ostiwe/go-toml
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Make error position tracking explicit with Offset field on ParserError

Browse Source 
Thread byte offset information through all error creation sites,
eliminating the need for SubsliceOffset to recover position from
pointer comparison.

Changes:
- Add Offset field to ParserError struct
- Add offset parameter to NewParserError
- Add Parser.offsetOf helper for suffix-length arithmetic
- Thread base offset through scanner functions (scanComment,
  scanBasicString, scanMultilineBasicString, scanLiteralString,
  scanMultilineLiteralString, scanWindowsNewline)
- Thread base offset through standalone functions (expect, hexToRune)
- Thread base offset through all decode functions (parseInteger,
  parseFloat, parseLocalDate, parseLocalTime, parseLocalDateTime,
  parseDateTime, checkAndRemoveUnderscores*)
- Update all unmarshaler call sites to pass value.Raw.Offset
- Update localtime.go UnmarshalText methods with base=0
- Update strict.go to populate Offset from key ranges
- Change wrapDecodeError to read de.Offset directly
- Change Utf8TomlValidAlreadyEscaped to return int index (-1 if valid)
  instead of a byte subslice
- Unexport SubsliceOffset (now only used internally by Range())

This makes error positions self-describing: each ParserError carries its
own byte offset, so callers no longer need the original document slice
and address arithmetic to determine where an error occurred.

Co-authored-by: Thomas Pelletier <thomas@pelletier.dev>
This commit is contained in:
Cursor Agent
2026-04-12 19:08:55 +00:00
parent d75117e61f
commit a646ffd9fa
11 changed files with 217 additions and 271 deletions
Download Patch File Download Diff File Expand all files Collapse all files
unstable/parser.go
+63 -55
View File
@@ -16,6 +16,7 @@ type ParserError struct {
Highlight []byte
Message string
Key []string // optional
Offset int
}
// Error is the implementation of the error interface.
@@ -27,9 +28,10 @@ func (e *ParserError) Error() string {
//
// Warning: Highlight needs to be a subslice of Parser.data, so only slices
// returned by Parser.Raw are valid candidates.
func NewParserError(highlight []byte, format string, args ...interface{}) error {
func NewParserError(highlight []byte, offset int, format string, args ...interface{}) error {
return &ParserError{
Highlight: highlight,
Offset: offset,
Message: fmt.Errorf(format, args...).Error(),
}
}
@@ -64,12 +66,18 @@ func (p *Parser) Data() []byte {
return p.data
}
func (p *Parser) offsetOf(b []byte) int {
return len(p.data) - len(b)
}
// Range returns a range description that corresponds to a given slice of the
// input. If the argument is not a subslice of the parser input, this function
// panics.
//
// Prefer using ParserError.Offset directly for error position information.
func (p *Parser) Range(b []byte) Range {
return Range{
Offset: uint32(SubsliceOffset(p.data, b)), //nolint:gosec // TOML documents are small
Offset: uint32(subsliceOffset(p.data, b)), //nolint:gosec // TOML documents are small
Length: uint32(len(b)), //nolint:gosec // TOML documents are small
}
}
@@ -191,16 +199,16 @@ func (p *Parser) parseNewline(b []byte) ([]byte, error) {
}
if b[0] == '\r' {
_, rest, err := scanWindowsNewline(b)
_, rest, err := scanWindowsNewline(b, p.offsetOf(b))
return rest, err
}
return nil, NewParserError(b[0:1], "expected newline but got %#U", b[0])
return nil, NewParserError(b[0:1], p.offsetOf(b), "expected newline but got %#U", b[0])
}
func (p *Parser) parseComment(b []byte) (reference, []byte, error) {
ref := invalidReference
data, rest, err := scanComment(b)
data, rest, err := scanComment(b, p.offsetOf(b))
if p.KeepComments && err == nil {
ref = p.builder.Push(Node{
Kind: Comment,
@@ -284,12 +292,12 @@ func (p *Parser) parseArrayTable(b []byte) (reference, []byte, error) {
p.builder.AttachChild(ref, k)
b = p.parseWhitespace(b)
b, err = expect(']', b)
b, err = expect(']', b, p.offsetOf(b))
if err != nil {
return ref, nil, err
}
b, err = expect(']', b)
b, err = expect(']', b, p.offsetOf(b))
return ref, b, err
}
@@ -314,7 +322,7 @@ func (p *Parser) parseStdTable(b []byte) (reference, []byte, error) {
b = p.parseWhitespace(b)
b, err = expect(']', b)
b, err = expect(']', b, p.offsetOf(b))
return ref, b, err
}
@@ -338,10 +346,10 @@ func (p *Parser) parseKeyval(b []byte) (reference, []byte, error) {
b = p.parseWhitespace(b)
if len(b) == 0 {
return invalidReference, nil, NewParserError(startB[:len(startB)-len(b)], "expected = after a key, but the document ends there")
return invalidReference, nil, NewParserError(startB[:len(startB)-len(b)], p.offsetOf(startB), "expected = after a key, but the document ends there")
}
b, err = expect('=', b)
b, err = expect('=', b, p.offsetOf(b))
if err != nil {
return invalidReference, nil, err
}
@@ -370,7 +378,7 @@ func (p *Parser) parseVal(b []byte) (reference, []byte, error) {
ref := invalidReference
if len(b) == 0 {
return ref, nil, NewParserError(b, "expected value, not eof")
return ref, nil, NewParserError(b, p.offsetOf(b), "expected value, not eof")
}
var err error
@@ -415,7 +423,7 @@ func (p *Parser) parseVal(b []byte) (reference, []byte, error) {
return ref, b, err
case 't':
if !scanFollowsTrue(b) {
return ref, nil, NewParserError(atmost(b, 4), "expected 'true'")
return ref, nil, NewParserError(atmost(b, 4), p.offsetOf(b), "expected 'true'")
}
ref = p.builder.Push(Node{
@@ -426,7 +434,7 @@ func (p *Parser) parseVal(b []byte) (reference, []byte, error) {
return ref, b[4:], nil
case 'f':
if !scanFollowsFalse(b) {
return ref, nil, NewParserError(atmost(b, 5), "expected 'false'")
return ref, nil, NewParserError(atmost(b, 5), p.offsetOf(b), "expected 'false'")
}
ref = p.builder.Push(Node{
@@ -453,7 +461,7 @@ func atmost(b []byte, n int) []byte {
}
func (p *Parser) parseLiteralString(b []byte) ([]byte, []byte, []byte, error) {
v, rest, err := scanLiteralString(b)
v, rest, err := scanLiteralString(b, p.offsetOf(b))
if err != nil {
return nil, nil, nil, err
}
@@ -485,7 +493,7 @@ func (p *Parser) parseInlineTable(b []byte) (reference, []byte, error) {
b = p.parseWhitespace(b)
if len(b) == 0 {
return parent, nil, NewParserError(previousB[:1], "inline table is incomplete")
return parent, nil, NewParserError(previousB[:1], p.offsetOf(previousB), "inline table is incomplete")
}
if b[0] == '}' {
@@ -493,7 +501,7 @@ func (p *Parser) parseInlineTable(b []byte) (reference, []byte, error) {
}
if !first {
b, err = expect(',', b)
b, err = expect(',', b, p.offsetOf(b))
if err != nil {
return parent, nil, err
}
@@ -517,7 +525,7 @@ func (p *Parser) parseInlineTable(b []byte) (reference, []byte, error) {
first = false
}
rest, err := expect('}', b)
rest, err := expect('}', b, p.offsetOf(b))
return parent, rest, err
}
@@ -566,7 +574,7 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
}
if len(b) == 0 {
return parent, nil, NewParserError(arrayStart[:1], "array is incomplete")
return parent, nil, NewParserError(arrayStart[:1], p.offsetOf(arrayStart), "array is incomplete")
}
if b[0] == ']' {
@@ -575,7 +583,7 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
if b[0] == ',' {
if first {
return parent, nil, NewParserError(b[0:1], "array cannot start with comma")
return parent, nil, NewParserError(b[0:1], p.offsetOf(b), "array cannot start with comma")
}
b = b[1:]
@@ -587,7 +595,7 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
addChild(cref)
}
} else if !first {
return parent, nil, NewParserError(b[0:1], "array elements must be separated by commas")
return parent, nil, NewParserError(b[0:1], p.offsetOf(b), "array elements must be separated by commas")
}
// TOML allows trailing commas in arrays.
@@ -614,7 +622,7 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
first = false
}
rest, err := expect(']', b)
rest, err := expect(']', b, p.offsetOf(b))
return parent, rest, err
}
@@ -669,7 +677,7 @@ func (p *Parser) parseOptionalWhitespaceCommentNewline(b []byte) (reference, []b
}
func (p *Parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, []byte, error) {
token, rest, err := scanMultilineLiteralString(b)
token, rest, err := scanMultilineLiteralString(b, p.offsetOf(b))
if err != nil {
return nil, nil, nil, err
}
@@ -698,7 +706,7 @@ func (p *Parser) parseMultilineBasicString(b []byte) ([]byte, []byte, []byte, er
// mlb-quotes = 1*2quotation-mark
// mlb-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
// mlb-escaped-nl = escape ws newline *( wschar / newline )
token, escaped, rest, err := scanMultilineBasicString(b)
token, escaped, rest, err := scanMultilineBasicString(b, p.offsetOf(b))
if err != nil {
return nil, nil, nil, err
}
@@ -715,14 +723,15 @@ func (p *Parser) parseMultilineBasicString(b []byte) ([]byte, []byte, []byte, er
// fast path
startIdx := i
endIdx := len(token) - len(`"""`)
tokenBase := p.offsetOf(token)
if !escaped {
str := token[startIdx:endIdx]
highlight := characters.Utf8TomlValidAlreadyEscaped(str)
if len(highlight) == 0 {
invalidIdx := characters.Utf8TomlValidAlreadyEscaped(str)
if invalidIdx < 0 {
return token, str, rest, nil
}
return nil, nil, nil, NewParserError(highlight, "invalid UTF-8")
return nil, nil, nil, NewParserError(str[invalidIdx:invalidIdx+1], tokenBase+startIdx+invalidIdx, "invalid UTF-8")
}
var builder bytes.Buffer
@@ -787,14 +796,14 @@ func (p *Parser) parseMultilineBasicString(b []byte) ([]byte, []byte, []byte, er
case 'e':
builder.WriteByte(0x1B)
case 'u':
x, err := hexToRune(atmost(token[i+1:], 4), 4)
x, err := hexToRune(atmost(token[i+1:], 4), tokenBase+i+1, 4)
if err != nil {
return nil, nil, nil, err
}
builder.WriteRune(x)
i += 4
case 'U':
x, err := hexToRune(atmost(token[i+1:], 8), 8)
x, err := hexToRune(atmost(token[i+1:], 8), tokenBase+i+1, 8)
if err != nil {
return nil, nil, nil, err
}
@@ -802,13 +811,13 @@ func (p *Parser) parseMultilineBasicString(b []byte) ([]byte, []byte, []byte, er
builder.WriteRune(x)
i += 8
default:
return nil, nil, nil, NewParserError(token[i:i+1], "invalid escaped character %#U", c)
return nil, nil, nil, NewParserError(token[i:i+1], tokenBase+i, "invalid escaped character %#U", c)
}
i++
} else {
size := characters.Utf8ValidNext(token[i:])
if size == 0 {
return nil, nil, nil, NewParserError(token[i:i+1], "invalid character %#U", c)
return nil, nil, nil, NewParserError(token[i:i+1], tokenBase+i, "invalid character %#U", c)
}
builder.Write(token[i : i+size])
i += size
@@ -863,12 +872,9 @@ func (p *Parser) parseKey(b []byte) (reference, []byte, error) {
func (p *Parser) parseSimpleKey(b []byte) (raw, key, rest []byte, err error) {
if len(b) == 0 {
return nil, nil, nil, NewParserError(b, "expected key but found none")
return nil, nil, nil, NewParserError(b, p.offsetOf(b), "expected key but found none")
}
// 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
switch {
case b[0] == '\'':
return p.parseLiteralString(b)
@@ -878,7 +884,7 @@ func (p *Parser) parseSimpleKey(b []byte) (raw, key, rest []byte, err error) {
key, rest = scanUnquotedKey(b)
return key, key, rest, nil
default:
return nil, nil, nil, NewParserError(b[0:1], "invalid character at start of key: %c", b[0])
return nil, nil, nil, NewParserError(b[0:1], p.offsetOf(b), "invalid character at start of key: %c", b[0])
}
}
@@ -898,7 +904,7 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
// escape-seq-char =/ %x74 ; t tab U+0009
// escape-seq-char =/ %x75 4HEXDIG ; uXXXX U+XXXX
// escape-seq-char =/ %x55 8HEXDIG ; UXXXXXXXX U+XXXXXXXX
token, escaped, rest, err := scanBasicString(b)
token, escaped, rest, err := scanBasicString(b, p.offsetOf(b))
if err != nil {
return nil, nil, nil, err
}
@@ -909,13 +915,15 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
// Fast path. If there is no escape sequence, the string should just be
// an UTF-8 encoded string, which is the same as Go. In that case,
// validate the string and return a direct reference to the buffer.
tokenBase := p.offsetOf(token)
if !escaped {
str := token[startIdx:endIdx]
highlight := characters.Utf8TomlValidAlreadyEscaped(str)
if len(highlight) == 0 {
invalidIdx := characters.Utf8TomlValidAlreadyEscaped(str)
if invalidIdx < 0 {
return token, str, rest, nil
}
return nil, nil, nil, NewParserError(highlight, "invalid UTF-8")
return nil, nil, nil, NewParserError(str[invalidIdx:invalidIdx+1], tokenBase+startIdx+invalidIdx, "invalid UTF-8")
}
i := startIdx
@@ -946,7 +954,7 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
case 'e':
builder.WriteByte(0x1B)
case 'u':
x, err := hexToRune(token[i+1:len(token)-1], 4)
x, err := hexToRune(token[i+1:len(token)-1], tokenBase+i+1, 4)
if err != nil {
return nil, nil, nil, err
}
@@ -954,7 +962,7 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
builder.WriteRune(x)
i += 4
case 'U':
x, err := hexToRune(token[i+1:len(token)-1], 8)
x, err := hexToRune(token[i+1:len(token)-1], tokenBase+i+1, 8)
if err != nil {
return nil, nil, nil, err
}
@@ -962,13 +970,13 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
builder.WriteRune(x)
i += 8
default:
return nil, nil, nil, NewParserError(token[i:i+1], "invalid escaped character %#U", c)
return nil, nil, nil, NewParserError(token[i:i+1], tokenBase+i, "invalid escaped character %#U", c)
}
i++
} else {
size := characters.Utf8ValidNext(token[i:])
if size == 0 {
return nil, nil, nil, NewParserError(token[i:i+1], "invalid character %#U", c)
return nil, nil, nil, NewParserError(token[i:i+1], tokenBase+i, "invalid character %#U", c)
}
builder.Write(token[i : i+size])
i += size
@@ -978,9 +986,9 @@ func (p *Parser) parseBasicString(b []byte) ([]byte, []byte, []byte, error) {
return token, builder.Bytes(), rest, nil
}
func hexToRune(b []byte, length int) (rune, error) {
func hexToRune(b []byte, base int, length int) (rune, error) {
if len(b) < length {
return -1, NewParserError(b, "unicode point needs %d character, not %d", length, len(b))
return -1, NewParserError(b, base, "unicode point needs %d character, not %d", length, len(b))
}
b = b[:length]
@@ -995,13 +1003,13 @@ func hexToRune(b []byte, length int) (rune, error) {
case 'A' <= c && c <= 'F':
d = uint32(c - 'A' + 10)
default:
return -1, NewParserError(b[i:i+1], "non-hex character")
return -1, NewParserError(b[i:i+1], base+i, "non-hex character")
}
r = r*16 + d
}
if r > unicode.MaxRune || 0xD800 <= r && r < 0xE000 {
return -1, NewParserError(b, "escape sequence is invalid Unicode code point")
return -1, NewParserError(b, base, "escape sequence is invalid Unicode code point")
}
return rune(r), nil
@@ -1021,7 +1029,7 @@ func (p *Parser) parseIntOrFloatOrDateTime(b []byte) (reference, []byte, error)
switch b[0] {
case 'i':
if !scanFollowsInf(b) {
return invalidReference, nil, NewParserError(atmost(b, 3), "expected 'inf'")
return invalidReference, nil, NewParserError(atmost(b, 3), p.offsetOf(b), "expected 'inf'")
}
return p.builder.Push(Node{
@@ -1031,7 +1039,7 @@ func (p *Parser) parseIntOrFloatOrDateTime(b []byte) (reference, []byte, error)
}), b[3:], nil
case 'n':
if !scanFollowsNan(b) {
return invalidReference, nil, NewParserError(atmost(b, 3), "expected 'nan'")
return invalidReference, nil, NewParserError(atmost(b, 3), p.offsetOf(b), "expected 'nan'")
}
return p.builder.Push(Node{
@@ -1190,7 +1198,7 @@ func (p *Parser) scanIntOrFloat(b []byte) (reference, []byte, error) {
}), b[i+3:], nil
}
return invalidReference, nil, NewParserError(b[i:i+1], "unexpected character 'i' while scanning for a number")
return invalidReference, nil, NewParserError(b[i:i+1], p.offsetOf(b)+i, "unexpected character 'i' while scanning for a number")
}
if c == 'n' {
@@ -1202,14 +1210,14 @@ func (p *Parser) scanIntOrFloat(b []byte) (reference, []byte, error) {
}), b[i+3:], nil
}
return invalidReference, nil, NewParserError(b[i:i+1], "unexpected character 'n' while scanning for a number")
return invalidReference, nil, NewParserError(b[i:i+1], p.offsetOf(b)+i, "unexpected character 'n' while scanning for a number")
}
break
}
if i == 0 {
return invalidReference, b, NewParserError(b, "incomplete number")
return invalidReference, b, NewParserError(b, p.offsetOf(b), "incomplete number")
}
kind := Integer
@@ -1246,13 +1254,13 @@ func isValidBinaryRune(r byte) bool {
return r == '0' || r == '1' || r == '_'
}
func expect(x byte, b []byte) ([]byte, error) {
func expect(x byte, b []byte, base int) ([]byte, error) {
if len(b) == 0 {
return nil, NewParserError(b, "expected character %c but the document ended here", x)
return nil, NewParserError(b, base, "expected character %c but the document ended here", x)
}
if b[0] != x {
return nil, NewParserError(b[0:1], "expected character %c", x)
return nil, NewParserError(b[0:1], base, "expected character %c", x)
}
return b[1:], nil