AST Tweaks (#551)

* Use pointers instead of copying around ast.Node

Node is a 56B struct that is constantly in the hot path. Passing nodes
around by copy had a cost that started to add up. This change replaces
them by pointers. Using unsafe pointer arithmetic and converting
sibling/child indexes to relative offsets, it removes the need to carry
around a pointer to the root of the tree. This saves 8B per Node. This
space will be used to store an extra []byte slice to provide contextual
error handling on all nodes, including the ones whose data is different
than the raw input (for example: strings with escaped characters), while
staying under the size of a cache line.

* Remove conditional

* Add Raw to track range in data for parsed values

* Simplify reference tracking

.gitattributes

@@ -0,0 +1,3 @@
+* text=auto
+
+benchmark/benchmark.toml text eol=lf

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,5 +1,19 @@
-**Issue:** add link to pelletier/go-toml issue here
+<!--
+
+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).
+More detailed description of the decisions being made and the reasons why (if
+the patch is non-trivial).
+
+---
+
+Paste `benchstat` results here

.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@master
+        with:
+          fetch-depth: 0
+      - name: Setup go
+        uses: actions/setup-go@master
+        with:
+          go-version: 1.16
+      - name: Run tests with coverage
+        run: ./ci.sh coverage -d "${GITHUB_BASE_REF-HEAD}"

.golangci.toml

@@ -24,7 +24,7 @@ enable = [
     # "exhaustivestruct",
     "exportloopref",
     "forbidigo",
-    "forcetypeassert",
+    # "forcetypeassert",
     "funlen",
     "gci",
     # "gochecknoglobals",
@@ -35,7 +35,7 @@ enable = [
     "gocyclo",
     "godot",
     "godox",
-    "goerr113",
+    # "goerr113",
     "gofmt",
     "gofumpt",
     "goheader",
@@ -57,10 +57,10 @@ enable = [
     "nakedret",
     "nestif",
     "nilerr",
-    "nlreturn",
+    # "nlreturn",
     "noctx",
     "nolintlint",
-    "paralleltest",
+    #"paralleltest",
     "prealloc",
     "predeclared",
     "revive",
@@ -80,5 +80,5 @@ enable = [
     "wastedassign",
     "whitespace",
     # "wrapcheck",
-    "wsl"
+    # "wsl"
 ]

CONTRIBUTING.md

@@ -1,74 +1,74 @@
-## Contributing
+# 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 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 –
+implementation for Go that gets the job done and gets out of your way – dealing
-dealing with TOML is probably not the central piece of your project.
+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
+As the single maintainer of go-toml, time is scarce. All help, big or small, is
-small, is more than welcomed!
+more than welcomed!
 
-### Ask questions
+## Ask questions
 
-Any question you may have, somebody else might have it too. Always feel
+Any question you may have, somebody else might have it too. Always feel free to
-free to ask them on the [issues tracker][issues-tracker].  We will try to
+ask them on the [discussion board][discussions]. We will try to answer them as
-answer them as clearly and quickly as possible, time permitting.
+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
+seemingly innocent question leads to the fix of a bug. Don't hesitate and ask
-ask away!
+away!
 
-### Improve the documentation
+[discussions]: https://github.com/pelletier/go-toml/discussions
 
-The best way to share your knowledge and experience with go-toml is to
+## Improve the documentation
-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
+The best way to share your knowledge and experience with go-toml is to improve
-source code. On release, it gets updated on [pkg.go.dev][pkg.go.dev]. To make a
+the documentation. Fix a typo, clarify an interface, add an example, anything
-change to the documentation, create a pull request with your proposed
+goes!
-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
+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.
 
-Found a bug! Sorry to hear that :(. Help us and other track them down and
+## Report a bug
-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
+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
+- A short proposal with some POC code is better than a lengthy piece of text
-  text with no code. Code speaks louder than words.
+  with no code. Code speaks louder than words. That being said, bigger changes
-* No backward-incompatible patch will be accepted unless discussed.
+  should probably start with a [discussion][discussions].
-  Sometimes it's hard, and Go's lack of versioning by default does not
+- No backward-incompatible patch will be accepted unless discussed. Sometimes
-  help, but we try not to break people's programs unless we absolutely have
+  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
+- If you are writing a new feature or extending an existing one, make sure to
-  to write some documentation.
+  write some documentation.
-* Bug fixes need to be accompanied with regression tests.
+- Bug fixes need to be accompanied with regression tests.
-* New code needs to be tested.
+- New code needs to be tested.
-* Your commit messages need to explain why the change is needed, even if
+- Your commit messages need to explain why the change is needed, even if already
-  already included in the PR description.
+  included in the PR description.
 
-It does sound like a lot, but those best practices are here to save time
+It does sound like a lot, but those best practices are here to save time overall
-overall and continuously improve the quality of the project, which is
+and continuously improve the quality of the project, which is something everyone
-something everyone benefits from.
+benefits from.
 
-#### Get started
+### Get started
 
 The fairly standard code contribution process looks like that:
 
@@ -76,42 +76,92 @@ The fairly standard code contribution process looks like that:
 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. You're in!
+5. Merge.
 
 Feel free to ask for help! You can create draft pull requests to gather
 some early feedback!
 
-#### Run the tests
+### Run the tests
 
-You can run tests for go-toml using Go's test tool: `go test ./...`.
+You can run tests for go-toml using Go's test tool: `go test -race ./...`.
-When creating a pull requests, all tests will be ran on Linux on a few Go
-versions (Travis CI), and on Windows using the latest Go version
-(AppVeyor).
 
-#### Style
+During the pull request process, all tests will be ran on Linux, Windows, and
+MacOS on the last two versions of Go.
 
-Try to look around and follow the same format and structure as the rest of
+However, given GitHub's new policy to _not_ run Actions on pull requests until a
-the code. We enforce using `go fmt` on the whole code base.
+maintainer clicks on button, it is highly recommended that you run them locally
+as you make changes.
+
+### 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
+## Maintainers-only
 
-#### Merge pull request
+### Merge pull request
 
 Checklist:
 
-* Passing CI.
+- Passing CI.
-* Does not introduce backward-incompatible changes (unless discussed).
+- Does not introduce backward-incompatible changes (unless discussed).
-* Has relevant doc changes.
+- Has relevant doc changes.
-* Has relevant unit tests.
+- Benchstat does not show performance regression.
 
 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
+### New release
 
 1. Go to [releases][releases]. Click on "X commits to master since this
    release".

README.md

@@ -4,7 +4,6 @@ Go library for the [TOML](https://toml.io/en/) format.
 
 This library supports [TOML v1.0.0](https://toml.io/en/v1.0.0).
 
-
 ## Development status
 
 This is the upcoming major version of go-toml. It is currently in active
@@ -14,8 +13,11 @@ with v1, and fixes a lot known bugs and performance issues along the way.
 If you do not need the advanced document editing features of v1, you are
 encouraged to try out this version.
 
-👉 [Roadmap for v2](https://github.com/pelletier/go-toml/discussions/506).
+[👉 Roadmap for v2](https://github.com/pelletier/go-toml/discussions/506)
 
+[🐞 Bug Reports](https://github.com/pelletier/go-toml/issues)
+
+[💬 Anything else](https://github.com/pelletier/go-toml/discussions)
 
 ## Documentation
 
@@ -23,7 +25,6 @@ Full API, examples, and implementation notes are available in the Go documentati
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/pelletier/go-toml/v2.svg)](https://pkg.go.dev/github.com/pelletier/go-toml/v2)
 
-
 ## Import
 
 ```go
@@ -40,7 +41,7 @@ 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.
+operations should not be shockingly slow. See [benchmarks](#benchmarks).
 
 ### Strict mode
 
@@ -146,6 +147,48 @@ fmt.Println(string(b))
 
 [marshal]: https://pkg.go.dev/github.com/pelletier/go-toml/v2#Marshal
 
+## 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</td><td>2.0x</td><td>2.0x</td></tr>
+        <tr><td>Marshal/ReferenceFile/map</td><td>1.8x</td><td>2.0x</td></tr>
+        <tr><td>Marshal/ReferenceFile/struct</td><td>2.7x</td><td>2.7x</td></tr>
+        <tr><td>Unmarshal/HugoFrontMatter</td><td>3.0x</td><td>2.6x</td></tr>
+        <tr><td>Unmarshal/ReferenceFile/map</td><td>3.0x</td><td>3.1x</td></tr>
+        <tr><td>Unmarshal/ReferenceFile/struct</td><td>5.9x</td><td>6.6x</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</td><td>1.7x</td><td>2.1x</td></tr>
+        <tr><td>Marshal/SimpleDocument/struct</td><td>2.6x</td><td>2.9x</td></tr>
+        <tr><td>Unmarshal/SimpleDocument/map</td><td>4.1x</td><td>2.9x</td></tr>
+        <tr><td>Unmarshal/SimpleDocument/struct</td><td>6.3x</td><td>4.1x</td></tr>
+        <tr><td>UnmarshalDataset/example</td><td>3.5x</td><td>2.4x</td></tr>
+        <tr><td>UnmarshalDataset/code</td><td>2.2x</td><td>2.8x</td></tr>
+        <tr><td>UnmarshalDataset/twitter</td><td>2.8x</td><td>2.1x</td></tr>
+        <tr><td>UnmarshalDataset/citm_catalog</td><td>2.3x</td><td>1.5x</td></tr>
+        <tr><td>UnmarshalDataset/config</td><td>4.2x</td><td>3.2x</td></tr>
+        <tr><td>[Geo mean]</td><td>3.0x</td><td>2.7x</td></tr>
+     </tbody>
+</table>
+<p>This table can be generated with <code>./ci.sh benchmark -a -html</code>.</p>
+</details>
+
 ## Migrating from v1
 
 This section describes the differences between v1 and v2, with some pointers on
@@ -248,6 +291,22 @@ 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
+
 ### Encoding / Marshal
 
 #### Default struct fields order
@@ -290,7 +349,6 @@ manually sort the fields alphabetically in the struct definition.
 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{

benchmark/bench_datasets_test.go

@@ -31,13 +31,14 @@ var bench_inputs = []struct {
 
 func TestUnmarshalDatasetCode(t *testing.T) {
 	for _, tc := range bench_inputs {
-		buf := fixture(t, tc.name)
 		t.Run(tc.name, func(t *testing.T) {
+			buf := fixture(t, tc.name)
+
 			var v interface{}
-			check(t, toml.Unmarshal(buf, &v))
+			require.NoError(t, toml.Unmarshal(buf, &v))
 
 			b, err := json.Marshal(v)
-			check(t, err)
+			require.NoError(t, err)
 			require.Equal(t, len(b), tc.jsonLen)
 		})
 	}
@@ -45,14 +46,14 @@ func TestUnmarshalDatasetCode(t *testing.T) {
 
 func BenchmarkUnmarshalDataset(b *testing.B) {
 	for _, tc := range bench_inputs {
-		buf := fixture(b, tc.name)
 		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{}
-				check(b, toml.Unmarshal(buf, &v))
+				require.NoError(b, toml.Unmarshal(buf, &v))
 			}
 		})
 	}
@@ -60,22 +61,20 @@ func BenchmarkUnmarshalDataset(b *testing.B) {
 
 // fixture returns the uncompressed contents of path.
 func fixture(tb testing.TB, path string) []byte {
-	f, err := os.Open(filepath.Join("testdata", path+".toml.gz"))
+	tb.Helper()
-	check(tb, err)
+
+	file := path + ".toml.gz"
+	f, err := os.Open(filepath.Join("testdata", file))
+	if os.IsNotExist(err) {
+		tb.Skip("benchmark fixture not found:", file)
+	}
+	require.NoError(tb, err)
 	defer f.Close()
 
 	gz, err := gzip.NewReader(f)
-	check(tb, err)
+	require.NoError(tb, err)
 
 	buf, err := ioutil.ReadAll(gz)
-	check(tb, err)
+	require.NoError(tb, err)
-
 	return buf
 }
-
-func check(tb testing.TB, err error) {
-	if err != nil {
-		tb.Helper()
-		tb.Fatal(err)
-	}
-}

benchmark/benchmark.toml

@@ -186,7 +186,7 @@ key3 = 1979-05-27T00:32:00.999999-07:00
 key1 = [ 1, 2, 3 ]
 key2 = [ "red", "yellow", "green" ]
 key3 = [ [ 1, 2 ], [3, 4, 5] ]
-#key4 = [ [ 1, 2 ], ["a", "b", "c"] ] # this is ok
+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

benchmark/benchmark_test.go

@@ -1,6 +1,7 @@
 package benchmark_test
 
 import (
+	"bytes"
 	"io/ioutil"
 	"testing"
 	"time"
@@ -9,17 +10,230 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func BenchmarkUnmarshalSimple(b *testing.B) {
+func TestUnmarshalSimple(t *testing.T) {
+	doc := []byte(`A = "hello"`)
 	d := struct {
 		A string
 	}{}
-	doc := []byte(`A = "hello"`)
+
-	for i := 0; i < b.N; i++ {
+	err := toml.Unmarshal(doc, &d)
-		err := toml.Unmarshal(doc, &d)
+	if err != nil {
+		panic(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 {
+					panic(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 {
+					panic(err)
+				}
+			}
+		})
+	})
+
+	b.Run("ReferenceFile", func(b *testing.B) {
+		bytes, err := ioutil.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 {
+					panic(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 {
+					panic(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 {
+				panic(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 {
+				panic(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					panic(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 {
+				panic(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					panic(err)
+				}
+			}
+
+			b.SetBytes(int64(len(out)))
+		})
+	})
+
+	b.Run("ReferenceFile", func(b *testing.B) {
+		bytes, err := ioutil.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 {
+				panic(err)
+			}
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					panic(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 {
+				panic(err)
+			}
+
+			b.ReportAllocs()
+			b.ResetTimer()
+
+			var out []byte
+			for i := 0; i < b.N; i++ {
+				out, err = marshal(d)
+				if err != nil {
+					panic(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 {
 			panic(err)
 		}
-	}
+
+		b.ReportAllocs()
+		b.ResetTimer()
+
+		var out []byte
+
+		for i := 0; i < b.N; i++ {
+			out, err = marshal(d)
+			if err != nil {
+				panic(err)
+			}
+		}
+
+		b.SetBytes(int64(len(out)))
+	})
 }
 
 type benchmarkDoc struct {
@@ -35,7 +249,7 @@ type benchmarkDoc struct {
 			}
 			Point struct {
 				X int64
-				U int64
+				Y int64
 			}
 		}
 	}
@@ -108,6 +322,7 @@ type benchmarkDoc struct {
 		Key2 []string
 		Key3 [][]int64
 		// TODO: Key4 not supported by go-toml's Unmarshal
+		Key4 []interface{}
 		Key5 []int64
 		Key6 []int64
 	}
@@ -119,36 +334,321 @@ type benchmarkDoc struct {
 	Fruit []struct {
 		Name     string
 		Physical struct {
-			Color   string
+			Color string
-			Shape   string
+			Shape string
-			Variety []struct {
+		}
-				Name string
+		Variety []struct {
-			}
+			Name string
 		}
 	}
 }
 
-func BenchmarkReferenceFile(b *testing.B) {
+func TestUnmarshalReferenceFile(t *testing.T) {
-	bytes, err := ioutil.ReadFile("benchmark.toml")
-	if err != nil {
-		b.Fatal(err)
-	}
-	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 {
-			panic(err)
-		}
-	}
-}
-
-func TestReferenceFile(t *testing.T) {
 	bytes, err := ioutil.ReadFile("benchmark.toml")
 	require.NoError(t, err)
 	d := benchmarkDoc{}
 	err = toml.Unmarshal(bytes, &d)
 	require.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"},
+				},
+			},
+		},
+	}
+
+	require.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 +1,273 @@
+#!/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 -coverprofile=coverage.out ./...
+    go tool cover -func=coverage.out
+    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="$(cat ${target_out} |sed -E 's/.*total.*\t([0-9.]+)%/\1/;t;d')"
+	    head_pct="$(cat ${head_out} |sed -E 's/.*total.*\t([0-9.]+)%/\1/;t;d')"
+	    echo "Results: ${target} ${target_pct}% HEAD ${head_pct}%"
+
+	    delta_pct=$(echo "$head_pct - $target_pct" | bc -l)
+	    echo "Delta: ${delta_pct}"
+
+	    if [[ $delta_pct = \-* ]]; then
+		echo "Regression!";
+		return 1
+	    fi
+	    return 0
+	    ;;
+    esac
+
+    cover "${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 "${replace}"
+        # hack: remove canada.toml.gz because it is not supported by
+        # burntsushi, and replace is only used for benchmark -a
+        rm -f benchmark/testdata/canada.toml.gz
+    fi
+
+    go test -bench=. -count=10 ./... | tee "${out}"
+    popd
+
+    if [ "${branch}" != "HEAD" ]; then
+	    git worktree remove --force "$dir"
+    fi
+}
+
+fmktemp() {
+    if mktemp --version|grep GNU >/dev/null; then
+        mktemp --suffix=-$1;
+    else
+        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[1:]):
+    v2 = float(line[1])
+    results.append([
+        line[0].replace("-32", ""),
+        "%.1fx" % (float(line[3])/v2),  # v1
+        "%.1fx" % (float(line[5])/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 -csv -geomean go-toml-v2.txt go-toml-v1.txt bs-toml.txt > $tmpcsv
+            benchstathtml $tmpcsv
+        else
+            benchstat -geomean 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

decode.go

@@ -1,6 +1,7 @@
 package toml
 
 import (
+	"fmt"
 	"math"
 	"strconv"
 	"time"
@@ -16,7 +17,7 @@ func parseInteger(b []byte) (int64, error) {
 		case 'o':
 			return parseIntOct(b)
 		default:
-			return 0, newDecodeError(b[1:2], "invalid base: '%c'", b[1])
+			panic(fmt.Errorf("invalid base '%c', should have been checked by scanIntOrFloat", b[1]))
 		}
 	}
 
@@ -34,41 +35,26 @@ func parseLocalDate(b []byte) (LocalDate, error) {
 		return date, newDecodeError(b, "dates are expected to have the format YYYY-MM-DD")
 	}
 
-	var err error
+	date.Year = parseDecimalDigits(b[0:4])
 
-	date.Year, err = parseDecimalDigits(b[0:4])
+	v := parseDecimalDigits(b[5:7])
-	if err != nil {
-		return date, err
-	}
-
-	v, err := parseDecimalDigits(b[5:7])
-	if err != nil {
-		return date, err
-	}
 
 	date.Month = time.Month(v)
 
-	date.Day, err = parseDecimalDigits(b[8:10])
+	date.Day = parseDecimalDigits(b[8:10])
-	if err != nil {
-		return date, err
-	}
 
 	return date, nil
 }
 
-func parseDecimalDigits(b []byte) (int, error) {
+func parseDecimalDigits(b []byte) int {
 	v := 0
 
-	for i, c := range b {
+	for _, c := range b {
-		if !isDigit(c) {
-			return 0, newDecodeError(b[i:i+1], "should be a digit (0-9)")
-		}
-
 		v *= 10
 		v += int(c - '0')
 	}
 
-	return v, nil
+	return v
 }
 
 func parseDateTime(b []byte) (time.Time, error) {
@@ -77,8 +63,6 @@ func parseDateTime(b []byte) (time.Time, error) {
 	// time-offset    = "Z" / time-numoffset
 	// time-numoffset = ( "+" / "-" ) time-hour ":" time-minute
 
-	originalBytes := b
-
 	dt, b, err := parseLocalDateTime(b)
 	if err != nil {
 		return time.Time{}, err
@@ -87,7 +71,8 @@ func parseDateTime(b []byte) (time.Time, error) {
 	var zone *time.Location
 
 	if len(b) == 0 {
-		return time.Time{}, newDecodeError(originalBytes, "date-time is missing timezone")
+		// parser should have checked that when assigning the date time node
+		panic("date time should have a timezone")
 	}
 
 	if b[0] == 'Z' {
@@ -99,18 +84,15 @@ func parseDateTime(b []byte) (time.Time, error) {
 			return time.Time{}, newDecodeError(b, "invalid date-time timezone")
 		}
 		direction := 1
-		switch b[0] {
+		if b[0] == '-' {
-		case '+':
-		case '-':
 			direction = -1
-		default:
-			return time.Time{}, newDecodeError(b[0:1], "invalid timezone offset character")
 		}
 
 		hours := digitsToInt(b[1:3])
 		minutes := digitsToInt(b[4:6])
 		seconds := direction * (hours*3600 + minutes*60)
 		zone = time.FixedZone("", seconds)
+		b = b[dateTimeByteLen:]
 	}
 
 	if len(b) > 0 {
@@ -161,7 +143,6 @@ func parseLocalDateTime(b []byte) (LocalDateTime, []byte, error) {
 // 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.
-//nolint:cyclop,funlen
 func parseLocalTime(b []byte) (LocalTime, []byte, error) {
 	var (
 		nspow = [10]int{0, 1e8, 1e7, 1e6, 1e5, 1e4, 1e3, 1e2, 1e1, 1e0}
@@ -173,36 +154,24 @@ func parseLocalTime(b []byte) (LocalTime, []byte, error) {
 		return t, nil, newDecodeError(b, "times are expected to have the format HH:MM:SS[.NNNNNN]")
 	}
 
-	var err error
+	t.Hour = parseDecimalDigits(b[0:2])
-
-	t.Hour, err = parseDecimalDigits(b[0:2])
-	if err != nil {
-		return t, nil, err
-	}
-
 	if b[2] != ':' {
 		return t, nil, newDecodeError(b[2:3], "expecting colon between hours and minutes")
 	}
 
-	t.Minute, err = parseDecimalDigits(b[3:5])
+	t.Minute = parseDecimalDigits(b[3:5])
-	if err != nil {
-		return t, nil, err
-	}
-
 	if b[5] != ':' {
 		return t, nil, newDecodeError(b[5:6], "expecting colon between minutes and seconds")
 	}
 
-	t.Second, err = parseDecimalDigits(b[6:8])
+	t.Second = parseDecimalDigits(b[6:8])
-	if err != nil {
-		return t, nil, err
-	}
 
-	if len(b) >= 9 && b[8] == '.' {
+	const minLengthWithFrac = 9
+	if len(b) >= minLengthWithFrac && b[minLengthWithFrac-1] == '.' {
 		frac := 0
 		digits := 0
 
-		for i, c := range b[9:] {
+		for i, c := range b[minLengthWithFrac:] {
 			if !isDigit(c) {
 				if i == 0 {
 					return t, nil, newDecodeError(b[i:i+1], "need at least one digit after fraction point")
@@ -211,8 +180,8 @@ func parseLocalTime(b []byte) (LocalTime, []byte, error) {
 				break
 			}
 
-			//nolint:gomnd
+			const maxFracPrecision = 9
-			if i >= 9 {
+			if i >= maxFracPrecision {
 				return t, nil, newDecodeError(b[i:i+1], "maximum precision for date time is nanosecond")
 			}
 
@@ -231,8 +200,6 @@ func parseLocalTime(b []byte) (LocalTime, []byte, error) {
 
 //nolint:cyclop
 func parseFloat(b []byte) (float64, error) {
-	//nolint:godox
-	// TODO: inefficient
 	if len(b) == 4 && (b[0] == '+' || b[0] == '-') && b[1] == 'n' && b[2] == 'a' && b[3] == 'n' {
 		return math.NaN(), nil
 	}
@@ -252,7 +219,7 @@ func parseFloat(b []byte) (float64, error) {
 
 	f, err := strconv.ParseFloat(string(cleaned), 64)
 	if err != nil {
-		return 0, newDecodeError(b, "coudn't parse float: %w", err)
+		return 0, newDecodeError(b, "unable to parse float: %w", err)
 	}
 
 	return f, nil
@@ -315,10 +282,6 @@ func parseIntDec(b []byte) (int64, error) {
 }
 
 func checkAndRemoveUnderscores(b []byte) ([]byte, error) {
-	if len(b) == 0 {
-		return b, nil
-	}
-
 	if b[0] == '_' {
 		return nil, newDecodeError(b[0:1], "number cannot start with underscore")
 	}

doc.go

@@ -1,4 +1,2 @@
-/*
+// Package toml is a library to read and write TOML documents.
-   Package toml is a library to read and write TOML documents.
-*/
 package toml

errors.go

@@ -5,7 +5,7 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/pelletier/go-toml/v2/internal/unsafe"
+	"github.com/pelletier/go-toml/v2/internal/danger"
 )
 
 // DecodeError represents an error encountered during the parsing or decoding
@@ -105,13 +105,9 @@ func (e *DecodeError) Key() Key {
 // highlight can be freely deallocated.
 //nolint:funlen
 func wrapDecodeError(document []byte, de *decodeError) *DecodeError {
-	if de == nil {
+	offset := danger.SubsliceOffset(document, de.highlight)
-		return nil
-	}
 
-	offset := unsafe.SubsliceOffset(document, de.highlight)
+	errMessage := de.Error()
-
-	errMessage := de.message
 	errLine, errColumn := positionAtEnd(document[:offset])
 	before, after := linesOfContext(document, de.highlight, offset, 3)
 

errors_test.go

@@ -12,7 +12,6 @@ import (
 
 //nolint:funlen
 func TestDecodeError(t *testing.T) {
-	t.Parallel()
 
 	examples := []struct {
 		desc     string
@@ -154,7 +153,7 @@ line 5`,
 	for _, e := range examples {
 		e := e
 		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
+
 			b := bytes.Buffer{}
 			b.Write([]byte(e.doc[0]))
 			start := b.Len()
@@ -181,6 +180,23 @@ line 5`,
 	}
 }
 
+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 ExampleDecodeError() {
 	doc := `name = 123__456`
 
@@ -189,14 +205,15 @@ func ExampleDecodeError() {
 
 	fmt.Println(err)
 
+	//nolint:errorlint
 	de := err.(*DecodeError)
 	fmt.Println(de.String())
 
 	row, col := de.Position()
-	fmt.Println("error occured at row", row, "column", col)
+	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 occured at row 1 column 11
+	// error occurred at row 1 column 11
 }

fast_test.go

@@ -0,0 +1,100 @@
+package toml_test
+
+import (
+	"testing"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFastSimple(t *testing.T) {
+	m := map[string]int64{}
+	err := toml.Unmarshal([]byte(`a = 42`), &m)
+	require.NoError(t, err)
+	require.Equal(t, map[string]int64{"a": 42}, m)
+}
+
+func TestFastSimpleString(t *testing.T) {
+	m := map[string]string{}
+	err := toml.Unmarshal([]byte(`a = "hello"`), &m)
+	require.NoError(t, err)
+	require.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)
+	require.NoError(t, err)
+	require.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)
+	require.NoError(t, err)
+	require.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)
+	require.NoError(t, err)
+	require.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)
+	require.NoError(t, err)
+
+	require.Equal(t, map[string]interface{}{
+		"root": map[string]interface{}{
+			"nested": []interface{}{
+				map[string]interface{}{
+					"name": "Bob",
+				},
+				map[string]interface{}{
+					"name": "Alice",
+				},
+			},
+		},
+	}, m)
+}

go.mod

@@ -2,4 +2,5 @@ module github.com/pelletier/go-toml/v2
 
 go 1.15
 
-require github.com/stretchr/testify v1.7.0
+// latest (v1.7.0) doesn't have the fix for time.Time
+require github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942

go.sum

@@ -3,8 +3,8 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942 h1:t0lM6y/M5IiUZyvbBTcngso8SZEZICH7is9B6g/obVU=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=

internal/ast/ast.go

@@ -2,6 +2,9 @@ package ast
 
 import (
 	"fmt"
+	"unsafe"
+
+	"github.com/pelletier/go-toml/v2/internal/danger"
 )
 
 // Iterator starts uninitialized, you need to call Next() first.
@@ -14,7 +17,7 @@ import (
 // }
 type Iterator struct {
 	started bool
-	node    Node
+	node    *Node
 }
 
 // Next moves the iterator forward and returns true if points to a node, false
@@ -28,8 +31,14 @@ func (c *Iterator) Next() bool {
 	return c.node.Valid()
 }
 
+// IsLast returns true if the current node of the iterator is the last one.
+// Subsequent call to Next() will return false.
+func (c *Iterator) IsLast() bool {
+	return c.node.next == 0
+}
+
 // Node returns a copy of the node pointed at by the iterator.
-func (c *Iterator) Node() Node {
+func (c *Iterator) Node() *Node {
 	return c.node
 }
 
@@ -44,14 +53,13 @@ type Root struct {
 func (r *Root) Iterator() Iterator {
 	it := Iterator{}
 	if len(r.nodes) > 0 {
-		it.node = r.nodes[0]
+		it.node = &r.nodes[0]
 	}
 	return it
 }
 
-func (r *Root) at(idx int) Node {
+func (r *Root) at(idx Reference) *Node {
-	// TODO: unsafe to point to the node directly
+	return &r.nodes[idx]
-	return r.nodes[idx]
 }
 
 // Arrays have one child per element in the array.
@@ -63,42 +71,48 @@ func (r *Root) at(idx int) Node {
 // children []Node
 type Node struct {
 	Kind Kind
-	Data []byte // Raw bytes from the input
+	Raw  Range  // Raw bytes from the input.
+	Data []byte // Node value (could be either allocated or referencing the input).
 
-	// next idx (in the root array). 0 if last of the collection.
+	// References to other nodes, as offsets in the backing array from this
-	next int
+	// node. References can go backward, so those can be negative.
-	// child idx (in the root array). 0 if no child.
+	next  int // 0 if last element
-	child int
+	child int // 0 if no child
-	// pointer to the root array
+}
-	root *Root
+
+type Range struct {
+	Offset uint32
+	Length uint32
 }
 
 // Next returns a copy of the next node, or an invalid Node if there is no
 // next node.
-func (n Node) Next() Node {
+func (n *Node) Next() *Node {
-	if n.next <= 0 {
+	if n.next == 0 {
-		return noNode
+		return nil
 	}
-	return n.root.at(n.next)
+	ptr := unsafe.Pointer(n)
+	size := unsafe.Sizeof(Node{})
+	return (*Node)(danger.Stride(ptr, size, n.next))
 }
 
 // Child returns a copy of the first child node of this node. Other children
 // can be accessed calling Next on the first child.
 // Returns an invalid Node if there is none.
-func (n Node) Child() Node {
+func (n *Node) Child() *Node {
-	if n.child <= 0 {
+	if n.child == 0 {
-		return noNode
+		return nil
 	}
-	return n.root.at(n.child)
+	ptr := unsafe.Pointer(n)
+	size := unsafe.Sizeof(Node{})
+	return (*Node)(danger.Stride(ptr, size, n.child))
 }
 
 // Valid returns true if the node's kind is set (not to Invalid).
-func (n Node) Valid() bool {
+func (n *Node) Valid() bool {
-	return n.Kind != Invalid
+	return n != nil
 }
 
-var noNode = Node{}
-
 // Key returns the child nodes making the Key on a supported node. Panics
 // otherwise.
 // They are guaranteed to be all be of the Kind Key. A simple key would return
@@ -121,13 +135,13 @@ func (n *Node) Key() Iterator {
 // Value returns a pointer to the value node of a KeyValue.
 // Guaranteed to be non-nil.
 // Panics if not called on a KeyValue node, or if the Children are malformed.
-func (n Node) Value() Node {
+func (n *Node) Value() *Node {
-	assertKind(KeyValue, n)
+	assertKind(KeyValue, *n)
 	return n.Child()
 }
 
 // Children returns an iterator over a node's children.
-func (n Node) Children() Iterator {
+func (n *Node) Children() Iterator {
 	return Iterator{node: n.Child()}
 }
 

internal/ast/builder.go

@@ -1,12 +1,11 @@
 package ast
 
-type Reference struct {
+type Reference int
-	idx int
+
-	set bool
+const InvalidReference Reference = -1
-}
 
 func (r Reference) Valid() bool {
-	return r.set
+	return r != InvalidReference
 }
 
 type Builder struct {
@@ -18,8 +17,8 @@ func (b *Builder) Tree() *Root {
 	return &b.tree
 }
 
-func (b *Builder) NodeAt(ref Reference) Node {
+func (b *Builder) NodeAt(ref Reference) *Node {
-	return b.tree.at(ref.idx)
+	return b.tree.at(ref)
 }
 
 func (b *Builder) Reset() {
@@ -28,33 +27,25 @@ func (b *Builder) Reset() {
 }
 
 func (b *Builder) Push(n Node) Reference {
-	n.root = &b.tree
 	b.lastIdx = len(b.tree.nodes)
 	b.tree.nodes = append(b.tree.nodes, n)
-	return Reference{
+	return Reference(b.lastIdx)
-		idx: b.lastIdx,
-		set: true,
-	}
 }
 
 func (b *Builder) PushAndChain(n Node) Reference {
-	n.root = &b.tree
 	newIdx := len(b.tree.nodes)
 	b.tree.nodes = append(b.tree.nodes, n)
 	if b.lastIdx >= 0 {
-		b.tree.nodes[b.lastIdx].next = newIdx
+		b.tree.nodes[b.lastIdx].next = newIdx - b.lastIdx
 	}
 	b.lastIdx = newIdx
-	return Reference{
+	return Reference(b.lastIdx)
-		idx: b.lastIdx,
-		set: true,
-	}
 }
 
 func (b *Builder) AttachChild(parent Reference, child Reference) {
-	b.tree.nodes[parent.idx].child = child.idx
+	b.tree.nodes[parent].child = int(child) - int(parent)
 }
 
 func (b *Builder) Chain(from Reference, to Reference) {
-	b.tree.nodes[from.idx].next = to.idx
+	b.tree.nodes[from].next = int(to) - int(from)
 }

internal/danger/danger.go

@@ -1,4 +1,4 @@
-package unsafe
+package danger
 
 import (
 	"fmt"
@@ -57,3 +57,9 @@ func BytesRange(start []byte, end []byte) []byte {
 
 	return start[:l]
 }
+
+func Stride(ptr unsafe.Pointer, size uintptr, offset int) unsafe.Pointer {
+	// TODO: replace with unsafe.Add when Go 1.17 is released
+	//   https://github.com/golang/go/issues/40481
+	return unsafe.Pointer(uintptr(ptr) + uintptr(int(size)*offset))
+}

internal/danger/danger_test.go

@@ -1,15 +1,16 @@
-package unsafe_test
+package danger_test
 
 import (
 	"testing"
+	"unsafe"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/pelletier/go-toml/v2/internal/unsafe"
+	"github.com/pelletier/go-toml/v2/internal/danger"
 )
 
-func TestUnsafeSubsliceOffsetValid(t *testing.T) {
+func TestSubsliceOffsetValid(t *testing.T) {
 	examples := []struct {
 		desc   string
 		test   func() ([]byte, []byte)
@@ -28,13 +29,13 @@ func TestUnsafeSubsliceOffsetValid(t *testing.T) {
 	for _, e := range examples {
 		t.Run(e.desc, func(t *testing.T) {
 			d, s := e.test()
-			offset := unsafe.SubsliceOffset(d, s)
+			offset := danger.SubsliceOffset(d, s)
 			assert.Equal(t, e.offset, offset)
 		})
 	}
 }
 
-func TestUnsafeSubsliceOffsetInvalid(t *testing.T) {
+func TestSubsliceOffsetInvalid(t *testing.T) {
 	examples := []struct {
 		desc string
 		test func() ([]byte, []byte)
@@ -72,13 +73,22 @@ func TestUnsafeSubsliceOffsetInvalid(t *testing.T) {
 		t.Run(e.desc, func(t *testing.T) {
 			d, s := e.test()
 			require.Panics(t, func() {
-				unsafe.SubsliceOffset(d, s)
+				danger.SubsliceOffset(d, s)
 			})
 		})
 	}
 }
 
-func TestUnsafeBytesRange(t *testing.T) {
+func TestStride(t *testing.T) {
+	a := []byte{1, 2, 3, 4}
+	x := &a[1]
+	n := (*byte)(danger.Stride(unsafe.Pointer(x), unsafe.Sizeof(byte(0)), 1))
+	require.Equal(t, &a[2], n)
+	n = (*byte)(danger.Stride(unsafe.Pointer(x), unsafe.Sizeof(byte(0)), -1))
+	require.Equal(t, &a[0], n)
+}
+
+func TestBytesRange(t *testing.T) {
 	type fn = func() ([]byte, []byte)
 	examples := []struct {
 		desc     string
@@ -157,10 +167,10 @@ func TestUnsafeBytesRange(t *testing.T) {
 			start, end := e.test()
 			if e.expected == nil {
 				require.Panics(t, func() {
-					unsafe.BytesRange(start, end)
+					danger.BytesRange(start, end)
 				})
 			} else {
-				res := unsafe.BytesRange(start, end)
+				res := danger.BytesRange(start, end)
 				require.Equal(t, e.expected, res)
 			}
 		})

internal/imported_tests/unmarshal_imported_test.go

@@ -223,11 +223,13 @@ type testSubDoc struct {
 	unexported int    `toml:"shouldntBeHere"`
 }
 
-var biteMe = "Bite me"
+var (
-var float1 float32 = 12.3
+	biteMe         = "Bite me"
-var float2 float32 = 45.6
+	float1 float32 = 12.3
-var float3 float32 = 78.9
+	float2 float32 = 45.6
-var subdoc = testSubDoc{"Second", 0}
+	float3 float32 = 78.9
+	subdoc         = testSubDoc{"Second", 0}
+)
 
 var docData = testDoc{
 	Title:       "TOML Marshal Testing",
@@ -382,7 +384,7 @@ var intErrTomls = []string{
 }
 
 func TestErrUnmarshal(t *testing.T) {
-	var errTomls = []string{
+	errTomls := []string{
 		"bool = truly\ndate = 1979-05-27T07:32:00Z\nfloat = 123.4\nint = 5000\nstring = \"Bite me\"",
 		"bool = true\ndate = 1979-05-27T07:3200Z\nfloat = 123.4\nint = 5000\nstring = \"Bite me\"",
 		"bool = true\ndate = 1979-05-27T07:32:00Z\nfloat = 123a4\nint = 5000\nstring = \"Bite me\"",
@@ -468,7 +470,7 @@ func TestEmptyUnmarshalOmit(t *testing.T) {
 		Map        map[string]string       `toml:"map,omitempty"`
 	}
 
-	var emptyTestData2 = emptyMarshalTestStruct2{
+	emptyTestData2 := emptyMarshalTestStruct2{
 		Title:      "Placeholder",
 		Bool:       false,
 		Int:        0,
@@ -496,21 +498,23 @@ type pointerMarshalTestStruct struct {
 	DblPtr    *[]*[]*string
 }
 
-var pointerStr = "Hello"
+var (
-var pointerList = []string{"Hello back"}
+	pointerStr      = "Hello"
-var pointerListPtr = []*string{&pointerStr}
+	pointerList     = []string{"Hello back"}
-var pointerMap = map[string]string{"response": "Goodbye"}
+	pointerListPtr  = []*string{&pointerStr}
-var pointerMapPtr = map[string]*string{"alternate": &pointerStr}
+	pointerMap      = map[string]string{"response": "Goodbye"}
-var pointerTestData = pointerMarshalTestStruct{
+	pointerMapPtr   = map[string]*string{"alternate": &pointerStr}
-	Str:       &pointerStr,
+	pointerTestData = pointerMarshalTestStruct{
-	List:      &pointerList,
+		Str:       &pointerStr,
-	ListPtr:   &pointerListPtr,
+		List:      &pointerList,
-	Map:       &pointerMap,
+		ListPtr:   &pointerListPtr,
-	MapPtr:    &pointerMapPtr,
+		Map:       &pointerMap,
-	EmptyStr:  nil,
+		MapPtr:    &pointerMapPtr,
-	EmptyList: nil,
+		EmptyStr:  nil,
-	EmptyMap:  nil,
+		EmptyList: nil,
-}
+		EmptyMap:  nil,
+	}
+)
 
 var pointerTestToml = []byte(`List = ["Hello back"]
 ListPtr = ["Hello"]
@@ -538,15 +542,17 @@ func TestUnmarshalTypeMismatch(t *testing.T) {
 
 type nestedMarshalTestStruct struct {
 	String [][]string
-	//Struct [][]basicMarshalTestSubStruct
+	// Struct [][]basicMarshalTestSubStruct
 	StringPtr *[]*[]*string
 	// StructPtr *[]*[]*basicMarshalTestSubStruct
 }
 
-var str1 = "Three"
+var (
-var str2 = "Four"
+	str1    = "Three"
-var strPtr = []*string{&str1, &str2}
+	str2    = "Four"
-var strPtr2 = []*[]*string{&strPtr}
+	strPtr  = []*string{&str1, &str2}
+	strPtr2 = []*[]*string{&strPtr}
+)
 
 var nestedTestData = nestedMarshalTestStruct{
 	String:    [][]string{{"Five", "Six"}, {"One", "Two"}},
@@ -597,6 +603,7 @@ var nestedCustomMarshalerData = customMarshalerParent{
 var nestedCustomMarshalerToml = []byte(`friends = ["Sally Fields"]
 me = "Maiku Suteda"
 `)
+
 var nestedCustomMarshalerTomlForUnmarshal = []byte(`[friends]
 FirstName = "Sally"
 LastName = "Fields"`)
@@ -613,11 +620,11 @@ func (x *IntOrString) MarshalTOML() ([]byte, error) {
 }
 
 func TestUnmarshalTextMarshaler(t *testing.T) {
-	var nested = struct {
+	nested := struct {
 		Friends textMarshaler `toml:"friends"`
 	}{}
 
-	var expected = struct {
+	expected := struct {
 		Friends textMarshaler `toml:"friends"`
 	}{
 		Friends: textMarshaler{FirstName: "Sally", LastName: "Fields"},
@@ -1360,7 +1367,6 @@ func TestUnmarshalPreservesUnexportedFields(t *testing.T) {
 	t.Run("unexported field should not be set from toml", func(t *testing.T) {
 		var actual unexportedFieldPreservationTest
 		err := toml.Unmarshal([]byte(doc), &actual)
-
 		if err != nil {
 			t.Fatal("did not expect an error")
 		}
@@ -1394,7 +1400,6 @@ func TestUnmarshalPreservesUnexportedFields(t *testing.T) {
 			Nested3:    &unexportedFieldPreservationTestNested{"baz", "bax"},
 		}
 		err := toml.Unmarshal([]byte(doc), &actual)
-
 		if err != nil {
 			t.Fatal("did not expect an error")
 		}
@@ -1431,7 +1436,6 @@ func TestUnmarshalLocalDate(t *testing.T) {
 		var obj dateStruct
 
 		err := toml.Unmarshal([]byte(doc), &obj)
-
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1457,7 +1461,6 @@ func TestUnmarshalLocalDate(t *testing.T) {
 		var obj dateStruct
 
 		err := toml.Unmarshal([]byte(doc), &obj)
-
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -1495,7 +1498,8 @@ func TestUnmarshalLocalDateTime(t *testing.T) {
 					Second:     0,
 					Nanosecond: 0,
 				},
-			}},
+			},
+		},
 		{
 			name: "with nanoseconds",
 			in:   "1979-05-27T00:32:00.999999",
@@ -1526,7 +1530,6 @@ func TestUnmarshalLocalDateTime(t *testing.T) {
 			var obj dateStruct
 
 			err := toml.Unmarshal([]byte(doc), &obj)
-
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -1544,7 +1547,6 @@ func TestUnmarshalLocalDateTime(t *testing.T) {
 			var obj dateStruct
 
 			err := toml.Unmarshal([]byte(doc), &obj)
-
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -1613,7 +1615,6 @@ func TestUnmarshalLocalTime(t *testing.T) {
 			var obj dateStruct
 
 			err := toml.Unmarshal([]byte(doc), &obj)
-
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -2283,8 +2284,7 @@ func (d *durationString) UnmarshalTOML(v interface{}) error {
 	return nil
 }
 
-type config437Error struct {
+type config437Error struct{}
-}
 
 func (e *config437Error) UnmarshalTOML(v interface{}) error {
 	return errors.New("expected")

internal/tracker/key.go

@@ -11,19 +11,19 @@ type KeyTracker struct {
 }
 
 // UpdateTable sets the state of the tracker with the AST table node.
-func (t *KeyTracker) UpdateTable(node ast.Node) {
+func (t *KeyTracker) UpdateTable(node *ast.Node) {
 	t.reset()
 	t.Push(node)
 }
 
 // UpdateArrayTable sets the state of the tracker with the AST array table node.
-func (t *KeyTracker) UpdateArrayTable(node ast.Node) {
+func (t *KeyTracker) UpdateArrayTable(node *ast.Node) {
 	t.reset()
 	t.Push(node)
 }
 
 // Push the given key on the stack.
-func (t *KeyTracker) Push(node ast.Node) {
+func (t *KeyTracker) Push(node *ast.Node) {
 	it := node.Key()
 	for it.Next() {
 		t.k = append(t.k, string(it.Node().Data))
@@ -31,7 +31,7 @@ func (t *KeyTracker) Push(node ast.Node) {
 }
 
 // Pop key from stack.
-func (t *KeyTracker) Pop(node ast.Node) {
+func (t *KeyTracker) Pop(node *ast.Node) {
 	it := node.Key()
 	for it.Next() {
 		t.k = t.k[:len(t.k)-1]

internal/tracker/seen.go

@@ -1,6 +1,7 @@
 package tracker
 
 import (
+	"bytes"
 	"fmt"
 
 	"github.com/pelletier/go-toml/v2/internal/ast"
@@ -29,67 +30,92 @@ func (k keyKind) String() string {
 	panic("missing keyKind string mapping")
 }
 
-// SeenTracker tracks which keys have been seen with which TOML type to flag duplicates
+// SeenTracker tracks which keys have been seen with which TOML type to flag
-// and mismatches according to the spec.
+// 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 {
-	root    *info
+	entries    []entry
-	current *info
+	currentIdx int
+	nextID     int
 }
 
-type info struct {
+type entry struct {
-	parent   *info
+	id       int
+	parent   int
+	name     []byte
 	kind     keyKind
-	children map[string]*info
 	explicit bool
 }
 
-func (i *info) Clear() {
+// Remove all descendent of node at position idx.
-	i.children = nil
+func (s *SeenTracker) clear(idx int) {
+	p := s.entries[idx].id
+	rest := clear(p, s.entries[idx+1:])
+	s.entries = s.entries[:idx+1+len(rest)]
 }
 
-func (i *info) Has(k string) (*info, bool) {
+func clear(parentID int, entries []entry) []entry {
-	c, ok := i.children[k]
+	for i := 0; i < len(entries); {
-	return c, ok
+		if entries[i].parent == parentID {
-}
+			id := entries[i].id
-
+			copy(entries[i:], entries[i+1:])
-func (i *info) SetKind(kind keyKind) {
+			entries = entries[:len(entries)-1]
-	i.kind = kind
+			rest := clear(id, entries[i:])
-}
+			entries = entries[:i+len(rest)]
-
+		} else {
-func (i *info) CreateTable(k string, explicit bool) *info {
+			i++
-	return i.createChild(k, tableKind, explicit)
+		}
-}
-
-func (i *info) CreateArrayTable(k string, explicit bool) *info {
-	return i.createChild(k, arrayTableKind, explicit)
-}
-
-func (i *info) createChild(k string, kind keyKind, explicit bool) *info {
-	if i.children == nil {
-		i.children = make(map[string]*info, 1)
 	}
+	return entries
+}
 
-	x := &info{
+func (s *SeenTracker) create(parentIdx int, name []byte, kind keyKind, explicit bool) int {
-		parent:   i,
+	parentID := s.id(parentIdx)
+
+	idx := len(s.entries)
+	s.entries = append(s.entries, entry{
+		id:       s.nextID,
+		parent:   parentID,
+		name:     name,
 		kind:     kind,
 		explicit: explicit,
-	}
+	})
-	i.children[k] = x
+	s.nextID++
-	return x
+	return idx
 }
 
 // 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.
-func (s *SeenTracker) CheckExpression(node ast.Node) error {
+func (s *SeenTracker) CheckExpression(node *ast.Node) error {
-	if s.root == nil {
+	if s.entries == nil {
-		s.root = &info{
+		// s.entries = make([]entry, 0, 8)
-			kind: tableKind,
+		// Skip ID = 0 to remove the confusion between nodes whose parent has
-		}
+		// id 0 and root nodes (parent id is 0 because it's the zero value).
-		s.current = s.root
+		s.nextID = 1
+		// Start unscoped, so idx is negative.
+		s.currentIdx = -1
 	}
 	switch node.Kind {
 	case ast.KeyValue:
-		return s.checkKeyValue(s.current, node)
+		return s.checkKeyValue(node)
 	case ast.Table:
 		return s.checkTable(node)
 	case ast.ArrayTable:
@@ -97,104 +123,135 @@ func (s *SeenTracker) CheckExpression(node ast.Node) error {
 	default:
 		panic(fmt.Errorf("this should not be a top level node type: %s", node.Kind))
 	}
-
 }
-func (s *SeenTracker) checkTable(node ast.Node) error {
-	s.current = s.root
 
+func (s *SeenTracker) checkTable(node *ast.Node) error {
 	it := node.Key()
-	// handle the first parts of the key, excluding the last one
+
+	parentIdx := -1
+
+	// 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.Node().Next().Valid() {
+		if it.IsLast() {
 			break
 		}
 
-		k := string(it.Node().Data)
+		k := it.Node().Data
-		child, found := s.current.Has(k)
+
-		if !found {
+		idx := s.find(parentIdx, k)
-			child = s.current.CreateTable(k, false)
+
+		if idx < 0 {
+			idx = s.create(parentIdx, k, tableKind, false)
 		}
-		s.current = child
+		parentIdx = idx
 	}
 
-	// handle the last part of the key
+	k := it.Node().Data
-	k := string(it.Node().Data)
+	idx := s.find(parentIdx, k)
 
-	i, found := s.current.Has(k)
+	if idx >= 0 {
-	if found {
+		kind := s.entries[idx].kind
-		if i.kind != tableKind {
+		if kind != tableKind {
-			return fmt.Errorf("toml: key %s should be a table, not a %s", k, i.kind)
+			return fmt.Errorf("toml: key %s should be a table, not a %s", string(k), kind)
 		}
-		if i.explicit {
+		if s.entries[idx].explicit {
-			return fmt.Errorf("toml: table %s already exists", k)
+			return fmt.Errorf("toml: table %s already exists", string(k))
 		}
-		i.explicit = true
+		s.entries[idx].explicit = true
-		s.current = i
 	} else {
-		s.current = s.current.CreateTable(k, true)
+		idx = s.create(parentIdx, k, tableKind, true)
 	}
 
+	s.currentIdx = idx
+
 	return nil
 }
 
-func (s *SeenTracker) checkArrayTable(node ast.Node) error {
+func (s *SeenTracker) checkArrayTable(node *ast.Node) error {
-	s.current = s.root
-
 	it := node.Key()
 
-	// handle the first parts of the key, excluding the last one
+	parentIdx := -1
+
 	for it.Next() {
-		if !it.Node().Next().Valid() {
+		if it.IsLast() {
 			break
 		}
 
-		k := string(it.Node().Data)
+		k := it.Node().Data
-		child, found := s.current.Has(k)
+
-		if !found {
+		idx := s.find(parentIdx, k)
-			child = s.current.CreateTable(k, false)
+
+		if idx < 0 {
+			idx = s.create(parentIdx, k, tableKind, false)
 		}
-		s.current = child
+		parentIdx = idx
 	}
 
-	// handle the last part of the key
+	k := it.Node().Data
-	k := string(it.Node().Data)
+	idx := s.find(parentIdx, k)
 
-	info, found := s.current.Has(k)
+	if idx >= 0 {
-	if found {
+		kind := s.entries[idx].kind
-		if info.kind != arrayTableKind {
+		if kind != arrayTableKind {
-			return fmt.Errorf("toml: key %s already exists as a %s,  but should be an array table", info.kind, k)
+			return fmt.Errorf("toml: key %s already exists as a %s,  but should be an array table", kind, string(k))
 		}
-		info.Clear()
+		s.clear(idx)
 	} else {
-		info = s.current.CreateArrayTable(k, true)
+		idx = s.create(parentIdx, k, arrayTableKind, true)
 	}
 
-	s.current = info
+	s.currentIdx = idx
+
 	return nil
 }
 
-func (s *SeenTracker) checkKeyValue(context *info, node ast.Node) error {
+func (s *SeenTracker) checkKeyValue(node *ast.Node) error {
 	it := node.Key()
 
-	// handle the first parts of the key, excluding the last one
+	parentIdx := s.currentIdx
+
 	for it.Next() {
-		k := string(it.Node().Data)
+		k := it.Node().Data
-		child, found := context.Has(k)
+
-		if found {
+		idx := s.find(parentIdx, k)
-			if child.kind != tableKind {
+
-				return fmt.Errorf("toml: expected %s to be a table, not a %s", k, child.kind)
+		if idx >= 0 {
+			if s.entries[idx].kind != tableKind {
+				return fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), s.entries[idx].kind)
 			}
 		} else {
-			child = context.CreateTable(k, false)
+			idx = s.create(parentIdx, k, tableKind, false)
 		}
-		context = child
+		parentIdx = idx
 	}
 
+	kind := valueKind
+
 	if node.Value().Kind == ast.InlineTable {
-		context.SetKind(tableKind)
+		kind = tableKind
-	} else {
-		context.SetKind(valueKind)
 	}
+	s.entries[parentIdx].kind = kind
 
 	return nil
 }
+
+func (s *SeenTracker) id(idx int) int {
+	if idx >= 0 {
+		return s.entries[idx].id
+	}
+	return 0
+}
+
+func (s *SeenTracker) find(parentIdx int, k []byte) int {
+	parentID := s.id(parentIdx)
+
+	for i := parentIdx + 1; i < len(s.entries); i++ {
+		if s.entries[i].parent == parentID && bytes.Equal(s.entries[i].name, k) {
+			return i
+		}
+	}
+
+	return -1
+}

localtime_test.go

@@ -26,7 +26,6 @@ func cmpEqual(x, y interface{}) bool {
 }
 
 func TestDates(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		date     LocalDate
@@ -64,7 +63,6 @@ func TestDates(t *testing.T) {
 }
 
 func TestDateIsValid(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		date LocalDate
@@ -91,7 +89,6 @@ func TestDateIsValid(t *testing.T) {
 }
 
 func TestParseDate(t *testing.T) {
-	t.Parallel()
 
 	var emptyDate LocalDate
 
@@ -118,7 +115,6 @@ func TestParseDate(t *testing.T) {
 }
 
 func TestDateArithmetic(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		desc  string
@@ -180,7 +176,6 @@ func TestDateArithmetic(t *testing.T) {
 }
 
 func TestDateBefore(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		d1, d2 LocalDate
@@ -198,7 +193,6 @@ func TestDateBefore(t *testing.T) {
 }
 
 func TestDateAfter(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		d1, d2 LocalDate
@@ -215,7 +209,6 @@ func TestDateAfter(t *testing.T) {
 }
 
 func TestTimeToString(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		str       string
@@ -249,7 +242,6 @@ func TestTimeToString(t *testing.T) {
 }
 
 func TestTimeOf(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		time time.Time
@@ -265,7 +257,6 @@ func TestTimeOf(t *testing.T) {
 }
 
 func TestTimeIsValid(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		time LocalTime
@@ -291,7 +282,6 @@ func TestTimeIsValid(t *testing.T) {
 }
 
 func TestDateTimeToString(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		str       string
@@ -323,7 +313,6 @@ func TestDateTimeToString(t *testing.T) {
 }
 
 func TestParseDateTimeErrors(t *testing.T) {
-	t.Parallel()
 
 	for _, str := range []string{
 		"",
@@ -339,7 +328,6 @@ func TestParseDateTimeErrors(t *testing.T) {
 }
 
 func TestDateTimeOf(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		time time.Time
@@ -361,7 +349,6 @@ func TestDateTimeOf(t *testing.T) {
 }
 
 func TestDateTimeIsValid(t *testing.T) {
-	t.Parallel()
 
 	// No need to be exhaustive here; it's just LocalDate.IsValid && LocalTime.IsValid.
 	for _, test := range []struct {
@@ -380,7 +367,6 @@ func TestDateTimeIsValid(t *testing.T) {
 }
 
 func TestDateTimeIn(t *testing.T) {
-	t.Parallel()
 
 	dt := LocalDateTime{LocalDate{2016, 1, 2}, LocalTime{3, 4, 5, 6}}
 
@@ -391,7 +377,6 @@ func TestDateTimeIn(t *testing.T) {
 }
 
 func TestDateTimeBefore(t *testing.T) {
-	t.Parallel()
 
 	d1 := LocalDate{2016, 12, 31}
 	d2 := LocalDate{2017, 1, 1}
@@ -414,7 +399,6 @@ func TestDateTimeBefore(t *testing.T) {
 }
 
 func TestDateTimeAfter(t *testing.T) {
-	t.Parallel()
 
 	d1 := LocalDate{2016, 12, 31}
 	d2 := LocalDate{2017, 1, 1}
@@ -437,7 +421,6 @@ func TestDateTimeAfter(t *testing.T) {
 }
 
 func TestMarshalJSON(t *testing.T) {
-	t.Parallel()
 
 	for _, test := range []struct {
 		value interface{}
@@ -459,7 +442,6 @@ func TestMarshalJSON(t *testing.T) {
 }
 
 func TestUnmarshalJSON(t *testing.T) {
-	t.Parallel()
 
 	var (
 		d  LocalDate

marshaler.go

@@ -127,6 +127,10 @@ func (enc *Encoder) Encode(v interface{}) error {
 
 	ctx.inline = enc.tablesInline
 
+	if v == nil {
+		return fmt.Errorf("toml: cannot encode a nil interface")
+	}
+
 	b, err := enc.encode(b, ctx, reflect.ValueOf(v))
 	if err != nil {
 		return err
@@ -193,9 +197,11 @@ func (ctx *encoderCtx) isRoot() bool {
 
 //nolint:cyclop,funlen
 func (enc *Encoder) encode(b []byte, ctx encoderCtx, v reflect.Value) ([]byte, error) {
-	i, ok := v.Interface().(time.Time)
+	if !v.IsZero() {
-	if ok {
+		i, ok := v.Interface().(time.Time)
-		return i.AppendFormat(b, time.RFC3339), nil
+		if ok {
+			return i.AppendFormat(b, time.RFC3339), nil
+		}
 	}
 
 	if v.Type().Implements(textMarshalerType) {
@@ -273,11 +279,6 @@ func (enc *Encoder) encodeKv(b []byte, ctx encoderCtx, options valueOptions, v r
 	if !ctx.hasKey {
 		panic("caller of encodeKv should have set the key in the context")
 	}
-
-	if isNil(v) {
-		return b, nil
-	}
-
 	b = enc.indent(ctx.indent, b)
 
 	b, err = enc.encodeKey(b, ctx.key)
@@ -470,12 +471,7 @@ func (enc *Encoder) encodeMap(b []byte, ctx encoderCtx, v reflect.Value) ([]byte
 			continue
 		}
 
-		table, err := willConvertToTableOrArrayTable(ctx, v)
+		if willConvertToTableOrArrayTable(ctx, v) {
-		if err != nil {
-			return nil, err
-		}
-
-		if table {
 			t.pushTable(k, v, emptyValueOptions)
 		} else {
 			t.pushKV(k, v, emptyValueOptions)
@@ -543,18 +539,13 @@ func (enc *Encoder) encodeStruct(b []byte, ctx encoderCtx, v reflect.Value) ([]b
 			continue
 		}
 
-		willConvert, err := willConvertToTableOrArrayTable(ctx, f)
-		if err != nil {
-			return nil, err
-		}
-
 		options := valueOptions{
 			multiline: fieldBoolTag(fieldType, "multiline"),
 		}
 
 		inline := fieldBoolTag(fieldType, "inline")
 
-		if inline || !willConvert {
+		if inline || !willConvertToTableOrArrayTable(ctx, f) {
 			t.pushKV(k, f, options)
 		} else {
 			t.pushTable(k, f, options)
@@ -640,21 +631,8 @@ func (enc *Encoder) encodeTableInline(b []byte, ctx encoderCtx, t table) ([]byte
 		}
 	}
 
-	for _, table := range t.tables {
+	if len(t.tables) > 0 {
-		if first {
+		panic("inline table cannot contain nested tables, online key-values")
-			first = false
-		} else {
-			b = append(b, `, `...)
-		}
-
-		ctx.setKey(table.Key)
-
-		b, err = enc.encode(b, ctx, table.Value)
-		if err != nil {
-			return nil, err
-		}
-
-		b = append(b, '\n')
 	}
 
 	b = append(b, "}"...)
@@ -662,63 +640,53 @@ func (enc *Encoder) encodeTableInline(b []byte, ctx encoderCtx, t table) ([]byte
 	return b, nil
 }
 
-var textMarshalerType = reflect.TypeOf(new(encoding.TextMarshaler)).Elem()
+func willConvertToTable(ctx encoderCtx, v reflect.Value) bool {
-
+	if !v.IsValid() {
-func willConvertToTable(ctx encoderCtx, v reflect.Value) (bool, error) {
+		return false
+	}
 	if v.Type() == timeType || v.Type().Implements(textMarshalerType) {
-		return false, nil
+		return false
 	}
 
 	t := v.Type()
 	switch t.Kind() {
 	case reflect.Map, reflect.Struct:
-		return !ctx.inline, nil
+		return !ctx.inline
 	case reflect.Interface:
-		if v.IsNil() {
-			return false, fmt.Errorf("toml: encoding a nil interface is not supported")
-		}
-
 		return willConvertToTable(ctx, v.Elem())
 	case reflect.Ptr:
 		if v.IsNil() {
-			return false, nil
+			return false
 		}
 
 		return willConvertToTable(ctx, v.Elem())
 	default:
-		return false, nil
+		return false
 	}
 }
 
-func willConvertToTableOrArrayTable(ctx encoderCtx, v reflect.Value) (bool, error) {
+func willConvertToTableOrArrayTable(ctx encoderCtx, v reflect.Value) bool {
 	t := v.Type()
 
 	if t.Kind() == reflect.Interface {
-		if v.IsNil() {
-			return false, fmt.Errorf("toml: encoding a nil interface is not supported")
-		}
-
 		return willConvertToTableOrArrayTable(ctx, v.Elem())
 	}
 
 	if t.Kind() == reflect.Slice {
 		if v.Len() == 0 {
 			// An empty slice should be a kv = [].
-			return false, nil
+			return false
 		}
 
 		for i := 0; i < v.Len(); i++ {
-			t, err := willConvertToTable(ctx, v.Index(i))
+			t := willConvertToTable(ctx, v.Index(i))
-			if err != nil {
-				return false, err
-			}
 
 			if !t {
-				return false, nil
+				return false
 			}
 		}
 
-		return true, nil
+		return true
 	}
 
 	return willConvertToTable(ctx, v)
@@ -731,12 +699,7 @@ func (enc *Encoder) encodeSlice(b []byte, ctx encoderCtx, v reflect.Value) ([]by
 		return b, nil
 	}
 
-	allTables, err := willConvertToTableOrArrayTable(ctx, v)
+	if willConvertToTableOrArrayTable(ctx, v) {
-	if err != nil {
-		return nil, err
-	}
-
-	if allTables {
 		return enc.encodeSliceAsArrayTable(b, ctx, v)
 	}
 
@@ -746,10 +709,6 @@ func (enc *Encoder) encodeSlice(b []byte, ctx encoderCtx, v reflect.Value) ([]by
 // caller should have checked that v is a slice that only contains values that
 // encode into tables.
 func (enc *Encoder) encodeSliceAsArrayTable(b []byte, ctx encoderCtx, v reflect.Value) ([]byte, error) {
-	if v.Len() == 0 {
-		return b, nil
-	}
-
 	ctx.shiftKey()
 
 	var err error

marshaler_test.go

@@ -14,7 +14,11 @@ import (
 
 //nolint:funlen
 func TestMarshal(t *testing.T) {
-	t.Parallel()
+	someInt := 42
+
+	type structInline struct {
+		A interface{} `inline:"true"`
+	}
 
 	examples := []struct {
 		desc     string
@@ -298,13 +302,218 @@ A = [
 ]
 `,
 		},
+		{
+			desc: "nil interface not supported at root",
+			v:    nil,
+			err:  true,
+		},
+		{
+			desc: "nil interface not supported in slice",
+			v: map[string]interface{}{
+				"a": []interface{}{"a", nil, 2},
+			},
+			err: true,
+		},
+		{
+			desc: "nil pointer in slice uses zero value",
+			v: struct {
+				A []*int
+			}{
+				A: []*int{nil},
+			},
+			expected: `A = [0]`,
+		},
+		{
+			desc: "nil pointer in slice uses zero value",
+			v: struct {
+				A []*int
+			}{
+				A: []*int{nil},
+			},
+			expected: `A = [0]`,
+		},
+		{
+			desc: "pointer in slice",
+			v: struct {
+				A []*int
+			}{
+				A: []*int{&someInt},
+			},
+			expected: `A = [42]`,
+		},
+		{
+			desc: "inline table in inline table",
+			v: structInline{
+				A: structInline{
+					A: structInline{
+						A: "hello",
+					},
+				},
+			},
+			expected: `A = {A = {A = 'hello'}}`,
+		},
+		{
+			desc: "empty slice in map",
+			v: map[string][]string{
+				"a": {},
+			},
+			expected: `a = []`,
+		},
+		{
+			desc: "map in slice",
+			v: map[string][]map[string]string{
+				"a": {{"hello": "world"}},
+			},
+			expected: `
+[[a]]
+hello = 'world'`,
+		},
+		{
+			desc: "newline in map in slice",
+			v: map[string][]map[string]string{
+				"a\n": {{"hello": "world"}},
+			},
+			err: true,
+		},
+		{
+			desc: "newline in map in slice",
+			v: map[string][]map[string]*customTextMarshaler{
+				"a": {{"hello": &customTextMarshaler{1}}},
+			},
+			err: true,
+		},
+		{
+			desc: "empty slice of empty struct",
+			v: struct {
+				A []struct{}
+			}{
+				A: []struct{}{},
+			},
+			expected: `A = []`,
+		},
+		{
+			desc: "nil field is ignored",
+			v: struct {
+				A interface{}
+			}{
+				A: nil,
+			},
+			expected: ``,
+		},
+		{
+			desc: "private fields are ignored",
+			v: struct {
+				Public  string
+				private string
+			}{
+				Public:  "shown",
+				private: "hidden",
+			},
+			expected: `Public = 'shown'`,
+		},
+		{
+			desc: "fields tagged - are ignored",
+			v: struct {
+				Public  string `toml:"-"`
+				private string
+			}{
+				Public: "hidden",
+			},
+			expected: ``,
+		},
+		{
+			desc: "nil value in map is ignored",
+			v: map[string]interface{}{
+				"A": nil,
+			},
+			expected: ``,
+		},
+		{
+			desc: "new line in table key",
+			v: map[string]interface{}{
+				"hello\nworld": 42,
+			},
+			err: true,
+		},
+		{
+			desc: "new line in parent of nested table key",
+			v: map[string]interface{}{
+				"hello\nworld": map[string]interface{}{
+					"inner": 42,
+				},
+			},
+			err: true,
+		},
+		{
+			desc: "new line in nested table key",
+			v: map[string]interface{}{
+				"parent": map[string]interface{}{
+					"in\ner": map[string]interface{}{
+						"foo": 42,
+					},
+				},
+			},
+			err: true,
+		},
+		{
+			desc: "invalid map key",
+			v:    map[int]interface{}{},
+			err:  true,
+		},
+		{
+			desc: "unhandled type",
+			v: struct {
+				A chan int
+			}{
+				A: make(chan int),
+			},
+			err: true,
+		},
+		{
+			desc: "numbers",
+			v: struct {
+				A float32
+				B uint64
+				C uint32
+				D uint16
+				E uint8
+				F uint
+				G int64
+				H int32
+				I int16
+				J int8
+				K int
+			}{
+				A: 1.1,
+				B: 42,
+				C: 42,
+				D: 42,
+				E: 42,
+				F: 42,
+				G: 42,
+				H: 42,
+				I: 42,
+				J: 42,
+				K: 42,
+			},
+			expected: `
+A = 1.1
+B = 42
+C = 42
+D = 42
+E = 42
+F = 42
+G = 42
+H = 42
+I = 42
+J = 42
+K = 42`,
+		},
 	}
 
 	for _, e := range examples {
 		e := e
 		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
-
 			b, err := toml.Marshal(e.v)
 			if e.err {
 				require.Error(t, err)
@@ -396,8 +605,6 @@ func equalStringsIgnoreNewlines(t *testing.T, expected string, actual string) {
 
 //nolint:funlen
 func TestMarshalIndentTables(t *testing.T) {
-	t.Parallel()
-
 	examples := []struct {
 		desc     string
 		v        interface{}
@@ -448,8 +655,6 @@ root = 'value0'
 	for _, e := range examples {
 		e := e
 		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
-
 			var buf strings.Builder
 			enc := toml.NewEncoder(&buf)
 			enc.SetIndentTables(true)
@@ -460,9 +665,76 @@ root = 'value0'
 	}
 }
 
-func TestIssue436(t *testing.T) {
+type customTextMarshaler struct {
-	t.Parallel()
+	value int64
+}
 
+func (c *customTextMarshaler) MarshalText() ([]byte, error) {
+	if c.value == 1 {
+		return nil, fmt.Errorf("cannot represent 1 because this is a silly test")
+	}
+	return []byte(fmt.Sprintf("::%d", c.value)), nil
+}
+
+func TestMarshalTextMarshaler_NoRoot(t *testing.T) {
+	c := customTextMarshaler{}
+	_, err := toml.Marshal(&c)
+	require.Error(t, err)
+}
+
+func TestMarshalTextMarshaler_Error(t *testing.T) {
+	m := map[string]interface{}{"a": &customTextMarshaler{value: 1}}
+	_, err := toml.Marshal(m)
+	require.Error(t, err)
+}
+
+func TestMarshalTextMarshaler_ErrorInline(t *testing.T) {
+	type s struct {
+		A map[string]interface{} `inline:"true"`
+	}
+
+	d := s{
+		A: map[string]interface{}{"a": &customTextMarshaler{value: 1}},
+	}
+
+	_, err := toml.Marshal(d)
+	require.Error(t, err)
+}
+
+func TestMarshalTextMarshaler(t *testing.T) {
+	m := map[string]interface{}{"a": &customTextMarshaler{value: 2}}
+	r, err := toml.Marshal(m)
+	require.NoError(t, err)
+	equalStringsIgnoreNewlines(t, "a = '::2'", string(r))
+}
+
+type brokenWriter struct{}
+
+func (b *brokenWriter) Write([]byte) (int, error) {
+	return 0, fmt.Errorf("dead")
+}
+
+func TestEncodeToBrokenWriter(t *testing.T) {
+	w := brokenWriter{}
+	enc := toml.NewEncoder(&w)
+	err := enc.Encode(map[string]string{"hello": "world"})
+	require.Error(t, err)
+}
+
+func TestEncoderSetIndentSymbol(t *testing.T) {
+	var w strings.Builder
+	enc := toml.NewEncoder(&w)
+	enc.SetIndentTables(true)
+	enc.SetIndentSymbol(">>>")
+	err := enc.Encode(map[string]map[string]string{"parent": {"hello": "world"}})
+	require.NoError(t, err)
+	expected := `
+[parent]
+>>>hello = 'world'`
+	equalStringsIgnoreNewlines(t, expected, w.String())
+}
+
+func TestIssue436(t *testing.T) {
 	data := []byte(`{"a": [ { "b": { "c": "d" } } ]}`)
 
 	var v interface{}
@@ -482,8 +754,6 @@ c = 'd'
 }
 
 func TestIssue424(t *testing.T) {
-	t.Parallel()
-
 	type Message1 struct {
 		Text string
 	}

parser.go

@@ -2,10 +2,10 @@ package toml
 
 import (
 	"bytes"
-	"fmt"
 	"strconv"
 
 	"github.com/pelletier/go-toml/v2/internal/ast"
+	"github.com/pelletier/go-toml/v2/internal/danger"
 )
 
 type parser struct {
@@ -17,9 +17,20 @@ type parser struct {
 	first   bool
 }
 
+func (p *parser) Range(b []byte) ast.Range {
+	return ast.Range{
+		Offset: uint32(danger.SubsliceOffset(p.data, b)),
+		Length: uint32(len(b)),
+	}
+}
+
+func (p *parser) Raw(raw ast.Range) []byte {
+	return p.data[raw.Offset : raw.Offset+raw.Length]
+}
+
 func (p *parser) Reset(b []byte) {
 	p.builder.Reset()
-	p.ref = ast.Reference{}
+	p.ref = ast.InvalidReference
 	p.data = b
 	p.left = b
 	p.err = nil
@@ -33,7 +44,7 @@ func (p *parser) NextExpression() bool {
 	}
 
 	p.builder.Reset()
-	p.ref = ast.Reference{}
+	p.ref = ast.InvalidReference
 
 	for {
 		if len(p.left) == 0 || p.err != nil {
@@ -62,7 +73,7 @@ func (p *parser) NextExpression() bool {
 	}
 }
 
-func (p *parser) Expression() ast.Node {
+func (p *parser) Expression() *ast.Node {
 	return p.builder.NodeAt(p.ref)
 }
 
@@ -77,7 +88,6 @@ func (p *parser) parseNewline(b []byte) ([]byte, error) {
 
 	if b[0] == '\r' {
 		_, rest, err := scanWindowsNewline(b)
-
 		return rest, err
 	}
 
@@ -88,7 +98,7 @@ func (p *parser) parseExpression(b []byte) (ast.Reference, []byte, error) {
 	// expression =  ws [ comment ]
 	// expression =/ ws keyval ws [ comment ]
 	// expression =/ ws table ws [ comment ]
-	var ref ast.Reference
+	ref := ast.InvalidReference
 
 	b = p.parseWhitespace(b)
 
@@ -199,16 +209,20 @@ func (p *parser) parseKeyval(b []byte) (ast.Reference, []byte, error) {
 
 	key, b, err := p.parseKey(b)
 	if err != nil {
-		return ast.Reference{}, nil, err
+		return ast.InvalidReference, nil, err
 	}
 
 	// keyval-sep = ws %x3D ws ; =
 
 	b = p.parseWhitespace(b)
 
+	if len(b) == 0 {
+		return ast.InvalidReference, nil, newDecodeError(b, "expected = after a key, but the document ends there")
+	}
+
 	b, err = expect('=', b)
 	if err != nil {
-		return ast.Reference{}, nil, err
+		return ast.InvalidReference, nil, err
 	}
 
 	b = p.parseWhitespace(b)
@@ -227,7 +241,7 @@ func (p *parser) parseKeyval(b []byte) (ast.Reference, []byte, error) {
 //nolint:cyclop,funlen
 func (p *parser) parseVal(b []byte) (ast.Reference, []byte, error) {
 	// val = string / boolean / array / inline-table / date-time / float / integer
-	var ref ast.Reference
+	ref := ast.InvalidReference
 
 	if len(b) == 0 {
 		return ref, nil, newDecodeError(b, "expected value, not eof")
@@ -238,32 +252,36 @@ func (p *parser) parseVal(b []byte) (ast.Reference, []byte, error) {
 
 	switch c {
 	case '"':
+		var raw []byte
 		var v []byte
 		if scanFollowsMultilineBasicStringDelimiter(b) {
-			v, b, err = p.parseMultilineBasicString(b)
+			raw, v, b, err = p.parseMultilineBasicString(b)
 		} else {
-			v, b, err = p.parseBasicString(b)
+			raw, v, b, err = p.parseBasicString(b)
 		}
 
 		if err == nil {
 			ref = p.builder.Push(ast.Node{
 				Kind: ast.String,
+				Raw:  p.Range(raw),
 				Data: v,
 			})
 		}
 
 		return ref, b, err
 	case '\'':
+		var raw []byte
 		var v []byte
 		if scanFollowsMultilineLiteralStringDelimiter(b) {
-			v, b, err = p.parseMultilineLiteralString(b)
+			raw, v, b, err = p.parseMultilineLiteralString(b)
 		} else {
-			v, b, err = p.parseLiteralString(b)
+			raw, v, b, err = p.parseLiteralString(b)
 		}
 
 		if err == nil {
 			ref = p.builder.Push(ast.Node{
 				Kind: ast.String,
+				Raw:  p.Range(raw),
 				Data: v,
 			})
 		}
@@ -304,16 +322,17 @@ func atmost(b []byte, n int) []byte {
 	if n >= len(b) {
 		return b
 	}
+
 	return b[:n]
 }
 
-func (p *parser) parseLiteralString(b []byte) ([]byte, []byte, error) {
+func (p *parser) parseLiteralString(b []byte) ([]byte, []byte, []byte, error) {
 	v, rest, err := scanLiteralString(b)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 
-	return v[1 : len(v)-1], rest, nil
+	return v, v[1 : len(v)-1], rest, nil
 }
 
 func (p *parser) parseInlineTable(b []byte) (ast.Reference, []byte, error) {
@@ -397,8 +416,7 @@ func (p *parser) parseValArray(b []byte) (ast.Reference, []byte, error) {
 		}
 
 		if len(b) == 0 {
-			//nolint:godox
+			return parent, nil, newDecodeError(b, "array is incomplete")
-			return parent, nil, unexpectedCharacter{b: b} // TODO: should be unexpected EOF
 		}
 
 		if b[0] == ']' {
@@ -474,10 +492,10 @@ func (p *parser) parseOptionalWhitespaceCommentNewline(b []byte) ([]byte, error)
 	return b, nil
 }
 
-func (p *parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, error) {
+func (p *parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, []byte, error) {
 	token, rest, err := scanMultilineLiteralString(b)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 
 	i := 3
@@ -489,11 +507,11 @@ func (p *parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, error) {
 		i += 2
 	}
 
-	return token[i : len(token)-3], rest, err
+	return token, token[i : len(token)-3], rest, err
 }
 
 //nolint:funlen,gocognit,cyclop
-func (p *parser) parseMultilineBasicString(b []byte) ([]byte, []byte, error) {
+func (p *parser) parseMultilineBasicString(b []byte) ([]byte, []byte, []byte, error) {
 	// ml-basic-string = ml-basic-string-delim [ newline ] ml-basic-body
 	// ml-basic-string-delim
 	// ml-basic-string-delim = 3quotation-mark
@@ -506,11 +524,9 @@ func (p *parser) parseMultilineBasicString(b []byte) ([]byte, []byte, error) {
 	// mlb-escaped-nl = escape ws newline *( wschar / newline )
 	token, rest, err := scanMultilineBasicString(b)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 
-	var builder bytes.Buffer
-
 	i := 3
 
 	// skip the immediate new line
@@ -520,6 +536,21 @@ func (p *parser) parseMultilineBasicString(b []byte) ([]byte, []byte, error) {
 		i += 2
 	}
 
+	// fast path
+	startIdx := i
+	endIdx := len(token) - len(`"""`)
+	for ; i < endIdx; i++ {
+		if token[i] == '\\' {
+			break
+		}
+	}
+	if i == endIdx {
+		return token, token[startIdx:endIdx], rest, nil
+	}
+
+	var builder bytes.Buffer
+	builder.Write(token[startIdx:i])
+
 	// The scanner ensures that the token starts and ends with quotes and that
 	// escapes are balanced.
 	for ; i < len(token)-3; i++ {
@@ -562,30 +593,30 @@ func (p *parser) parseMultilineBasicString(b []byte) ([]byte, []byte, error) {
 			case 't':
 				builder.WriteByte('\t')
 			case 'u':
-				x, err := hexToString(token[i+3:len(token)-3], 4)
+				x, err := hexToString(atmost(token[i+1:], 4), 4)
 				if err != nil {
-					return nil, nil, err
+					return nil, nil, nil, err
 				}
 
 				builder.WriteString(x)
 				i += 4
 			case 'U':
-				x, err := hexToString(token[i+3:len(token)-3], 8)
+				x, err := hexToString(atmost(token[i+1:], 8), 8)
 				if err != nil {
-					return nil, nil, err
+					return nil, nil, nil, err
 				}
 
 				builder.WriteString(x)
 				i += 8
 			default:
-				return nil, nil, newDecodeError(token[i:i+1], "invalid escaped character %#U", c)
+				return nil, nil, nil, newDecodeError(token[i:i+1], "invalid escaped character %#U", c)
 			}
 		} else {
 			builder.WriteByte(c)
 		}
 	}
 
-	return builder.Bytes(), rest, nil
+	return token, builder.Bytes(), rest, nil
 }
 
 func (p *parser) parseKey(b []byte) (ast.Reference, []byte, error) {
@@ -597,33 +628,30 @@ func (p *parser) parseKey(b []byte) (ast.Reference, []byte, error) {
 	// dotted-key = simple-key 1*( dot-sep simple-key )
 	//
 	// dot-sep   = ws %x2E ws  ; . Period
-	key, b, err := p.parseSimpleKey(b)
+	raw, key, b, err := p.parseSimpleKey(b)
 	if err != nil {
-		return ast.Reference{}, nil, err
+		return ast.InvalidReference, nil, err
 	}
 
 	ref := p.builder.Push(ast.Node{
 		Kind: ast.Key,
+		Raw:  p.Range(raw),
 		Data: key,
 	})
 
 	for {
 		b = p.parseWhitespace(b)
 		if len(b) > 0 && b[0] == '.' {
-			b, err = expect('.', b)
+			b = p.parseWhitespace(b[1:])
-			if err != nil {
-				return ref, nil, err
-			}
 
-			b = p.parseWhitespace(b)
+			raw, key, b, err = p.parseSimpleKey(b)
-
-			key, b, err = p.parseSimpleKey(b)
 			if err != nil {
 				return ref, nil, err
 			}
 
 			p.builder.PushAndChain(ast.Node{
 				Kind: ast.Key,
+				Raw:  p.Range(raw),
 				Data: key,
 			})
 		} else {
@@ -634,13 +662,12 @@ func (p *parser) parseKey(b []byte) (ast.Reference, []byte, error) {
 	return ref, b, nil
 }
 
-func (p *parser) parseSimpleKey(b []byte) (key, rest []byte, err error) {
+func (p *parser) parseSimpleKey(b []byte) (raw, key, rest []byte, err error) {
 	// 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
 	if len(b) == 0 {
-		//nolint:godox
+		return nil, nil, nil, newDecodeError(b, "key is incomplete")
-		return nil, nil, unexpectedCharacter{b: b} // TODO: should be unexpected EOF
 	}
 
 	switch {
@@ -649,15 +676,15 @@ func (p *parser) parseSimpleKey(b []byte) (key, rest []byte, err error) {
 	case b[0] == '"':
 		return p.parseBasicString(b)
 	case isUnquotedKeyChar(b[0]):
-		return scanUnquotedKey(b)
+		key, rest = scanUnquotedKey(b)
+		return key, key, rest, nil
 	default:
-		//nolint:godox
+		return nil, nil, nil, newDecodeError(b[0:1], "invalid character at start of key: %c", b[0])
-		return nil, nil, unexpectedCharacter{b: b} // TODO: should be unexpected EOF
 	}
 }
 
 //nolint:funlen,cyclop
-func (p *parser) parseBasicString(b []byte) ([]byte, []byte, error) {
+func (p *parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
 	// basic-string = quotation-mark *basic-char quotation-mark
 	// quotation-mark = %x22            ; "
 	// basic-char = basic-unescaped / escaped
@@ -674,14 +701,28 @@ func (p *parser) parseBasicString(b []byte) ([]byte, []byte, error) {
 	// escape-seq-char =/ %x55 8HEXDIG ; UXXXXXXXX            U+XXXXXXXX
 	token, rest, err := scanBasicString(b)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
+	}
+
+	// fast path
+	i := len(`"`)
+	startIdx := i
+	endIdx := len(token) - len(`"`)
+	for ; i < endIdx; i++ {
+		if token[i] == '\\' {
+			break
+		}
+	}
+	if i == endIdx {
+		return token, token[startIdx:endIdx], rest, nil
 	}
 
 	var builder bytes.Buffer
+	builder.Write(token[startIdx:i])
 
 	// The scanner ensures that the token starts and ends with quotes and that
 	// escapes are balanced.
-	for i := 1; i < len(token)-1; i++ {
+	for ; i < len(token)-1; i++ {
 		c := token[i]
 		if c == '\\' {
 			i++
@@ -703,7 +744,7 @@ func (p *parser) parseBasicString(b []byte) ([]byte, []byte, error) {
 			case 'u':
 				x, err := hexToString(token[i+1:len(token)-1], 4)
 				if err != nil {
-					return nil, nil, err
+					return nil, nil, nil, err
 				}
 
 				builder.WriteString(x)
@@ -711,20 +752,20 @@ func (p *parser) parseBasicString(b []byte) ([]byte, []byte, error) {
 			case 'U':
 				x, err := hexToString(token[i+1:len(token)-1], 8)
 				if err != nil {
-					return nil, nil, err
+					return nil, nil, nil, err
 				}
 
 				builder.WriteString(x)
 				i += 8
 			default:
-				return nil, nil, newDecodeError(token[i:i+1], "invalid escaped character %#U", c)
+				return nil, nil, nil, newDecodeError(token[i:i+1], "invalid escaped character %#U", c)
 			}
 		} else {
 			builder.WriteByte(c)
 		}
 	}
 
-	return builder.Bytes(), rest, nil
+	return token, builder.Bytes(), rest, nil
 }
 
 func hexToString(b []byte, length int) (string, error) {
@@ -757,7 +798,7 @@ func (p *parser) parseIntOrFloatOrDateTime(b []byte) (ast.Reference, []byte, err
 	switch b[0] {
 	case 'i':
 		if !scanFollowsInf(b) {
-			return ast.Reference{}, nil, newDecodeError(atmost(b, 3), "expected 'inf'")
+			return ast.InvalidReference, nil, newDecodeError(atmost(b, 3), "expected 'inf'")
 		}
 
 		return p.builder.Push(ast.Node{
@@ -766,7 +807,7 @@ func (p *parser) parseIntOrFloatOrDateTime(b []byte) (ast.Reference, []byte, err
 		}), b[3:], nil
 	case 'n':
 		if !scanFollowsNan(b) {
-			return ast.Reference{}, nil, newDecodeError(atmost(b, 3), "expected 'nan'")
+			return ast.InvalidReference, nil, newDecodeError(atmost(b, 3), "expected 'nan'")
 		}
 
 		return p.builder.Push(ast.Node{
@@ -825,11 +866,14 @@ byteLoop:
 		c := b[i]
 
 		switch {
-		case isDigit(c) || c == '-':
+		case isDigit(c):
+		case c == '-':
+			const minOffsetOfTz = 8
+			if i >= minOffsetOfTz {
+				hasTz = true
+			}
 		case c == 'T' || c == ':' || c == '.':
 			hasTime = true
-
-			continue byteLoop
 		case c == '+' || c == '-' || c == 'Z':
 			hasTz = true
 		case c == ' ':
@@ -854,9 +898,6 @@ byteLoop:
 			kind = ast.LocalDateTime
 		}
 	} else {
-		if hasTz {
-			return ast.Reference{}, nil, newDecodeError(b, "date-time has timezone but not time component")
-		}
 		kind = ast.LocalDate
 	}
 
@@ -922,7 +963,7 @@ func (p *parser) scanIntOrFloat(b []byte) (ast.Reference, []byte, error) {
 				}), b[i+3:], nil
 			}
 
-			return ast.Reference{}, nil, newDecodeError(b[i:i+1], "unexpected character 'i' while scanning for a number")
+			return ast.InvalidReference, nil, newDecodeError(b[i:i+1], "unexpected character 'i' while scanning for a number")
 		}
 
 		if c == 'n' {
@@ -933,14 +974,14 @@ func (p *parser) scanIntOrFloat(b []byte) (ast.Reference, []byte, error) {
 				}), b[i+3:], nil
 			}
 
-			return ast.Reference{}, nil, newDecodeError(b[i:i+1], "unexpected character 'n' while scanning for a number")
+			return ast.InvalidReference, nil, newDecodeError(b[i:i+1], "unexpected character 'n' while scanning for a number")
 		}
 
 		break
 	}
 
 	if i == 0 {
-		return ast.Reference{}, b, newDecodeError(b, "incomplete number")
+		return ast.InvalidReference, b, newDecodeError(b, "incomplete number")
 	}
 
 	kind := ast.Integer
@@ -977,26 +1018,9 @@ func isValidBinaryRune(r byte) bool {
 }
 
 func expect(x byte, b []byte) ([]byte, error) {
-	if len(b) == 0 {
-		return nil, newDecodeError(b[:0], "expecting %#U", x)
-	}
-
 	if b[0] != x {
 		return nil, newDecodeError(b[0:1], "expected character %U", x)
 	}
 
 	return b[1:], nil
 }
-
-type unexpectedCharacter struct {
-	r byte
-	b []byte
-}
-
-func (u unexpectedCharacter) Error() string {
-	if len(u.b) == 0 {
-		return fmt.Sprintf("expected %#U, not EOF", u.r)
-	}
-
-	return fmt.Sprintf("expected %#U, not %#U", u.r, u.b[0])
-}

parser_test.go

@@ -9,8 +9,6 @@ import (
 
 //nolint:funlen
 func TestParser_AST_Numbers(t *testing.T) {
-	t.Parallel()
-
 	examples := []struct {
 		desc  string
 		input string
@@ -137,7 +135,6 @@ func TestParser_AST_Numbers(t *testing.T) {
 	for _, e := range examples {
 		e := e
 		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
 			p := parser{}
 			p.Reset([]byte(`A = ` + e.input))
 			p.NextExpression()
@@ -168,7 +165,7 @@ type (
 	}
 )
 
-func compareNode(t *testing.T, e astNode, n ast.Node) {
+func compareNode(t *testing.T, e astNode, n *ast.Node) {
 	t.Helper()
 	require.Equal(t, e.Kind, n.Kind)
 	require.Equal(t, e.Data, n.Data)
@@ -200,8 +197,6 @@ func compareIterator(t *testing.T, expected []astNode, actual ast.Iterator) {
 
 //nolint:funlen
 func TestParser_AST(t *testing.T) {
-	t.Parallel()
-
 	examples := []struct {
 		desc  string
 		input string
@@ -340,7 +335,6 @@ func TestParser_AST(t *testing.T) {
 	for _, e := range examples {
 		e := e
 		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
 			p := parser{}
 			p.Reset([]byte(e.input))
 			p.NextExpression()

scanner.go

@@ -30,15 +30,15 @@ func scanFollowsNan(b []byte) bool {
 	return scanFollows(b, `nan`)
 }
 
-func scanUnquotedKey(b []byte) ([]byte, []byte, error) {
+func scanUnquotedKey(b []byte) ([]byte, []byte) {
 	// unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
 	for i := 0; i < len(b); i++ {
 		if !isUnquotedKeyChar(b[i]) {
-			return b[:i], b[i:], nil
+			return b[:i], b[i:]
 		}
 	}
 
-	return b, b[len(b):], nil
+	return b, b[len(b):]
 }
 
 func isUnquotedKeyChar(r byte) bool {

strict.go

@@ -2,6 +2,7 @@ package toml
 
 import (
 	"github.com/pelletier/go-toml/v2/internal/ast"
+	"github.com/pelletier/go-toml/v2/internal/danger"
 	"github.com/pelletier/go-toml/v2/internal/tracker"
 )
 
@@ -14,7 +15,7 @@ type strict struct {
 	missing []decodeError
 }
 
-func (s *strict) EnterTable(node ast.Node) {
+func (s *strict) EnterTable(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -22,7 +23,7 @@ func (s *strict) EnterTable(node ast.Node) {
 	s.key.UpdateTable(node)
 }
 
-func (s *strict) EnterArrayTable(node ast.Node) {
+func (s *strict) EnterArrayTable(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -30,7 +31,7 @@ func (s *strict) EnterArrayTable(node ast.Node) {
 	s.key.UpdateArrayTable(node)
 }
 
-func (s *strict) EnterKeyValue(node ast.Node) {
+func (s *strict) EnterKeyValue(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -38,7 +39,7 @@ func (s *strict) EnterKeyValue(node ast.Node) {
 	s.key.Push(node)
 }
 
-func (s *strict) ExitKeyValue(node ast.Node) {
+func (s *strict) ExitKeyValue(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -46,7 +47,7 @@ func (s *strict) ExitKeyValue(node ast.Node) {
 	s.key.Pop(node)
 }
 
-func (s *strict) MissingTable(node ast.Node) {
+func (s *strict) MissingTable(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -58,7 +59,7 @@ func (s *strict) MissingTable(node ast.Node) {
 	})
 }
 
-func (s *strict) MissingField(node ast.Node) {
+func (s *strict) MissingField(node *ast.Node) {
 	if !s.Enabled {
 		return
 	}
@@ -86,3 +87,21 @@ func (s *strict) Error(doc []byte) error {
 
 	return err
 }
+
+func keyLocation(node *ast.Node) []byte {
+	k := node.Key()
+
+	hasOne := k.Next()
+	if !hasOne {
+		panic("should not be called with empty key")
+	}
+
+	start := k.Node().Data
+	end := k.Node().Data
+
+	for k.Next() {
+		end = k.Node().Data
+	}
+
+	return danger.BytesRange(start, end)
+}

targets.go

@@ -1,540 +0,0 @@
-package toml
-
-import (
-	"fmt"
-	"math"
-	"reflect"
-	"strings"
-	"sync"
-)
-
-type target interface {
-	// Dereferences the target.
-	get() reflect.Value
-
-	// Store a string at the target.
-	setString(v string)
-
-	// Store a boolean at the target
-	setBool(v bool)
-
-	// Store an int64 at the target
-	setInt64(v int64)
-
-	// Store a float64 at the target
-	setFloat64(v float64)
-
-	// Stores any value at the target
-	set(v reflect.Value)
-}
-
-// valueTarget just contains a reflect.Value that can be set.
-// It is used for struct fields.
-type valueTarget reflect.Value
-
-func (t valueTarget) get() reflect.Value {
-	return reflect.Value(t)
-}
-
-func (t valueTarget) set(v reflect.Value) {
-	reflect.Value(t).Set(v)
-}
-
-func (t valueTarget) setString(v string) {
-	t.get().SetString(v)
-}
-
-func (t valueTarget) setBool(v bool) {
-	t.get().SetBool(v)
-}
-
-func (t valueTarget) setInt64(v int64) {
-	t.get().SetInt(v)
-}
-
-func (t valueTarget) setFloat64(v float64) {
-	t.get().SetFloat(v)
-}
-
-// interfaceTarget wraps an other target to dereference on get.
-type interfaceTarget struct {
-	x target
-}
-
-func (t interfaceTarget) get() reflect.Value {
-	return t.x.get().Elem()
-}
-
-func (t interfaceTarget) set(v reflect.Value) {
-	t.x.set(v)
-}
-
-func (t interfaceTarget) setString(v string) {
-	t.x.setString(v)
-}
-
-func (t interfaceTarget) setBool(v bool) {
-	t.x.setBool(v)
-}
-
-func (t interfaceTarget) setInt64(v int64) {
-	t.x.setInt64(v)
-}
-
-func (t interfaceTarget) setFloat64(v float64) {
-	t.x.setFloat64(v)
-}
-
-// mapTarget targets a specific key of a map.
-type mapTarget struct {
-	v reflect.Value
-	k reflect.Value
-}
-
-func (t mapTarget) get() reflect.Value {
-	return t.v.MapIndex(t.k)
-}
-
-func (t mapTarget) set(v reflect.Value) {
-	t.v.SetMapIndex(t.k, v)
-}
-
-func (t mapTarget) setString(v string) {
-	t.set(reflect.ValueOf(v))
-}
-
-func (t mapTarget) setBool(v bool) {
-	t.set(reflect.ValueOf(v))
-}
-
-func (t mapTarget) setInt64(v int64) {
-	t.set(reflect.ValueOf(v))
-}
-
-func (t mapTarget) setFloat64(v float64) {
-	t.set(reflect.ValueOf(v))
-}
-
-//nolint:cyclop
-// makes sure that the value pointed at by t is indexable (Slice, Array), or
-// dereferences to an indexable (Ptr, Interface).
-func ensureValueIndexable(t target) error {
-	f := t.get()
-
-	switch f.Type().Kind() {
-	case reflect.Slice:
-		if f.IsNil() {
-			t.set(reflect.MakeSlice(f.Type(), 0, 0))
-			return nil
-		}
-	case reflect.Interface:
-		if f.IsNil() || f.Elem().Type() != sliceInterfaceType {
-			t.set(reflect.MakeSlice(sliceInterfaceType, 0, 0))
-			return nil
-		}
-	case reflect.Ptr:
-		panic("pointer should have already been dereferenced")
-	case reflect.Array:
-		// arrays are always initialized.
-	default:
-		return fmt.Errorf("toml: cannot store array in a %s", f.Kind())
-	}
-
-	return nil
-}
-
-var (
-	sliceInterfaceType     = reflect.TypeOf([]interface{}{})
-	mapStringInterfaceType = reflect.TypeOf(map[string]interface{}{})
-)
-
-func ensureMapIfInterface(x target) {
-	v := x.get()
-
-	if v.Kind() == reflect.Interface && v.IsNil() {
-		newElement := reflect.MakeMap(mapStringInterfaceType)
-
-		x.set(newElement)
-	}
-}
-
-func setString(t target, v string) error {
-	f := t.get()
-
-	switch f.Kind() {
-	case reflect.String:
-		t.setString(v)
-	case reflect.Interface:
-		t.set(reflect.ValueOf(v))
-	default:
-		return fmt.Errorf("toml: cannot assign string to a %s", f.Kind())
-	}
-
-	return nil
-}
-
-func setBool(t target, v bool) error {
-	f := t.get()
-
-	switch f.Kind() {
-	case reflect.Bool:
-		t.setBool(v)
-	case reflect.Interface:
-		t.set(reflect.ValueOf(v))
-	default:
-		return fmt.Errorf("toml: cannot assign boolean to a %s", f.Kind())
-	}
-
-	return nil
-}
-
-const (
-	maxInt = int64(^uint(0) >> 1)
-	minInt = -maxInt - 1
-)
-
-//nolint:funlen,gocognit,cyclop,gocyclo
-func setInt64(t target, v int64) error {
-	f := t.get()
-
-	switch f.Kind() {
-	case reflect.Int64:
-		t.setInt64(v)
-	case reflect.Int32:
-		if v < math.MinInt32 || v > math.MaxInt32 {
-			return fmt.Errorf("toml: number %d does not fit in an int32", v)
-		}
-
-		t.set(reflect.ValueOf(int32(v)))
-		return nil
-	case reflect.Int16:
-		if v < math.MinInt16 || v > math.MaxInt16 {
-			return fmt.Errorf("toml: number %d does not fit in an int16", v)
-		}
-
-		t.set(reflect.ValueOf(int16(v)))
-	case reflect.Int8:
-		if v < math.MinInt8 || v > math.MaxInt8 {
-			return fmt.Errorf("toml: number %d does not fit in an int8", v)
-		}
-
-		t.set(reflect.ValueOf(int8(v)))
-	case reflect.Int:
-		if v < minInt || v > maxInt {
-			return fmt.Errorf("toml: number %d does not fit in an int", v)
-		}
-
-		t.set(reflect.ValueOf(int(v)))
-	case reflect.Uint64:
-		if v < 0 {
-			return fmt.Errorf("toml: negative number %d does not fit in an uint64", v)
-		}
-
-		t.set(reflect.ValueOf(uint64(v)))
-	case reflect.Uint32:
-		if v < 0 || v > math.MaxUint32 {
-			return fmt.Errorf("toml: negative number %d does not fit in an uint32", v)
-		}
-
-		t.set(reflect.ValueOf(uint32(v)))
-	case reflect.Uint16:
-		if v < 0 || v > math.MaxUint16 {
-			return fmt.Errorf("toml: negative number %d does not fit in an uint16", v)
-		}
-
-		t.set(reflect.ValueOf(uint16(v)))
-	case reflect.Uint8:
-		if v < 0 || v > math.MaxUint8 {
-			return fmt.Errorf("toml: negative number %d does not fit in an uint8", v)
-		}
-
-		t.set(reflect.ValueOf(uint8(v)))
-	case reflect.Uint:
-		if v < 0 {
-			return fmt.Errorf("toml: negative number %d does not fit in an uint", v)
-		}
-
-		t.set(reflect.ValueOf(uint(v)))
-	case reflect.Interface:
-		t.set(reflect.ValueOf(v))
-	default:
-		return fmt.Errorf("toml: integer cannot be assigned to %s", f.Kind())
-	}
-
-	return nil
-}
-
-func setFloat64(t target, v float64) error {
-	f := t.get()
-
-	switch f.Kind() {
-	case reflect.Float64:
-		t.setFloat64(v)
-	case reflect.Float32:
-		if v > math.MaxFloat32 {
-			return fmt.Errorf("toml: number %f does not fit in a float32", v)
-		}
-
-		t.set(reflect.ValueOf(float32(v)))
-	case reflect.Interface:
-		t.set(reflect.ValueOf(v))
-	default:
-		return fmt.Errorf("toml: float cannot be assigned to %s", f.Kind())
-	}
-
-	return nil
-}
-
-//nolint:cyclop
-// Returns the element at idx of the value pointed at by target, or an error if
-// t does not point to an indexable.
-// If the target points to an Array and idx is out of bounds, it returns
-// (nil, nil) as this is not a fatal error (the unmarshaler will skip).
-func elementAt(t target, idx int) target {
-	f := t.get()
-
-	switch f.Kind() {
-	case reflect.Slice:
-		//nolint:godox
-		// TODO: use the idx function argument and avoid alloc if possible.
-		idx := f.Len()
-
-		t.set(reflect.Append(f, reflect.New(f.Type().Elem()).Elem()))
-
-		return valueTarget(t.get().Index(idx))
-	case reflect.Array:
-		if idx >= f.Len() {
-			return nil
-		}
-
-		return valueTarget(f.Index(idx))
-	case reflect.Interface:
-		// This function is called after ensureValueIndexable, so it's
-		// guaranteed that f contains an initialized slice.
-
-		ifaceElem := f.Elem()
-		idx := ifaceElem.Len()
-		newElem := reflect.New(ifaceElem.Type().Elem()).Elem()
-		newSlice := reflect.Append(ifaceElem, newElem)
-
-		t.set(newSlice)
-
-		return valueTarget(t.get().Elem().Index(idx))
-	default:
-		// Why ensureValueIndexable let it go through?
-		panic(fmt.Errorf("elementAt received unhandled value type: %s", f.Kind()))
-	}
-}
-
-//nolint:cyclop
-func (d *decoder) scopeTableTarget(shouldAppend bool, t target, name string) (target, bool, error) {
-	x := t.get()
-
-	switch x.Kind() {
-	// Kinds that need to recurse
-	case reflect.Interface:
-		t := scopeInterface(shouldAppend, t)
-		return d.scopeTableTarget(shouldAppend, t, name)
-	case reflect.Ptr:
-		t := scopePtr(t)
-		return d.scopeTableTarget(shouldAppend, t, name)
-	case reflect.Slice:
-		t := scopeSlice(shouldAppend, t)
-		shouldAppend = false
-		return d.scopeTableTarget(shouldAppend, t, name)
-	case reflect.Array:
-		t, err := d.scopeArray(shouldAppend, t)
-		if err != nil {
-			return t, false, err
-		}
-		shouldAppend = false
-
-		return d.scopeTableTarget(shouldAppend, t, name)
-
-	// Terminal kinds
-	case reflect.Struct:
-		return scopeStruct(x, name)
-	case reflect.Map:
-		if x.IsNil() {
-			t.set(reflect.MakeMap(x.Type()))
-			x = t.get()
-		}
-
-		return scopeMap(x, name)
-	default:
-		panic(fmt.Sprintf("can't scope on a %s", x.Kind()))
-	}
-}
-
-func scopeInterface(shouldAppend bool, t target) target {
-	initInterface(shouldAppend, t)
-	return interfaceTarget{t}
-}
-
-func scopePtr(t target) target {
-	initPtr(t)
-	return valueTarget(t.get().Elem())
-}
-
-func initPtr(t target) {
-	x := t.get()
-	if !x.IsNil() {
-		return
-	}
-
-	t.set(reflect.New(x.Type().Elem()))
-}
-
-// initInterface makes sure that the interface pointed at by the target is not
-// nil.
-// Returns the target to the initialized value of the target.
-func initInterface(shouldAppend bool, t target) {
-	x := t.get()
-
-	if x.Kind() != reflect.Interface {
-		panic("this should only be called on interfaces")
-	}
-
-	if !x.IsNil() && (x.Elem().Type() == sliceInterfaceType || x.Elem().Type() == mapStringInterfaceType) {
-		return
-	}
-
-	var newElement reflect.Value
-	if shouldAppend {
-		newElement = reflect.MakeSlice(sliceInterfaceType, 0, 0)
-	} else {
-		newElement = reflect.MakeMap(mapStringInterfaceType)
-	}
-
-	t.set(newElement)
-}
-
-func scopeSlice(shouldAppend bool, t target) target {
-	v := t.get()
-
-	if shouldAppend {
-		newElem := reflect.New(v.Type().Elem())
-		newSlice := reflect.Append(v, newElem.Elem())
-
-		t.set(newSlice)
-
-		v = t.get()
-	}
-
-	return valueTarget(v.Index(v.Len() - 1))
-}
-
-func (d *decoder) scopeArray(shouldAppend bool, t target) (target, error) {
-	v := t.get()
-
-	idx := d.arrayIndex(shouldAppend, v)
-
-	if idx >= v.Len() {
-		return nil, fmt.Errorf("toml: impossible to insert element beyond array's size: %d", v.Len())
-	}
-
-	return valueTarget(v.Index(idx)), nil
-}
-
-func scopeMap(v reflect.Value, name string) (target, bool, error) {
-	k := reflect.ValueOf(name)
-
-	keyType := v.Type().Key()
-	if !k.Type().AssignableTo(keyType) {
-		if !k.Type().ConvertibleTo(keyType) {
-			return nil, false, fmt.Errorf("toml: cannot convert map key of type %s to expected type %s", k.Type(), keyType)
-		}
-
-		k = k.Convert(keyType)
-	}
-
-	if !v.MapIndex(k).IsValid() {
-		newElem := reflect.New(v.Type().Elem())
-		v.SetMapIndex(k, newElem.Elem())
-	}
-
-	return mapTarget{
-		v: v,
-		k: k,
-	}, true, nil
-}
-
-type fieldPathsMap = map[string][]int
-
-type fieldPathsCache struct {
-	m map[reflect.Type]fieldPathsMap
-	l sync.RWMutex
-}
-
-func (c *fieldPathsCache) get(t reflect.Type) (fieldPathsMap, bool) {
-	c.l.RLock()
-	paths, ok := c.m[t]
-	c.l.RUnlock()
-
-	return paths, ok
-}
-
-func (c *fieldPathsCache) set(t reflect.Type, m fieldPathsMap) {
-	c.l.Lock()
-	c.m[t] = m
-	c.l.Unlock()
-}
-
-var globalFieldPathsCache = fieldPathsCache{
-	m: map[reflect.Type]fieldPathsMap{},
-	l: sync.RWMutex{},
-}
-
-func scopeStruct(v reflect.Value, name string) (target, bool, error) {
-	//nolint:godox
-	// TODO: cache this, and reduce allocations
-	fieldPaths, ok := globalFieldPathsCache.get(v.Type())
-	if !ok {
-		fieldPaths = map[string][]int{}
-
-		path := make([]int, 0, 16)
-
-		var walk func(reflect.Value)
-		walk = func(v reflect.Value) {
-			t := v.Type()
-			for i := 0; i < t.NumField(); i++ {
-				l := len(path)
-				path = append(path, i)
-				f := t.Field(i)
-
-				if f.Anonymous {
-					walk(v.Field(i))
-				} else if f.PkgPath == "" {
-					// only consider exported fields
-					fieldName, ok := f.Tag.Lookup("toml")
-					if !ok {
-						fieldName = f.Name
-					}
-
-					pathCopy := make([]int, len(path))
-					copy(pathCopy, path)
-
-					fieldPaths[fieldName] = pathCopy
-					// extra copy for the case-insensitive match
-					fieldPaths[strings.ToLower(fieldName)] = pathCopy
-				}
-				path = path[:l]
-			}
-		}
-
-		walk(v)
-
-		globalFieldPathsCache.set(v.Type(), fieldPaths)
-	}
-
-	path, ok := fieldPaths[name]
-	if !ok {
-		path, ok = fieldPaths[strings.ToLower(name)]
-	}
-
-	if !ok {
-		return nil, false, nil
-	}
-
-	return valueTarget(v.FieldByIndex(path)), true, nil
-}

targets_test.go

@@ -1,207 +0,0 @@
-package toml
-
-import (
-	"reflect"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-func TestStructTarget_Ensure(t *testing.T) {
-	t.Parallel()
-
-	examples := []struct {
-		desc  string
-		input reflect.Value
-		name  string
-		test  func(v reflect.Value, err error)
-	}{
-		{
-			desc:  "handle a nil slice of string",
-			input: reflect.ValueOf(&struct{ A []string }{}).Elem(),
-			name:  "A",
-			test: func(v reflect.Value, err error) {
-				assert.NoError(t, err)
-				assert.False(t, v.IsNil())
-			},
-		},
-		{
-			desc:  "handle an existing slice of string",
-			input: reflect.ValueOf(&struct{ A []string }{A: []string{"foo"}}).Elem(),
-			name:  "A",
-			test: func(v reflect.Value, err error) {
-				assert.NoError(t, err)
-				require.False(t, v.IsNil())
-
-				s, ok := v.Interface().([]string)
-				if !ok {
-					t.Errorf("interface %v should be castable into []string", s)
-					return
-				}
-
-				assert.Equal(t, []string{"foo"}, s)
-			},
-		},
-	}
-
-	for _, e := range examples {
-		e := e
-		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
-
-			d := decoder{}
-			target, _, err := d.scopeTableTarget(false, valueTarget(e.input), e.name)
-			require.NoError(t, err)
-			err = ensureValueIndexable(target)
-			v := target.get()
-			e.test(v, err)
-		})
-	}
-}
-
-func TestStructTarget_SetString(t *testing.T) {
-	t.Parallel()
-
-	str := "value"
-
-	examples := []struct {
-		desc  string
-		input reflect.Value
-		name  string
-		test  func(v reflect.Value, err error)
-	}{
-		{
-			desc:  "sets a string",
-			input: reflect.ValueOf(&struct{ A string }{}).Elem(),
-			name:  "A",
-			test: func(v reflect.Value, err error) {
-				assert.NoError(t, err)
-				assert.Equal(t, str, v.String())
-			},
-		},
-		{
-			desc:  "fails on a float",
-			input: reflect.ValueOf(&struct{ A float64 }{}).Elem(),
-			name:  "A",
-			test: func(v reflect.Value, err error) {
-				assert.Error(t, err)
-			},
-		},
-		{
-			desc:  "fails on a slice",
-			input: reflect.ValueOf(&struct{ A []string }{}).Elem(),
-			name:  "A",
-			test: func(v reflect.Value, err error) {
-				assert.Error(t, err)
-			},
-		},
-	}
-
-	for _, e := range examples {
-		e := e
-		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
-
-			d := decoder{}
-			target, _, err := d.scopeTableTarget(false, valueTarget(e.input), e.name)
-			require.NoError(t, err)
-			err = setString(target, str)
-			v := target.get()
-			e.test(v, err)
-		})
-	}
-}
-
-func TestPushNew(t *testing.T) {
-	t.Parallel()
-
-	t.Run("slice of strings", func(t *testing.T) {
-		t.Parallel()
-
-		type Doc struct {
-			A []string
-		}
-		d := Doc{}
-
-		dec := decoder{}
-		x, _, err := dec.scopeTableTarget(false, valueTarget(reflect.ValueOf(&d).Elem()), "A")
-		require.NoError(t, err)
-
-		n := elementAt(x, 0)
-		n.setString("hello")
-		require.Equal(t, []string{"hello"}, d.A)
-
-		n = elementAt(x, 1)
-		n.setString("world")
-		require.Equal(t, []string{"hello", "world"}, d.A)
-	})
-
-	t.Run("slice of interfaces", func(t *testing.T) {
-		t.Parallel()
-
-		type Doc struct {
-			A []interface{}
-		}
-		d := Doc{}
-
-		dec := decoder{}
-		x, _, err := dec.scopeTableTarget(false, valueTarget(reflect.ValueOf(&d).Elem()), "A")
-		require.NoError(t, err)
-
-		n := elementAt(x, 0)
-		require.NoError(t, setString(n, "hello"))
-		require.Equal(t, []interface{}{"hello"}, d.A)
-
-		n = elementAt(x, 1)
-		require.NoError(t, setString(n, "world"))
-		require.Equal(t, []interface{}{"hello", "world"}, d.A)
-	})
-}
-
-func TestScope_Struct(t *testing.T) {
-	t.Parallel()
-
-	examples := []struct {
-		desc  string
-		input reflect.Value
-		name  string
-		err   bool
-		found bool
-		idx   []int
-	}{
-		{
-			desc:  "simple field",
-			input: reflect.ValueOf(&struct{ A string }{}).Elem(),
-			name:  "A",
-			idx:   []int{0},
-			found: true,
-		},
-		{
-			desc:  "fails not-exported field",
-			input: reflect.ValueOf(&struct{ a string }{}).Elem(),
-			name:  "a",
-			err:   false,
-			found: false,
-		},
-	}
-
-	for _, e := range examples {
-		e := e
-		t.Run(e.desc, func(t *testing.T) {
-			t.Parallel()
-
-			dec := decoder{}
-			x, found, err := dec.scopeTableTarget(false, valueTarget(e.input), e.name)
-			assert.Equal(t, e.found, found)
-			if e.err {
-				assert.Error(t, err)
-			}
-			if found {
-				x2, ok := x.(valueTarget)
-				require.True(t, ok)
-				x2.get()
-			}
-		})
-	}
-}

toml_testgen_test.go

@@ -6,35 +6,30 @@ import (
 )
 
 func TestInvalidDatetimeMalformedNoLeads(t *testing.T) {
-	t.Parallel()
 
 	input := `no-leads = 1987-7-05T17:45:00Z`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidDatetimeMalformedNoSecs(t *testing.T) {
-	t.Parallel()
 
 	input := `no-secs = 1987-07-05T17:45Z`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidDatetimeMalformedNoT(t *testing.T) {
-	t.Parallel()
 
 	input := `no-t = 1987-07-0517:45:00Z`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidDatetimeMalformedWithMilli(t *testing.T) {
-	t.Parallel()
 
 	input := `with-milli = 1987-07-5T17:45:00.12Z`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidDuplicateKeyTable(t *testing.T) {
-	t.Parallel()
 
 	input := `[fruit]
 type = "apple"
@@ -45,7 +40,6 @@ apple = "yes"`
 }
 
 func TestInvalidDuplicateKeys(t *testing.T) {
-	t.Parallel()
 
 	input := `dupe = false
 dupe = true`
@@ -53,7 +47,6 @@ dupe = true`
 }
 
 func TestInvalidDuplicateTables(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]
 [a]`
@@ -61,21 +54,18 @@ func TestInvalidDuplicateTables(t *testing.T) {
 }
 
 func TestInvalidEmptyImplicitTable(t *testing.T) {
-	t.Parallel()
 
 	input := `[naughty..naughty]`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidEmptyTable(t *testing.T) {
-	t.Parallel()
 
 	input := `[]`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidFloatNoLeadingZero(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = .12345
 neganswer = -.12345`
@@ -83,7 +73,6 @@ neganswer = -.12345`
 }
 
 func TestInvalidFloatNoTrailingDigits(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = 1.
 neganswer = -1.`
@@ -91,21 +80,18 @@ neganswer = -1.`
 }
 
 func TestInvalidKeyEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := ` = 1`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidKeyHash(t *testing.T) {
-	t.Parallel()
 
 	input := `a# = 1`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidKeyNewline(t *testing.T) {
-	t.Parallel()
 
 	input := `a
 = 1`
@@ -113,28 +99,24 @@ func TestInvalidKeyNewline(t *testing.T) {
 }
 
 func TestInvalidKeyOpenBracket(t *testing.T) {
-	t.Parallel()
 
 	input := `[abc = 1`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidKeySingleOpenBracket(t *testing.T) {
-	t.Parallel()
 
 	input := `[`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidKeySpace(t *testing.T) {
-	t.Parallel()
 
 	input := `a b = 1`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidKeyStartBracket(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]
 [xyz = 5
@@ -143,42 +125,36 @@ func TestInvalidKeyStartBracket(t *testing.T) {
 }
 
 func TestInvalidKeyTwoEquals(t *testing.T) {
-	t.Parallel()
 
 	input := `key= = 1`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidStringBadByteEscape(t *testing.T) {
-	t.Parallel()
 
 	input := `naughty = "\xAg"`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidStringBadEscape(t *testing.T) {
-	t.Parallel()
 
 	input := `invalid-escape = "This string has a bad \a escape character."`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidStringByteEscapes(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = "\x33"`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidStringNoClose(t *testing.T) {
-	t.Parallel()
 
 	input := `no-ending-quote = "One time, at band camp`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTableArrayImplicit(t *testing.T) {
-	t.Parallel()
 
 	input := "# This test is a bit tricky. It should fail because the first use of\n" +
 		"# `[[albums.songs]]` without first declaring `albums` implies that `albums`\n" +
@@ -198,7 +174,6 @@ func TestInvalidTableArrayImplicit(t *testing.T) {
 }
 
 func TestInvalidTableArrayMalformedBracket(t *testing.T) {
-	t.Parallel()
 
 	input := `[[albums]
 name = "Born to Run"`
@@ -206,7 +181,6 @@ name = "Born to Run"`
 }
 
 func TestInvalidTableArrayMalformedEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `[[]]
 name = "Born to Run"`
@@ -214,14 +188,12 @@ name = "Born to Run"`
 }
 
 func TestInvalidTableEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `[]`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTableNestedBracketsClose(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]b]
 zyx = 42`
@@ -229,7 +201,6 @@ zyx = 42`
 }
 
 func TestInvalidTableNestedBracketsOpen(t *testing.T) {
-	t.Parallel()
 
 	input := `[a[b]
 zyx = 42`
@@ -237,14 +208,12 @@ zyx = 42`
 }
 
 func TestInvalidTableWhitespace(t *testing.T) {
-	t.Parallel()
 
 	input := `[invalid key]`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTableWithPound(t *testing.T) {
-	t.Parallel()
 
 	input := `[key#group]
 answer = 42`
@@ -252,7 +221,6 @@ answer = 42`
 }
 
 func TestInvalidTextAfterArrayEntries(t *testing.T) {
-	t.Parallel()
 
 	input := `array = [
   "Is there life after an array separator?", No
@@ -262,28 +230,24 @@ func TestInvalidTextAfterArrayEntries(t *testing.T) {
 }
 
 func TestInvalidTextAfterInteger(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = 42 the ultimate answer?`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTextAfterString(t *testing.T) {
-	t.Parallel()
 
 	input := `string = "Is there life after strings?" No.`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTextAfterTable(t *testing.T) {
-	t.Parallel()
 
 	input := `[error] this shouldn't be here`
 	testgenInvalid(t, input)
 }
 
 func TestInvalidTextBeforeArraySeparator(t *testing.T) {
-	t.Parallel()
 
 	input := `array = [
   "Is there life before an array separator?" No,
@@ -293,7 +257,6 @@ func TestInvalidTextBeforeArraySeparator(t *testing.T) {
 }
 
 func TestInvalidTextInArray(t *testing.T) {
-	t.Parallel()
 
 	input := `array = [
   "Entry 1",
@@ -304,7 +267,6 @@ func TestInvalidTextInArray(t *testing.T) {
 }
 
 func TestValidArrayEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `thevoid = [[[[[]]]]]`
 	jsonRef := `{
@@ -322,7 +284,6 @@ func TestValidArrayEmpty(t *testing.T) {
 }
 
 func TestValidArrayNospaces(t *testing.T) {
-	t.Parallel()
 
 	input := `ints = [1,2,3]`
 	jsonRef := `{
@@ -339,7 +300,6 @@ func TestValidArrayNospaces(t *testing.T) {
 }
 
 func TestValidArraysHetergeneous(t *testing.T) {
-	t.Parallel()
 
 	input := `mixed = [[1, 2], ["a", "b"], [1.1, 2.1]]`
 	jsonRef := `{
@@ -365,7 +325,6 @@ func TestValidArraysHetergeneous(t *testing.T) {
 }
 
 func TestValidArraysNested(t *testing.T) {
-	t.Parallel()
 
 	input := `nest = [["a"], ["b"]]`
 	jsonRef := `{
@@ -385,7 +344,6 @@ func TestValidArraysNested(t *testing.T) {
 }
 
 func TestValidArrays(t *testing.T) {
-	t.Parallel()
 
 	input := `ints = [1, 2, 3]
 floats = [1.1, 2.1, 3.1]
@@ -433,7 +391,6 @@ dates = [
 }
 
 func TestValidBool(t *testing.T) {
-	t.Parallel()
 
 	input := `t = true
 f = false`
@@ -445,7 +402,6 @@ f = false`
 }
 
 func TestValidCommentsEverywhere(t *testing.T) {
-	t.Parallel()
 
 	input := `# Top comment.
   # Top comment.
@@ -487,7 +443,6 @@ more = [ # Comment
 }
 
 func TestValidDatetime(t *testing.T) {
-	t.Parallel()
 
 	input := `bestdayever = 1987-07-05T17:45:00Z`
 	jsonRef := `{
@@ -497,7 +452,6 @@ func TestValidDatetime(t *testing.T) {
 }
 
 func TestValidEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := ``
 	jsonRef := `{}`
@@ -505,7 +459,6 @@ func TestValidEmpty(t *testing.T) {
 }
 
 func TestValidExample(t *testing.T) {
-	t.Parallel()
 
 	input := `best-day-ever = 1987-07-05T17:45:00Z
 
@@ -530,7 +483,6 @@ perfection = [6, 28, 496]`
 }
 
 func TestValidFloat(t *testing.T) {
-	t.Parallel()
 
 	input := `pi = 3.14
 negpi = -3.14`
@@ -542,7 +494,6 @@ negpi = -3.14`
 }
 
 func TestValidImplicitAndExplicitAfter(t *testing.T) {
-	t.Parallel()
 
 	input := `[a.b.c]
 answer = 42
@@ -563,7 +514,6 @@ better = 43`
 }
 
 func TestValidImplicitAndExplicitBefore(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]
 better = 43
@@ -584,7 +534,6 @@ answer = 42`
 }
 
 func TestValidImplicitGroups(t *testing.T) {
-	t.Parallel()
 
 	input := `[a.b.c]
 answer = 42`
@@ -601,7 +550,6 @@ answer = 42`
 }
 
 func TestValidInteger(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = 42
 neganswer = -42`
@@ -613,7 +561,6 @@ neganswer = -42`
 }
 
 func TestValidKeyEqualsNospace(t *testing.T) {
-	t.Parallel()
 
 	input := `answer=42`
 	jsonRef := `{
@@ -623,7 +570,6 @@ func TestValidKeyEqualsNospace(t *testing.T) {
 }
 
 func TestValidKeySpace(t *testing.T) {
-	t.Parallel()
 
 	input := `"a b" = 1`
 	jsonRef := `{
@@ -633,7 +579,6 @@ func TestValidKeySpace(t *testing.T) {
 }
 
 func TestValidKeySpecialChars(t *testing.T) {
-	t.Parallel()
 
 	input := "\"~!@$^&*()_+-`1234567890[]|/?><.,;:'\" = 1\n"
 	jsonRef := "{\n" +
@@ -645,7 +590,6 @@ func TestValidKeySpecialChars(t *testing.T) {
 }
 
 func TestValidLongFloat(t *testing.T) {
-	t.Parallel()
 
 	input := `longpi = 3.141592653589793
 neglongpi = -3.141592653589793`
@@ -657,7 +601,6 @@ neglongpi = -3.141592653589793`
 }
 
 func TestValidLongInteger(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = 9223372036854775807
 neganswer = -9223372036854775808`
@@ -669,7 +612,6 @@ neganswer = -9223372036854775808`
 }
 
 func TestValidMultilineString(t *testing.T) {
-	t.Parallel()
 
 	input := `multiline_empty_one = """"""
 multiline_empty_two = """
@@ -728,7 +670,6 @@ equivalent_three = """\
 }
 
 func TestValidRawMultilineString(t *testing.T) {
-	t.Parallel()
 
 	input := `oneline = '''This string has a ' quote character.'''
 firstnl = '''
@@ -757,7 +698,6 @@ in it.'''`
 }
 
 func TestValidRawString(t *testing.T) {
-	t.Parallel()
 
 	input := `backspace = 'This string has a \b backspace character.'
 tab = 'This string has a \t tab character.'
@@ -800,7 +740,6 @@ backslash = 'This string has a \\ backslash character.'`
 }
 
 func TestValidStringEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = ""`
 	jsonRef := `{
@@ -813,7 +752,6 @@ func TestValidStringEmpty(t *testing.T) {
 }
 
 func TestValidStringEscapes(t *testing.T) {
-	t.Parallel()
 
 	input := `backspace = "This string has a \b backspace character."
 tab = "This string has a \t tab character."
@@ -876,7 +814,6 @@ notunicode4 = "This string does not have a unicode \\\u0075 escape."`
 }
 
 func TestValidStringSimple(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = "You are not drinking enough whisky."`
 	jsonRef := `{
@@ -889,7 +826,6 @@ func TestValidStringSimple(t *testing.T) {
 }
 
 func TestValidStringWithPound(t *testing.T) {
-	t.Parallel()
 
 	input := `pound = "We see no # comments here."
 poundcomment = "But there are # some comments here." # Did I # mess you up?`
@@ -904,7 +840,6 @@ poundcomment = "But there are # some comments here." # Did I # mess you up?`
 }
 
 func TestValidTableArrayImplicit(t *testing.T) {
-	t.Parallel()
 
 	input := `[[albums.songs]]
 name = "Glory Days"`
@@ -919,7 +854,6 @@ name = "Glory Days"`
 }
 
 func TestValidTableArrayMany(t *testing.T) {
-	t.Parallel()
 
 	input := `[[people]]
 first_name = "Bruce"
@@ -952,7 +886,6 @@ last_name = "Seger"`
 }
 
 func TestValidTableArrayNest(t *testing.T) {
-	t.Parallel()
 
 	input := `[[albums]]
 name = "Born to Run"
@@ -993,7 +926,6 @@ name = "Born in the USA"
 }
 
 func TestValidTableArrayOne(t *testing.T) {
-	t.Parallel()
 
 	input := `[[people]]
 first_name = "Bruce"
@@ -1010,7 +942,6 @@ last_name = "Springsteen"`
 }
 
 func TestValidTableEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]`
 	jsonRef := `{
@@ -1020,7 +951,6 @@ func TestValidTableEmpty(t *testing.T) {
 }
 
 func TestValidTableSubEmpty(t *testing.T) {
-	t.Parallel()
 
 	input := `[a]
 [a.b]`
@@ -1031,7 +961,6 @@ func TestValidTableSubEmpty(t *testing.T) {
 }
 
 func TestValidTableWhitespace(t *testing.T) {
-	t.Parallel()
 
 	input := `["valid key"]`
 	jsonRef := `{
@@ -1041,7 +970,6 @@ func TestValidTableWhitespace(t *testing.T) {
 }
 
 func TestValidTableWithPound(t *testing.T) {
-	t.Parallel()
 
 	input := `["key#group"]
 answer = 42`
@@ -1054,7 +982,6 @@ answer = 42`
 }
 
 func TestValidUnicodeEscape(t *testing.T) {
-	t.Parallel()
 
 	input := `answer4 = "\u03B4"
 answer8 = "\U000003B4"`
@@ -1066,7 +993,6 @@ answer8 = "\U000003B4"`
 }
 
 func TestValidUnicodeLiteral(t *testing.T) {
-	t.Parallel()
 
 	input := `answer = "δ"`
 	jsonRef := `{

types.go

@@ -0,0 +1,13 @@
+package toml
+
+import (
+	"encoding"
+	"reflect"
+	"time"
+)
+
+var timeType = reflect.TypeOf(time.Time{})
+var textMarshalerType = reflect.TypeOf(new(encoding.TextMarshaler)).Elem()
+var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
+var mapStringInterfaceType = reflect.TypeOf(map[string]interface{}{})
+var sliceInterfaceType = reflect.TypeOf([]interface{}{})