
+        -html   When used with -a, emits the output as HTML, ready to be
+                embedded in the README.
+
+coverage [OPTIONS...] [BRANCH]
+
+    Generates code coverage.
+
+    ARGUMENTS
+
+        BRANCH  Optional. Defines which Git branch to use when reporting
+                coverage. Defaults to HEAD.
+
+    OPTIONS
+
+        -d      Compare coverage of HEAD with the one of BRANCH. In this form,
+                the BRANCH argument is required. Exit code is non-zero when
+                coverage percentage decreased.
+EOF
+    exit 1
+}
+
+cover() {
+    branch="${1}"
+    dir="$(mktemp -d)"
+
+    stderr "Executing coverage for ${branch} at ${dir}"
+
+    if [ "${branch}" = "HEAD" ]; then
+	    cp -r . "${dir}/"
+    else
+	    git worktree add "$dir" "$branch"
+    fi
+
+    pushd "$dir"
+    go test -covermode=atomic  -coverpkg=./... -coverprofile=coverage.out.tmp ./...
+    grep -Ev '(fuzz|testsuite|tomltestgen|gotoml-test-decoder|gotoml-test-encoder)' coverage.out.tmp > coverage.out
+    go tool cover -func=coverage.out
+    echo "Coverage profile for ${branch}: ${dir}/coverage.out" >&2
+    popd
+
+    if [ "${branch}" != "HEAD" ]; then
+	    git worktree remove --force "$dir"
+    fi
+}
+
+coverage() {
+    case "$1" in
+	-d)
+	    shift
+	    target="${1?Need to provide a target branch argument}"
+
+	    output_dir="$(mktemp -d)"
+	    target_out="${output_dir}/target.txt"
+	    head_out="${output_dir}/head.txt"
+	    
+	    cover "${target}" > "${target_out}"
+	    cover "HEAD" > "${head_out}"
+
+	    cat "${target_out}"
+	    cat "${head_out}"
+
+	    echo ""
+
+	    target_pct="$(tail -n2 ${target_out} | head -n1 | sed -E 's/.*total.*\t([0-9.]+)%.*/\1/')"
+	    head_pct="$(tail -n2 ${head_out} | head -n1 | sed -E 's/.*total.*\t([0-9.]+)%/\1/')"
+	    echo "Results: ${target} ${target_pct}% HEAD ${head_pct}%"
+
+	    delta_pct=$(echo "$head_pct - $target_pct" | bc -l)
+	    echo "Delta: ${delta_pct}"
+
+	    if [[ $delta_pct = \-* ]]; then
+		    echo "Regression!";
+
+            target_diff="${output_dir}/target.diff.txt"
+            head_diff="${output_dir}/head.diff.txt"
+            cat "${target_out}" | grep -E '^github.com/pelletier/go-toml' | tr -s "\t " | cut -f 2,3 | sort > "${target_diff}"
+            cat "${head_out}" | grep -E '^github.com/pelletier/go-toml' | tr -s "\t " | cut -f 2,3 | sort > "${head_diff}"
+
+            diff --side-by-side --suppress-common-lines "${target_diff}" "${head_diff}"
+		    return 1
+	    fi
+	    return 0
+	    ;;
+    esac
+
+    cover "${1-HEAD}"
+}
+
+bench() {
+    branch="${1}"
+    out="${2}"
+    replace="${3}"
+    dir="$(mktemp -d)"
+
+    stderr "Executing benchmark for ${branch} at ${dir}"
+
+    if [ "${branch}" = "HEAD" ]; then
+    	cp -r . "${dir}/"
+    else
+	    git worktree add "$dir" "$branch"
+    fi
+
+    pushd "$dir"
+
+    if [ "${replace}" != "" ]; then
+        find ./benchmark/ -iname '*.go' -exec sed -i -E "s|github.com/pelletier/go-toml/v2|${replace}|g" {} \;
+        go get "${replace}"
+    fi
+
+    export GOMAXPROCS=2
+    go test '-bench=^Benchmark(Un)?[mM]arshal' -count=10 -run=Nothing ./... | tee "${out}"
+    popd
+
+    if [ "${branch}" != "HEAD" ]; then
+	    git worktree remove --force "$dir"
+    fi
+}
+
+fmktemp() {
+    if mktemp --version &> /dev/null; then
+	# GNU
+        mktemp --suffix=-$1
+    else
+	# BSD
+	mktemp -t $1
+    fi
+}
+
+benchstathtml() {
+python3 - $1 <<'EOF'
+import sys
+
+lines = []
+stop = False
+
+with open(sys.argv[1]) as f:
+    for line in f.readlines():
+        line = line.strip()
+        if line == "":
+            stop = True
+        if not stop:
+            lines.append(line.split(','))
+
+results = []
+for line in reversed(lines[2:]):
+    if len(line) < 8 or line[0] == "":
+        continue
+    v2 = float(line[1])
+    results.append([
+        line[0].replace("-32", ""),
+        "%.1fx" % (float(line[3])/v2),  # v1
+        "%.1fx" % (float(line[7])/v2),  # bs
+    ])
+# move geomean to the end
+results.append(results[0])
+del results[0]
+
+
+def printtable(data):
+    print("""
+<table>
+    <thead>
+        <tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
+    </thead>
+    <tbody>""")
+
+    for r in data:
+        print("        <tr><td>{}</td><td>{}</td><td>{}</td></tr>".format(*r))
+
+    print("""     </tbody>
+</table>""")
+
+
+def match(x):
+    return "ReferenceFile" in x[0] or "HugoFrontMatter" in x[0]
+
+above = [x for x in results if match(x)]
+below = [x for x in results if not match(x)]
+
+printtable(above)
+print("<details><summary>See more</summary>")
+print("""<p>The table above has the results of the most common use-cases. The table below
+contains the results of all benchmarks, including unrealistic ones. It is
+provided for completeness.</p>""")
+printtable(below)
+print('<p>This table can be generated with <code>./ci.sh benchmark -a -html</code>.</p>')
+print("</details>")
+
+EOF
+}
+
+benchmark() {
+    case "$1" in
+    -d)
+        shift
+     	target="${1?Need to provide a target branch argument}"
+
+        old=`fmktemp ${target}`
+        bench "${target}" "${old}"
+
+        new=`fmktemp HEAD`
+        bench HEAD "${new}"
+
+        benchstat "${old}" "${new}"
+        return 0
+        ;;
+    -a)
+        shift
+
+        v2stats=`fmktemp go-toml-v2`
+        bench HEAD "${v2stats}" "github.com/pelletier/go-toml/v2"
+        v1stats=`fmktemp go-toml-v1`
+        bench HEAD "${v1stats}" "github.com/pelletier/go-toml"
+        bsstats=`fmktemp bs-toml`
+        bench HEAD "${bsstats}" "github.com/BurntSushi/toml"
+
+        cp "${v2stats}" go-toml-v2.txt
+        cp "${v1stats}" go-toml-v1.txt
+        cp "${bsstats}" bs-toml.txt
+
+        if [ "$1" = "-html" ]; then
+            tmpcsv=`fmktemp csv`
+            benchstat -format csv go-toml-v2.txt go-toml-v1.txt bs-toml.txt > $tmpcsv
+            benchstathtml $tmpcsv
+        else
+            benchstat go-toml-v2.txt go-toml-v1.txt bs-toml.txt
+        fi
+
+        rm -f go-toml-v2.txt go-toml-v1.txt bs-toml.txt
+        return $?
+    esac
+
+    bench "${1-HEAD}" `mktemp`
+}
+
+case "$1" in
+    coverage) shift; coverage $@;;
+    benchmark) shift; benchmark $@;;
+    *) usage "bad argument $1";;
+esac

clean.sh

@@ -1,6 +0,0 @@
-#!/bin/bash
-# fail out of the script if anything here fails
-set -e
-
-# clear out stuff generated by test.sh
-rm -rf src test_program_bin toml-test

cmd/gotoml-test-decoder/main.go

@@ -0,0 +1,31 @@
+// Package gotoml-test-decoder is a minimal decoder program used to compare this library with other TOML implementations.
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"path"
+
+	"github.com/pelletier/go-toml/v2/internal/testsuite"
+)
+
+func main() {
+	log.SetFlags(0)
+	flag.Usage = usage
+	flag.Parse()
+	if flag.NArg() != 0 {
+		flag.Usage()
+	}
+
+	err := testsuite.DecodeStdin()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func usage() {
+	log.Printf("Usage: %s < toml-file\n", path.Base(os.Args[0]))
+	flag.PrintDefaults()
+	os.Exit(1)
+}

cmd/gotoml-test-encoder/main.go

@@ -0,0 +1,31 @@
+// Package gotoml-test-encoder is a minimal encoder program used to compare this library with other TOML implementations.
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"path"
+
+	"github.com/pelletier/go-toml/v2/internal/testsuite"
+)
+
+func main() {
+	log.SetFlags(0)
+	flag.Usage = usage
+	flag.Parse()
+	if flag.NArg() != 0 {
+		flag.Usage()
+	}
+
+	err := testsuite.EncodeStdin()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func usage() {
+	log.Printf("Usage: %s < json-file\n", path.Base(os.Args[0]))
+	flag.PrintDefaults()
+	os.Exit(1)
+}

cmd/jsontoml/main.go

@@ -0,0 +1,66 @@
+// Package jsontoml is a program that converts JSON to TOML.
+//
+// # Usage
+//
+// Reading from stdin:
+//
+//	cat file.json | jsontoml > file.toml
+//
+// Reading from a file:
+//
+//	jsontoml file.json > file.toml
+//
+// # Installation
+//
+// Using Go:
+//
+//	go install github.com/pelletier/go-toml/v2/cmd/jsontoml@latest
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"io"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/cli"
+)
+
+const usage = `jsontoml can be used in two ways:
+Reading from stdin:
+  cat file.json | jsontoml > file.toml
+
+Reading from a file:
+  jsontoml file.json > file.toml
+`
+
+var useJSONNumber bool
+
+func main() {
+	flag.BoolVar(&useJSONNumber, "use-json-number", false, "unmarshal numbers into `json.Number` type instead of as `float64`")
+
+	p := cli.Program{
+		Usage: usage,
+		Fn:    convert,
+	}
+	p.Execute()
+}
+
+func convert(r io.Reader, w io.Writer) error {
+	var v interface{}
+
+	d := json.NewDecoder(r)
+	e := toml.NewEncoder(w)
+
+	if useJSONNumber {
+		d.UseNumber()
+		e.SetMarshalJSONNumbers(true)
+	}
+
+	err := d.Decode(&v)
+	if err != nil {
+		return err
+	}
+
+	return e.Encode(v)
+}

cmd/jsontoml/main_test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestConvert(t *testing.T) {
+	examples := []struct {
+		name          string
+		input         string
+		expected      string
+		errors        bool
+		useJSONNumber bool
+	}{
+		{
+			name: "valid json",
+			input: `
+{
+  "mytoml": {
+    "a": 42
+  }
+}`,
+			expected: `[mytoml]
+a = 42.0
+`,
+		},
+		{
+			name:          "use json number",
+			useJSONNumber: true,
+			input: `
+{
+  "mytoml": {
+    "a": 42
+  }
+}`,
+			expected: `[mytoml]
+a = 42
+`,
+		},
+		{
+			name:   "invalid json",
+			input:  `{ foo`,
+			errors: true,
+		},
+	}
+
+	for _, e := range examples {
+		b := new(bytes.Buffer)
+		useJSONNumber = e.useJSONNumber
+		err := convert(strings.NewReader(e.input), b)
+		if e.errors {
+			assert.Error(t, err)
+		} else {
+			assert.NoError(t, err)
+			assert.Equal(t, e.expected, b.String())
+		}
+	}
+}

cmd/test_program.go

@@ -1,81 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"github.com/pelletier/go-toml"
-	"io/ioutil"
-	"log"
-	"os"
-	"time"
-)
-
-func main() {
-	bytes, err := ioutil.ReadAll(os.Stdin)
-	if err != nil {
-		os.Exit(2)
-	}
-	tree, err := toml.Load(string(bytes))
-	if err != nil {
-		os.Exit(1)
-	}
-
-	typedTree := translate((map[string]interface{})(*tree))
-
-	if err := json.NewEncoder(os.Stdout).Encode(typedTree); err != nil {
-		log.Fatalf("Error encoding JSON: %s", err)
-	}
-
-	os.Exit(0)
-}
-
-func translate(tomlData interface{}) interface{} {
-
-	switch orig := tomlData.(type) {
-	case map[string]interface{}:
-		typed := make(map[string]interface{}, len(orig))
-		for k, v := range orig {
-			typed[k] = translate(v)
-		}
-		return typed
-	case *toml.TomlTree:
-		return translate((map[string]interface{})(*orig))
-	case []*toml.TomlTree:
-		typed := make([]map[string]interface{}, len(orig))
-		for i, v := range orig {
-			typed[i] = translate(v).(map[string]interface{})
-		}
-		return typed
-	case []map[string]interface{}:
-		typed := make([]map[string]interface{}, len(orig))
-		for i, v := range orig {
-			typed[i] = translate(v).(map[string]interface{})
-		}
-		return typed
-	case []interface{}:
-		typed := make([]interface{}, len(orig))
-		for i, v := range orig {
-			typed[i] = translate(v)
-		}
-		return tag("array", typed)
-	case time.Time:
-		return tag("datetime", orig.Format("2006-01-02T15:04:05Z"))
-	case bool:
-		return tag("bool", fmt.Sprintf("%v", orig))
-	case int64:
-		return tag("integer", fmt.Sprintf("%d", orig))
-	case float64:
-		return tag("float", fmt.Sprintf("%v", orig))
-	case string:
-		return tag("string", orig)
-	}
-
-	panic(fmt.Sprintf("Unknown type: %T", tomlData))
-}
-
-func tag(typeName string, data interface{}) map[string]interface{} {
-	return map[string]interface{}{
-		"type":  typeName,
-		"value": data,
-	}
-}

cmd/tomljson/main.go

@@ -0,0 +1,63 @@
+// Package tomljson is a program that converts TOML to JSON.
+//
+// # Usage
+//
+// Reading from stdin:
+//
+//	cat file.toml | tomljson > file.json
+//
+// Reading from a file:
+//
+//	tomljson file.toml > file.json
+//
+// # Installation
+//
+// Using Go:
+//
+//	go install github.com/pelletier/go-toml/v2/cmd/tomljson@latest
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/cli"
+)
+
+const usage = `tomljson can be used in two ways:
+Reading from stdin:
+  cat file.toml | tomljson > file.json
+
+Reading from a file:
+  tomljson file.toml > file.json
+`
+
+func main() {
+	p := cli.Program{
+		Usage: usage,
+		Fn:    convert,
+	}
+	p.Execute()
+}
+
+func convert(r io.Reader, w io.Writer) error {
+	var v interface{}
+
+	d := toml.NewDecoder(r)
+	err := d.Decode(&v)
+	if err != nil {
+		var derr *toml.DecodeError
+		if errors.As(err, &derr) {
+			row, col := derr.Position()
+			return fmt.Errorf("%s\nerror occurred at row %d column %d", derr.String(), row, col)
+		}
+		return err
+	}
+
+	e := json.NewEncoder(w)
+	e.SetIndent("", "  ")
+	return e.Encode(v)
+}

cmd/tomljson/main_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestConvert(t *testing.T) {
+	examples := []struct {
+		name     string
+		input    io.Reader
+		expected string
+		errors   bool
+	}{
+		{
+			name: "valid toml",
+			input: strings.NewReader(`
+[mytoml]
+a = 42`),
+			expected: `{
+  "mytoml": {
+    "a": 42
+  }
+}
+`,
+		},
+		{
+			name:   "invalid toml",
+			input:  strings.NewReader(`bad = []]`),
+			errors: true,
+		},
+		{
+			name:   "bad reader",
+			input:  &badReader{},
+			errors: true,
+		},
+	}
+
+	for _, e := range examples {
+		b := new(bytes.Buffer)
+		err := convert(e.input, b)
+		if e.errors {
+			assert.Error(t, err)
+		} else {
+			assert.NoError(t, err)
+			assert.Equal(t, e.expected, b.String())
+		}
+	}
+}
+
+type badReader struct{}
+
+func (r *badReader) Read([]byte) (int, error) {
+	return 0, errors.New("reader failed on purpose")
+}

cmd/tomll/main.go

@@ -0,0 +1,58 @@
+// Package tomll is a linter program for TOML.
+//
+// # Usage
+//
+// Reading from stdin, writing to stdout:
+//
+//	cat file.toml | tomll
+//
+// Reading and updating a list of files in place:
+//
+//	tomll a.toml b.toml c.toml
+//
+// # Installation
+//
+// Using Go:
+//
+//	go install github.com/pelletier/go-toml/v2/cmd/tomll@latest
+package main
+
+import (
+	"io"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/cli"
+)
+
+const usage = `tomll can be used in two ways:
+
+Reading from stdin, writing to stdout:
+  cat file.toml | tomll > file.toml
+
+Reading and updating a list of files in place:
+  tomll a.toml b.toml c.toml
+
+When given a list of files, tomll will modify all files in place without asking.
+`
+
+func main() {
+	p := cli.Program{
+		Usage:   usage,
+		Fn:      convert,
+		Inplace: true,
+	}
+	p.Execute()
+}
+
+func convert(r io.Reader, w io.Writer) error {
+	var v interface{}
+
+	d := toml.NewDecoder(r)
+	err := d.Decode(&v)
+	if err != nil {
+		return err
+	}
+
+	e := toml.NewEncoder(w)
+	return e.Encode(v)
+}

cmd/tomll/main_test.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestConvert(t *testing.T) {
+	examples := []struct {
+		name     string
+		input    string
+		expected string
+		errors   bool
+	}{
+		{
+			name: "valid toml",
+			input: `
+mytoml.a = 42.0
+`,
+			expected: `[mytoml]
+a = 42.0
+`,
+		},
+		{
+			name:   "invalid toml",
+			input:  `[what`,
+			errors: true,
+		},
+	}
+
+	for _, e := range examples {
+		b := new(bytes.Buffer)
+		err := convert(strings.NewReader(e.input), b)
+		if e.errors {
+			assert.Error(t, err)
+		} else {
+			assert.NoError(t, err)
+			assert.Equal(t, e.expected, b.String())
+		}
+	}
+}

cmd/tomltestgen/main.go

@@ -0,0 +1,183 @@
+// tomltestgen retrieves a given version of the language-agnostic TOML test suite in
+// https://github.com/BurntSushi/toml-test and generates go-toml unit tests.
+//
+// Within the go-toml package, run `go generate`.  Otherwise, use:
+//
+//	go run github.com/pelletier/go-toml/cmd/tomltestgen -o toml_testgen_test.go
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/format"
+	"log"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"text/template"
+	"time"
+	"unicode"
+)
+
+type invalid struct {
+	Name  string
+	Input string
+}
+
+type valid struct {
+	Name    string
+	Input   string
+	JSONRef string
+}
+
+type testsCollection struct {
+	Ref       string
+	Timestamp string
+	Invalid   []invalid
+	Valid     []valid
+	Count     int
+}
+
+const srcTemplate = "// Code generated by tomltestgen for toml-test ref {{.Ref}} on {{.Timestamp}}. DO NOT EDIT.\n" +
+	"package toml_test\n" +
+	" import (\n" +
+	"	\"testing\"\n" +
+	")\n" +
+	"{{range .Invalid}}\n" +
+	"func TestTOMLTest_Invalid_{{.Name}}(t *testing.T) {\n" +
+	"	input := {{.Input|gostr}}\n" +
+	"	testgenInvalid(t, input)\n" +
+	"}\n" +
+	"{{end}}\n" +
+	"\n" +
+	"{{range .Valid}}\n" +
+	"func TestTOMLTest_Valid_{{.Name}}(t *testing.T) {\n" +
+	"   input := {{.Input|gostr}}\n" +
+	"   jsonRef := {{.JSONRef|gostr}}\n" +
+	"   testgenValid(t, input, jsonRef)\n" +
+	"}\n" +
+	"{{end}}\n"
+
+func kebabToCamel(kebab string) string {
+	var buf strings.Builder
+	nextUpper := true
+	for _, c := range kebab {
+		if nextUpper {
+			buf.WriteRune(unicode.ToUpper(c))
+			nextUpper = false
+		} else {
+			switch c {
+			case '-':
+				nextUpper = true
+			case '/':
+				nextUpper = true
+				buf.WriteByte('_')
+			default:
+				buf.WriteRune(c)
+			}
+		}
+	}
+	return buf.String()
+}
+
+func templateGoStr(input string) string {
+	return strconv.Quote(input)
+}
+
+var (
+	ref = flag.String("r", "master", "git reference")
+	out = flag.String("o", "", "output file")
+)
+
+func usage() {
+	_, _ = fmt.Fprintf(os.Stderr, "usage: tomltestgen [flags]\n")
+	flag.PrintDefaults()
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	collection := testsCollection{
+		Ref:       *ref,
+		Timestamp: time.Now().Format(time.RFC3339),
+	}
+
+	dirContent, _ := filepath.Glob("tests/invalid/**/*.toml")
+	for _, f := range dirContent {
+		filename := strings.TrimPrefix(f, "tests/valid/")
+		name := kebabToCamel(strings.TrimSuffix(filename, ".toml"))
+		name = strings.ReplaceAll(name, ".", "_")
+
+		log.Printf("> [%s] %s\n", "invalid", name)
+
+		tomlContent, err := os.ReadFile(f) // #nosec G304
+		if err != nil {
+			fmt.Printf("failed to read test file: %s\n", err)
+			os.Exit(1)
+		}
+
+		collection.Invalid = append(collection.Invalid, invalid{
+			Name:  name,
+			Input: string(tomlContent),
+		})
+		collection.Count++
+	}
+
+	dirContent, _ = filepath.Glob("tests/valid/**/*.toml")
+	for _, f := range dirContent {
+		filename := strings.TrimPrefix(f, "tests/valid/")
+		name := kebabToCamel(strings.TrimSuffix(filename, ".toml"))
+		name = strings.ReplaceAll(name, ".", "_")
+
+		log.Printf("> [%s] %s\n", "valid", name)
+
+		tomlContent, err := os.ReadFile(f) // #nosec G304
+		if err != nil {
+			fmt.Printf("failed reading test file: %s\n", err)
+			os.Exit(1)
+		}
+
+		filename = strings.TrimSuffix(f, ".toml")
+		jsonContent, err := os.ReadFile(filename + ".json") // #nosec G304
+		if err != nil {
+			fmt.Printf("failed reading validation json: %s\n", err)
+			os.Exit(1)
+		}
+
+		collection.Valid = append(collection.Valid, valid{
+			Name:    name,
+			Input:   string(tomlContent),
+			JSONRef: string(jsonContent),
+		})
+		collection.Count++
+	}
+
+	log.Printf("Collected %d tests from toml-test\n", collection.Count)
+
+	funcMap := template.FuncMap{
+		"gostr": templateGoStr,
+	}
+	t := template.Must(template.New("src").Funcs(funcMap).Parse(srcTemplate))
+	buf := new(bytes.Buffer)
+	err := t.Execute(buf, collection)
+	if err != nil {
+		panic(err)
+	}
+	outputBytes, err := format.Source(buf.Bytes())
+	if err != nil {
+		panic(err)
+	}
+
+	if *out == "" {
+		fmt.Println(string(outputBytes))
+		return
+	}
+
+	err = os.WriteFile(*out, outputBytes, 0o600)
+	if err != nil {
+		panic(err)
+	}
+}

decode.go

@@ -0,0 +1,549 @@
+package toml
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+func parseInteger(b []byte) (int64, error) {
+	if len(b) > 2 && b[0] == '0' {
+		switch b[1] {
+		case 'x':
+			return parseIntHex(b)
+		case 'b':
+			return parseIntBin(b)
+		case 'o':
+			return parseIntOct(b)
+		default:
+			panic(fmt.Errorf("invalid base '%c', should have been checked by scanIntOrFloat", b[1]))
+		}
+	}
+
+	return parseIntDec(b)
+}
+
+func parseLocalDate(b []byte) (LocalDate, error) {
+	// full-date      = date-fullyear "-" date-month "-" date-mday
+	// date-fullyear  = 4DIGIT
+	// date-month     = 2DIGIT  ; 01-12
+	// date-mday      = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on month/year
+	var date LocalDate
+
+	if len(b) != 10 || b[4] != '-' || b[7] != '-' {
+		return date, unstable.NewParserError(b, "dates are expected to have the format YYYY-MM-DD")
+	}
+
+	var err error
+
+	date.Year, err = parseDecimalDigits(b[0:4])
+	if err != nil {
+		return LocalDate{}, err
+	}
+
+	date.Month, err = parseDecimalDigits(b[5:7])
+	if err != nil {
+		return LocalDate{}, err
+	}
+
+	date.Day, err = parseDecimalDigits(b[8:10])
+	if err != nil {
+		return LocalDate{}, err
+	}
+
+	if !isValidDate(date.Year, date.Month, date.Day) {
+		return LocalDate{}, unstable.NewParserError(b, "impossible date")
+	}
+
+	return date, nil
+}
+
+func parseDecimalDigits(b []byte) (int, error) {
+	v := 0
+
+	for i, c := range b {
+		if c < '0' || c > '9' {
+			return 0, unstable.NewParserError(b[i:i+1], "expected digit (0-9)")
+		}
+		v *= 10
+		v += int(c - '0')
+	}
+
+	return v, nil
+}
+
+func parseDateTime(b []byte) (time.Time, error) {
+	// offset-date-time = full-date time-delim full-time
+	// full-time      = partial-time time-offset
+	// time-offset    = "Z" / time-numoffset
+	// time-numoffset = ( "+" / "-" ) time-hour ":" time-minute
+
+	dt, b, err := parseLocalDateTime(b)
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	var zone *time.Location
+
+	if len(b) == 0 {
+		// parser should have checked that when assigning the date time node
+		panic("date time should have a timezone")
+	}
+
+	if b[0] == 'Z' || b[0] == 'z' {
+		b = b[1:]
+		zone = time.UTC
+	} else {
+		const dateTimeByteLen = 6
+		if len(b) != dateTimeByteLen {
+			return time.Time{}, unstable.NewParserError(b, "invalid date-time timezone")
+		}
+		var direction int
+		switch b[0] {
+		case '-':
+			direction = -1
+		case '+':
+			direction = +1
+		default:
+			return time.Time{}, unstable.NewParserError(b[:1], "invalid timezone offset character")
+		}
+
+		if b[3] != ':' {
+			return time.Time{}, unstable.NewParserError(b[3:4], "expected a : separator")
+		}
+
+		hours, err := parseDecimalDigits(b[1:3])
+		if err != nil {
+			return time.Time{}, err
+		}
+		if hours > 23 {
+			return time.Time{}, unstable.NewParserError(b[:1], "invalid timezone offset hours")
+		}
+
+		minutes, err := parseDecimalDigits(b[4:6])
+		if err != nil {
+			return time.Time{}, err
+		}
+		if minutes > 59 {
+			return time.Time{}, unstable.NewParserError(b[:1], "invalid timezone offset minutes")
+		}
+
+		seconds := direction * (hours*3600 + minutes*60)
+		if seconds == 0 {
+			zone = time.UTC
+		} else {
+			zone = time.FixedZone("", seconds)
+		}
+		b = b[dateTimeByteLen:]
+	}
+
+	if len(b) > 0 {
+		return time.Time{}, unstable.NewParserError(b, "extra bytes at the end of the timezone")
+	}
+
+	t := time.Date(
+		dt.Year,
+		time.Month(dt.Month),
+		dt.Day,
+		dt.Hour,
+		dt.Minute,
+		dt.Second,
+		dt.Nanosecond,
+		zone)
+
+	return t, nil
+}
+
+func parseLocalDateTime(b []byte) (LocalDateTime, []byte, error) {
+	var dt LocalDateTime
+
+	const localDateTimeByteMinLen = 11
+	if len(b) < localDateTimeByteMinLen {
+		return dt, nil, unstable.NewParserError(b, "local datetimes are expected to have the format YYYY-MM-DDTHH:MM:SS[.NNNNNNNNN]")
+	}
+
+	date, err := parseLocalDate(b[:10])
+	if err != nil {
+		return dt, nil, err
+	}
+	dt.LocalDate = date
+
+	sep := b[10]
+	if sep != 'T' && sep != ' ' && sep != 't' {
+		return dt, nil, unstable.NewParserError(b[10:11], "datetime separator is expected to be T or a space")
+	}
+
+	t, rest, err := parseLocalTime(b[11:])
+	if err != nil {
+		return dt, nil, err
+	}
+	dt.LocalTime = t
+
+	return dt, rest, nil
+}
+
+// parseLocalTime is a bit different because it also returns the remaining
+// []byte that is didn't need. This is to allow parseDateTime to parse those
+// remaining bytes as a timezone.
+func parseLocalTime(b []byte) (LocalTime, []byte, error) {
+	var (
+		nspow = [10]int{0, 1e8, 1e7, 1e6, 1e5, 1e4, 1e3, 1e2, 1e1, 1e0}
+		t     LocalTime
+	)
+
+	// check if b matches to have expected format HH:MM:SS[.NNNNNN]
+	const localTimeByteLen = 8
+	if len(b) < localTimeByteLen {
+		return t, nil, unstable.NewParserError(b, "times are expected to have the format HH:MM:SS[.NNNNNN]")
+	}
+
+	var err error
+
+	t.Hour, err = parseDecimalDigits(b[0:2])
+	if err != nil {
+		return t, nil, err
+	}
+
+	if t.Hour > 23 {
+		return t, nil, unstable.NewParserError(b[0:2], "hour cannot be greater 23")
+	}
+	if b[2] != ':' {
+		return t, nil, unstable.NewParserError(b[2:3], "expecting colon between hours and minutes")
+	}
+
+	t.Minute, err = parseDecimalDigits(b[3:5])
+	if err != nil {
+		return t, nil, err
+	}
+	if t.Minute > 59 {
+		return t, nil, unstable.NewParserError(b[3:5], "minutes cannot be greater 59")
+	}
+	if b[5] != ':' {
+		return t, nil, unstable.NewParserError(b[5:6], "expecting colon between minutes and seconds")
+	}
+
+	t.Second, err = parseDecimalDigits(b[6:8])
+	if err != nil {
+		return t, nil, err
+	}
+
+	if t.Second > 59 {
+		return t, nil, unstable.NewParserError(b[6:8], "seconds cannot be greater than 59")
+	}
+
+	b = b[8:]
+
+	if len(b) >= 1 && b[0] == '.' {
+		frac := 0
+		precision := 0
+		digits := 0
+
+		for i, c := range b[1:] {
+			if !isDigit(c) {
+				if i == 0 {
+					return t, nil, unstable.NewParserError(b[0:1], "need at least one digit after fraction point")
+				}
+				break
+			}
+			digits++
+
+			const maxFracPrecision = 9
+			if i >= maxFracPrecision {
+				// go-toml allows decoding fractional seconds
+				// beyond the supported precision of 9
+				// digits. It truncates the fractional component
+				// to the supported precision and ignores the
+				// remaining digits.
+				//
+				// https://github.com/pelletier/go-toml/discussions/707
+				continue
+			}
+
+			frac *= 10
+			frac += int(c - '0')
+			precision++
+		}
+
+		if precision == 0 {
+			return t, nil, unstable.NewParserError(b[:1], "nanoseconds need at least one digit")
+		}
+
+		t.Nanosecond = frac * nspow[precision]
+		t.Precision = precision
+
+		return t, b[1+digits:], nil
+	}
+	return t, b, nil
+}
+
+func parseFloat(b []byte) (float64, error) {
+	if len(b) == 4 && (b[0] == '+' || b[0] == '-') && b[1] == 'n' && b[2] == 'a' && b[3] == 'n' {
+		return math.NaN(), nil
+	}
+
+	cleaned, err := checkAndRemoveUnderscoresFloats(b)
+	if err != nil {
+		return 0, err
+	}
+
+	if cleaned[0] == '.' {
+		return 0, unstable.NewParserError(b, "float cannot start with a dot")
+	}
+
+	if cleaned[len(cleaned)-1] == '.' {
+		return 0, unstable.NewParserError(b, "float cannot end with a dot")
+	}
+
+	dotAlreadySeen := false
+	for i, c := range cleaned {
+		if c == '.' {
+			if dotAlreadySeen {
+				return 0, unstable.NewParserError(b[i:i+1], "float can have at most one decimal point")
+			}
+			if !isDigit(cleaned[i-1]) {
+				return 0, unstable.NewParserError(b[i-1:i+1], "float decimal point must be preceded by a digit")
+			}
+			if !isDigit(cleaned[i+1]) {
+				return 0, unstable.NewParserError(b[i:i+2], "float decimal point must be followed by a digit")
+			}
+			dotAlreadySeen = true
+		}
+	}
+
+	start := 0
+	if cleaned[0] == '+' || cleaned[0] == '-' {
+		start = 1
+	}
+	if cleaned[start] == '0' && len(cleaned) > start+1 && isDigit(cleaned[start+1]) {
+		return 0, unstable.NewParserError(b, "float integer part cannot have leading zeroes")
+	}
+
+	f, err := strconv.ParseFloat(string(cleaned), 64)
+	if err != nil {
+		return 0, unstable.NewParserError(b, "unable to parse float: %w", err)
+	}
+
+	return f, nil
+}
+
+func parseIntHex(b []byte) (int64, error) {
+	cleaned, err := checkAndRemoveUnderscoresIntegers(b[2:])
+	if err != nil {
+		return 0, err
+	}
+
+	i, err := strconv.ParseInt(string(cleaned), 16, 64)
+	if err != nil {
+		return 0, unstable.NewParserError(b, "couldn't parse hexadecimal number: %w", err)
+	}
+
+	return i, nil
+}
+
+func parseIntOct(b []byte) (int64, error) {
+	cleaned, err := checkAndRemoveUnderscoresIntegers(b[2:])
+	if err != nil {
+		return 0, err
+	}
+
+	i, err := strconv.ParseInt(string(cleaned), 8, 64)
+	if err != nil {
+		return 0, unstable.NewParserError(b, "couldn't parse octal number: %w", err)
+	}
+
+	return i, nil
+}
+
+func parseIntBin(b []byte) (int64, error) {
+	cleaned, err := checkAndRemoveUnderscoresIntegers(b[2:])
+	if err != nil {
+		return 0, err
+	}
+
+	i, err := strconv.ParseInt(string(cleaned), 2, 64)
+	if err != nil {
+		return 0, unstable.NewParserError(b, "couldn't parse binary number: %w", err)
+	}
+
+	return i, nil
+}
+
+func isSign(b byte) bool {
+	return b == '+' || b == '-'
+}
+
+func parseIntDec(b []byte) (int64, error) {
+	cleaned, err := checkAndRemoveUnderscoresIntegers(b)
+	if err != nil {
+		return 0, err
+	}
+
+	startIdx := 0
+
+	if isSign(cleaned[0]) {
+		startIdx++
+	}
+
+	if len(cleaned) > startIdx+1 && cleaned[startIdx] == '0' {
+		return 0, unstable.NewParserError(b, "leading zero not allowed on decimal number")
+	}
+
+	i, err := strconv.ParseInt(string(cleaned), 10, 64)
+	if err != nil {
+		return 0, unstable.NewParserError(b, "couldn't parse decimal number: %w", err)
+	}
+
+	return i, nil
+}
+
+func checkAndRemoveUnderscoresIntegers(b []byte) ([]byte, error) {
+	start := 0
+	if b[start] == '+' || b[start] == '-' {
+		start++
+	}
+
+	if len(b) == start {
+		return b, nil
+	}
+
+	if b[start] == '_' {
+		return nil, unstable.NewParserError(b[start:start+1], "number cannot start with underscore")
+	}
+
+	if b[len(b)-1] == '_' {
+		return nil, unstable.NewParserError(b[len(b)-1:], "number cannot end with underscore")
+	}
+
+	// fast path
+	i := 0
+	for ; i < len(b); i++ {
+		if b[i] == '_' {
+			break
+		}
+	}
+	if i == len(b) {
+		return b, nil
+	}
+
+	before := false
+	cleaned := make([]byte, i, len(b))
+	copy(cleaned, b)
+
+	for i++; i < len(b); i++ {
+		c := b[i]
+		if c == '_' {
+			if !before {
+				return nil, unstable.NewParserError(b[i-1:i+1], "number must have at least one digit between underscores")
+			}
+			before = false
+		} else {
+			before = true
+			cleaned = append(cleaned, c)
+		}
+	}
+
+	return cleaned, nil
+}
+
+func checkAndRemoveUnderscoresFloats(b []byte) ([]byte, error) {
+	if b[0] == '_' {
+		return nil, unstable.NewParserError(b[0:1], "number cannot start with underscore")
+	}
+
+	if b[len(b)-1] == '_' {
+		return nil, unstable.NewParserError(b[len(b)-1:], "number cannot end with underscore")
+	}
+
+	// fast path
+	i := 0
+	for ; i < len(b); i++ {
+		if b[i] == '_' {
+			break
+		}
+	}
+	if i == len(b) {
+		return b, nil
+	}
+
+	before := false
+	cleaned := make([]byte, 0, len(b))
+
+	for i := 0; i < len(b); i++ {
+		c := b[i]
+
+		switch c {
+		case '_':
+			if !before {
+				return nil, unstable.NewParserError(b[i-1:i+1], "number must have at least one digit between underscores")
+			}
+			if i < len(b)-1 && (b[i+1] == 'e' || b[i+1] == 'E') {
+				return nil, unstable.NewParserError(b[i+1:i+2], "cannot have underscore before exponent")
+			}
+			before = false
+		case '+', '-':
+			// signed exponents
+			cleaned = append(cleaned, c)
+			before = false
+		case 'e', 'E':
+			if i < len(b)-1 && b[i+1] == '_' {
+				return nil, unstable.NewParserError(b[i+1:i+2], "cannot have underscore after exponent")
+			}
+			cleaned = append(cleaned, c)
+		case '.':
+			if i < len(b)-1 && b[i+1] == '_' {
+				return nil, unstable.NewParserError(b[i+1:i+2], "cannot have underscore after decimal point")
+			}
+			if i > 0 && b[i-1] == '_' {
+				return nil, unstable.NewParserError(b[i-1:i], "cannot have underscore before decimal point")
+			}
+			cleaned = append(cleaned, c)
+		default:
+			before = true
+			cleaned = append(cleaned, c)
+		}
+	}
+
+	return cleaned, nil
+}
+
+// isValidDate checks if a provided date is a date that exists.
+func isValidDate(year int, month int, day int) bool {
+	return month > 0 && month < 13 && day > 0 && day <= daysIn(month, year)
+}
+
+// daysBefore[m] counts the number of days in a non-leap year
+// before month m begins. There is an entry for m=12, counting
+// the number of days before January of next year (365).
+var daysBefore = [...]int32{
+	0,
+	31,
+	31 + 28,
+	31 + 28 + 31,
+	31 + 28 + 31 + 30,
+	31 + 28 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30,
+	31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + 31,
+}
+
+func daysIn(m int, year int) int {
+	if m == 2 && isLeap(year) {
+		return 29
+	}
+	return int(daysBefore[m] - daysBefore[m-1])
+}
+
+func isLeap(year int) bool {
+	return year%4 == 0 && (year%100 != 0 || year%400 == 0)
+}
+
+func isDigit(r byte) bool {
+	return r >= '0' && r <= '9'
+}

doc.go

@@ -0,0 +1,2 @@
+// Package toml is a library to read and write TOML documents.
+package toml

errors.go

@@ -0,0 +1,283 @@
+package toml
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+// DecodeError represents an error encountered during the parsing or decoding
+// of a TOML document.
+//
+// In addition to the error message, it contains the position in the document
+// where it happened, as well as a human-readable representation that shows
+// where the error occurred in the document.
+type DecodeError struct {
+	message string
+	line    int
+	column  int
+	key     Key
+
+	human string
+}
+
+// StrictMissingError occurs in a TOML document that does not have a
+// corresponding field in the target value. It contains all the missing fields
+// in Errors.
+//
+// Emitted by Decoder when DisallowUnknownFields() was called.
+type StrictMissingError struct {
+	// One error per field that could not be found.
+	Errors []DecodeError
+}
+
+// Error returns the canonical string for this error.
+func (s *StrictMissingError) Error() string {
+	return "strict mode: fields in the document are missing in the target struct"
+}
+
+// String returns a human readable description of all errors.
+func (s *StrictMissingError) String() string {
+	var buf strings.Builder
+
+	for i, e := range s.Errors {
+		if i > 0 {
+			buf.WriteString("\n---\n")
+		}
+
+		buf.WriteString(e.String())
+	}
+
+	return buf.String()
+}
+
+// Unwrap returns wrapped decode errors
+//
+// Implements errors.Join() interface.
+func (s *StrictMissingError) Unwrap() []error {
+	errs := make([]error, len(s.Errors))
+	for i := range s.Errors {
+		errs[i] = &s.Errors[i]
+	}
+	return errs
+}
+
+// Key represents a TOML key as a sequence of key parts.
+type Key []string
+
+// Error returns the error message contained in the DecodeError.
+func (e *DecodeError) Error() string {
+	return "toml: " + e.message
+}
+
+// String returns the human-readable contextualized error. This string is multi-line.
+func (e *DecodeError) String() string {
+	return e.human
+}
+
+// Position returns the (line, column) pair indicating where the error
+// occurred in the document. Positions are 1-indexed.
+func (e *DecodeError) Position() (row int, column int) {
+	return e.line, e.column
+}
+
+// Key that was being processed when the error occurred. The key is present only
+// if this DecodeError is part of a StrictMissingError.
+func (e *DecodeError) Key() Key {
+	return e.key
+}
+
+// wrapDecodeError creates a DecodeError referencing a highlighted
+// range of bytes from document.
+//
+// highlight needs to be a sub-slice of document, or this function panics.
+//
+// The function copies all bytes used in DecodeError, so that document and
+// highlight can be freely deallocated.
+//
+//nolint:funlen
+func wrapDecodeError(document []byte, de *unstable.ParserError) *DecodeError {
+	offset := subsliceOffset(document, de.Highlight)
+
+	errMessage := de.Error()
+	errLine, errColumn := positionAtEnd(document[:offset])
+	before, after := linesOfContext(document, de.Highlight, offset, 3)
+
+	var buf strings.Builder
+
+	maxLine := errLine + len(after) - 1
+	lineColumnWidth := len(strconv.Itoa(maxLine))
+
+	// Write the lines of context strictly before the error.
+	for i := len(before) - 1; i > 0; i-- {
+		line := errLine - i
+		buf.WriteString(formatLineNumber(line, lineColumnWidth))
+		buf.WriteString("|")
+
+		if len(before[i]) > 0 {
+			buf.WriteString(" ")
+			buf.Write(before[i])
+		}
+
+		buf.WriteRune('\n')
+	}
+
+	// Write the document line that contains the error.
+
+	buf.WriteString(formatLineNumber(errLine, lineColumnWidth))
+	buf.WriteString("| ")
+
+	if len(before) > 0 {
+		buf.Write(before[0])
+	}
+
+	buf.Write(de.Highlight)
+
+	if len(after) > 0 {
+		buf.Write(after[0])
+	}
+
+	buf.WriteRune('\n')
+
+	// Write the line with the error message itself (so it does not have a line
+	// number).
+
+	buf.WriteString(strings.Repeat(" ", lineColumnWidth))
+	buf.WriteString("| ")
+
+	if len(before) > 0 {
+		buf.WriteString(strings.Repeat(" ", len(before[0])))
+	}
+
+	buf.WriteString(strings.Repeat("~", len(de.Highlight)))
+
+	if len(errMessage) > 0 {
+		buf.WriteString(" ")
+		buf.WriteString(errMessage)
+	}
+
+	// Write the lines of context strictly after the error.
+
+	for i := 1; i < len(after); i++ {
+		buf.WriteRune('\n')
+		line := errLine + i
+		buf.WriteString(formatLineNumber(line, lineColumnWidth))
+		buf.WriteString("|")
+
+		if len(after[i]) > 0 {
+			buf.WriteString(" ")
+			buf.Write(after[i])
+		}
+	}
+
+	return &DecodeError{
+		message: errMessage,
+		line:    errLine,
+		column:  errColumn,
+		key:     de.Key,
+		human:   buf.String(),
+	}
+}
+
+func formatLineNumber(line int, width int) string {
+	format := "%" + strconv.Itoa(width) + "d"
+
+	return fmt.Sprintf(format, line)
+}
+
+func linesOfContext(document []byte, highlight []byte, offset int, linesAround int) ([][]byte, [][]byte) {
+	return beforeLines(document, offset, linesAround), afterLines(document, highlight, offset, linesAround)
+}
+
+func beforeLines(document []byte, offset int, linesAround int) [][]byte {
+	var beforeLines [][]byte
+
+	// Walk the document backward from the highlight to find previous lines
+	// of context.
+	rest := document[:offset]
+backward:
+	for o := len(rest) - 1; o >= 0 && len(beforeLines) <= linesAround && len(rest) > 0; {
+		switch {
+		case rest[o] == '\n':
+			// handle individual lines
+			beforeLines = append(beforeLines, rest[o+1:])
+			rest = rest[:o]
+			o = len(rest) - 1
+		case o == 0:
+			// add the first line only if it's non-empty
+			beforeLines = append(beforeLines, rest)
+
+			break backward
+		default:
+			o--
+		}
+	}
+
+	return beforeLines
+}
+
+func afterLines(document []byte, highlight []byte, offset int, linesAround int) [][]byte {
+	var afterLines [][]byte
+
+	// Walk the document forward from the highlight to find the following
+	// lines of context.
+	rest := document[offset+len(highlight):]
+forward:
+	for o := 0; o < len(rest) && len(afterLines) <= linesAround; {
+		switch {
+		case rest[o] == '\n':
+			// handle individual lines
+			afterLines = append(afterLines, rest[:o])
+			rest = rest[o+1:]
+			o = 0
+
+		case o == len(rest)-1:
+			// add last line only if it's non-empty
+			afterLines = append(afterLines, rest)
+
+			break forward
+		default:
+			o++
+		}
+	}
+
+	return afterLines
+}
+
+func positionAtEnd(b []byte) (row int, column int) {
+	row = 1
+	column = 1
+
+	for _, c := range b {
+		if c == '\n' {
+			row++
+			column = 1
+		} else {
+			column++
+		}
+	}
+
+	return row, column
+}
+
+// subsliceOffset returns the byte offset of subslice within data.
+// subslice must share the same backing array as data.
+func subsliceOffset(data []byte, subslice []byte) int {
+	if len(subslice) == 0 {
+		return 0
+	}
+
+	// Use reflect to get the data pointers of both slices.
+	// This is safe because we're only reading the pointer values for comparison.
+	dataPtr := reflect.ValueOf(data).Pointer()
+	subPtr := reflect.ValueOf(subslice).Pointer()
+
+	offset := int(subPtr - dataPtr)
+	if offset < 0 || offset > len(data) {
+		panic("subslice is not within data")
+	}
+	return offset
+}

errors_test.go

@@ -0,0 +1,317 @@
+package toml
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2/internal/assert"
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+//nolint:funlen
+func TestDecodeError(t *testing.T) {
+	examples := []struct {
+		desc     string
+		doc      [3]string
+		msg      string
+		expected string
+	}{
+		{
+			desc: "no context",
+			doc:  [3]string{"", "morning", ""},
+			msg:  "this is wrong",
+			expected: `
+1| morning
+ | ~~~~~~~ this is wrong`,
+		},
+		{
+			desc: "one line",
+			doc:  [3]string{"good ", "morning", " everyone"},
+			msg:  "this is wrong",
+			expected: `
+1| good morning everyone
+ |      ~~~~~~~ this is wrong`,
+		},
+		{
+			desc: "exactly 3 lines",
+			doc: [3]string{`line1
+line2
+line3
+before `, "highlighted", ` after
+post line 1
+post line 2
+post line 3`},
+			msg: "this is wrong",
+			expected: `
+1| line1
+2| line2
+3| line3
+4| before highlighted after
+ |        ~~~~~~~~~~~ this is wrong
+5| post line 1
+6| post line 2
+7| post line 3`,
+		},
+		{
+			desc: "more than 3 lines",
+			doc: [3]string{`should not be seen1
+should not be seen2
+line1
+line2
+line3
+before `, "highlighted", ` after
+post line 1
+post line 2
+post line 3
+should not be seen3
+should not be seen4`},
+			msg: "this is wrong",
+			expected: `
+3| line1
+4| line2
+5| line3
+6| before highlighted after
+ |        ~~~~~~~~~~~ this is wrong
+7| post line 1
+8| post line 2
+9| post line 3`,
+		},
+		{
+			desc: "more than 10 total lines",
+			doc: [3]string{`should not be seen 0
+should not be seen1
+should not be seen2
+should not be seen3
+line1
+line2
+line3
+before `, "highlighted", ` after
+post line 1
+post line 2
+post line 3
+should not be seen3
+should not be seen4`},
+			msg: "this is wrong",
+			expected: `
+ 5| line1
+ 6| line2
+ 7| line3
+ 8| before highlighted after
+  |        ~~~~~~~~~~~ this is wrong
+ 9| post line 1
+10| post line 2
+11| post line 3`,
+		},
+		{
+			desc: "last line of more than 10",
+			doc: [3]string{`should not be seen
+should not be seen
+should not be seen
+should not be seen
+should not be seen
+should not be seen
+should not be seen
+line1
+line2
+line3
+before `, "highlighted", ``},
+			msg: "this is wrong",
+			expected: `
+ 8| line1
+ 9| line2
+10| line3
+11| before highlighted
+  |        ~~~~~~~~~~~ this is wrong
+`,
+		},
+		{
+			desc: "handle empty lines in the before/after blocks",
+			doc: [3]string{
+				`line1
+
+line 2
+before `, "highlighted", ` after
+line 3
+
+line 4
+line 5`,
+			},
+			expected: `1| line1
+2|
+3| line 2
+4| before highlighted after
+ |        ~~~~~~~~~~~
+5| line 3
+6|
+7| line 4`,
+		},
+		{
+			desc: "handle remainder of the error line when there is only one line",
+			doc:  [3]string{`P=`, `[`, `#`},
+			msg:  "array is incomplete",
+			expected: `1| P=[#
+ |   ~ array is incomplete`,
+		},
+	}
+
+	for _, e := range examples {
+		e := e
+		t.Run(e.desc, func(t *testing.T) {
+			b := bytes.Buffer{}
+			b.WriteString(e.doc[0])
+			start := b.Len()
+			b.WriteString(e.doc[1])
+			end := b.Len()
+			b.WriteString(e.doc[2])
+			doc := b.Bytes()
+			hl := doc[start:end]
+
+			err := wrapDecodeError(doc, &unstable.ParserError{
+				Highlight: hl,
+				Message:   e.msg,
+			})
+
+			var derr *DecodeError
+			if !errors.As(err, &derr) {
+				t.Errorf("error not in expected format")
+
+				return
+			}
+
+			assert.Equal(t, strings.Trim(e.expected, "\n"), derr.String())
+		})
+	}
+}
+
+func TestDecodeError_Accessors(t *testing.T) {
+	e := DecodeError{
+		message: "foo",
+		line:    1,
+		column:  2,
+		key:     []string{"one", "two"},
+		human:   "bar",
+	}
+	assert.Equal(t, "toml: foo", e.Error())
+	r, c := e.Position()
+	assert.Equal(t, 1, r)
+	assert.Equal(t, 2, c)
+	assert.Equal(t, Key{"one", "two"}, e.Key())
+	assert.Equal(t, "bar", e.String())
+}
+
+func TestDecodeError_DuplicateContent(t *testing.T) {
+	// This test verifies that when the same content appears multiple times
+	// in the document, the error correctly points to the actual location
+	// of the error, not the first occurrence of the content.
+	//
+	// The document has "1__2" on line 1 and "3__4" on line 2.
+	// Both have "__" which is invalid, but we want to ensure errors
+	// on line 2 report line 2, not line 1.
+
+	doc := `a = 1
+b = 3__4`
+
+	var v map[string]int
+	err := Unmarshal([]byte(doc), &v)
+
+	var derr *DecodeError
+	if !errors.As(err, &derr) {
+		t.Fatal("error not in expected format")
+	}
+
+	row, col := derr.Position()
+	// The error should be on line 2 where "3__4" is
+	if row != 2 {
+		t.Errorf("expected error on row 2, got row %d", row)
+	}
+	// Column should point to the "__" part (after "3")
+	if col < 5 {
+		t.Errorf("expected error at column >= 5, got column %d", col)
+	}
+}
+
+func TestDecodeError_Position(t *testing.T) {
+	// Test that error positions are correctly reported for various error locations
+	examples := []struct {
+		name        string
+		doc         string
+		expectedRow int
+		minCol      int
+	}{
+		{
+			name:        "error on first line",
+			doc:         `a = 1__2`,
+			expectedRow: 1,
+			minCol:      5,
+		},
+		{
+			name:        "error on second line",
+			doc:         "a = 1\nb = 2__3",
+			expectedRow: 2,
+			minCol:      5,
+		},
+		{
+			name:        "error on third line",
+			doc:         "a = 1\nb = 2\nc = 3__4",
+			expectedRow: 3,
+			minCol:      5,
+		},
+	}
+
+	for _, e := range examples {
+		t.Run(e.name, func(t *testing.T) {
+			var v map[string]int
+			err := Unmarshal([]byte(e.doc), &v)
+
+			var derr *DecodeError
+			if !errors.As(err, &derr) {
+				t.Fatal("error not in expected format")
+			}
+
+			row, col := derr.Position()
+			assert.Equal(t, e.expectedRow, row)
+			if col < e.minCol {
+				t.Errorf("expected column >= %d, got %d", e.minCol, col)
+			}
+		})
+	}
+}
+
+func TestStrictErrorUnwrap(t *testing.T) {
+	fo := bytes.NewBufferString(`
+Missing = 1
+OtherMissing = 1
+`)
+	var out struct{}
+	err := NewDecoder(fo).DisallowUnknownFields().Decode(&out)
+	assert.Error(t, err)
+
+	strictErr := &StrictMissingError{}
+	assert.True(t, errors.As(err, &strictErr))
+
+	assert.Equal(t, 2, len(strictErr.Unwrap()))
+}
+
+func ExampleDecodeError() {
+	doc := `name = 123__456`
+
+	s := map[string]interface{}{}
+	err := Unmarshal([]byte(doc), &s)
+
+	fmt.Println(err)
+
+	var derr *DecodeError
+	if errors.As(err, &derr) {
+		fmt.Println(derr.String())
+		row, col := derr.Position()
+		fmt.Println("error occurred at row", row, "column", col)
+	}
+	// Output:
+	// toml: number must have at least one digit between underscores
+	// 1| name = 123__456
+	//  |           ~~ number must have at least one digit between underscores
+	// error occurred at row 1 column 11
+}

example.toml

@@ -1,29 +0,0 @@
-# This is a TOML document. Boom.
-
-title = "TOML Example"
-
-[owner]
-name = "Tom Preston-Werner"
-organization = "GitHub"
-bio = "GitHub Cofounder & CEO\nLikes tater tots and beer."
-dob = 1979-05-27T07:32:00Z # First class dates? Why not?
-
-[database]
-server = "192.168.1.1"
-ports = [ 8001, 8001, 8002 ]
-connection_max = 5000
-enabled = true
-
-[servers]
-
-  # You can indent as you please. Tabs or spaces. TOML don't care.
-  [servers.alpha]
-  ip = "10.0.0.1"
-  dc = "eqdc10"
-
-  [servers.beta]
-  ip = "10.0.0.2"
-  dc = "eqdc10"
-
-[clients]
-data = [ ["gamma", "delta"], [1, 2] ] # just an update to make sure parsers support it

example_text_marshaling_test.go

@@ -0,0 +1,37 @@
+package toml_test
+
+import (
+	"fmt"
+	"log"
+	"strconv"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+type customInt int
+
+func (i *customInt) UnmarshalText(b []byte) error {
+	x, err := strconv.ParseInt(string(b), 10, 32)
+	if err != nil {
+		return err
+	}
+	*i = customInt(x * 100)
+	return nil
+}
+
+type doc struct {
+	Value customInt
+}
+
+func ExampleUnmarshal_textUnmarshal() {
+	var x doc
+
+	data := []byte(`value  = "42"`)
+	err := toml.Unmarshal(data, &x)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(x)
+	// Output:
+	// {4200}
+}

fast_test.go

@@ -0,0 +1,107 @@
+package toml_test
+
+import (
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestFastSimpleInt(t *testing.T) {
+	m := map[string]int64{}
+	err := toml.Unmarshal([]byte(`a = 42`), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]int64{"a": 42}, m)
+}
+
+func TestFastSimpleFloat(t *testing.T) {
+	m := map[string]float64{}
+	err := toml.Unmarshal([]byte("a = 42\nb = 1.1\nc = 12341234123412341234123412341234"), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]float64{"a": 42, "b": 1.1, "c": 1.2341234123412342e+31}, m)
+}
+
+func TestFastSimpleString(t *testing.T) {
+	m := map[string]string{}
+	err := toml.Unmarshal([]byte(`a = "hello"`), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]string{"a": "hello"}, m)
+}
+
+func TestFastSimpleInterface(t *testing.T) {
+	m := map[string]interface{}{}
+	err := toml.Unmarshal([]byte(`
+	a = "hello"
+	b = 42`), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]interface{}{
+		"a": "hello",
+		"b": int64(42),
+	}, m)
+}
+
+func TestFastMultipartKeyInterface(t *testing.T) {
+	m := map[string]interface{}{}
+	err := toml.Unmarshal([]byte(`
+	a.interim = "test"
+	a.b.c = "hello"
+	b = 42`), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]interface{}{
+		"a": map[string]interface{}{
+			"interim": "test",
+			"b": map[string]interface{}{
+				"c": "hello",
+			},
+		},
+		"b": int64(42),
+	}, m)
+}
+
+func TestFastExistingMap(t *testing.T) {
+	m := map[string]interface{}{
+		"ints": map[string]int{},
+	}
+	err := toml.Unmarshal([]byte(`
+	ints.one = 1
+	ints.two = 2
+	strings.yo = "hello"`), &m)
+	assert.NoError(t, err)
+	assert.Equal(t, map[string]interface{}{
+		"ints": map[string]interface{}{
+			"one": int64(1),
+			"two": int64(2),
+		},
+		"strings": map[string]interface{}{
+			"yo": "hello",
+		},
+	}, m)
+}
+
+func TestFastArrayTable(t *testing.T) {
+	b := []byte(`
+	[root]
+	[[root.nested]]
+	name = 'Bob'
+	[[root.nested]]
+	name = 'Alice'
+	`)
+
+	m := map[string]interface{}{}
+
+	err := toml.Unmarshal(b, &m)
+	assert.NoError(t, err)
+
+	assert.Equal(t, map[string]interface{}{
+		"root": map[string]interface{}{
+			"nested": []interface{}{
+				map[string]interface{}{
+					"name": "Bob",
+				},
+				map[string]interface{}{
+					"name": "Alice",
+				},
+			},
+		},
+	}, m)
+}

fuzz_test.go

@@ -0,0 +1,53 @@
+package toml_test
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func FuzzUnmarshal(f *testing.F) {
+	file, err := os.ReadFile("benchmark/benchmark.toml")
+	if err != nil {
+		f.Error(err)
+	}
+	f.Add(file)
+
+	f.Fuzz(func(t *testing.T, b []byte) {
+		if strings.Contains(string(b), "nan") {
+			// Current limitation of testify.
+			// https://github.com/stretchr/testify/issues/624
+			t.Skip("can't compare NaNs")
+		}
+
+		t.Log("INITIAL DOCUMENT ===========================")
+		t.Log(string(b))
+
+		var v interface{}
+		err := toml.Unmarshal(b, &v)
+		if err != nil {
+			return
+		}
+
+		t.Log("DECODED VALUE ===========================")
+		t.Logf("%#+v", v)
+
+		encoded, err := toml.Marshal(v)
+		if err != nil {
+			t.Fatalf("cannot marshal unmarshaled document: %s", err)
+		}
+
+		t.Log("ENCODED DOCUMENT ===========================")
+		t.Log(string(encoded))
+
+		var v2 interface{}
+		err = toml.Unmarshal(encoded, &v2)
+		if err != nil {
+			t.Fatalf("failed round trip: %s", err)
+		}
+		assert.Equal(t, v, v2)
+	})
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/pelletier/go-toml/v2
+
+go 1.21.0

internal/assert/assertions.go

@@ -0,0 +1,141 @@
+// Package assert provides assertion functions for unit testing.
+package assert
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// True asserts that an expression is true.
+func True(tb testing.TB, ok bool, msgAndArgs ...any) {
+	tb.Helper()
+	if ok {
+		return
+	}
+	tb.Fatal(formatMsgAndArgs("Expected expression to be true", msgAndArgs...))
+}
+
+// False asserts that an expression is false.
+func False(tb testing.TB, ok bool, msgAndArgs ...any) {
+	tb.Helper()
+	if !ok {
+		return
+	}
+	tb.Fatal(formatMsgAndArgs("Expected expression to be false", msgAndArgs...))
+}
+
+// Equal asserts that "expected" and "actual" are equal.
+func Equal[T any](tb testing.TB, expected, actual T, msgAndArgs ...any) {
+	tb.Helper()
+	if objectsAreEqual(expected, actual) {
+		return
+	}
+	msg := formatMsgAndArgs("Expected values to be equal:", msgAndArgs...)
+	tb.Fatalf("%s\n%s", msg, diff(expected, actual))
+}
+
+// Error asserts that an error is not nil.
+func Error(tb testing.TB, err error, msgAndArgs ...any) {
+	tb.Helper()
+	if err != nil {
+		return
+	}
+	tb.Fatal(formatMsgAndArgs("Expected an error", msgAndArgs...))
+}
+
+// NoError asserts that an error is nil.
+func NoError(tb testing.TB, err error, msgAndArgs ...any) {
+	tb.Helper()
+	if err == nil {
+		return
+	}
+	msg := formatMsgAndArgs("Unexpected error:", msgAndArgs...)
+	tb.Fatalf("%s\n%+v", msg, err)
+}
+
+// Panics asserts that the given function panics.
+func Panics(tb testing.TB, fn func(), msgAndArgs ...any) {
+	tb.Helper()
+	defer func() {
+		if recover() == nil {
+			msg := formatMsgAndArgs("Expected function to panic", msgAndArgs...)
+			tb.Fatal(msg)
+		}
+	}()
+	fn()
+}
+
+// Zero asserts that a value is its zero value.
+func Zero[T any](tb testing.TB, value T, msgAndArgs ...any) {
+	tb.Helper()
+	var zero T
+	if objectsAreEqual(value, zero) {
+		return
+	}
+	val := reflect.ValueOf(value)
+	if (val.Kind() == reflect.Slice || val.Kind() == reflect.Map || val.Kind() == reflect.Array) && val.Len() == 0 {
+		return
+	}
+	msg := formatMsgAndArgs("Expected zero value but got:", msgAndArgs...)
+	tb.Fatalf("%s\n%v", msg, value)
+}
+
+func NotZero[T any](tb testing.TB, value T, msgAndArgs ...any) {
+	tb.Helper()
+	var zero T
+	if !objectsAreEqual(value, zero) {
+		val := reflect.ValueOf(value)
+		switch val.Kind() {
+		case reflect.Slice, reflect.Map, reflect.Array:
+			if val.Len() > 0 {
+				return
+			}
+		default:
+			return
+		}
+	}
+	msg := formatMsgAndArgs("Unexpected zero value:", msgAndArgs...)
+	tb.Fatalf("%s\n%v", msg, value)
+}
+
+func formatMsgAndArgs(msg string, args ...any) string {
+	if len(args) == 0 {
+		return msg
+	}
+	format, ok := args[0].(string)
+	if !ok {
+		panic("message argument must be a fmt string")
+	}
+	return fmt.Sprintf(format, args[1:]...)
+}
+
+func diff(expected, actual any) string {
+	lines := []string{
+		"expected:",
+		fmt.Sprintf("%v", expected),
+		"actual:",
+		fmt.Sprintf("%v", actual),
+	}
+	return strings.Join(lines, "\n")
+}
+
+func objectsAreEqual(expected, actual any) bool {
+	if expected == nil || actual == nil {
+		return expected == actual
+	}
+	if exp, eok := expected.([]byte); eok {
+		if act, aok := actual.([]byte); aok {
+			return bytes.Equal(exp, act)
+		}
+	}
+	if exp, eok := expected.(string); eok {
+		if act, aok := actual.(string); aok {
+			return exp == act
+		}
+	}
+
+	return reflect.DeepEqual(expected, actual)
+}

internal/assert/assertions_test.go

@@ -0,0 +1,217 @@
+package assert
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+type Data struct {
+	Label string
+	Value int64
+}
+
+func TestBadMessage(t *testing.T) {
+	invalidMessage := func() { True(t, false, 1234) }
+	assertOk(t, "Non-fmt message value", func(tb testing.TB) {
+		tb.Helper()
+		Panics(tb, invalidMessage)
+	})
+	assertFail(t, "Non-fmt message value", func(tb testing.TB) {
+		tb.Helper()
+		True(tb, false, "example %s", "message")
+	})
+}
+
+func TestTrue(t *testing.T) {
+	assertOk(t, "Succeed", func(tb testing.TB) {
+		tb.Helper()
+		True(tb, 1 > 0)
+	})
+	assertFail(t, "Fail", func(tb testing.TB) {
+		tb.Helper()
+		True(tb, 1 < 0)
+	})
+}
+
+func TestFalse(t *testing.T) {
+	assertOk(t, "Succeed", func(tb testing.TB) {
+		tb.Helper()
+		False(tb, 1 < 0)
+	})
+	assertFail(t, "Fail", func(tb testing.TB) {
+		tb.Helper()
+		False(tb, 1 > 0)
+	})
+}
+
+func TestEqual(t *testing.T) {
+	assertOk(t, "Nil", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, interface{}(nil), interface{}(nil))
+	})
+	assertOk(t, "Identical structs", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, Data{"expected", 1234}, Data{"expected", 1234})
+	})
+	assertFail(t, "Different structs", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, Data{"expected", 1234}, Data{"actual", 1234})
+	})
+	assertOk(t, "Identical numbers", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, 1234, 1234)
+	})
+	assertFail(t, "Identical numbers", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, 1234, 1324)
+	})
+	assertOk(t, "Zero-length byte arrays", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, []byte(nil), []byte(""))
+	})
+	assertOk(t, "Identical byte arrays", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, []byte{1, 2, 3, 4}, []byte{1, 2, 3, 4})
+	})
+	assertFail(t, "Different byte arrays", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, []byte{1, 2, 3, 4}, []byte{1, 3, 2, 4})
+	})
+	assertOk(t, "Identical strings", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, "example", "example")
+	})
+	assertFail(t, "Identical strings", func(tb testing.TB) {
+		tb.Helper()
+		Equal(tb, "example", "elpmaxe")
+	})
+}
+
+func TestError(t *testing.T) {
+	assertOk(t, "Error", func(tb testing.TB) {
+		tb.Helper()
+		Error(tb, errors.New("example"))
+	})
+	assertFail(t, "Nil", func(tb testing.TB) {
+		tb.Helper()
+		Error(tb, nil)
+	})
+}
+
+func TestNoError(t *testing.T) {
+	assertFail(t, "Error", func(tb testing.TB) {
+		tb.Helper()
+		NoError(tb, errors.New("example"))
+	})
+	assertOk(t, "Nil", func(tb testing.TB) {
+		tb.Helper()
+		NoError(tb, nil)
+	})
+}
+
+func TestPanics(t *testing.T) {
+	willPanic := func() { panic("example") }
+	wontPanic := func() {}
+	assertOk(t, "Will panic", func(tb testing.TB) {
+		tb.Helper()
+		Panics(tb, willPanic)
+	})
+	assertFail(t, "Won't panic", func(tb testing.TB) {
+		tb.Helper()
+		Panics(tb, wontPanic)
+	})
+}
+
+func TestZero(t *testing.T) {
+	assertOk(t, "Empty struct", func(tb testing.TB) {
+		tb.Helper()
+		Zero(tb, Data{})
+	})
+	assertFail(t, "Non-empty struct", func(tb testing.TB) {
+		tb.Helper()
+		Zero(tb, Data{Label: "example"})
+	})
+	assertOk(t, "Nil slice", func(tb testing.TB) {
+		tb.Helper()
+		var slice []int
+		Zero(tb, slice)
+	})
+	assertFail(t, "Non-empty slice", func(tb testing.TB) {
+		tb.Helper()
+		slice := []int{1, 2, 3, 4}
+		Zero(tb, slice)
+	})
+	assertOk(t, "Zero-length slice", func(tb testing.TB) {
+		tb.Helper()
+		slice := []int{}
+		Zero(tb, slice)
+	})
+}
+
+func TestNotZero(t *testing.T) {
+	assertFail(t, "Empty struct", func(tb testing.TB) {
+		tb.Helper()
+		zero := Data{}
+		NotZero(tb, zero)
+	})
+	assertOk(t, "Non-empty struct", func(tb testing.TB) {
+		tb.Helper()
+		notZero := Data{Label: "example"}
+		NotZero(tb, notZero)
+	})
+	assertFail(t, "Nil slice", func(tb testing.TB) {
+		tb.Helper()
+		var slice []int
+		NotZero(tb, slice)
+	})
+	assertFail(t, "Zero-length slice", func(tb testing.TB) {
+		tb.Helper()
+		slice := []int{}
+		NotZero(tb, slice)
+	})
+	assertOk(t, "Non-empty slice", func(tb testing.TB) {
+		tb.Helper()
+		slice := []int{1, 2, 3, 4}
+		NotZero(tb, slice)
+	})
+}
+
+type testCase struct {
+	*testing.T
+	failed string
+}
+
+func (t *testCase) Fatal(args ...interface{}) {
+	t.failed = fmt.Sprint(args...)
+}
+
+func (t *testCase) Fatalf(message string, args ...interface{}) {
+	t.failed = fmt.Sprintf(message, args...)
+}
+
+func assertFail(t *testing.T, name string, fn func(testing.TB)) {
+	t.Helper()
+	t.Run(name, func(t *testing.T) {
+		t.Helper()
+		test := &testCase{T: t}
+		fn(test)
+		if test.failed == "" {
+			t.Fatal("Test expected to fail but did not")
+		} else {
+			t.Log(test.failed)
+		}
+	})
+}
+
+func assertOk(t *testing.T, name string, fn func(testing.TB)) {
+	t.Helper()
+	t.Run(name, func(t *testing.T) {
+		t.Helper()
+		test := &testCase{T: t}
+		fn(test)
+		if test.failed != "" {
+			t.Fatal("Test expected to succeed but did not:\n", test.failed)
+		}
+	})
+}

internal/characters/ascii.go

@@ -0,0 +1,42 @@
+package characters
+
+var invalidASCIITable = [256]bool{
+	0x00: true,
+	0x01: true,
+	0x02: true,
+	0x03: true,
+	0x04: true,
+	0x05: true,
+	0x06: true,
+	0x07: true,
+	0x08: true,
+	// 0x09 TAB
+	// 0x0A LF
+	0x0B: true,
+	0x0C: true,
+	// 0x0D CR
+	0x0E: true,
+	0x0F: true,
+	0x10: true,
+	0x11: true,
+	0x12: true,
+	0x13: true,
+	0x14: true,
+	0x15: true,
+	0x16: true,
+	0x17: true,
+	0x18: true,
+	0x19: true,
+	0x1A: true,
+	0x1B: true,
+	0x1C: true,
+	0x1D: true,
+	0x1E: true,
+	0x1F: true,
+	// 0x20 - 0x7E Printable ASCII characters
+	0x7F: true,
+}
+
+func InvalidASCII(b byte) bool {
+	return invalidASCIITable[b]
+}

internal/characters/utf8.go

@@ -0,0 +1,175 @@
+// Package characters provides functions for working with string encodings.
+package characters
+
+import (
+	"unicode/utf8"
+)
+
+// Utf8TomlValidAlreadyEscaped verifies that a given string is only made of
+// valid UTF-8 characters allowed by the TOML spec:
+//
+// Any Unicode character may be used except those that must be escaped:
+// quotation mark, backslash, and the control characters other than tab (U+0000
+// to U+0008, U+000A to U+001F, U+007F).
+//
+// It is a copy of the Go 1.17 utf8.Valid implementation, tweaked to exit early
+// when a character is not allowed.
+//
+// The returned slice is empty if the string is valid, or contains the bytes
+// of the invalid character.
+//
+// quotation mark => already checked
+// backslash => already checked
+// 0-0x8 => invalid
+// 0x9 => tab, ok
+// 0xA - 0x1F => invalid
+// 0x7F => invalid
+func Utf8TomlValidAlreadyEscaped(p []byte) []byte {
+	// Fast path. Check for and skip 8 bytes of ASCII characters per iteration.
+	for len(p) >= 8 {
+		// Combining two 32 bit loads allows the same code to be used
+		// for 32 and 64 bit platforms.
+		// The compiler can generate a 32bit load for first32 and second32
+		// on many platforms. See test/codegen/memcombine.go.
+		first32 := uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 | uint32(p[3])<<24
+		second32 := uint32(p[4]) | uint32(p[5])<<8 | uint32(p[6])<<16 | uint32(p[7])<<24
+		if (first32|second32)&0x80808080 != 0 {
+			// Found a non ASCII byte (>= RuneSelf).
+			break
+		}
+
+		for i, b := range p[:8] {
+			if InvalidASCII(b) {
+				return p[i : i+1]
+			}
+		}
+
+		p = p[8:]
+	}
+	n := len(p)
+	for i := 0; i < n; {
+		pi := p[i]
+		if pi < utf8.RuneSelf {
+			if InvalidASCII(pi) {
+				return p[i : i+1]
+			}
+			i++
+			continue
+		}
+		x := first[pi]
+		if x == xx {
+			// Illegal starter byte.
+			return p[i : i+1]
+		}
+		size := int(x & 7)
+		if i+size > n {
+			// Short or invalid.
+			return p[i:n]
+		}
+		accept := acceptRanges[x>>4]
+		if c := p[i+1]; c < accept.lo || accept.hi < c {
+			return p[i : i+2]
+		} else if size == 2 { //revive:disable:empty-block
+		} else if c := p[i+2]; c < locb || hicb < c {
+			return p[i : i+3]
+		} else if size == 3 { //revive:disable:empty-block
+		} else if c := p[i+3]; c < locb || hicb < c {
+			return p[i : i+4]
+		}
+		i += size
+	}
+	return nil
+}
+
+// Utf8ValidNext returns the size of the next rune if valid, 0 otherwise.
+func Utf8ValidNext(p []byte) int {
+	c := p[0]
+
+	if c < utf8.RuneSelf {
+		if InvalidASCII(c) {
+			return 0
+		}
+		return 1
+	}
+
+	x := first[c]
+	if x == xx {
+		// Illegal starter byte.
+		return 0
+	}
+	size := int(x & 7)
+	if size > len(p) {
+		// Short or invalid.
+		return 0
+	}
+	accept := acceptRanges[x>>4]
+	if c := p[1]; c < accept.lo || accept.hi < c {
+		return 0
+	} else if size == 2 { //nolint:revive
+	} else if c := p[2]; c < locb || hicb < c {
+		return 0
+	} else if size == 3 { //nolint:revive
+	} else if c := p[3]; c < locb || hicb < c {
+		return 0
+	}
+
+	return size
+}
+
+// acceptRange gives the range of valid values for the second byte in a UTF-8
+// sequence.
+type acceptRange struct {
+	lo uint8 // lowest value for second byte.
+	hi uint8 // highest value for second byte.
+}
+
+// acceptRanges has size 16 to avoid bounds checks in the code that uses it.
+var acceptRanges = [16]acceptRange{
+	0: {locb, hicb},
+	1: {0xA0, hicb},
+	2: {locb, 0x9F},
+	3: {0x90, hicb},
+	4: {locb, 0x8F},
+}
+
+// first is information about the first byte in a UTF-8 sequence.
+var first = [256]uint8{
+	//   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x00-0x0F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x10-0x1F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x20-0x2F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x30-0x3F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x40-0x4F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x50-0x5F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x60-0x6F
+	as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x70-0x7F
+	//   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
+	xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0x80-0x8F
+	xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0x90-0x9F
+	xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xA0-0xAF
+	xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xB0-0xBF
+	xx, xx, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, // 0xC0-0xCF
+	s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, // 0xD0-0xDF
+	s2, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s4, s3, s3, // 0xE0-0xEF
+	s5, s6, s6, s6, s7, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xF0-0xFF
+}
+
+const (
+	// The default lowest and highest continuation byte.
+	locb = 0b10000000
+	hicb = 0b10111111
+
+	// These names of these constants are chosen to give nice alignment in the
+	// table below. The first nibble is an index into acceptRanges or F for
+	// special one-byte cases. The second nibble is the Rune length or the
+	// Status for the special one-byte case.
+	xx = 0xF1 // invalid: size 1
+	as = 0xF0 // ASCII: size 1
+	s1 = 0x02 // accept 0, size 2
+	s2 = 0x13 // accept 1, size 3
+	s3 = 0x03 // accept 0, size 3
+	s4 = 0x23 // accept 2, size 3
+	s5 = 0x34 // accept 3, size 4
+	s6 = 0x04 // accept 0, size 4
+	s7 = 0x44 // accept 4, size 4
+)

internal/cli/cli.go

@@ -0,0 +1,87 @@
+// Package cli provides common functions for command-line programs.
+package cli
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+type ConvertFn func(r io.Reader, w io.Writer) error
+
+type Program struct {
+	Usage string
+	Fn    ConvertFn
+	// Inplace allows the command to take more than one file as argument and
+	// perform conversion in place on each provided file.
+	Inplace bool
+}
+
+func (p *Program) Execute() {
+	flag.Usage = func() { fmt.Fprint(os.Stderr, p.Usage) }
+	flag.Parse()
+	os.Exit(p.main(flag.Args(), os.Stdin, os.Stdout, os.Stderr))
+}
+
+func (p *Program) main(files []string, input io.Reader, output, stderr io.Writer) int {
+	err := p.run(files, input, output)
+	if err != nil {
+		var derr *toml.DecodeError
+		if errors.As(err, &derr) {
+			_, _ = fmt.Fprintln(stderr, derr.String())
+			row, col := derr.Position()
+			_, _ = fmt.Fprintln(stderr, "error occurred at row", row, "column", col)
+		} else {
+			_, _ = fmt.Fprintln(stderr, err.Error())
+		}
+
+		return -1
+	}
+	return 0
+}
+
+func (p *Program) run(files []string, input io.Reader, output io.Writer) error {
+	if len(files) > 0 {
+		if p.Inplace {
+			return p.runAllFilesInPlace(files)
+		}
+		f, err := os.Open(files[0])
+		if err != nil {
+			return err
+		}
+		defer func() { _ = f.Close() }()
+		input = f
+	}
+	return p.Fn(input, output)
+}
+
+func (p *Program) runAllFilesInPlace(files []string) error {
+	for _, path := range files {
+		err := p.runFileInPlace(path)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *Program) runFileInPlace(path string) error {
+	in, err := os.ReadFile(path) // #nosec G304
+	if err != nil {
+		return err
+	}
+
+	out := new(bytes.Buffer)
+
+	err = p.Fn(bytes.NewReader(in), out)
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(path, out.Bytes(), 0o600)
+}

internal/cli/cli_test.go

@@ -0,0 +1,166 @@
+package cli
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"os"
+	"path"
+	"strings"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func processMain(args []string, input io.Reader, stdout, stderr io.Writer, f ConvertFn) int {
+	p := Program{Fn: f}
+	return p.main(args, input, stdout, stderr)
+}
+
+func TestProcessMainStdin(t *testing.T) {
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	input := strings.NewReader("this is the input")
+
+	exit := processMain([]string{}, input, stdout, stderr, func(io.Reader, io.Writer) error {
+		return nil
+	})
+
+	assert.Equal(t, 0, exit)
+	assert.Zero(t, stdout.String())
+	assert.Zero(t, stderr.String())
+}
+
+func TestProcessMainStdinErr(t *testing.T) {
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	input := strings.NewReader("this is the input")
+
+	exit := processMain([]string{}, input, stdout, stderr, func(io.Reader, io.Writer) error {
+		return errors.New("something bad")
+	})
+
+	assert.Equal(t, -1, exit)
+	assert.Zero(t, stdout.String())
+	assert.NotZero(t, stderr.String())
+}
+
+func TestProcessMainStdinDecodeErr(t *testing.T) {
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	input := strings.NewReader("this is the input")
+
+	exit := processMain([]string{}, input, stdout, stderr, func(io.Reader, io.Writer) error {
+		var v interface{}
+		return toml.Unmarshal([]byte(`qwe = 001`), &v)
+	})
+
+	assert.Equal(t, -1, exit)
+	assert.Zero(t, stdout.String())
+	assert.True(t, strings.Contains(stderr.String(), "error occurred at"))
+}
+
+func TestProcessMainFileExists(t *testing.T) {
+	tmpfile, err := os.CreateTemp(t.TempDir(), "example")
+	assert.NoError(t, err)
+	_, err = tmpfile.WriteString(`some data`)
+	assert.NoError(t, err)
+	assert.NoError(t, tmpfile.Close())
+
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+
+	exit := processMain([]string{tmpfile.Name()}, nil, stdout, stderr, func(io.Reader, io.Writer) error {
+		return nil
+	})
+
+	assert.Equal(t, 0, exit)
+	assert.Zero(t, stdout.String())
+	assert.Zero(t, stderr.String())
+}
+
+func TestProcessMainFileDoesNotExist(t *testing.T) {
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+
+	exit := processMain([]string{"/lets/hope/this/does/not/exist"}, nil, stdout, stderr, func(io.Reader, io.Writer) error {
+		return nil
+	})
+
+	assert.Equal(t, -1, exit)
+	assert.Zero(t, stdout.String())
+	assert.NotZero(t, stderr.String())
+}
+
+func TestProcessMainFilesInPlace(t *testing.T) {
+	dir := t.TempDir()
+
+	path1 := path.Join(dir, "file1")
+	path2 := path.Join(dir, "file2")
+
+	err := os.WriteFile(path1, []byte("content 1"), 0o600)
+	assert.NoError(t, err)
+	err = os.WriteFile(path2, []byte("content 2"), 0o600)
+	assert.NoError(t, err)
+
+	p := Program{
+		Fn:      dummyFileFn,
+		Inplace: true,
+	}
+
+	exit := p.main([]string{path1, path2}, os.Stdin, os.Stdout, os.Stderr)
+
+	assert.Equal(t, 0, exit)
+
+	v1, err := os.ReadFile(path1)
+	assert.NoError(t, err)
+	assert.Equal(t, "1", string(v1))
+
+	v2, err := os.ReadFile(path2)
+	assert.NoError(t, err)
+	assert.Equal(t, "2", string(v2))
+}
+
+func TestProcessMainFilesInPlaceErrRead(t *testing.T) {
+	p := Program{
+		Fn:      dummyFileFn,
+		Inplace: true,
+	}
+
+	exit := p.main([]string{"/this/path/is/invalid"}, os.Stdin, os.Stdout, os.Stderr)
+
+	assert.Equal(t, -1, exit)
+}
+
+func TestProcessMainFilesInPlaceFailFn(t *testing.T) {
+	dir := t.TempDir()
+
+	path1 := path.Join(dir, "file1")
+
+	err := os.WriteFile(path1, []byte("content 1"), 0o600)
+	assert.NoError(t, err)
+
+	p := Program{
+		Fn:      func(io.Reader, io.Writer) error { return errors.New("oh no") },
+		Inplace: true,
+	}
+
+	exit := p.main([]string{path1}, os.Stdin, os.Stdout, os.Stderr)
+
+	assert.Equal(t, -1, exit)
+
+	v1, err := os.ReadFile(path1)
+	assert.NoError(t, err)
+	assert.Equal(t, "content 1", string(v1))
+}
+
+func dummyFileFn(r io.Reader, w io.Writer) error {
+	b, err := io.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	v := strings.SplitN(string(b), " ", 2)[1]
+	_, err = w.Write([]byte(v))
+	return err
+}

internal/imported_tests/marshal_imported_test.go

@@ -0,0 +1,198 @@
+package imported_tests //revive:disable:var-naming
+
+// Those tests have been imported from v1, but adjust to match the new
+// defaults of v2.
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestDocMarshal(t *testing.T) {
+	type testDoc struct {
+		Title       string            `toml:"title"`
+		BasicLists  testDocBasicLists `toml:"basic_lists"`
+		SubDocPtrs  []*testSubDoc     `toml:"subdocptrs"`
+		BasicMap    map[string]string `toml:"basic_map"`
+		Subdocs     testDocSubs       `toml:"subdoc"`
+		Basics      testDocBasics     `toml:"basic"`
+		SubDocList  []testSubDoc      `toml:"subdoclist"`
+		err         int               `toml:"shouldntBeHere"` //nolint:unused
+		unexported  int               `toml:"shouldntBeHere"`
+		Unexported2 int               `toml:"-"`
+	}
+
+	docData := testDoc{
+		Title:       "TOML Marshal Testing",
+		unexported:  0,
+		Unexported2: 0,
+		Basics: testDocBasics{
+			Bool:       true,
+			Date:       time.Date(1979, 5, 27, 7, 32, 0, 0, time.UTC),
+			Float32:    123.4,
+			Float64:    123.456782132399,
+			Int:        5000,
+			Uint:       5001,
+			String:     &biteMe,
+			unexported: 0,
+		},
+		BasicLists: testDocBasicLists{
+			Floats: []*float32{&float1, &float2, &float3},
+			Bools:  []bool{true, false, true},
+			Dates: []time.Time{
+				time.Date(1979, 5, 27, 7, 32, 0, 0, time.UTC),
+				time.Date(1980, 5, 27, 7, 32, 0, 0, time.UTC),
+			},
+			Ints:    []int{8001, 8001, 8002},
+			Strings: []string{"One", "Two", "Three"},
+			UInts:   []uint{5002, 5003},
+		},
+		BasicMap: map[string]string{
+			"one": "one",
+			"two": "two",
+		},
+		Subdocs: testDocSubs{
+			First:  testSubDoc{"First", 0},
+			Second: &subdoc,
+		},
+		SubDocList: []testSubDoc{
+			{"List.First", 0},
+			{"List.Second", 0},
+		},
+		SubDocPtrs: []*testSubDoc{&subdoc},
+	}
+
+	marshalTestToml := `title = 'TOML Marshal Testing'
+
+[basic_lists]
+floats = [12.3, 45.6, 78.9]
+bools = [true, false, true]
+dates = [1979-05-27T07:32:00Z, 1980-05-27T07:32:00Z]
+ints = [8001, 8001, 8002]
+uints = [5002, 5003]
+strings = ['One', 'Two', 'Three']
+
+[[subdocptrs]]
+name = 'Second'
+
+[basic_map]
+one = 'one'
+two = 'two'
+
+[subdoc]
+[subdoc.second]
+name = 'Second'
+
+[subdoc.first]
+name = 'First'
+
+[basic]
+uint = 5001
+bool = true
+float = 123.4
+float64 = 123.456782132399
+int = 5000
+string = 'Bite me'
+date = 1979-05-27T07:32:00Z
+
+[[subdoclist]]
+name = 'List.First'
+
+[[subdoclist]]
+name = 'List.Second'
+`
+
+	result, err := toml.Marshal(docData)
+	assert.NoError(t, err)
+	assert.Equal(t, marshalTestToml, string(result))
+}
+
+func TestBasicMarshalQuotedKey(t *testing.T) {
+	result, err := toml.Marshal(quotedKeyMarshalTestData)
+	assert.NoError(t, err)
+
+	expected := `'Z.string-àéù' = 'Hello'
+'Yfloat-𝟘' = 3.5
+
+['Xsubdoc-àéù']
+String2 = 'One'
+
+[['W.sublist-𝟘']]
+String2 = 'Two'
+
+[['W.sublist-𝟘']]
+String2 = 'Three'
+`
+
+	assert.Equal(t, expected, string(result))
+}
+
+func TestEmptyMarshal(t *testing.T) {
+	type emptyMarshalTestStruct struct {
+		Title      string                  `toml:"title"`
+		Bool       bool                    `toml:"bool"`
+		Int        int                     `toml:"int"`
+		String     string                  `toml:"string"`
+		StringList []string                `toml:"stringlist"`
+		Ptr        *basicMarshalTestStruct `toml:"ptr"`
+		Map        map[string]string       `toml:"map"`
+	}
+
+	doc := emptyMarshalTestStruct{
+		Title:      "Placeholder",
+		Bool:       false,
+		Int:        0,
+		String:     "",
+		StringList: []string{},
+		Ptr:        nil,
+		Map:        map[string]string{},
+	}
+	result, err := toml.Marshal(doc)
+	assert.NoError(t, err)
+
+	expected := `title = 'Placeholder'
+bool = false
+int = 0
+string = ''
+stringlist = []
+
+[map]
+`
+
+	assert.Equal(t, expected, string(result))
+}
+
+type textMarshaler struct {
+	FirstName string
+	LastName  string
+}
+
+func (m textMarshaler) MarshalText() ([]byte, error) {
+	fullName := fmt.Sprintf("%s %s", m.FirstName, m.LastName)
+	return []byte(fullName), nil
+}
+
+func TestTextMarshaler(t *testing.T) {
+	type wrap struct {
+		TM textMarshaler
+	}
+
+	m := textMarshaler{FirstName: "Sally", LastName: "Fields"}
+
+	t.Run("at root", func(t *testing.T) {
+		_, err := toml.Marshal(m)
+		// in v2 we do not allow TextMarshaler at root
+		assert.Error(t, err)
+	})
+
+	t.Run("leaf", func(t *testing.T) {
+		res, err := toml.Marshal(wrap{m})
+		assert.NoError(t, err)
+
+		assert.Equal(t, "TM = 'Sally Fields'\n", string(res))
+	})
+}

internal/testsuite/add.go

@@ -0,0 +1,75 @@
+package testsuite
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"time"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+// addTag adds JSON tags to a data structure as expected by toml-test.
+func addTag(tomlData interface{}) interface{} {
+	// Switch on the data type.
+	switch orig := tomlData.(type) {
+	default:
+		// return map[string]interface{}{}
+		panic(fmt.Sprintf("Unknown type: %T", tomlData))
+
+	// A table: we don't need to add any tags, just recurse for every table
+	// entry.
+	case map[string]interface{}:
+		typed := make(map[string]interface{}, len(orig))
+		for k, v := range orig {
+			typed[k] = addTag(v)
+		}
+		return typed
+
+	// An array: we don't need to add any tags, just recurse for every table
+	// entry.
+	case []map[string]interface{}:
+		typed := make([]map[string]interface{}, len(orig))
+		for i, v := range orig {
+			typed[i] = addTag(v).(map[string]interface{})
+		}
+		return typed
+	case []interface{}:
+		typed := make([]interface{}, len(orig))
+		for i, v := range orig {
+			typed[i] = addTag(v)
+		}
+		return typed
+
+	// Datetime: tag as datetime.
+	case toml.LocalTime:
+		return tag("time-local", orig.String())
+	case toml.LocalDate:
+		return tag("date-local", orig.String())
+	case toml.LocalDateTime:
+		return tag("datetime-local", orig.String())
+	case time.Time:
+		return tag("datetime", orig.Format("2006-01-02T15:04:05.999999999Z07:00"))
+
+	// Tag primitive values: bool, string, int, and float64.
+	case bool:
+		return tag("bool", strconv.FormatBool(orig))
+	case string:
+		return tag("string", orig)
+	case int64:
+		return tag("integer", strconv.FormatInt(orig, 10))
+	case float64:
+		// Special case for nan since NaN == NaN is false.
+		if math.IsNaN(orig) {
+			return tag("float", "nan")
+		}
+		return tag("float", fmt.Sprintf("%v", orig))
+	}
+}
+
+func tag(typeName string, data interface{}) map[string]interface{} {
+	return map[string]interface{}{
+		"type":  typeName,
+		"value": data,
+	}
+}

internal/testsuite/json.go

@@ -0,0 +1,244 @@
+package testsuite
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+func CmpJSON(t *testing.T, key string, want, have interface{}) {
+	t.Helper()
+	switch w := want.(type) {
+	case map[string]interface{}:
+		cmpJSONMaps(t, key, w, have)
+	case []interface{}:
+		cmpJSONArrays(t, key, w, have)
+	default:
+		t.Errorf(
+			"Key '%s' in expected output should be a map or a list of maps, but it's a %T",
+			key, want)
+	}
+}
+
+func cmpJSONMaps(t *testing.T, key string, want map[string]interface{}, have interface{}) {
+	t.Helper()
+	haveMap, ok := have.(map[string]interface{})
+	if !ok {
+		mismatch(t, key, "table", want, haveMap)
+		return
+	}
+
+	// Check to make sure both or neither are values.
+	if isValue(want) && !isValue(haveMap) {
+		t.Fatalf("Key '%s' is supposed to be a value, but the parser reports it as a table", key)
+	}
+	if !isValue(want) && isValue(haveMap) {
+		t.Fatalf("Key '%s' is supposed to be a table, but the parser reports it as a value", key)
+	}
+	if isValue(want) && isValue(haveMap) {
+		cmpJSONValues(t, key, want, haveMap)
+		return
+	}
+
+	// Check that the keys of each map are equivalent.
+	for k := range want {
+		if _, ok := haveMap[k]; !ok {
+			bunk := kjoin(key, k)
+			t.Fatalf("Could not find key '%s' in parser output.", bunk)
+		}
+	}
+	for k := range haveMap {
+		if _, ok := want[k]; !ok {
+			bunk := kjoin(key, k)
+			t.Fatalf("Could not find key '%s' in expected output.", bunk)
+		}
+	}
+
+	// Okay, now make sure that each value is equivalent.
+	for k := range want {
+		CmpJSON(t, kjoin(key, k), want[k], haveMap[k])
+	}
+}
+
+func cmpJSONArrays(t *testing.T, key string, want, have interface{}) {
+	t.Helper()
+	wantSlice, ok := want.([]interface{})
+	if !ok {
+		panic(fmt.Sprintf("'value' should be a JSON array when 'type=array', but it is a %T", want))
+	}
+
+	haveSlice, ok := have.([]interface{})
+	if !ok {
+		t.Fatalf("Malformed output from your encoder: 'value' is not a JSON array: %T", have)
+	}
+
+	if len(wantSlice) != len(haveSlice) {
+		t.Fatalf("Array lengths differ for key '%s':\n"+
+			"  Expected:     %d\n"+
+			"  Your encoder: %d",
+			key, len(wantSlice), len(haveSlice))
+	}
+	for i := 0; i < len(wantSlice); i++ {
+		CmpJSON(t, key, wantSlice[i], haveSlice[i])
+	}
+}
+
+func cmpJSONValues(t *testing.T, key string, want, have map[string]interface{}) {
+	t.Helper()
+	wantType, ok := want["type"].(string)
+	if !ok {
+		panic(fmt.Sprintf("'type' should be a string, but it is a %T", want["type"]))
+	}
+
+	haveType, ok := have["type"].(string)
+	if !ok {
+		t.Fatalf("Malformed output from your encoder: 'type' is not a string: %T", have["type"])
+	}
+
+	if wantType != haveType {
+		valMismatch(t, key, wantType, haveType, want, have)
+	}
+
+	// If this is an array, then we've got to do some work to check equality.
+	if wantType == "array" {
+		cmpJSONArrays(t, key, want, have)
+		return
+	}
+
+	// Atomic values are always strings
+	wantVal, ok := want["value"].(string)
+	if !ok {
+		panic(fmt.Sprintf("'value' %v should be a string, but it is a %[1]T", want["value"]))
+	}
+
+	haveVal, ok := have["value"].(string)
+	if !ok {
+		panic(fmt.Sprintf("Malformed output from your encoder: %T is not a string", have["value"]))
+	}
+
+	// Excepting floats and datetimes, other values can be compared as strings.
+	switch wantType {
+	case "float":
+		cmpFloats(t, key, wantVal, haveVal)
+	case "datetime", "datetime-local", "date-local", "time-local":
+		cmpAsDatetimes(t, key, wantType, wantVal, haveVal)
+	default:
+		cmpAsStrings(t, key, wantVal, haveVal)
+	}
+}
+
+func cmpAsStrings(t *testing.T, key string, want, have string) {
+	t.Helper()
+	if want != have {
+		t.Fatalf("Values for key '%s' don't match:\n"+
+			"  Expected:     %s\n"+
+			"  Your encoder: %s",
+			key, want, have)
+	}
+}
+
+func cmpFloats(t *testing.T, key string, want, have string) {
+	t.Helper()
+	// Special case for NaN, since NaN != NaN.
+	if strings.HasSuffix(want, "nan") || strings.HasSuffix(have, "nan") {
+		if want != have {
+			t.Fatalf("Values for key '%s' don't match:\n"+
+				"  Expected:     %v\n"+
+				"  Your encoder: %v",
+				key, want, have)
+		}
+		return
+	}
+
+	wantF, err := strconv.ParseFloat(want, 64)
+	if err != nil {
+		panic(fmt.Sprintf("Could not read '%s' as a float value for key '%s'", want, key))
+	}
+
+	haveF, err := strconv.ParseFloat(have, 64)
+	if err != nil {
+		panic(fmt.Sprintf("Malformed output from your encoder: key '%s' is not a float: '%s'", key, have))
+	}
+
+	if wantF != haveF {
+		t.Fatalf("Values for key '%s' don't match:\n"+
+			"  Expected:     %v\n"+
+			"  Your encoder: %v",
+			key, wantF, haveF)
+	}
+}
+
+var datetimeRepl = strings.NewReplacer(
+	" ", "T",
+	"t", "T",
+	"z", "Z")
+
+var layouts = map[string]string{
+	"datetime":       time.RFC3339Nano,
+	"datetime-local": "2006-01-02T15:04:05.999999999",
+	"date-local":     "2006-01-02",
+	"time-local":     "15:04:05",
+}
+
+func cmpAsDatetimes(t *testing.T, key string, kind, want, have string) {
+	t.Helper()
+	layout, ok := layouts[kind]
+	if !ok {
+		panic("should never happen")
+	}
+
+	wantT, err := time.Parse(layout, datetimeRepl.Replace(want))
+	if err != nil {
+		panic(fmt.Sprintf("Could not read '%s' as a datetime value for key '%s'", want, key))
+	}
+
+	haveT, err := time.Parse(layout, datetimeRepl.Replace(want))
+	if err != nil {
+		t.Fatalf("Malformed output from your encoder: key '%s' is not a datetime: '%s'", key, have)
+		return
+	}
+	if !wantT.Equal(haveT) {
+		t.Fatalf("Values for key '%s' don't match:\n"+
+			"  Expected:     %v\n"+
+			"  Your encoder: %v",
+			key, wantT, haveT)
+	}
+}
+
+func kjoin(old, key string) string {
+	if len(old) == 0 {
+		return key
+	}
+	return old + "." + key
+}
+
+func isValue(m map[string]interface{}) bool {
+	if len(m) != 2 {
+		return false
+	}
+	if _, ok := m["type"]; !ok {
+		return false
+	}
+	if _, ok := m["value"]; !ok {
+		return false
+	}
+	return true
+}
+
+func mismatch(t *testing.T, key string, wantType string, want, have interface{}) {
+	t.Helper()
+	t.Fatalf("Key '%s' is not an %s but %[4]T:\n"+
+		"  Expected:     %#[3]v\n"+
+		"  Your encoder: %#[4]v",
+		key, wantType, want, have)
+}
+
+func valMismatch(t *testing.T, key string, wantType, haveType string, want, have interface{}) {
+	t.Helper()
+	t.Fatalf("Key '%s' is not an %s but %s:\n"+
+		"  Expected:     %#[3]v\n"+
+		"  Your encoder: %#[4]v",
+		key, wantType, haveType, want, have)
+}

internal/testsuite/rm.go

@@ -0,0 +1,116 @@
+package testsuite
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+// Remove JSON tags to a data structure as returned by toml-test.
+func rmTag(typedJSON interface{}) (interface{}, error) {
+	// Check if key is in the table m.
+	in := func(key string, m map[string]interface{}) bool {
+		_, ok := m[key]
+		return ok
+	}
+
+	// Switch on the data type.
+	switch v := typedJSON.(type) {
+	// Object: this can either be a TOML table or a primitive with tags.
+	case map[string]interface{}:
+		// This value represents a primitive: remove the tags and return just
+		// the primitive value.
+		if len(v) == 2 && in("type", v) && in("value", v) {
+			ut, err := untag(v)
+			if err != nil {
+				return ut, fmt.Errorf("tag.Remove: %w", err)
+			}
+			return ut, nil
+		}
+
+		// Table: remove tags on all children.
+		m := make(map[string]interface{}, len(v))
+		for k, v2 := range v {
+			var err error
+			m[k], err = rmTag(v2)
+			if err != nil {
+				return nil, err
+			}
+		}
+		return m, nil
+
+	// Array: remove tags from all items.
+	case []interface{}:
+		a := make([]interface{}, len(v))
+		for i := range v {
+			var err error
+			a[i], err = rmTag(v[i])
+			if err != nil {
+				return nil, err
+			}
+		}
+		return a, nil
+	}
+
+	// The top level must be an object or array.
+	return nil, fmt.Errorf("unrecognized JSON format '%T'", typedJSON)
+}
+
+// Return a primitive: read the "type" and convert the "value" to that.
+func untag(typed map[string]interface{}) (interface{}, error) {
+	t := typed["type"].(string)
+	v := typed["value"].(string)
+	switch t {
+	case "string":
+		return v, nil
+	case "integer":
+		n, err := strconv.ParseInt(v, 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("untag: %w", err)
+		}
+		return n, nil
+	case "float":
+		f, err := strconv.ParseFloat(v, 64)
+		if err != nil {
+			return nil, fmt.Errorf("untag: %w", err)
+		}
+		return f, nil
+
+		// toml.LocalDate{Year:2020, Month:12, Day:12}
+	case "datetime":
+		return time.Parse("2006-01-02T15:04:05.999999999Z07:00", v)
+	case "datetime-local":
+		var t toml.LocalDateTime
+		err := t.UnmarshalText([]byte(v))
+		if err != nil {
+			return nil, fmt.Errorf("untag: %w", err)
+		}
+		return t, nil
+	case "date-local":
+		var t toml.LocalDate
+		err := t.UnmarshalText([]byte(v))
+		if err != nil {
+			return nil, fmt.Errorf("untag: %w", err)
+		}
+		return t, nil
+	case "time-local":
+		var t toml.LocalTime
+		err := t.UnmarshalText([]byte(v))
+		if err != nil {
+			return nil, fmt.Errorf("untag: %w", err)
+		}
+		return t, nil
+	case "bool":
+		switch v {
+		case "true":
+			return true, nil
+		case "false":
+			return false, nil
+		}
+		return nil, fmt.Errorf("untag: could not parse %q as a boolean", v)
+	}
+
+	return nil, fmt.Errorf("untag: unrecognized tag type %q", t)
+}

internal/testsuite/testsuite.go

@@ -0,0 +1,68 @@
+// Package testsuite provides helper functions for interoperating with the
+// language-agnostic TOML test suite at github.com/BurntSushi/toml-test.
+package testsuite
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+// Marshal is a helper function for calling toml.Marshal
+//
+// Only needed to avoid package import loops.
+func Marshal(v interface{}) ([]byte, error) {
+	return toml.Marshal(v)
+}
+
+// Unmarshal is a helper function for calling toml.Unmarshal.
+//
+// Only needed to avoid package import loops.
+func Unmarshal(data []byte, v interface{}) error {
+	return toml.Unmarshal(data, v)
+}
+
+// ValueToTaggedJSON takes a data structure and returns the tagged JSON
+// representation.
+func ValueToTaggedJSON(doc interface{}) ([]byte, error) {
+	return json.MarshalIndent(addTag(doc), "", "  ")
+}
+
+// DecodeStdin is a helper function for the toml-test binary interface.  TOML input
+// is read from STDIN and a resulting tagged JSON representation is written to
+// STDOUT.
+func DecodeStdin() error {
+	var decoded map[string]interface{}
+
+	if err := toml.NewDecoder(os.Stdin).Decode(&decoded); err != nil {
+		return fmt.Errorf("error decoding TOML: %w", err)
+	}
+
+	j := json.NewEncoder(os.Stdout)
+	j.SetIndent("", "  ")
+	if err := j.Encode(addTag(decoded)); err != nil {
+		return fmt.Errorf("error encoding JSON: %w", err)
+	}
+
+	return nil
+}
+
+// EncodeStdin is a helper function for the toml-test binary interface.  Tagged
+// JSON is read from STDIN and a resulting TOML representation is written to
+// STDOUT.
+func EncodeStdin() error {
+	var j interface{}
+	err := json.NewDecoder(os.Stdin).Decode(&j)
+	if err != nil {
+		return err
+	}
+
+	rm, err := rmTag(j)
+	if err != nil {
+		return fmt.Errorf("removing tags: %w", err)
+	}
+
+	return toml.NewEncoder(os.Stdout).Encode(rm)
+}

internal/tracker/key.go

@@ -0,0 +1,48 @@
+package tracker
+
+import "github.com/pelletier/go-toml/v2/unstable"
+
+// KeyTracker is a tracker that keeps track of the current Key as the AST is
+// walked.
+type KeyTracker struct {
+	k []string
+}
+
+// UpdateTable sets the state of the tracker with the AST table node.
+func (t *KeyTracker) UpdateTable(node *unstable.Node) {
+	t.reset()
+	t.Push(node)
+}
+
+// UpdateArrayTable sets the state of the tracker with the AST array table node.
+func (t *KeyTracker) UpdateArrayTable(node *unstable.Node) {
+	t.reset()
+	t.Push(node)
+}
+
+// Push the given key on the stack.
+func (t *KeyTracker) Push(node *unstable.Node) {
+	it := node.Key()
+	for it.Next() {
+		t.k = append(t.k, string(it.Node().Data))
+	}
+}
+
+// Pop key from stack.
+func (t *KeyTracker) Pop(node *unstable.Node) {
+	it := node.Key()
+	for it.Next() {
+		t.k = t.k[:len(t.k)-1]
+	}
+}
+
+// Key returns the current key.
+func (t *KeyTracker) Key() []string {
+	k := make([]string, len(t.k))
+	copy(k, t.k)
+	return k
+}
+
+func (t *KeyTracker) reset() {
+	t.k = t.k[:0]
+}

internal/tracker/seen.go

@@ -0,0 +1,359 @@
+package tracker
+
+import (
+	"bytes"
+	"fmt"
+	"sync"
+
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+type keyKind uint8
+
+const (
+	invalidKind keyKind = iota
+	valueKind
+	tableKind
+	arrayTableKind
+)
+
+func (k keyKind) String() string {
+	switch k {
+	case invalidKind:
+		return "invalid"
+	case valueKind:
+		return "value"
+	case tableKind:
+		return "table"
+	case arrayTableKind:
+		return "array table"
+	}
+	panic("missing keyKind string mapping")
+}
+
+// SeenTracker tracks which keys have been seen with which TOML type to flag
+// duplicates and mismatches according to the spec.
+//
+// Each node in the visited tree is represented by an entry. Each entry has an
+// identifier, which is provided by a counter. Entries are stored in the array
+// entries. As new nodes are discovered (referenced for the first time in the
+// TOML document), entries are created and appended to the array. An entry
+// points to its parent using its id.
+//
+// To find whether a given key (sequence of []byte) has already been visited,
+// the entries are linearly searched, looking for one with the right name and
+// parent id.
+//
+// Given that all keys appear in the document after their parent, it is
+// guaranteed that all descendants of a node are stored after the node, this
+// speeds up the search process.
+//
+// When encountering [[array tables]], the descendants of that node are removed
+// to allow that branch of the tree to be "rediscovered". To maintain the
+// invariant above, the deletion process needs to keep the order of entries.
+// This results in more copies in that case.
+type SeenTracker struct {
+	entries    []entry
+	currentIdx int
+}
+
+var pool = sync.Pool{
+	New: func() interface{} {
+		return &SeenTracker{}
+	},
+}
+
+func (s *SeenTracker) reset() {
+	// Always contains a root element at index 0.
+	s.currentIdx = 0
+	if len(s.entries) == 0 {
+		s.entries = make([]entry, 1, 2)
+	} else {
+		s.entries = s.entries[:1]
+	}
+	s.entries[0].child = -1
+	s.entries[0].next = -1
+}
+
+type entry struct {
+	// Use -1 to indicate no child or no sibling.
+	child int
+	next  int
+
+	name     []byte
+	kind     keyKind
+	explicit bool
+	kv       bool
+}
+
+// Find the index of the child of parentIdx with key k. Returns -1 if
+// it does not exist.
+func (s *SeenTracker) find(parentIdx int, k []byte) int {
+	for i := s.entries[parentIdx].child; i >= 0; i = s.entries[i].next {
+		if bytes.Equal(s.entries[i].name, k) {
+			return i
+		}
+	}
+	return -1
+}
+
+// Remove all descendants of node at position idx.
+func (s *SeenTracker) clear(idx int) {
+	if idx >= len(s.entries) {
+		return
+	}
+
+	for i := s.entries[idx].child; i >= 0; {
+		next := s.entries[i].next
+		n := s.entries[0].next
+		s.entries[0].next = i
+		s.entries[i].next = n
+		s.entries[i].name = nil
+		s.clear(i)
+		i = next
+	}
+
+	s.entries[idx].child = -1
+}
+
+func (s *SeenTracker) create(parentIdx int, name []byte, kind keyKind, explicit bool, kv bool) int {
+	e := entry{
+		child: -1,
+		next:  s.entries[parentIdx].child,
+
+		name:     name,
+		kind:     kind,
+		explicit: explicit,
+		kv:       kv,
+	}
+	var idx int
+	if s.entries[0].next >= 0 {
+		idx = s.entries[0].next
+		s.entries[0].next = s.entries[idx].next
+		s.entries[idx] = e
+	} else {
+		idx = len(s.entries)
+		s.entries = append(s.entries, e)
+	}
+
+	s.entries[parentIdx].child = idx
+
+	return idx
+}
+
+func (s *SeenTracker) setExplicitFlag(parentIdx int) {
+	for i := s.entries[parentIdx].child; i >= 0; i = s.entries[i].next {
+		if s.entries[i].kv {
+			s.entries[i].explicit = true
+			s.entries[i].kv = false
+		}
+		s.setExplicitFlag(i)
+	}
+}
+
+// CheckExpression takes a top-level node and checks that it does not contain
+// keys that have been seen in previous calls, and validates that types are
+// consistent. It returns true if it is the first time this node's key is seen.
+// Useful to clear array tables on first use.
+func (s *SeenTracker) CheckExpression(node *unstable.Node) (bool, error) {
+	if s.entries == nil {
+		s.reset()
+	}
+	switch node.Kind {
+	case unstable.KeyValue:
+		return s.checkKeyValue(node)
+	case unstable.Table:
+		return s.checkTable(node)
+	case unstable.ArrayTable:
+		return s.checkArrayTable(node)
+	default:
+		panic(fmt.Errorf("this should not be a top level node type: %s", node.Kind))
+	}
+}
+
+func (s *SeenTracker) checkTable(node *unstable.Node) (bool, error) {
+	if s.currentIdx >= 0 {
+		s.setExplicitFlag(s.currentIdx)
+	}
+
+	it := node.Key()
+
+	parentIdx := 0
+
+	// This code is duplicated in checkArrayTable. This is because factoring
+	// it in a function requires to copy the iterator, or allocate it to the
+	// heap, which is not cheap.
+	for it.Next() {
+		if it.IsLast() {
+			break
+		}
+
+		k := it.Node().Data
+
+		idx := s.find(parentIdx, k)
+
+		if idx < 0 {
+			idx = s.create(parentIdx, k, tableKind, false, false)
+		} else {
+			entry := s.entries[idx]
+			if entry.kind == valueKind {
+				return false, fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind)
+			}
+		}
+		parentIdx = idx
+	}
+
+	k := it.Node().Data
+	idx := s.find(parentIdx, k)
+
+	first := false
+	if idx >= 0 {
+		kind := s.entries[idx].kind
+		if kind != tableKind {
+			return false, fmt.Errorf("toml: key %s should be a table, not a %s", string(k), kind)
+		}
+		if s.entries[idx].explicit {
+			return false, fmt.Errorf("toml: table %s already exists", string(k))
+		}
+		s.entries[idx].explicit = true
+	} else {
+		idx = s.create(parentIdx, k, tableKind, true, false)
+		first = true
+	}
+
+	s.currentIdx = idx
+
+	return first, nil
+}
+
+func (s *SeenTracker) checkArrayTable(node *unstable.Node) (bool, error) {
+	if s.currentIdx >= 0 {
+		s.setExplicitFlag(s.currentIdx)
+	}
+
+	it := node.Key()
+
+	parentIdx := 0
+
+	for it.Next() {
+		if it.IsLast() {
+			break
+		}
+
+		k := it.Node().Data
+
+		idx := s.find(parentIdx, k)
+
+		if idx < 0 {
+			idx = s.create(parentIdx, k, tableKind, false, false)
+		} else {
+			entry := s.entries[idx]
+			if entry.kind == valueKind {
+				return false, fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind)
+			}
+		}
+
+		parentIdx = idx
+	}
+
+	k := it.Node().Data
+	idx := s.find(parentIdx, k)
+
+	firstTime := idx < 0
+	if firstTime {
+		idx = s.create(parentIdx, k, arrayTableKind, true, false)
+	} else {
+		kind := s.entries[idx].kind
+		if kind != arrayTableKind {
+			return false, fmt.Errorf("toml: key %s already exists as a %s,  but should be an array table", kind, string(k))
+		}
+		s.clear(idx)
+	}
+
+	s.currentIdx = idx
+
+	return firstTime, nil
+}
+
+func (s *SeenTracker) checkKeyValue(node *unstable.Node) (bool, error) {
+	parentIdx := s.currentIdx
+	it := node.Key()
+
+	for it.Next() {
+		k := it.Node().Data
+
+		idx := s.find(parentIdx, k)
+
+		if idx < 0 {
+			idx = s.create(parentIdx, k, tableKind, false, true)
+		} else {
+			entry := s.entries[idx]
+			switch {
+			case it.IsLast():
+				return false, fmt.Errorf("toml: key %s is already defined", string(k))
+			case entry.kind != tableKind:
+				return false, fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind)
+			case entry.explicit:
+				return false, fmt.Errorf("toml: cannot redefine table %s that has already been explicitly defined", string(k))
+			}
+		}
+
+		parentIdx = idx
+	}
+
+	s.entries[parentIdx].kind = valueKind
+
+	value := node.Value()
+
+	switch value.Kind {
+	case unstable.InlineTable:
+		return s.checkInlineTable(value)
+	case unstable.Array:
+		return s.checkArray(value)
+	default:
+		return false, nil
+	}
+}
+
+func (s *SeenTracker) checkArray(node *unstable.Node) (first bool, err error) {
+	it := node.Children()
+	for it.Next() {
+		n := it.Node()
+		switch n.Kind { //nolint:exhaustive
+		case unstable.InlineTable:
+			first, err = s.checkInlineTable(n)
+			if err != nil {
+				return false, err
+			}
+		case unstable.Array:
+			first, err = s.checkArray(n)
+			if err != nil {
+				return false, err
+			}
+		}
+	}
+	return first, nil
+}
+
+func (s *SeenTracker) checkInlineTable(node *unstable.Node) (first bool, err error) {
+	s = pool.Get().(*SeenTracker)
+	s.reset()
+
+	it := node.Children()
+	for it.Next() {
+		n := it.Node()
+		first, err = s.checkKeyValue(n)
+		if err != nil {
+			return false, err
+		}
+	}
+
+	// As inline tables are self-contained, the tracker does not
+	// need to retain the details of what they contain. The
+	// keyValue element that creates the inline table is kept to
+	// mark the presence of the inline table and prevent
+	// redefinition of its keys: check* functions cannot walk into
+	// a value.
+	pool.Put(s)
+	return first, nil
+}

internal/tracker/seen_test.go

@@ -0,0 +1,21 @@
+package tracker
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestEntrySize(t *testing.T) {
+	// Validate no regression on the size of entry{}. This is a critical bit for
+	// performance of unmarshaling documents. Should only be increased with care
+	// and a very good reason.
+	maxExpectedEntrySize := 48
+	entrySize := int(reflect.TypeOf(entry{}).Size())
+	assert.True(t,
+		entrySize <= maxExpectedEntrySize,
+		"Expected entry to be less than or equal to %d, got: %d",
+		maxExpectedEntrySize, entrySize,
+	)
+}

internal/tracker/tracker.go

@@ -0,0 +1,2 @@
+// Package tracker provides functions for keeping track of AST nodes.
+package tracker

lexer.go

@@ -1,510 +0,0 @@
-// TOML lexer.// Written using the principles developped by Rob Pike in
-// http://www.youtube.com/watch?v=HxaD_trXwRE
-
-package toml
-
-import (
-	"fmt"
-	"regexp"
-	"strconv"
-	"strings"
-	"unicode"
-	"unicode/utf8"
-)
-
-var dateRegexp *regexp.Regexp
-
-// Define tokens
-type tokenType int
-
-const (
-	eof = -(iota + 1)
-)
-
-const (
-	tokenError tokenType = iota
-	tokenEOF
-	tokenComment
-	tokenKey
-	tokenEqual
-	tokenString
-	tokenInteger
-	tokenTrue
-	tokenFalse
-	tokenFloat
-	tokenLeftBracket
-	tokenRightBracket
-	tokenDoubleLeftBracket
-	tokenDoubleRightBracket
-	tokenDate
-	tokenKeyGroup
-	tokenKeyGroupArray
-	tokenComma
-	tokenEOL
-)
-
-type token struct {
-	typ tokenType
-	val string
-}
-
-func (i token) String() string {
-	switch i.typ {
-	case tokenEOF:
-		return "EOF"
-	case tokenError:
-		return i.val
-	}
-
-	if len(i.val) > 10 {
-		return fmt.Sprintf("%.10q...", i.val)
-	}
-	return fmt.Sprintf("%q", i.val)
-}
-
-func isSpace(r rune) bool {
-	return r == ' ' || r == '\t'
-}
-
-func isAlphanumeric(r rune) bool {
-	return unicode.IsLetter(r) || r == '_'
-}
-
-func isKeyChar(r rune) bool {
-	// "Keys start with the first non-whitespace character and end with the last
-	// non-whitespace character before the equals sign."
-	return !(isSpace(r) || r == '\r' || r == '\n' || r == eof || r == '=')
-}
-
-func isDigit(r rune) bool {
-	return unicode.IsNumber(r)
-}
-
-func isHexDigit(r rune) bool {
-	return isDigit(r) ||
-		r == 'A' || r == 'B' || r == 'C' || r == 'D' || r == 'E' || r == 'F'
-}
-
-// Define lexer
-type lexer struct {
-	input  string
-	start  int
-	pos    int
-	width  int
-	tokens chan token
-	depth  int
-}
-
-func (l *lexer) run() {
-	for state := lexVoid; state != nil; {
-		state = state(l)
-	}
-	close(l.tokens)
-}
-
-func (l *lexer) emit(t tokenType) {
-	l.tokens <- token{t, l.input[l.start:l.pos]}
-	l.start = l.pos
-}
-
-func (l *lexer) emitWithValue(t tokenType, value string) {
-	l.tokens <- token{t, value}
-	l.start = l.pos
-}
-
-func (l *lexer) next() rune {
-	if l.pos >= len(l.input) {
-		l.width = 0
-		return eof
-	}
-	var r rune
-	r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
-	l.pos += l.width
-	return r
-}
-
-func (l *lexer) ignore() {
-	l.start = l.pos
-}
-
-func (l *lexer) backup() {
-	l.pos -= l.width
-}
-
-func (l *lexer) errorf(format string, args ...interface{}) stateFn {
-	l.tokens <- token{
-		tokenError,
-		fmt.Sprintf(format, args...),
-	}
-	return nil
-}
-
-func (l *lexer) peek() rune {
-	r := l.next()
-	l.backup()
-	return r
-}
-
-func (l *lexer) accept(valid string) bool {
-	if strings.IndexRune(valid, l.next()) >= 0 {
-		return true
-	}
-	l.backup()
-	return false
-}
-
-func (l *lexer) follow(next string) bool {
-	return strings.HasPrefix(l.input[l.pos:], next)
-}
-
-// Define state functions
-type stateFn func(*lexer) stateFn
-
-func lexVoid(l *lexer) stateFn {
-	for {
-		next := l.peek()
-		switch next {
-		case '[':
-			return lexKeyGroup
-		case '#':
-			return lexComment
-		case '=':
-			return lexEqual
-		}
-
-		if isSpace(next) {
-			l.ignore()
-		}
-
-		if l.depth > 0 {
-			return lexRvalue
-		}
-
-		if isKeyChar(next) {
-			return lexKey
-		}
-
-		if l.next() == eof {
-			break
-		}
-	}
-
-	l.emit(tokenEOF)
-	return nil
-}
-
-func lexRvalue(l *lexer) stateFn {
-	for {
-		next := l.peek()
-		switch next {
-		case '.':
-			return l.errorf("cannot start float with a dot")
-		case '=':
-			return l.errorf("cannot have multiple equals for the same key")
-		case '[':
-			l.depth += 1
-			return lexLeftBracket
-		case ']':
-			l.depth -= 1
-			return lexRightBracket
-		case '#':
-			return lexComment
-		case '"':
-			return lexString
-		case ',':
-			return lexComma
-		case '\n':
-			l.ignore()
-			l.pos += 1
-			if l.depth == 0 {
-				return lexVoid
-			} else {
-				return lexRvalue
-			}
-		}
-
-		if l.follow("true") {
-			return lexTrue
-		}
-
-		if l.follow("false") {
-			return lexFalse
-		}
-
-		if isAlphanumeric(next) {
-			return lexKey
-		}
-
-		if dateRegexp.FindString(l.input[l.pos:]) != "" {
-			return lexDate
-		}
-
-		if next == '+' || next == '-' || isDigit(next) {
-			return lexNumber
-		}
-
-		if isSpace(next) {
-			l.ignore()
-		}
-
-		if l.next() == eof {
-			break
-		}
-	}
-
-	l.emit(tokenEOF)
-	return nil
-}
-
-func lexDate(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 20 // Fixed size of a date in TOML
-	l.emit(tokenDate)
-	return lexRvalue
-}
-
-func lexTrue(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 4
-	l.emit(tokenTrue)
-	return lexRvalue
-}
-
-func lexFalse(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 5
-	l.emit(tokenFalse)
-	return lexRvalue
-}
-
-func lexEqual(l *lexer) stateFn {
-	l.ignore()
-	l.accept("=")
-	l.emit(tokenEqual)
-	return lexRvalue
-}
-
-func lexComma(l *lexer) stateFn {
-	l.ignore()
-	l.accept(",")
-	l.emit(tokenComma)
-	return lexRvalue
-}
-
-func lexKey(l *lexer) stateFn {
-	l.ignore()
-	for isKeyChar(l.next()) {
-	}
-	l.backup()
-	l.emit(tokenKey)
-	return lexVoid
-}
-
-func lexComment(l *lexer) stateFn {
-	for {
-		next := l.next()
-		if next == '\n' || next == eof {
-			break
-		}
-	}
-	l.ignore()
-	return lexVoid
-}
-
-func lexLeftBracket(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 1
-	l.emit(tokenLeftBracket)
-	return lexRvalue
-}
-
-func lexString(l *lexer) stateFn {
-	l.pos += 1
-	l.ignore()
-	growing_string := ""
-
-	for {
-		if l.peek() == '"' {
-			l.emitWithValue(tokenString, growing_string)
-			l.pos += 1
-			l.ignore()
-			return lexRvalue
-		}
-
-		if l.follow("\\\"") {
-			l.pos += 1
-			growing_string += "\""
-		} else if l.follow("\\n") {
-			l.pos += 1
-			growing_string += "\n"
-		} else if l.follow("\\b") {
-			l.pos += 1
-			growing_string += "\b"
-		} else if l.follow("\\f") {
-			l.pos += 1
-			growing_string += "\f"
-		} else if l.follow("\\/") {
-			l.pos += 1
-			growing_string += "/"
-		} else if l.follow("\\t") {
-			l.pos += 1
-			growing_string += "\t"
-		} else if l.follow("\\r") {
-			l.pos += 1
-			growing_string += "\r"
-		} else if l.follow("\\\\") {
-			l.pos += 1
-			growing_string += "\\"
-		} else if l.follow("\\u") {
-			l.pos += 2
-			code := ""
-			for i := 0; i < 4; i++ {
-				c := l.peek()
-				l.pos += 1
-				if !isHexDigit(c) {
-					return l.errorf("unfinished unicode escape")
-				}
-				code = code + string(c)
-			}
-			l.pos -= 1
-			intcode, err := strconv.ParseInt(code, 16, 32)
-			if err != nil {
-				return l.errorf("invalid unicode escape: \\u" + code)
-			}
-			growing_string += string(rune(intcode))
-		} else if l.follow("\\") {
-			l.pos += 1
-			return l.errorf("invalid escape sequence: \\" + string(l.peek()))
-		} else {
-			growing_string += string(l.peek())
-		}
-
-		if l.next() == eof {
-			break
-		}
-	}
-
-	return l.errorf("unclosed string")
-}
-
-func lexKeyGroup(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 1
-
-	if l.peek() == '[' {
-		// token '[[' signifies an array of anonymous key groups
-		l.pos += 1
-		l.emit(tokenDoubleLeftBracket)
-		return lexInsideKeyGroupArray
-	} else {
-		// vanilla key group
-		l.emit(tokenLeftBracket)
-		return lexInsideKeyGroup
-	}
-}
-
-func lexInsideKeyGroupArray(l *lexer) stateFn {
-	for {
-		if l.peek() == ']' {
-			if l.pos > l.start {
-				l.emit(tokenKeyGroupArray)
-			}
-			l.ignore()
-			l.pos += 1
-			if l.peek() != ']' {
-				break // error
-			}
-			l.pos += 1
-			l.emit(tokenDoubleRightBracket)
-			return lexVoid
-		} else if l.peek() == '[' {
-			return l.errorf("group name cannot contain ']'")
-		}
-
-		if l.next() == eof {
-			break
-		}
-	}
-	return l.errorf("unclosed key group array")
-}
-
-func lexInsideKeyGroup(l *lexer) stateFn {
-	for {
-		if l.peek() == ']' {
-			if l.pos > l.start {
-				l.emit(tokenKeyGroup)
-			}
-			l.ignore()
-			l.pos += 1
-			l.emit(tokenRightBracket)
-			return lexVoid
-		} else if l.peek() == '[' {
-			return l.errorf("group name cannot contain ']'")
-		}
-
-		if l.next() == eof {
-			break
-		}
-	}
-	return l.errorf("unclosed key group")
-}
-
-func lexRightBracket(l *lexer) stateFn {
-	l.ignore()
-	l.pos += 1
-	l.emit(tokenRightBracket)
-	return lexRvalue
-}
-
-func lexNumber(l *lexer) stateFn {
-	l.ignore()
-	if !l.accept("+") {
-		l.accept("-")
-	}
-	point_seen := false
-	digit_seen := false
-	for {
-		next := l.next()
-		if next == '.' {
-			if point_seen {
-				return l.errorf("cannot have two dots in one float")
-			}
-			if !isDigit(l.peek()) {
-				return l.errorf("float cannot end with a dot")
-			}
-			point_seen = true
-		} else if isDigit(next) {
-			digit_seen = true
-		} else {
-			l.backup()
-			break
-		}
-		if point_seen && !digit_seen {
-			return l.errorf("cannot start float with a dot")
-		}
-	}
-
-	if !digit_seen {
-		return l.errorf("no digit in that number")
-	}
-	if point_seen {
-		l.emit(tokenFloat)
-	} else {
-		l.emit(tokenInteger)
-	}
-	return lexRvalue
-}
-
-func init() {
-	dateRegexp = regexp.MustCompile("^\\d{1,4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")
-}
-
-// Entry point
-func lex(input string) (*lexer, chan token) {
-	l := &lexer{
-		input:  input,
-		tokens: make(chan token),
-	}
-	go l.run()
-	return l, l.tokens
-}

lexer_test.go

@@ -1,415 +0,0 @@
-package toml
-
-import "testing"
-
-func testFlow(t *testing.T, input string, expectedFlow []token) {
-	_, ch := lex(input)
-	for _, expected := range expectedFlow {
-		token := <-ch
-		if token != expected {
-			t.Log("compared", token, "to", expected)
-			t.Log(token.val, "<->", expected.val)
-			t.Log(token.typ, "<->", expected.typ)
-			t.FailNow()
-		}
-	}
-
-	tok, ok := <-ch
-	if ok {
-		t.Log("channel is not closed!")
-		t.Log(len(ch)+1, "tokens remaining:")
-
-		t.Log("token ->", tok)
-		for token := range ch {
-			t.Log("token ->", token)
-		}
-		t.FailNow()
-	}
-}
-
-func TestValidKeyGroup(t *testing.T) {
-	testFlow(t, "[hello world]", []token{
-		token{tokenLeftBracket, "["},
-		token{tokenKeyGroup, "hello world"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestUnclosedKeyGroup(t *testing.T) {
-	testFlow(t, "[hello world", []token{
-		token{tokenLeftBracket, "["},
-		token{tokenError, "unclosed key group"},
-	})
-}
-
-func TestComment(t *testing.T) {
-	testFlow(t, "# blahblah", []token{
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyGroupComment(t *testing.T) {
-	testFlow(t, "[hello world] # blahblah", []token{
-		token{tokenLeftBracket, "["},
-		token{tokenKeyGroup, "hello world"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestMultipleKeyGroupsComment(t *testing.T) {
-	testFlow(t, "[hello world] # blahblah\n[test]", []token{
-		token{tokenLeftBracket, "["},
-		token{tokenKeyGroup, "hello world"},
-		token{tokenRightBracket, "]"},
-		token{tokenLeftBracket, "["},
-		token{tokenKeyGroup, "test"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKey(t *testing.T) {
-	testFlow(t, "hello", []token{
-		token{tokenKey, "hello"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKeyWithUnderscore(t *testing.T) {
-	testFlow(t, "hello_hello", []token{
-		token{tokenKey, "hello_hello"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKeyWithDash(t *testing.T) {
-	testFlow(t, "hello-world", []token{
-		token{tokenKey, "hello-world"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKeyWithUppercaseMix(t *testing.T) {
-	testFlow(t, "helloHELLOHello", []token{
-		token{tokenKey, "helloHELLOHello"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKeyWithInternationalCharacters(t *testing.T) {
-	testFlow(t, "héllÖ", []token{
-		token{tokenKey, "héllÖ"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestBasicKeyAndEqual(t *testing.T) {
-	testFlow(t, "hello =", []token{
-		token{tokenKey, "hello"},
-		token{tokenEqual, "="},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyWithSharpAndEqual(t *testing.T) {
-	testFlow(t, "key#name = 5", []token{
-		token{tokenKey, "key#name"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "5"},
-		token{tokenEOF, ""},
-	})
-}
-func TestKeyWithSymbolsAndEqual(t *testing.T) {
-	testFlow(t, "~!@#$^&*()_+-`1234567890[]\\|/?><.,;:' = 5", []token{
-		token{tokenKey, "~!@#$^&*()_+-`1234567890[]\\|/?><.,;:'"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "5"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualStringEscape(t *testing.T) {
-	testFlow(t, "foo = \"hello\\\"\"", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenString, "hello\""},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualStringUnfinished(t *testing.T) {
-	testFlow(t, "foo = \"bar", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenError, "unclosed string"},
-	})
-}
-
-func TestKeyEqualString(t *testing.T) {
-	testFlow(t, "foo = \"bar\"", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenString, "bar"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualTrue(t *testing.T) {
-	testFlow(t, "foo = true", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenTrue, "true"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualFalse(t *testing.T) {
-	testFlow(t, "foo = false", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenFalse, "false"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestArrayNestedString(t *testing.T) {
-	testFlow(t, "a = [ [\"hello\", \"world\"] ]", []token{
-		token{tokenKey, "a"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenLeftBracket, "["},
-		token{tokenString, "hello"},
-		token{tokenComma, ","},
-		token{tokenString, "world"},
-		token{tokenRightBracket, "]"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestArrayNestedInts(t *testing.T) {
-	testFlow(t, "a = [ [42, 21], [10] ]", []token{
-		token{tokenKey, "a"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenLeftBracket, "["},
-		token{tokenInteger, "42"},
-		token{tokenComma, ","},
-		token{tokenInteger, "21"},
-		token{tokenRightBracket, "]"},
-		token{tokenComma, ","},
-		token{tokenLeftBracket, "["},
-		token{tokenInteger, "10"},
-		token{tokenRightBracket, "]"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestArrayInts(t *testing.T) {
-	testFlow(t, "a = [ 42, 21, 10, ]", []token{
-		token{tokenKey, "a"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenInteger, "42"},
-		token{tokenComma, ","},
-		token{tokenInteger, "21"},
-		token{tokenComma, ","},
-		token{tokenInteger, "10"},
-		token{tokenComma, ","},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestMultilineArrayComments(t *testing.T) {
-	testFlow(t, "a = [1, # wow\n2, # such items\n3, # so array\n]", []token{
-		token{tokenKey, "a"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenInteger, "1"},
-		token{tokenComma, ","},
-		token{tokenInteger, "2"},
-		token{tokenComma, ","},
-		token{tokenInteger, "3"},
-		token{tokenComma, ","},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualArrayBools(t *testing.T) {
-	testFlow(t, "foo = [true, false, true]", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenTrue, "true"},
-		token{tokenComma, ","},
-		token{tokenFalse, "false"},
-		token{tokenComma, ","},
-		token{tokenTrue, "true"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualArrayBoolsWithComments(t *testing.T) {
-	testFlow(t, "foo = [true, false, true] # YEAH", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenTrue, "true"},
-		token{tokenComma, ","},
-		token{tokenFalse, "false"},
-		token{tokenComma, ","},
-		token{tokenTrue, "true"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestDateRegexp(t *testing.T) {
-	if dateRegexp.FindString("1979-05-27T07:32:00Z") == "" {
-		t.Fail()
-	}
-}
-
-func TestKeyEqualDate(t *testing.T) {
-	testFlow(t, "foo = 1979-05-27T07:32:00Z", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenDate, "1979-05-27T07:32:00Z"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestFloatEndingWithDot(t *testing.T) {
-	testFlow(t, "foo = 42.", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenError, "float cannot end with a dot"},
-	})
-}
-
-func TestFloatWithTwoDots(t *testing.T) {
-	testFlow(t, "foo = 4.2.", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenError, "cannot have two dots in one float"},
-	})
-}
-
-func TestDoubleEqualKey(t *testing.T) {
-	testFlow(t, "foo= = 2", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenError, "cannot have multiple equals for the same key"},
-	})
-}
-
-func TestInvalidEsquapeSequence(t *testing.T) {
-	testFlow(t, "foo = \"\\x\"", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenError, "invalid escape sequence: \\x"},
-	})
-}
-
-func TestNestedArrays(t *testing.T) {
-	testFlow(t, "foo = [[[]]]", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenLeftBracket, "["},
-		token{tokenLeftBracket, "["},
-		token{tokenLeftBracket, "["},
-		token{tokenRightBracket, "]"},
-		token{tokenRightBracket, "]"},
-		token{tokenRightBracket, "]"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualNumber(t *testing.T) {
-	testFlow(t, "foo = 42", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "42"},
-		token{tokenEOF, ""},
-	})
-
-	testFlow(t, "foo = +42", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "+42"},
-		token{tokenEOF, ""},
-	})
-
-	testFlow(t, "foo = -42", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "-42"},
-		token{tokenEOF, ""},
-	})
-
-	testFlow(t, "foo = 4.2", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenFloat, "4.2"},
-		token{tokenEOF, ""},
-	})
-
-	testFlow(t, "foo = +4.2", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenFloat, "+4.2"},
-		token{tokenEOF, ""},
-	})
-
-	testFlow(t, "foo = -4.2", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenFloat, "-4.2"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestMultiline(t *testing.T) {
-	testFlow(t, "foo = 42\nbar=21", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "42"},
-		token{tokenKey, "bar"},
-		token{tokenEqual, "="},
-		token{tokenInteger, "21"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyEqualStringUnicodeEscape(t *testing.T) {
-	testFlow(t, "foo = \"hello \\u2665\"", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenString, "hello ♥"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestUnicodeString(t *testing.T) {
-	testFlow(t, "foo = \"hello ♥ world\"", []token{
-		token{tokenKey, "foo"},
-		token{tokenEqual, "="},
-		token{tokenString, "hello ♥ world"},
-		token{tokenEOF, ""},
-	})
-}
-
-func TestKeyGroupArray(t *testing.T) {
-	testFlow(t, "[[foo]]", []token{
-		token{tokenDoubleLeftBracket, "[["},
-		token{tokenKeyGroupArray, "foo"},
-		token{tokenDoubleRightBracket, "]]"},
-		token{tokenEOF, ""},
-	})
-}

localtime.go

@@ -0,0 +1,122 @@
+package toml
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+// LocalDate represents a calendar day in no specific timezone.
+type LocalDate struct {
+	Year  int
+	Month int
+	Day   int
+}
+
+// AsTime converts d into a specific time instance at midnight in zone.
+func (d LocalDate) AsTime(zone *time.Location) time.Time {
+	return time.Date(d.Year, time.Month(d.Month), d.Day, 0, 0, 0, 0, zone)
+}
+
+// String returns RFC 3339 representation of d.
+func (d LocalDate) String() string {
+	return fmt.Sprintf("%04d-%02d-%02d", d.Year, d.Month, d.Day)
+}
+
+// MarshalText returns RFC 3339 representation of d.
+func (d LocalDate) MarshalText() ([]byte, error) {
+	return []byte(d.String()), nil
+}
+
+// UnmarshalText parses b using RFC 3339 to fill d.
+func (d *LocalDate) UnmarshalText(b []byte) error {
+	res, err := parseLocalDate(b)
+	if err != nil {
+		return err
+	}
+	*d = res
+	return nil
+}
+
+// LocalTime represents a time of day of no specific day in no specific
+// timezone.
+type LocalTime struct {
+	Hour       int // Hour of the day: [0; 24[
+	Minute     int // Minute of the hour: [0; 60[
+	Second     int // Second of the minute: [0; 59]
+	Nanosecond int // Nanoseconds within the second:  [0, 1000000000[
+	Precision  int // Number of digits to display for Nanosecond.
+}
+
+// String returns RFC 3339 representation of d.
+// If d.Nanosecond and d.Precision are zero, the time won't have a nanosecond
+// component. If d.Nanosecond > 0 but d.Precision = 0, then the minimum number
+// of digits for nanoseconds is provided.
+func (d LocalTime) String() string {
+	s := fmt.Sprintf("%02d:%02d:%02d", d.Hour, d.Minute, d.Second)
+
+	if d.Precision > 0 {
+		s += fmt.Sprintf(".%09d", d.Nanosecond)[:d.Precision+1]
+	} else if d.Nanosecond > 0 {
+		// Nanoseconds are specified, but precision is not provided. Use the
+		// minimum.
+		s += strings.Trim(fmt.Sprintf(".%09d", d.Nanosecond), "0")
+	}
+
+	return s
+}
+
+// MarshalText returns RFC 3339 representation of d.
+func (d LocalTime) MarshalText() ([]byte, error) {
+	return []byte(d.String()), nil
+}
+
+// UnmarshalText parses b using RFC 3339 to fill d.
+func (d *LocalTime) UnmarshalText(b []byte) error {
+	res, left, err := parseLocalTime(b)
+	if err == nil && len(left) != 0 {
+		err = unstable.NewParserError(left, "extra characters")
+	}
+	if err != nil {
+		return err
+	}
+	*d = res
+	return nil
+}
+
+// LocalDateTime represents a time of a specific day in no specific timezone.
+type LocalDateTime struct {
+	LocalDate
+	LocalTime
+}
+
+// AsTime converts d into a specific time instance in zone.
+func (d LocalDateTime) AsTime(zone *time.Location) time.Time {
+	return time.Date(d.Year, time.Month(d.Month), d.Day, d.Hour, d.Minute, d.Second, d.Nanosecond, zone)
+}
+
+// String returns RFC 3339 representation of d.
+func (d LocalDateTime) String() string {
+	return d.LocalDate.String() + "T" + d.LocalTime.String()
+}
+
+// MarshalText returns RFC 3339 representation of d.
+func (d LocalDateTime) MarshalText() ([]byte, error) {
+	return []byte(d.String()), nil
+}
+
+// UnmarshalText parses b using RFC 3339 to fill d.
+func (d *LocalDateTime) UnmarshalText(data []byte) error {
+	res, left, err := parseLocalDateTime(data)
+	if err == nil && len(left) != 0 {
+		err = unstable.NewParserError(left, "extra characters")
+	}
+	if err != nil {
+		return err
+	}
+
+	*d = res
+	return nil
+}

localtime_test.go

@@ -0,0 +1,118 @@
+package toml_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+)
+
+func TestLocalDate_AsTime(t *testing.T) {
+	d := toml.LocalDate{2021, 6, 8}
+	cast := d.AsTime(time.UTC)
+	assert.Equal(t, time.Date(2021, time.June, 8, 0, 0, 0, 0, time.UTC), cast)
+}
+
+func TestLocalDate_String(t *testing.T) {
+	d := toml.LocalDate{2021, 6, 8}
+	assert.Equal(t, "2021-06-08", d.String())
+}
+
+func TestLocalDate_MarshalText(t *testing.T) {
+	d := toml.LocalDate{2021, 6, 8}
+	b, err := d.MarshalText()
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("2021-06-08"), b)
+}
+
+func TestLocalDate_UnmarshalMarshalText(t *testing.T) {
+	d := toml.LocalDate{}
+	err := d.UnmarshalText([]byte("2021-06-08"))
+	assert.NoError(t, err)
+	assert.Equal(t, toml.LocalDate{2021, 6, 8}, d)
+
+	err = d.UnmarshalText([]byte("what"))
+	assert.Error(t, err)
+}
+
+func TestLocalTime_String(t *testing.T) {
+	d := toml.LocalTime{20, 12, 1, 2, 9}
+	assert.Equal(t, "20:12:01.000000002", d.String())
+	d = toml.LocalTime{20, 12, 1, 0, 0}
+	assert.Equal(t, "20:12:01", d.String())
+	d = toml.LocalTime{20, 12, 1, 0, 9}
+	assert.Equal(t, "20:12:01.000000000", d.String())
+	d = toml.LocalTime{20, 12, 1, 100, 0}
+	assert.Equal(t, "20:12:01.0000001", d.String())
+}
+
+func TestLocalTime_MarshalText(t *testing.T) {
+	d := toml.LocalTime{20, 12, 1, 2, 9}
+	b, err := d.MarshalText()
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("20:12:01.000000002"), b)
+}
+
+func TestLocalTime_UnmarshalMarshalText(t *testing.T) {
+	d := toml.LocalTime{}
+	err := d.UnmarshalText([]byte("20:12:01.000000002"))
+	assert.NoError(t, err)
+	assert.Equal(t, toml.LocalTime{20, 12, 1, 2, 9}, d)
+
+	err = d.UnmarshalText([]byte("what"))
+	assert.Error(t, err)
+
+	err = d.UnmarshalText([]byte("20:12:01.000000002 bad"))
+	assert.Error(t, err)
+}
+
+func TestLocalTime_RoundTrip(t *testing.T) {
+	var d struct{ A toml.LocalTime }
+	err := toml.Unmarshal([]byte("a=20:12:01.500"), &d)
+	assert.NoError(t, err)
+	assert.Equal(t, "20:12:01.500", d.A.String())
+}
+
+func TestLocalDateTime_AsTime(t *testing.T) {
+	d := toml.LocalDateTime{
+		toml.LocalDate{2021, 6, 8},
+		toml.LocalTime{20, 12, 1, 2, 9},
+	}
+	cast := d.AsTime(time.UTC)
+	assert.Equal(t, time.Date(2021, time.June, 8, 20, 12, 1, 2, time.UTC), cast)
+}
+
+func TestLocalDateTime_String(t *testing.T) {
+	d := toml.LocalDateTime{
+		toml.LocalDate{2021, 6, 8},
+		toml.LocalTime{20, 12, 1, 2, 9},
+	}
+	assert.Equal(t, "2021-06-08T20:12:01.000000002", d.String())
+}
+
+func TestLocalDateTime_MarshalText(t *testing.T) {
+	d := toml.LocalDateTime{
+		toml.LocalDate{2021, 6, 8},
+		toml.LocalTime{20, 12, 1, 2, 9},
+	}
+	b, err := d.MarshalText()
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("2021-06-08T20:12:01.000000002"), b)
+}
+
+func TestLocalDateTime_UnmarshalMarshalText(t *testing.T) {
+	d := toml.LocalDateTime{}
+	err := d.UnmarshalText([]byte("2021-06-08 20:12:01.000000002"))
+	assert.NoError(t, err)
+	assert.Equal(t, toml.LocalDateTime{
+		toml.LocalDate{2021, 6, 8},
+		toml.LocalTime{20, 12, 1, 2, 9},
+	}, d)
+
+	err = d.UnmarshalText([]byte("what"))
+	assert.Error(t, err)
+
+	err = d.UnmarshalText([]byte("2021-06-08 20:12:01.000000002 bad"))
+	assert.Error(t, err)
+}

ossfuzz/fuzz.go

@@ -0,0 +1,44 @@
+// Package ossfuzz provides a fuzzing target for OSS-Fuzz.
+package ossfuzz
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+// FuzzToml is the fuzzing target.
+func FuzzToml(data []byte) int {
+	if len(data) >= 2048 {
+		return 0
+	}
+
+	if strings.Contains(string(data), "nan") {
+		return 0
+	}
+
+	var v interface{}
+	err := toml.Unmarshal(data, &v)
+	if err != nil {
+		return 0
+	}
+
+	encoded, err := toml.Marshal(v)
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal unmarshaled document: %s", err))
+	}
+
+	var v2 interface{}
+	err = toml.Unmarshal(encoded, &v2)
+	if err != nil {
+		panic(fmt.Sprintf("failed round trip: %s", err))
+	}
+
+	if !reflect.DeepEqual(v, v2) {
+		panic(fmt.Sprintf("not equal: %#+v %#+v", v, v2))
+	}
+
+	return 1
+}

parser.go

@@ -1,257 +0,0 @@
-// TOML Parser.
-
-package toml
-
-import (
-	"fmt"
-	"reflect"
-	"strconv"
-	"strings"
-	"time"
-)
-
-type parser struct {
-	flow          chan token
-	tree          *TomlTree
-	tokensBuffer  []token
-	currentGroup  []string
-	seenGroupKeys []string
-}
-
-type parserStateFn func(*parser) parserStateFn
-
-func (p *parser) run() {
-	for state := parseStart; state != nil; {
-		state = state(p)
-	}
-}
-
-func (p *parser) peek() *token {
-	if len(p.tokensBuffer) != 0 {
-		return &(p.tokensBuffer[0])
-	}
-
-	tok, ok := <-p.flow
-	if !ok {
-		return nil
-	}
-	p.tokensBuffer = append(p.tokensBuffer, tok)
-	return &tok
-}
-
-func (p *parser) assume(typ tokenType) {
-	tok := p.getToken()
-	if tok == nil {
-		panic(fmt.Sprintf("was expecting token %s, but token stream is empty", typ))
-	}
-	if tok.typ != typ {
-		panic(fmt.Sprintf("was expecting token %s, but got %s", typ, tok.typ))
-	}
-}
-
-func (p *parser) getToken() *token {
-	if len(p.tokensBuffer) != 0 {
-		tok := p.tokensBuffer[0]
-		p.tokensBuffer = p.tokensBuffer[1:]
-		return &tok
-	}
-	tok, ok := <-p.flow
-	if !ok {
-		return nil
-	}
-	return &tok
-}
-
-func parseStart(p *parser) parserStateFn {
-	tok := p.peek()
-
-	// end of stream, parsing is finished
-	if tok == nil {
-		return nil
-	}
-
-	switch tok.typ {
-	case tokenDoubleLeftBracket:
-		return parseGroupArray
-	case tokenLeftBracket:
-		return parseGroup
-	case tokenKey:
-		return parseAssign
-	case tokenEOF:
-		return nil
-	default:
-		panic("unexpected token")
-	}
-	return nil
-}
-
-func parseGroupArray(p *parser) parserStateFn {
-	p.getToken() // discard the [[
-	key := p.getToken()
-	if key.typ != tokenKeyGroupArray {
-		panic(fmt.Sprintf("unexpected token %s, was expecting a key group array", key))
-	}
-
-	// get or create group array element at the indicated part in the path
-	p.currentGroup = strings.Split(key.val, ".")
-	dest_tree := p.tree.GetPath(p.currentGroup)
-	var array []*TomlTree
-	if dest_tree == nil {
-		array = make([]*TomlTree, 0)
-	} else if dest_tree.([]*TomlTree) != nil {
-		array = dest_tree.([]*TomlTree)
-	} else {
-		panic(fmt.Sprintf("key %s is already assigned and not of type group array", key))
-	}
-
-	// add a new tree to the end of the group array
-	new_tree := make(TomlTree)
-	array = append(array, &new_tree)
-	p.tree.SetPath(p.currentGroup, array)
-
-	// keep this key name from use by other kinds of assignments
-	p.seenGroupKeys = append(p.seenGroupKeys, key.val)
-
-	// move to next parser state
-	p.assume(tokenDoubleRightBracket)
-	return parseStart(p)
-}
-
-func parseGroup(p *parser) parserStateFn {
-	p.getToken() // discard the [
-	key := p.getToken()
-	if key.typ != tokenKeyGroup {
-		panic(fmt.Sprintf("unexpected token %s, was expecting a key group", key))
-	}
-	for _, item := range p.seenGroupKeys {
-		if item == key.val {
-			panic("duplicated tables")
-		}
-	}
-	p.seenGroupKeys = append(p.seenGroupKeys, key.val)
-	p.tree.createSubTree(key.val)
-	p.assume(tokenRightBracket)
-	p.currentGroup = strings.Split(key.val, ".")
-	return parseStart(p)
-}
-
-func parseAssign(p *parser) parserStateFn {
-	key := p.getToken()
-	p.assume(tokenEqual)
-	value := parseRvalue(p)
-	var group_key []string
-	if len(p.currentGroup) > 0 {
-		group_key = p.currentGroup
-	} else {
-		group_key = make([]string, 0)
-	}
-
-	// find the group to assign, looking out for arrays of groups
-	var target_node *TomlTree
-	switch node := p.tree.GetPath(group_key).(type) {
-	case []*TomlTree:
-		target_node = node[len(node)-1]
-	case *TomlTree:
-		target_node = node
-	default:
-		panic(fmt.Sprintf("Unknown group type for path %v", group_key))
-	}
-
-	// assign value to the found group
-	local_key := []string{key.val}
-	final_key := append(group_key, key.val)
-	if target_node.GetPath(local_key) != nil {
-		panic(fmt.Sprintf("the following key was defined twice: %s", strings.Join(final_key, ".")))
-	}
-	target_node.SetPath(local_key, value)
-	return parseStart(p)
-}
-
-func parseRvalue(p *parser) interface{} {
-	tok := p.getToken()
-	if tok == nil || tok.typ == tokenEOF {
-		panic("expecting a value")
-	}
-
-	switch tok.typ {
-	case tokenString:
-		return tok.val
-	case tokenTrue:
-		return true
-	case tokenFalse:
-		return false
-	case tokenInteger:
-		val, err := strconv.ParseInt(tok.val, 10, 64)
-		if err != nil {
-			panic(err)
-		}
-		return val
-	case tokenFloat:
-		val, err := strconv.ParseFloat(tok.val, 64)
-		if err != nil {
-			panic(err)
-		}
-		return val
-	case tokenDate:
-		val, err := time.Parse(time.RFC3339, tok.val)
-		if err != nil {
-			panic(err)
-		}
-		return val
-	case tokenLeftBracket:
-		return parseArray(p)
-	case tokenError:
-		panic(tok.val)
-	}
-
-	panic("never reached")
-
-	return nil
-}
-
-func parseArray(p *parser) []interface{} {
-	array := make([]interface{}, 0)
-	arrayType := reflect.TypeOf(nil)
-	for {
-		follow := p.peek()
-		if follow == nil || follow.typ == tokenEOF {
-			panic("unterminated array")
-		}
-		if follow.typ == tokenRightBracket {
-			p.getToken()
-			return array
-		}
-		val := parseRvalue(p)
-		if arrayType == nil {
-			arrayType = reflect.TypeOf(val)
-		}
-		if reflect.TypeOf(val) != arrayType {
-			panic("mixed types in array")
-		}
-		array = append(array, val)
-		follow = p.peek()
-		if follow == nil {
-			panic("unterminated array")
-		}
-		if follow.typ != tokenRightBracket && follow.typ != tokenComma {
-			panic("missing comma")
-		}
-		if follow.typ == tokenComma {
-			p.getToken()
-		}
-	}
-	return array
-}
-
-func parse(flow chan token) *TomlTree {
-	result := make(TomlTree)
-	parser := &parser{
-		flow:          flow,
-		tree:          &result,
-		tokensBuffer:  make([]token, 0),
-		currentGroup:  make([]string, 0),
-		seenGroupKeys: make([]string, 0),
-	}
-	parser.run()
-	return parser.tree
-}

parser_test.go

@@ -1,339 +0,0 @@
-package toml
-
-import (
-	"fmt"
-	"testing"
-	"time"
-)
-
-func assertTree(t *testing.T, tree *TomlTree, err error, ref map[string]interface{}) {
-	if err != nil {
-		t.Error("Non-nil error:", err.Error())
-		return
-	}
-	for k, v := range ref {
-		node := tree.Get(k)
-		switch cast_node := node.(type) {
-		case []*TomlTree:
-			for idx, item := range cast_node {
-				assertTree(t, item, err, v.([]map[string]interface{})[idx])
-			}
-		case *TomlTree:
-			assertTree(t, cast_node, err, v.(map[string]interface{}))
-		default:
-			if fmt.Sprintf("%v", node) != fmt.Sprintf("%v", v) {
-				t.Errorf("was expecting %v at %v but got %v", v, k, node)
-			}
-		}
-	}
-}
-
-func TestCreateSubTree(t *testing.T) {
-	tree := make(TomlTree)
-	tree.createSubTree("a.b.c")
-	tree.Set("a.b.c", 42)
-	if tree.Get("a.b.c") != 42 {
-		t.Fail()
-	}
-}
-
-func TestSimpleKV(t *testing.T) {
-	tree, err := Load("a = 42")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": int64(42),
-	})
-
-	tree, _ = Load("a = 42\nb = 21")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": int64(42),
-		"b": int64(21),
-	})
-}
-
-func TestSimpleNumbers(t *testing.T) {
-	tree, err := Load("a = +42\nb = -21\nc = +4.2\nd = -2.1")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": int64(42),
-		"b": int64(-21),
-		"c": float64(4.2),
-		"d": float64(-2.1),
-	})
-}
-
-func TestSimpleDate(t *testing.T) {
-	tree, err := Load("a = 1979-05-27T07:32:00Z")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": time.Date(1979, time.May, 27, 7, 32, 0, 0, time.UTC),
-	})
-}
-
-func TestSimpleString(t *testing.T) {
-	tree, err := Load("a = \"hello world\"")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": "hello world",
-	})
-}
-
-func TestStringEscapables(t *testing.T) {
-	tree, err := Load("a = \"a \\n b\"")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": "a \n b",
-	})
-
-	tree, err = Load("a = \"a \\t b\"")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": "a \t b",
-	})
-
-	tree, err = Load("a = \"a \\r b\"")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": "a \r b",
-	})
-
-	tree, err = Load("a = \"a \\\\ b\"")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": "a \\ b",
-	})
-}
-
-func TestBools(t *testing.T) {
-	tree, err := Load("a = true\nb = false")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": true,
-		"b": false,
-	})
-}
-
-func TestNestedKeys(t *testing.T) {
-	tree, err := Load("[a.b.c]\nd = 42")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a.b.c.d": int64(42),
-	})
-}
-
-func TestArrayOne(t *testing.T) {
-	tree, err := Load("a = [1]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(1)},
-	})
-}
-
-func TestArrayZero(t *testing.T) {
-	tree, err := Load("a = []")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []interface{}{},
-	})
-}
-
-func TestArraySimple(t *testing.T) {
-	tree, err := Load("a = [42, 21, 10]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(42), int64(21), int64(10)},
-	})
-
-	tree, _ = Load("a = [42, 21, 10,]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(42), int64(21), int64(10)},
-	})
-}
-
-func TestArrayMultiline(t *testing.T) {
-	tree, err := Load("a = [42,\n21, 10,]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(42), int64(21), int64(10)},
-	})
-}
-
-func TestArrayNested(t *testing.T) {
-	tree, err := Load("a = [[42, 21], [10]]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": [][]int64{[]int64{int64(42), int64(21)}, []int64{int64(10)}},
-	})
-}
-
-func TestNestedEmptyArrays(t *testing.T) {
-	tree, err := Load("a = [[[]]]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": [][][]interface{}{[][]interface{}{[]interface{}{}}},
-	})
-}
-
-func TestArrayMixedTypes(t *testing.T) {
-	_, err := Load("a = [42, 16.0]")
-	if err.Error() != "mixed types in array" {
-		t.Error("Bad error message:", err.Error())
-	}
-
-	_, err = Load("a = [42, \"hello\"]")
-	if err.Error() != "mixed types in array" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestArrayNestedStrings(t *testing.T) {
-	tree, err := Load("data = [ [\"gamma\", \"delta\"], [\"Foo\"] ]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"data": [][]string{[]string{"gamma", "delta"}, []string{"Foo"}},
-	})
-}
-
-func TestMissingValue(t *testing.T) {
-	_, err := Load("a = ")
-	if err.Error() != "expecting a value" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestUnterminatedArray(t *testing.T) {
-	_, err := Load("a = [1,")
-	if err.Error() != "unterminated array" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestNewlinesInArrays(t *testing.T) {
-	tree, err := Load("a = [1,\n2,\n3]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(1), int64(2), int64(3)},
-	})
-}
-
-func TestArrayWithExtraComma(t *testing.T) {
-	tree, err := Load("a = [1,\n2,\n3,\n]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(1), int64(2), int64(3)},
-	})
-}
-
-func TestArrayWithExtraCommaComment(t *testing.T) {
-	tree, err := Load("a = [1, # wow\n2, # such items\n3, # so array\n]")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": []int64{int64(1), int64(2), int64(3)},
-	})
-}
-
-func TestDuplicateGroups(t *testing.T) {
-	_, err := Load("[foo]\na=2\n[foo]b=3")
-	if err.Error() != "duplicated tables" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestDuplicateKeys(t *testing.T) {
-	_, err := Load("foo = 2\nfoo = 3")
-	if err.Error() != "the following key was defined twice: foo" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestEmptyIntermediateTable(t *testing.T) {
-	_, err := Load("[foo..bar]")
-	if err.Error() != "empty intermediate table" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestImplicitDeclarationBefore(t *testing.T) {
-	tree, err := Load("[a.b.c]\nanswer = 42\n[a]\nbetter = 43")
-	assertTree(t, tree, err, map[string]interface{}{
-		"a": map[string]interface{}{
-			"b": map[string]interface{}{
-				"c": map[string]interface{}{
-					"answer": int64(42),
-				},
-			},
-			"better": int64(43),
-		},
-	})
-}
-
-func TestFloatsWithoutLeadingZeros(t *testing.T) {
-	_, err := Load("a = .42")
-	if err.Error() != "cannot start float with a dot" {
-		t.Error("Bad error message:", err.Error())
-	}
-
-	_, err = Load("a = -.42")
-	if err.Error() != "cannot start float with a dot" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestMissingFile(t *testing.T) {
-	_, err := LoadFile("foo.toml")
-	if err.Error() != "open foo.toml: no such file or directory" {
-		t.Error("Bad error message:", err.Error())
-	}
-}
-
-func TestParseFile(t *testing.T) {
-	tree, err := LoadFile("example.toml")
-
-	assertTree(t, tree, err, map[string]interface{}{
-		"title":                   "TOML Example",
-		"owner.name":              "Tom Preston-Werner",
-		"owner.organization":      "GitHub",
-		"owner.bio":               "GitHub Cofounder & CEO\nLikes tater tots and beer.",
-		"owner.dob":               time.Date(1979, time.May, 27, 7, 32, 0, 0, time.UTC),
-		"database.server":         "192.168.1.1",
-		"database.ports":          []int64{8001, 8001, 8002},
-		"database.connection_max": 5000,
-		"database.enabled":        true,
-		"servers.alpha.ip":        "10.0.0.1",
-		"servers.alpha.dc":        "eqdc10",
-		"servers.beta.ip":         "10.0.0.2",
-		"servers.beta.dc":         "eqdc10",
-		"clients.data":            []interface{}{[]string{"gamma", "delta"}, []int64{1, 2}},
-	})
-}
-
-func TestParseKeyGroupArray(t *testing.T) {
-	tree, err := Load("[[foo.bar]] a = 42\n[[foo.bar]] a = 69")
-	assertTree(t, tree, err, map[string]interface{}{
-		"foo": map[string]interface{}{
-			"bar": []map[string]interface{}{
-				{"a": int64(42)},
-				{"a": int64(69)},
-			},
-		},
-	})
-}
-
-func TestToTomlValue(t *testing.T) {
-	for idx, item := range []struct {
-		Value  interface{}
-		Expect string
-	}{
-		{int64(12345), "12345"},
-		{float64(123.45), "123.45"},
-		{bool(true), "true"},
-		{"hello world", "\"hello world\""},
-		{"\b\t\n\f\r\"\\", "\"\\b\\t\\n\\f\\r\\\"\\\\\""},
-		{"\x05", "\"\\u0005\""},
-		{time.Date(1979, time.May, 27, 7, 32, 0, 0, time.UTC),
-			"1979-05-27T07:32:00Z"},
-		{[]interface{}{"gamma", "delta"},
-			"[\n  \"gamma\",\n  \"delta\",\n]"},
-	} {
-		result := toTomlValue(item.Value, 0)
-		if result != item.Expect {
-			t.Errorf("Test %d - got '%s', expected '%s'", idx, result, item.Expect)
-		}
-	}
-}
-
-func TestToString(t *testing.T) {
-	tree := &TomlTree{
-		"foo": &TomlTree{
-			"bar": []*TomlTree{
-				{"a": int64(42)},
-				{"a": int64(69)},
-			},
-		},
-	}
-	result := tree.ToString()
-	expected := "\n[foo]\n\n[[foo.bar]]\na = 42\n\n[[foo.bar]]\na = 69\n"
-	if result != expected {
-		t.Errorf("Expected got '%s', expected '%s'", result, expected)
-	}
-}

strict.go

@@ -0,0 +1,114 @@
+package toml
+
+import (
+	"github.com/pelletier/go-toml/v2/internal/tracker"
+	"github.com/pelletier/go-toml/v2/unstable"
+)
+
+type strict struct {
+	Enabled bool
+
+	// Tracks the current key being processed.
+	key tracker.KeyTracker
+
+	missing []unstable.ParserError
+
+	// Reference to the document for computing key ranges.
+	doc []byte
+}
+
+func (s *strict) EnterTable(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.key.UpdateTable(node)
+}
+
+func (s *strict) EnterArrayTable(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.key.UpdateArrayTable(node)
+}
+
+func (s *strict) EnterKeyValue(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.key.Push(node)
+}
+
+func (s *strict) ExitKeyValue(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.key.Pop(node)
+}
+
+func (s *strict) MissingTable(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.missing = append(s.missing, unstable.ParserError{
+		Highlight: s.keyLocation(node),
+		Message:   "missing table",
+		Key:       s.key.Key(),
+	})
+}
+
+func (s *strict) MissingField(node *unstable.Node) {
+	if !s.Enabled {
+		return
+	}
+
+	s.missing = append(s.missing, unstable.ParserError{
+		Highlight: s.keyLocation(node),
+		Message:   "missing field",
+		Key:       s.key.Key(),
+	})
+}
+
+func (s *strict) Error(doc []byte) error {
+	if !s.Enabled || len(s.missing) == 0 {
+		return nil
+	}
+
+	err := &StrictMissingError{
+		Errors: make([]DecodeError, 0, len(s.missing)),
+	}
+
+	for _, derr := range s.missing {
+		derr := derr
+		err.Errors = append(err.Errors, *wrapDecodeError(doc, &derr))
+	}
+
+	return err
+}
+
+func (s *strict) keyLocation(node *unstable.Node) []byte {
+	k := node.Key()
+
+	hasOne := k.Next()
+	if !hasOne {
+		panic("should not be called with empty key")
+	}
+
+	// Get the range from the first key to the last key.
+	firstRaw := k.Node().Raw
+	lastRaw := firstRaw
+
+	for k.Next() {
+		lastRaw = k.Node().Raw
+	}
+
+	// Compute the slice from the document using the ranges.
+	start := firstRaw.Offset
+	end := lastRaw.Offset + lastRaw.Length
+
+	return s.doc[start:end]
+}

test-go-versions.sh

@@ -0,0 +1,596 @@
+#!/usr/bin/env bash
+
+set -uo pipefail
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Go versions to test (1.11 through 1.25)
+GO_VERSIONS=(
+    "1.11"
+    "1.12"
+    "1.13"
+    "1.14"
+    "1.15"
+    "1.16"
+    "1.17"
+    "1.18"
+    "1.19"
+    "1.20"
+    "1.21"
+    "1.22"
+    "1.23"
+    "1.24"
+    "1.25"
+)
+
+# Default values
+PARALLEL=true
+VERBOSE=false
+OUTPUT_DIR="test-results"
+DOCKER_TIMEOUT="10m"
+
+usage() {
+    cat << EOF
+Usage: $0 [OPTIONS] [GO_VERSIONS...]
+
+Test go-toml across multiple Go versions using Docker containers.
+
+The script reports the lowest continuous supported Go version (where all subsequent 
+versions pass) and only exits with non-zero status if either of the two most recent 
+Go versions fail, indicating immediate attention is needed.
+
+Note: For Go versions < 1.21, the script automatically updates go.mod to match the 
+target version, but older versions may still fail due to missing standard library 
+features (e.g., the 'slices' package introduced in Go 1.21).
+
+OPTIONS:
+    -h, --help          Show this help message
+    -s, --sequential    Run tests sequentially instead of in parallel
+    -v, --verbose       Enable verbose output
+    -o, --output DIR    Output directory for test results (default: test-results)
+    -t, --timeout TIME  Docker timeout for each test (default: 10m)
+    --list              List available Go versions and exit
+
+ARGUMENTS:
+    GO_VERSIONS         Specific Go versions to test (default: all supported versions)
+                        Examples: 1.21 1.22 1.23
+
+EXAMPLES:
+    $0                          # Test all Go versions in parallel
+    $0 --sequential             # Test all Go versions sequentially
+    $0 1.21 1.22 1.23          # Test specific versions
+    $0 --verbose --output ./results 1.24 1.25  # Verbose output to custom directory
+
+EXIT CODES:
+    0                   Recent Go versions pass (good compatibility)
+    1                   Recent Go versions fail (needs attention) or script error
+
+EOF
+}
+
+log() {
+    echo -e "${BLUE}[$(date +'%H:%M:%S')]${NC} $*" >&2
+}
+
+log_success() {
+    echo -e "${GREEN}[$(date +'%H:%M:%S')] ✓${NC} $*" >&2
+}
+
+log_error() {
+    echo -e "${RED}[$(date +'%H:%M:%S')] ✗${NC} $*" >&2
+}
+
+log_warning() {
+    echo -e "${YELLOW}[$(date +'%H:%M:%S')] ⚠${NC} $*" >&2
+}
+
+# Parse command line arguments
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        -h|--help)
+            usage
+            exit 0
+            ;;
+        -s|--sequential)
+            PARALLEL=false
+            shift
+            ;;
+        -v|--verbose)
+            VERBOSE=true
+            shift
+            ;;
+        -o|--output)
+            OUTPUT_DIR="$2"
+            shift 2
+            ;;
+        -t|--timeout)
+            DOCKER_TIMEOUT="$2"
+            shift 2
+            ;;
+        --list)
+            echo "Available Go versions:"
+            printf '%s\n' "${GO_VERSIONS[@]}"
+            exit 0
+            ;;
+        -*)
+            echo "Unknown option: $1" >&2
+            usage
+            exit 1
+            ;;
+        *)
+            # Remaining arguments are Go versions
+            break
+            ;;
+    esac
+done
+
+# If specific versions provided, use those instead of defaults
+if [[ $# -gt 0 ]]; then
+    GO_VERSIONS=("$@")
+fi
+
+# Validate Go versions
+for version in "${GO_VERSIONS[@]}"; do
+    if ! [[ "$version" =~ ^1\.(1[1-9]|2[0-5])$ ]]; then
+        log_error "Invalid Go version: $version. Supported versions: 1.11-1.25"
+        exit 1
+    fi
+done
+
+# Check if Docker is available
+if ! command -v docker &> /dev/null; then
+    log_error "Docker is required but not installed or not in PATH"
+    exit 1
+fi
+
+# Check if Docker daemon is running
+if ! docker info &> /dev/null; then
+    log_error "Docker daemon is not running"
+    exit 1
+fi
+
+# Create output directory
+mkdir -p "$OUTPUT_DIR"
+
+# Function to test a single Go version
+test_go_version() {
+    local go_version="$1"
+    local container_name="go-toml-test-${go_version}"
+    local result_file="${OUTPUT_DIR}/go-${go_version}.txt"
+    local dockerfile_content
+
+    log "Testing Go $go_version..."
+
+    # Create a temporary Dockerfile for this version
+    # For Go versions < 1.21, we need to update go.mod to match the Go version
+    local needs_go_mod_update=false
+    if [[ $(echo "$go_version 1.21" | tr ' ' '\n' | sort -V | head -n1) == "$go_version" && "$go_version" != "1.21" ]]; then
+        needs_go_mod_update=true
+    fi
+    
+    dockerfile_content="FROM golang:${go_version}-alpine
+
+# Install git (required for go mod)
+RUN apk add --no-cache git
+
+# Set working directory
+WORKDIR /app
+
+# Copy source code
+COPY . ."
+
+    # Add go.mod update step for older Go versions
+    if [[ "$needs_go_mod_update" == true ]]; then
+        dockerfile_content="$dockerfile_content
+
+# Update go.mod to match Go version (required for Go < 1.21)
+RUN if [ -f go.mod ]; then sed -i 's/^go [0-9]\\+\\.[0-9]\\+\\(\\.[0-9]\\+\\)\\?/go $go_version/' go.mod; fi
+
+# Note: Go versions < 1.21 may fail due to missing standard library packages (e.g., slices)
+# This is expected for projects that use Go 1.21+ features"
+    fi
+    
+    dockerfile_content="$dockerfile_content
+
+# Run tests
+CMD [\"sh\", \"-c\", \"go version && echo '--- Running go test ./... ---' && go test ./...\"]"
+
+    # Create temporary directory for this test
+    local temp_dir
+    temp_dir=$(mktemp -d)
+
+    # Copy source to temp directory (excluding test results and git)
+    rsync -a --exclude="$OUTPUT_DIR" --exclude=".git" --exclude="*.test" . "$temp_dir/"
+
+    # Create Dockerfile in temp directory
+    echo "$dockerfile_content" > "$temp_dir/Dockerfile"
+
+    # Build and run container
+    local exit_code=0
+    local output
+
+    if $VERBOSE; then
+        log "Building Docker image for Go $go_version..."
+    fi
+
+    # Capture both stdout and stderr, and the exit code
+    if output=$(cd "$temp_dir" && timeout "$DOCKER_TIMEOUT" docker build -t "$container_name" . 2>&1 && \
+                timeout "$DOCKER_TIMEOUT" docker run --rm "$container_name" 2>&1); then
+        log_success "Go $go_version: PASSED"
+        echo "PASSED" > "${result_file}.status"
+    else
+        exit_code=$?
+        log_error "Go $go_version: FAILED (exit code: $exit_code)"
+        echo "FAILED" > "${result_file}.status"
+    fi
+
+    # Save full output
+    echo "$output" > "$result_file"
+
+    # Clean up
+    docker rmi "$container_name" &> /dev/null || true
+    rm -rf "$temp_dir"
+
+    if $VERBOSE; then
+        echo "--- Go $go_version output ---"
+        echo "$output"
+        echo "--- End Go $go_version output ---"
+    fi
+
+    return $exit_code
+}
+
+# Function to run tests in parallel
+run_parallel() {
+    local pids=()
+    local failed_versions=()
+
+    log "Starting parallel tests for ${#GO_VERSIONS[@]} Go versions..."
+
+    # Start all tests in background
+    for version in "${GO_VERSIONS[@]}"; do
+        test_go_version "$version" &
+        pids+=($!)
+    done
+
+    # Wait for all tests to complete
+    for i in "${!pids[@]}"; do
+        local pid=${pids[$i]}
+        local version=${GO_VERSIONS[$i]}
+
+        if ! wait $pid; then
+            failed_versions+=("$version")
+        fi
+    done
+
+    return ${#failed_versions[@]}
+}
+
+# Function to run tests sequentially
+run_sequential() {
+    local failed_versions=()
+
+    log "Starting sequential tests for ${#GO_VERSIONS[@]} Go versions..."
+
+    for version in "${GO_VERSIONS[@]}"; do
+        if ! test_go_version "$version"; then
+            failed_versions+=("$version")
+        fi
+    done
+
+    return ${#failed_versions[@]}
+}
+
+# Main execution
+main() {
+    local start_time
+    start_time=$(date +%s)
+
+    log "Starting Go version compatibility tests..."
+    log "Testing versions: ${GO_VERSIONS[*]}"
+    log "Output directory: $OUTPUT_DIR"
+    log "Parallel execution: $PARALLEL"
+
+    local failed_count
+    if $PARALLEL; then
+        run_parallel
+        failed_count=$?
+    else
+        run_sequential
+        failed_count=$?
+    fi
+
+    local end_time
+    end_time=$(date +%s)
+    local duration=$((end_time - start_time))
+
+    # Collect results for display
+    local passed_versions=()
+    local failed_versions=()
+    local unknown_versions=()
+    local passed_count=0
+
+    for version in "${GO_VERSIONS[@]}"; do
+        local status_file="${OUTPUT_DIR}/go-${version}.txt.status"
+        if [[ -f "$status_file" ]]; then
+            local status
+            status=$(cat "$status_file")
+            if [[ "$status" == "PASSED" ]]; then
+                passed_versions+=("$version")
+                ((passed_count++))
+            else
+                failed_versions+=("$version")
+            fi
+        else
+            unknown_versions+=("$version")
+        fi
+    done
+
+    # Generate summary report
+    local summary_file="${OUTPUT_DIR}/summary.txt"
+    {
+        echo "Go Version Compatibility Test Summary"
+        echo "====================================="
+        echo "Date: $(date)"
+        echo "Duration: ${duration}s"
+        echo "Parallel: $PARALLEL"
+        echo ""
+        echo "Results:"
+
+        for version in "${GO_VERSIONS[@]}"; do
+            local status_file="${OUTPUT_DIR}/go-${version}.txt.status"
+            if [[ -f "$status_file" ]]; then
+                local status
+                status=$(cat "$status_file")
+                if [[ "$status" == "PASSED" ]]; then
+                    echo "  Go $version: ✓ PASSED"
+                else
+                    echo "  Go $version: ✗ FAILED"
+                fi
+            else
+                echo "  Go $version: ? UNKNOWN (no status file)"
+            fi
+        done
+
+        echo ""
+        echo "Summary: $passed_count/${#GO_VERSIONS[@]} versions passed"
+
+        if [[ $failed_count -gt 0 ]]; then
+            echo ""
+            echo "Failed versions details:"
+            for version in "${failed_versions[@]}"; do
+                echo ""
+                echo "--- Go $version (FAILED) ---"
+                local result_file="${OUTPUT_DIR}/go-${version}.txt"
+                if [[ -f "$result_file" ]]; then
+                    tail -n 30 "$result_file"
+                fi
+            done
+        fi
+    } > "$summary_file"
+
+        # Find lowest continuous supported version and check recent versions
+    local lowest_continuous_version=""
+    local recent_versions_failed=false
+    
+    # Sort versions to ensure proper order
+    local sorted_versions=()
+    for version in "${GO_VERSIONS[@]}"; do
+        sorted_versions+=("$version")
+    done
+    # Sort versions numerically (1.11, 1.12, ..., 1.25)
+    IFS=$'\n' sorted_versions=($(sort -V <<< "${sorted_versions[*]}"))
+    
+    # Find lowest continuous supported version (all versions from this point onwards pass)
+    for version in "${sorted_versions[@]}"; do
+        local status_file="${OUTPUT_DIR}/go-${version}.txt.status"
+        local all_subsequent_pass=true
+        
+        # Check if this version and all subsequent versions pass
+        local found_current=false
+        for check_version in "${sorted_versions[@]}"; do
+            if [[ "$check_version" == "$version" ]]; then
+                found_current=true
+            fi
+            
+            if [[ "$found_current" == true ]]; then
+                local check_status_file="${OUTPUT_DIR}/go-${check_version}.txt.status"
+                if [[ -f "$check_status_file" ]]; then
+                    local status
+                    status=$(cat "$check_status_file")
+                    if [[ "$status" != "PASSED" ]]; then
+                        all_subsequent_pass=false
+                        break
+                    fi
+                else
+                    all_subsequent_pass=false
+                    break
+                fi
+            fi
+        done
+        
+        if [[ "$all_subsequent_pass" == true ]]; then
+            lowest_continuous_version="$version"
+            break
+        fi
+    done
+    
+    # Check if the two most recent versions failed
+    local num_versions=${#sorted_versions[@]}
+    if [[ $num_versions -ge 2 ]]; then
+        local second_recent="${sorted_versions[$((num_versions-2))]}"
+        local most_recent="${sorted_versions[$((num_versions-1))]}"
+        
+        local second_recent_status_file="${OUTPUT_DIR}/go-${second_recent}.txt.status"
+        local most_recent_status_file="${OUTPUT_DIR}/go-${most_recent}.txt.status"
+        
+        local second_recent_failed=false
+        local most_recent_failed=false
+        
+        if [[ -f "$second_recent_status_file" ]]; then
+            local status
+            status=$(cat "$second_recent_status_file")
+            if [[ "$status" != "PASSED" ]]; then
+                second_recent_failed=true
+            fi
+        else
+            second_recent_failed=true
+        fi
+        
+        if [[ -f "$most_recent_status_file" ]]; then
+            local status
+            status=$(cat "$most_recent_status_file")
+            if [[ "$status" != "PASSED" ]]; then
+                most_recent_failed=true
+            fi
+        else
+            most_recent_failed=true
+        fi
+        
+        if [[ "$second_recent_failed" == true || "$most_recent_failed" == true ]]; then
+            recent_versions_failed=true
+        fi
+    elif [[ $num_versions -eq 1 ]]; then
+        # Only one version tested, check if it's the most recent and failed
+        local only_version="${sorted_versions[0]}"
+        local only_status_file="${OUTPUT_DIR}/go-${only_version}.txt.status"
+        
+        if [[ -f "$only_status_file" ]]; then
+            local status
+            status=$(cat "$only_status_file")
+            if [[ "$status" != "PASSED" ]]; then
+                recent_versions_failed=true
+            fi
+        else
+            recent_versions_failed=true
+        fi
+    fi
+    
+    # Display summary
+    echo ""
+    log "Test completed in ${duration}s"
+    log "Summary report: $summary_file"
+    
+    echo ""
+    echo "========================================"
+    echo "           FINAL RESULTS"
+    echo "========================================"
+    echo ""
+    
+    # Display passed versions
+    if [[ ${#passed_versions[@]} -gt 0 ]]; then
+        log_success "PASSED (${#passed_versions[@]}/${#GO_VERSIONS[@]}):"
+        # Sort passed versions for display
+        local sorted_passed=()
+        for version in "${sorted_versions[@]}"; do
+            for passed_version in "${passed_versions[@]}"; do
+                if [[ "$version" == "$passed_version" ]]; then
+                    sorted_passed+=("$version")
+                    break
+                fi
+            done
+        done
+        for version in "${sorted_passed[@]}"; do
+            echo -e "  ${GREEN}✓${NC} Go $version"
+        done
+        echo ""
+    fi
+    
+    # Display failed versions
+    if [[ ${#failed_versions[@]} -gt 0 ]]; then
+        log_error "FAILED (${#failed_versions[@]}/${#GO_VERSIONS[@]}):"
+        # Sort failed versions for display
+        local sorted_failed=()
+        for version in "${sorted_versions[@]}"; do
+            for failed_version in "${failed_versions[@]}"; do
+                if [[ "$version" == "$failed_version" ]]; then
+                    sorted_failed+=("$version")
+                    break
+                fi
+            done
+        done
+        for version in "${sorted_failed[@]}"; do
+            echo -e "  ${RED}✗${NC} Go $version"
+        done
+        echo ""
+        
+        # Show failure details
+        echo "========================================"
+        echo "         FAILURE DETAILS"
+        echo "========================================"
+        echo ""
+        
+        for version in "${sorted_failed[@]}"; do
+            echo -e "${RED}--- Go $version FAILURE LOGS (last 30 lines) ---${NC}"
+            local result_file="${OUTPUT_DIR}/go-${version}.txt"
+            if [[ -f "$result_file" ]]; then
+                tail -n 30 "$result_file" | sed 's/^/  /'
+            else
+                echo "  No log file found: $result_file"
+            fi
+            echo ""
+        done
+    fi
+    
+    # Display unknown versions
+    if [[ ${#unknown_versions[@]} -gt 0 ]]; then
+        log_warning "UNKNOWN (${#unknown_versions[@]}/${#GO_VERSIONS[@]}):"
+        for version in "${unknown_versions[@]}"; do
+            echo -e "  ${YELLOW}?${NC} Go $version (no status file)"
+        done
+        echo ""
+    fi
+    
+    echo "========================================"
+    echo "         COMPATIBILITY SUMMARY"
+    echo "========================================"
+    echo ""
+    
+    if [[ -n "$lowest_continuous_version" ]]; then
+        log_success "Lowest continuous supported version: Go $lowest_continuous_version"
+        echo "  (All versions from Go $lowest_continuous_version onwards pass)"
+    else
+        log_error "No continuous version support found"
+        echo "  (No version has all subsequent versions passing)"
+    fi
+    
+    echo ""
+    echo "========================================"
+    echo "Full detailed logs available in: $OUTPUT_DIR"
+    echo "========================================"
+    
+    # Determine exit code based on recent versions
+    if [[ "$recent_versions_failed" == true ]]; then
+        log_error "OVERALL RESULT: Recent Go versions failed - this needs attention!"
+        if [[ -n "$lowest_continuous_version" ]]; then
+            echo "Note: Continuous support starts from Go $lowest_continuous_version"
+        fi
+        exit 1
+    else
+        log_success "OVERALL RESULT: Recent Go versions pass - compatibility looks good!"
+        if [[ -n "$lowest_continuous_version" ]]; then
+            echo "Continuous support starts from Go $lowest_continuous_version"
+        fi
+        exit 0
+    fi
+}
+
+# Trap to clean up on exit
+cleanup() {
+    # Kill any remaining background processes
+    jobs -p | xargs -r kill 2>/dev/null || true
+
+    # Clean up any remaining Docker containers
+    docker ps -q --filter "name=go-toml-test-" | xargs -r docker stop 2>/dev/null || true
+    docker images -q --filter "reference=go-toml-test-*" | xargs -r docker rmi 2>/dev/null || true
+}
+
+trap cleanup EXIT
+
+# Run main function
+main

test.sh

@@ -1,28 +0,0 @@
-#!/bin/bash
-# fail out of the script if anything here fails
-set -e
-
-# set the path to the present working directory
-export GOPATH=`pwd`
-
-# Vendorize the BurntSushi test suite
-# NOTE: this gets a specific release to avoid versioning issues
-if [ ! -d 'src/github.com/BurntSushi/toml-test' ]; then
-  mkdir -p src/github.com/BurntSushi
-  git clone https://github.com/BurntSushi/toml-test.git src/github.com/BurntSushi/toml-test
-fi
-pushd src/github.com/BurntSushi/toml-test
-git reset --hard '0.2.0'  # use the released version, NOT tip
-popd
-go build -o toml-test github.com/BurntSushi/toml-test
-
-# vendorize the current lib for testing
-# NOTE: this basically mocks an install without having to go back out to github for code
-mkdir -p src/github.com/pelletier/go-toml/cmd
-cp *.go *.toml src/github.com/pelletier/go-toml
-cp cmd/*.go src/github.com/pelletier/go-toml/cmd
-go build -o test_program_bin src/github.com/pelletier/go-toml/cmd/test_program.go
-
-# Run basic unit tests and then the BurntSushi test suite
-go test -v github.com/pelletier/go-toml
-./toml-test ./test_program_bin | tee test_out

testdata/fuzz/FuzzUnmarshal/0c08b924aa26af23d16b77029b4f5567a96af93402e0472fef7b837b37580d7c

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=0000-01-01 00:00:00")

testdata/fuzz/FuzzUnmarshal/249a017d8ffa0d88d41c594ada5399f764833f64050180cb39f106d12666853f

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\"\\n\"=\"\"")

testdata/fuzz/FuzzUnmarshal/391ce67b866d58464d067c5981e99951fd499896453a2fe2779a6bfe7df11bf5

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("''=0")

testdata/fuzz/FuzzUnmarshal/49ae83283c5cfbed874bcacbfb342de107b69c2a3d3c35c2d99f67345fe89946

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=0000-01-01")

testdata/fuzz/FuzzUnmarshal/69ea82e85bb4ad966ae86bb05eea3af69ed1a826c846f1bf2282f329b4d8fb36

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=\"\"\"\\U00000000\"\"\"")

testdata/fuzz/FuzzUnmarshal/746910fac6deb42e7e62dce60b333c81c39d844a122c9075894c023400e8fdbf

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=[[{}]]")

testdata/fuzz/FuzzUnmarshal/844d1171a3adc95e51627f0e9378bbaa193fe2d0284f4ba8ed19a5226a8cbc74

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\"\\b\"=\"\"")

testdata/fuzz/FuzzUnmarshal/900c54b5071113ae2a5365b3156377ddd775b9d38add61629544903cb9c94b00

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=inf")

testdata/fuzz/FuzzUnmarshal/c87e8eb4e8fa40fd3c89d8ed16a049ce81592ded710965ee29a4e506eb5427b3

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=0000-01-01 00:00:00+00:00")

testdata/fuzz/FuzzUnmarshal/d0e5d6fc3b865cfae5480c01f301b87c932722ae0c1d692deea413349ea028be

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=[{}]")

testdata/fuzz/FuzzUnmarshal/d2cecea5b8ee5f148419671cef0644178cdba1ee91d3f295be38da576e89ef40

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("0=nan")

toml.abnf

@@ -0,0 +1,243 @@
+;; This document describes TOML's syntax, using the ABNF format (defined in
+;; RFC 5234 -- https://www.ietf.org/rfc/rfc5234.txt).
+;;
+;; All valid TOML documents will match this description, however certain
+;; invalid documents would need to be rejected as per the semantics described
+;; in the supporting text description.
+
+;; It is possible to try this grammar interactively, using instaparse.
+;;     http://instaparse.mojombo.com/
+;;
+;; To do so, in the lower right, click on Options and change `:input-format` to
+;; ':abnf'. Then paste this entire ABNF document into the grammar entry box
+;; (above the options). Then you can type or paste a sample TOML document into
+;; the beige box on the left. Tada!
+
+;; Overall Structure
+
+toml = expression *( newline expression )
+
+expression =  ws [ comment ]
+expression =/ ws keyval ws [ comment ]
+expression =/ ws table ws [ comment ]
+
+;; Whitespace
+
+ws = *wschar
+wschar =  %x20  ; Space
+wschar =/ %x09  ; Horizontal tab
+
+;; Newline
+
+newline =  %x0A     ; LF
+newline =/ %x0D.0A  ; CRLF
+
+;; Comment
+
+comment-start-symbol = %x23 ; #
+non-ascii = %x80-D7FF / %xE000-10FFFF
+non-eol = %x09 / %x20-7F / non-ascii
+
+comment = comment-start-symbol *non-eol
+
+;; Key-Value pairs
+
+keyval = key keyval-sep val
+
+key = simple-key / dotted-key
+simple-key = quoted-key / unquoted-key
+
+unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
+quoted-key = basic-string / literal-string
+dotted-key = simple-key 1*( dot-sep simple-key )
+
+dot-sep   = ws %x2E ws  ; . Period
+keyval-sep = ws %x3D ws ; =
+
+val = string / boolean / array / inline-table / date-time / float / integer
+
+;; String
+
+string = ml-basic-string / basic-string / ml-literal-string / literal-string
+
+;; Basic String
+
+basic-string = quotation-mark *basic-char quotation-mark
+
+quotation-mark = %x22            ; "
+
+basic-char = basic-unescaped / escaped
+basic-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
+escaped = escape escape-seq-char
+
+escape = %x5C                   ; \
+escape-seq-char =  %x22         ; "    quotation mark  U+0022
+escape-seq-char =/ %x5C         ; \    reverse solidus U+005C
+escape-seq-char =/ %x62         ; b    backspace       U+0008
+escape-seq-char =/ %x66         ; f    form feed       U+000C
+escape-seq-char =/ %x6E         ; n    line feed       U+000A
+escape-seq-char =/ %x72         ; r    carriage return U+000D
+escape-seq-char =/ %x74         ; t    tab             U+0009
+escape-seq-char =/ %x75 4HEXDIG ; uXXXX                U+XXXX
+escape-seq-char =/ %x55 8HEXDIG ; UXXXXXXXX            U+XXXXXXXX
+
+;; Multiline Basic String
+
+ml-basic-string = ml-basic-string-delim [ newline ] ml-basic-body
+                  ml-basic-string-delim
+ml-basic-string-delim = 3quotation-mark
+ml-basic-body = *mlb-content *( mlb-quotes 1*mlb-content ) [ mlb-quotes ]
+
+mlb-content = mlb-char / newline / mlb-escaped-nl
+mlb-char = mlb-unescaped / escaped
+mlb-quotes = 1*2quotation-mark
+mlb-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
+mlb-escaped-nl = escape ws newline *( wschar / newline )
+
+;; Literal String
+
+literal-string = apostrophe *literal-char apostrophe
+
+apostrophe = %x27 ; ' apostrophe
+
+literal-char = %x09 / %x20-26 / %x28-7E / non-ascii
+
+;; Multiline Literal String
+
+ml-literal-string = ml-literal-string-delim [ newline ] ml-literal-body
+                    ml-literal-string-delim
+ml-literal-string-delim = 3apostrophe
+ml-literal-body = *mll-content *( mll-quotes 1*mll-content ) [ mll-quotes ]
+
+mll-content = mll-char / newline
+mll-char = %x09 / %x20-26 / %x28-7E / non-ascii
+mll-quotes = 1*2apostrophe
+
+;; Integer
+
+integer = dec-int / hex-int / oct-int / bin-int
+
+minus = %x2D                       ; -
+plus = %x2B                        ; +
+underscore = %x5F                  ; _
+digit1-9 = %x31-39                 ; 1-9
+digit0-7 = %x30-37                 ; 0-7
+digit0-1 = %x30-31                 ; 0-1
+
+hex-prefix = %x30.78               ; 0x
+oct-prefix = %x30.6F               ; 0o
+bin-prefix = %x30.62               ; 0b
+
+dec-int = [ minus / plus ] unsigned-dec-int
+unsigned-dec-int = DIGIT / digit1-9 1*( DIGIT / underscore DIGIT )
+
+hex-int = hex-prefix HEXDIG *( HEXDIG / underscore HEXDIG )
+oct-int = oct-prefix digit0-7 *( digit0-7 / underscore digit0-7 )
+bin-int = bin-prefix digit0-1 *( digit0-1 / underscore digit0-1 )
+
+;; Float
+
+float = float-int-part ( exp / frac [ exp ] )
+float =/ special-float
+
+float-int-part = dec-int
+frac = decimal-point zero-prefixable-int
+decimal-point = %x2E               ; .
+zero-prefixable-int = DIGIT *( DIGIT / underscore DIGIT )
+
+exp = "e" float-exp-part
+float-exp-part = [ minus / plus ] zero-prefixable-int
+
+special-float = [ minus / plus ] ( inf / nan )
+inf = %x69.6e.66  ; inf
+nan = %x6e.61.6e  ; nan
+
+;; Boolean
+
+boolean = true / false
+
+true    = %x74.72.75.65     ; true
+false   = %x66.61.6C.73.65  ; false
+
+;; Date and Time (as defined in RFC 3339)
+
+date-time      = offset-date-time / local-date-time / local-date / local-time
+
+date-fullyear  = 4DIGIT
+date-month     = 2DIGIT  ; 01-12
+date-mday      = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on month/year
+time-delim     = "T" / %x20 ; T, t, or space
+time-hour      = 2DIGIT  ; 00-23
+time-minute    = 2DIGIT  ; 00-59
+time-second    = 2DIGIT  ; 00-58, 00-59, 00-60 based on leap second rules
+time-secfrac   = "." 1*DIGIT
+time-numoffset = ( "+" / "-" ) time-hour ":" time-minute
+time-offset    = "Z" / time-numoffset
+
+partial-time   = time-hour ":" time-minute ":" time-second [ time-secfrac ]
+full-date      = date-fullyear "-" date-month "-" date-mday
+full-time      = partial-time time-offset
+
+;; Offset Date-Time
+
+offset-date-time = full-date time-delim full-time
+
+;; Local Date-Time
+
+local-date-time = full-date time-delim partial-time
+
+;; Local Date
+
+local-date = full-date
+
+;; Local Time
+
+local-time = partial-time
+
+;; Array
+
+array = array-open [ array-values ] ws-comment-newline array-close
+
+array-open =  %x5B ; [
+array-close = %x5D ; ]
+
+array-values =  ws-comment-newline val ws-comment-newline array-sep array-values
+array-values =/ ws-comment-newline val ws-comment-newline [ array-sep ]
+
+array-sep = %x2C  ; , Comma
+
+ws-comment-newline = *( wschar / [ comment ] newline )
+
+;; Table
+
+table = std-table / array-table
+
+;; Standard Table
+
+std-table = std-table-open key std-table-close
+
+std-table-open  = %x5B ws     ; [ Left square bracket
+std-table-close = ws %x5D     ; ] Right square bracket
+
+;; Inline Table
+
+inline-table = inline-table-open [ inline-table-keyvals ] inline-table-close
+
+inline-table-open  = %x7B ws     ; {
+inline-table-close = ws %x7D     ; }
+inline-table-sep   = ws %x2C ws  ; , Comma
+
+inline-table-keyvals = keyval [ inline-table-sep inline-table-keyvals ]
+
+;; Array Table
+
+array-table = array-table-open key array-table-close
+
+array-table-open  = %x5B.5B ws  ; [[ Double left square bracket
+array-table-close = ws %x5D.5D  ; ]] Double right square bracket
+
+;; Built-in ABNF terms, reproduced here for clarity
+
+ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
+DIGIT = %x30-39 ; 0-9
+HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"

toml.go

@@ -1,262 +0,0 @@
-// TOML markup language parser.
-//
-// This version supports the specification as described in
-// https://github.com/toml-lang/toml/blob/master/versions/toml-v0.2.0.md
-package toml
-
-import (
-	"errors"
-	"fmt"
-	"io/ioutil"
-	"runtime"
-	"strconv"
-	"strings"
-	"time"
-)
-
-// Definition of a TomlTree.
-// This is the result of the parsing of a TOML file.
-type TomlTree map[string]interface{}
-
-// Has returns a boolean indicating if the toplevel tree contains the given
-// key.
-func (t *TomlTree) Has(key string) bool {
-	mp := (map[string]interface{})(*t)
-	for k, _ := range mp {
-		if k == key {
-			return true
-		}
-	}
-	return false
-}
-
-// Keys returns the keys of the toplevel tree.
-// Warning: this is a costly operation.
-func (t *TomlTree) Keys() []string {
-	keys := make([]string, 0)
-	mp := (map[string]interface{})(*t)
-	for k, _ := range mp {
-		keys = append(keys, k)
-	}
-	return keys
-}
-
-// Get the value at key in the TomlTree.
-// Key is a dot-separated path (e.g. a.b.c).
-// Returns nil if the path does not exist in the tree.
-// If keys is of length zero, the current tree is returned.
-func (t *TomlTree) Get(key string) interface{} {
-	if key == "" {
-		return t
-	}
-	return t.GetPath(strings.Split(key, "."))
-}
-
-// Returns the element in the tree indicated by 'keys'.
-// If keys is of length zero, the current tree is returned.
-func (t *TomlTree) GetPath(keys []string) interface{} {
-	if len(keys) == 0 {
-		return t
-	}
-	subtree := t
-	for _, intermediate_key := range keys[:len(keys)-1] {
-		_, exists := (*subtree)[intermediate_key]
-		if !exists {
-			return nil
-		}
-		switch node := (*subtree)[intermediate_key].(type) {
-		case *TomlTree:
-			subtree = node
-		case []*TomlTree:
-			// go to most recent element
-			if len(node) == 0 {
-				return nil //(*subtree)[intermediate_key] = append(node, &TomlTree{})
-			}
-			subtree = node[len(node)-1]
-		}
-	}
-	return (*subtree)[keys[len(keys)-1]]
-}
-
-// Same as Get but with a default value
-func (t *TomlTree) GetDefault(key string, def interface{}) interface{} {
-	val := t.Get(key)
-	if val == nil {
-		return def
-	}
-	return val
-}
-
-// Set an element in the tree.
-// Key is a dot-separated path (e.g. a.b.c).
-// Creates all necessary intermediates trees, if needed.
-func (t *TomlTree) Set(key string, value interface{}) {
-	t.SetPath(strings.Split(key, "."), value)
-}
-
-func (t *TomlTree) SetPath(keys []string, value interface{}) {
-	subtree := t
-	for _, intermediate_key := range keys[:len(keys)-1] {
-		_, exists := (*subtree)[intermediate_key]
-		if !exists {
-			var new_tree TomlTree = make(TomlTree)
-			(*subtree)[intermediate_key] = &new_tree
-		}
-		switch node := (*subtree)[intermediate_key].(type) {
-		case *TomlTree:
-			subtree = node
-		case []*TomlTree:
-			// go to most recent element
-			if len(node) == 0 {
-				(*subtree)[intermediate_key] = append(node, &TomlTree{})
-			}
-			subtree = node[len(node)-1]
-		}
-	}
-	(*subtree)[keys[len(keys)-1]] = value
-}
-
-// createSubTree takes a tree and a key and create the necessary intermediate
-// subtrees to create a subtree at that point. In-place.
-//
-// e.g. passing a.b.c will create (assuming tree is empty) tree[a], tree[a][b]
-// and tree[a][b][c]
-func (t *TomlTree) createSubTree(key string) {
-	subtree := t
-	for _, intermediate_key := range strings.Split(key, ".") {
-		if intermediate_key == "" {
-			panic("empty intermediate table")
-		}
-		_, exists := (*subtree)[intermediate_key]
-		if !exists {
-			var new_tree TomlTree = make(TomlTree)
-			(*subtree)[intermediate_key] = &new_tree
-		}
-		subtree = ((*subtree)[intermediate_key]).(*TomlTree)
-	}
-}
-
-// encodes a string to a TOML-compliant string value
-func encodeTomlString(value string) string {
-	result := ""
-	for _, rr := range value {
-		int_rr := uint16(rr)
-		switch rr {
-		case '\b':
-			result += "\\b"
-		case '\t':
-			result += "\\t"
-		case '\n':
-			result += "\\n"
-		case '\f':
-			result += "\\f"
-		case '\r':
-			result += "\\r"
-		case '"':
-			result += "\\\""
-		case '\\':
-			result += "\\\\"
-		default:
-			if int_rr < 0x001F {
-				result += fmt.Sprintf("\\u%0.4X", int_rr)
-			} else {
-				result += string(rr)
-			}
-		}
-	}
-	return result
-}
-
-// Value print support function for ToString()
-// Outputs the TOML compliant string representation of a value
-func toTomlValue(item interface{}, indent int) string {
-	tab := strings.Repeat(" ", indent)
-	switch value := item.(type) {
-	case int64:
-		return tab + strconv.FormatInt(value, 10)
-	case float64:
-		return tab + strconv.FormatFloat(value, 'f', -1, 64)
-	case string:
-		return tab + "\"" + encodeTomlString(value) + "\""
-	case bool:
-		if value {
-			return "true"
-		} else {
-			return "false"
-		}
-	case time.Time:
-		return tab + value.Format(time.RFC3339)
-	case []interface{}:
-		result := tab + "[\n"
-		for _, item := range value {
-			result += toTomlValue(item, indent+2) + ",\n"
-		}
-		return result + tab + "]"
-	default:
-		panic(fmt.Sprintf("unsupported value type: %v", value))
-	}
-}
-
-// Recursive support function for ToString()
-// Outputs a tree, using the provided keyspace to prefix group names
-func (t *TomlTree) toToml(keyspace string) string {
-	result := ""
-	for k, v := range (map[string]interface{})(*t) {
-		// figure out the keyspace
-		combined_key := k
-		if keyspace != "" {
-			combined_key = keyspace + "." + combined_key
-		}
-		// output based on type
-		switch node := v.(type) {
-		case []*TomlTree:
-			for _, item := range node {
-				if len(item.Keys()) > 0 {
-					result += fmt.Sprintf("\n[[%s]]\n", combined_key)
-				}
-				result += item.toToml(combined_key)
-			}
-		case *TomlTree:
-			if len(node.Keys()) > 0 {
-				result += fmt.Sprintf("\n[%s]\n", combined_key)
-			}
-			result += node.toToml(combined_key)
-		default:
-			result += fmt.Sprintf("%s = %s\n", k, toTomlValue(node, 0))
-		}
-	}
-	return result
-}
-
-// Generates a human-readable representation of the current tree.
-// Output spans multiple lines, and is suitable for ingest by a TOML parser
-func (t *TomlTree) ToString() string {
-	return t.toToml("")
-}
-
-// Create a TomlTree from a string.
-func Load(content string) (tree *TomlTree, err error) {
-	defer func() {
-		if r := recover(); r != nil {
-			if _, ok := r.(runtime.Error); ok {
-				panic(r)
-			}
-			err = errors.New(r.(string))
-		}
-	}()
-	_, flow := lex(content)
-	tree = parse(flow)
-	return
-}
-
-// Create a TomlTree from a file.
-func LoadFile(path string) (tree *TomlTree, err error) {
-	buff, ferr := ioutil.ReadFile(path)
-	if ferr != nil {
-		err = ferr
-	} else {
-		s := string(buff)
-		tree, err = Load(s)
-	}
-	return
-}

toml_test.go

@@ -1,25 +0,0 @@
-package toml
-
-import (
-	"testing"
-)
-
-func TestTomlGetPath(t *testing.T) {
-	node := make(TomlTree)
-	//TODO: set other node data
-
-	for idx, item := range []struct {
-		Path     []string
-		Expected interface{}
-	}{
-		{ // empty path test
-			[]string{},
-			&node,
-		},
-	} {
-		result := node.GetPath(item.Path)
-		if result != item.Expected {
-			t.Errorf("GetPath[%d] %v - expected %v, got %v instead.", idx, item.Path, item.Expected, result)
-		}
-	}
-}

toml_testgen_support_test.go

@@ -0,0 +1,60 @@
+//go:generate go run github.com/toml-lang/toml-test/cmd/toml-test@v1.6.0 -copy ./tests
+//go:generate go run ./cmd/tomltestgen/main.go -r v1.6.0 -o toml_testgen_test.go
+
+package toml_test
+
+import (
+	"encoding/json"
+	"errors"
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/assert"
+	"github.com/pelletier/go-toml/v2/internal/testsuite"
+)
+
+func testgenInvalid(t *testing.T, input string) {
+	t.Helper()
+	t.Logf("Input TOML:\n%s", input)
+
+	doc := map[string]interface{}{}
+	err := testsuite.Unmarshal([]byte(input), &doc)
+
+	if err == nil {
+		out, err := json.Marshal(doc)
+		if err != nil {
+			panic("could not marshal map to json")
+		}
+		t.Log("JSON output from unmarshal:", string(out))
+		t.Fatalf("test did not fail")
+	}
+}
+
+func testgenValid(t *testing.T, input string, jsonRef string) {
+	t.Helper()
+	t.Logf("Input TOML:\n%s", input)
+
+	// TODO: change this to interface{}
+	var doc map[string]interface{}
+
+	err := testsuite.Unmarshal([]byte(input), &doc)
+	if err != nil {
+		de := &toml.DecodeError{}
+		if errors.As(err, &de) {
+			t.Logf("%s\n%s", err, de)
+		}
+		t.Fatalf("failed parsing toml: %s", err)
+	}
+	j, err := testsuite.ValueToTaggedJSON(doc)
+	assert.NoError(t, err)
+
+	var ref interface{}
+	err = json.Unmarshal([]byte(jsonRef), &ref)
+	assert.NoError(t, err)
+
+	var actual interface{}
+	err = json.Unmarshal(j, &actual)
+	assert.NoError(t, err)
+
+	testsuite.CmpJSON(t, "", ref, actual)
+}

types.go

@@ -0,0 +1,23 @@
+package toml
+
+import (
+	"encoding"
+	"reflect"
+	"time"
+)
+
+// isZeroer is used to check if a type has a custom IsZero method.
+// This allows custom types to define their own zero-value semantics.
+type isZeroer interface {
+	IsZero() bool
+}
+
+var (
+	timeType               = reflect.TypeOf((*time.Time)(nil)).Elem()
+	textMarshalerType      = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+	textUnmarshalerType    = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+	isZeroerType           = reflect.TypeOf((*isZeroer)(nil)).Elem()
+	mapStringInterfaceType = reflect.TypeOf(map[string]interface{}(nil))
+	sliceInterfaceType     = reflect.TypeOf([]interface{}(nil))
+	stringType             = reflect.TypeOf("")
+)