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gitea/vendor/github.com/pelletier/go-toml/lexer.go

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// TOML lexer.
//
// Written using the principles developed by Rob Pike in
// http://www.youtube.com/watch?v=HxaD_trXwRE
package toml
import (
"bytes"
"errors"
"fmt"
"regexp"
"strconv"
"strings"
)
var dateRegexp *regexp.Regexp
// Define state functions
type tomlLexStateFn func() tomlLexStateFn
// Define lexer
type tomlLexer struct {
inputIdx int
input []rune // Textual source
currentTokenStart int
currentTokenStop int
tokens []token
depth int
line int
col int
endbufferLine int
endbufferCol int
}
// Basic read operations on input
func (l *tomlLexer) read() rune {
r := l.peek()
if r == '\n' {
l.endbufferLine++
l.endbufferCol = 1
} else {
l.endbufferCol++
}
l.inputIdx++
return r
}
func (l *tomlLexer) next() rune {
r := l.read()
if r != eof {
l.currentTokenStop++
}
return r
}
func (l *tomlLexer) ignore() {
l.currentTokenStart = l.currentTokenStop
l.line = l.endbufferLine
l.col = l.endbufferCol
}
func (l *tomlLexer) skip() {
l.next()
l.ignore()
}
func (l *tomlLexer) fastForward(n int) {
for i := 0; i < n; i++ {
l.next()
}
}
func (l *tomlLexer) emitWithValue(t tokenType, value string) {
l.tokens = append(l.tokens, token{
Position: Position{l.line, l.col},
typ: t,
val: value,
})
l.ignore()
}
func (l *tomlLexer) emit(t tokenType) {
l.emitWithValue(t, string(l.input[l.currentTokenStart:l.currentTokenStop]))
}
func (l *tomlLexer) peek() rune {
if l.inputIdx >= len(l.input) {
return eof
}
return l.input[l.inputIdx]
}
func (l *tomlLexer) peekString(size int) string {
maxIdx := len(l.input)
upperIdx := l.inputIdx + size // FIXME: potential overflow
if upperIdx > maxIdx {
upperIdx = maxIdx
}
return string(l.input[l.inputIdx:upperIdx])
}
func (l *tomlLexer) follow(next string) bool {
return next == l.peekString(len(next))
}
// Error management
func (l *tomlLexer) errorf(format string, args ...interface{}) tomlLexStateFn {
l.tokens = append(l.tokens, token{
Position: Position{l.line, l.col},
typ: tokenError,
val: fmt.Sprintf(format, args...),
})
return nil
}
// State functions
func (l *tomlLexer) lexVoid() tomlLexStateFn {
for {
next := l.peek()
switch next {
case '[':
return l.lexTableKey
case '#':
return l.lexComment(l.lexVoid)
case '=':
return l.lexEqual
case '\r':
fallthrough
case '\n':
l.skip()
continue
}
if isSpace(next) {
l.skip()
}
if l.depth > 0 {
return l.lexRvalue
}
if isKeyStartChar(next) {
return l.lexKey
}
if next == eof {
l.next()
break
}
}
l.emit(tokenEOF)
return nil
}
func (l *tomlLexer) lexRvalue() tomlLexStateFn {
for {
next := l.peek()
switch next {
case '.':
return l.errorf("cannot start float with a dot")
case '=':
return l.lexEqual
case '[':
l.depth++
return l.lexLeftBracket
case ']':
l.depth--
return l.lexRightBracket
case '{':
return l.lexLeftCurlyBrace
case '}':
return l.lexRightCurlyBrace
case '#':
return l.lexComment(l.lexRvalue)
case '"':
return l.lexString
case '\'':
return l.lexLiteralString
case ',':
return l.lexComma
case '\r':
fallthrough
case '\n':
l.skip()
if l.depth == 0 {
return l.lexVoid
}
return l.lexRvalue
case '_':
return l.errorf("cannot start number with underscore")
}
if l.follow("true") {
return l.lexTrue
}
if l.follow("false") {
return l.lexFalse
}
if l.follow("inf") {
return l.lexInf
}
if l.follow("nan") {
return l.lexNan
}
if isSpace(next) {
l.skip()
continue
}
if next == eof {
l.next()
break
}
possibleDate := l.peekString(35)
dateMatch := dateRegexp.FindString(possibleDate)
if dateMatch != "" {
l.fastForward(len(dateMatch))
return l.lexDate
}
if next == '+' || next == '-' || isDigit(next) {
return l.lexNumber
}
if isAlphanumeric(next) {
return l.lexKey
}
return l.errorf("no value can start with %c", next)
}
l.emit(tokenEOF)
return nil
}
func (l *tomlLexer) lexLeftCurlyBrace() tomlLexStateFn {
l.next()
l.emit(tokenLeftCurlyBrace)
return l.lexRvalue
}
func (l *tomlLexer) lexRightCurlyBrace() tomlLexStateFn {
l.next()
l.emit(tokenRightCurlyBrace)
return l.lexRvalue
}
func (l *tomlLexer) lexDate() tomlLexStateFn {
l.emit(tokenDate)
return l.lexRvalue
}
func (l *tomlLexer) lexTrue() tomlLexStateFn {
l.fastForward(4)
l.emit(tokenTrue)
return l.lexRvalue
}
func (l *tomlLexer) lexFalse() tomlLexStateFn {
l.fastForward(5)
l.emit(tokenFalse)
return l.lexRvalue
}
func (l *tomlLexer) lexInf() tomlLexStateFn {
l.fastForward(3)
l.emit(tokenInf)
return l.lexRvalue
}
func (l *tomlLexer) lexNan() tomlLexStateFn {
l.fastForward(3)
l.emit(tokenNan)
return l.lexRvalue
}
func (l *tomlLexer) lexEqual() tomlLexStateFn {
l.next()
l.emit(tokenEqual)
return l.lexRvalue
}
func (l *tomlLexer) lexComma() tomlLexStateFn {
l.next()
l.emit(tokenComma)
return l.lexRvalue
}
// Parse the key and emits its value without escape sequences.
// bare keys, basic string keys and literal string keys are supported.
func (l *tomlLexer) lexKey() tomlLexStateFn {
growingString := ""
for r := l.peek(); isKeyChar(r) || r == '\n' || r == '\r'; r = l.peek() {
if r == '"' {
l.next()
str, err := l.lexStringAsString(`"`, false, true)
if err != nil {
return l.errorf(err.Error())
}
growingString += "\"" + str + "\""
l.next()
continue
} else if r == '\'' {
l.next()
str, err := l.lexLiteralStringAsString(`'`, false)
if err != nil {
return l.errorf(err.Error())
}
growingString += "'" + str + "'"
l.next()
continue
} else if r == '\n' {
return l.errorf("keys cannot contain new lines")
} else if isSpace(r) {
break
} else if r == '.' {
// skip
} else if !isValidBareChar(r) {
return l.errorf("keys cannot contain %c character", r)
}
growingString += string(r)
l.next()
}
l.emitWithValue(tokenKey, growingString)
return l.lexVoid
}
func (l *tomlLexer) lexComment(previousState tomlLexStateFn) tomlLexStateFn {
return func() tomlLexStateFn {
for next := l.peek(); next != '\n' && next != eof; next = l.peek() {
if next == '\r' && l.follow("\r\n") {
break
}
l.next()
}
l.ignore()
return previousState
}
}
func (l *tomlLexer) lexLeftBracket() tomlLexStateFn {
l.next()
l.emit(tokenLeftBracket)
return l.lexRvalue
}
func (l *tomlLexer) lexLiteralStringAsString(terminator string, discardLeadingNewLine bool) (string, error) {
growingString := ""
if discardLeadingNewLine {
if l.follow("\r\n") {
l.skip()
l.skip()
} else if l.peek() == '\n' {
l.skip()
}
}
// find end of string
for {
if l.follow(terminator) {
return growingString, nil
}
next := l.peek()
if next == eof {
break
}
growingString += string(l.next())
}
return "", errors.New("unclosed string")
}
func (l *tomlLexer) lexLiteralString() tomlLexStateFn {
l.skip()
// handle special case for triple-quote
terminator := "'"
discardLeadingNewLine := false
if l.follow("''") {
l.skip()
l.skip()
terminator = "'''"
discardLeadingNewLine = true
}
str, err := l.lexLiteralStringAsString(terminator, discardLeadingNewLine)
if err != nil {
return l.errorf(err.Error())
}
l.emitWithValue(tokenString, str)
l.fastForward(len(terminator))
l.ignore()
return l.lexRvalue
}
// Lex a string and return the results as a string.
// Terminator is the substring indicating the end of the token.
// The resulting string does not include the terminator.
func (l *tomlLexer) lexStringAsString(terminator string, discardLeadingNewLine, acceptNewLines bool) (string, error) {
growingString := ""
if discardLeadingNewLine {
if l.follow("\r\n") {
l.skip()
l.skip()
} else if l.peek() == '\n' {
l.skip()
}
}
for {
if l.follow(terminator) {
return growingString, nil
}
if l.follow("\\") {
l.next()
switch l.peek() {
case '\r':
fallthrough
case '\n':
fallthrough
case '\t':
fallthrough
case ' ':
// skip all whitespace chars following backslash
for strings.ContainsRune("\r\n\t ", l.peek()) {
l.next()
}
case '"':
growingString += "\""
l.next()
case 'n':
growingString += "\n"
l.next()
case 'b':
growingString += "\b"
l.next()
case 'f':
growingString += "\f"
l.next()
case '/':
growingString += "/"
l.next()
case 't':
growingString += "\t"
l.next()
case 'r':
growingString += "\r"
l.next()
case '\\':
growingString += "\\"
l.next()
case 'u':
l.next()
code := ""
for i := 0; i < 4; i++ {
c := l.peek()
if !isHexDigit(c) {
return "", errors.New("unfinished unicode escape")
}
l.next()
code = code + string(c)
}
intcode, err := strconv.ParseInt(code, 16, 32)
if err != nil {
return "", errors.New("invalid unicode escape: \\u" + code)
}
growingString += string(rune(intcode))
case 'U':
l.next()
code := ""
for i := 0; i < 8; i++ {
c := l.peek()
if !isHexDigit(c) {
return "", errors.New("unfinished unicode escape")
}
l.next()
code = code + string(c)
}
intcode, err := strconv.ParseInt(code, 16, 64)
if err != nil {
return "", errors.New("invalid unicode escape: \\U" + code)
}
growingString += string(rune(intcode))
default:
return "", errors.New("invalid escape sequence: \\" + string(l.peek()))
}
} else {
r := l.peek()
if 0x00 <= r && r <= 0x1F && !(acceptNewLines && (r == '\n' || r == '\r')) {
return "", fmt.Errorf("unescaped control character %U", r)
}
l.next()
growingString += string(r)
}
if l.peek() == eof {
break
}
}
return "", errors.New("unclosed string")
}
func (l *tomlLexer) lexString() tomlLexStateFn {
l.skip()
// handle special case for triple-quote
terminator := `"`
discardLeadingNewLine := false
acceptNewLines := false
if l.follow(`""`) {
l.skip()
l.skip()
terminator = `"""`
discardLeadingNewLine = true
acceptNewLines = true
}
str, err := l.lexStringAsString(terminator, discardLeadingNewLine, acceptNewLines)
if err != nil {
return l.errorf(err.Error())
}
l.emitWithValue(tokenString, str)
l.fastForward(len(terminator))
l.ignore()
return l.lexRvalue
}
func (l *tomlLexer) lexTableKey() tomlLexStateFn {
l.next()
if l.peek() == '[' {
// token '[[' signifies an array of tables
l.next()
l.emit(tokenDoubleLeftBracket)
return l.lexInsideTableArrayKey
}
// vanilla table key
l.emit(tokenLeftBracket)
return l.lexInsideTableKey
}
// Parse the key till "]]", but only bare keys are supported
func (l *tomlLexer) lexInsideTableArrayKey() tomlLexStateFn {
for r := l.peek(); r != eof; r = l.peek() {
switch r {
case ']':
if l.currentTokenStop > l.currentTokenStart {
l.emit(tokenKeyGroupArray)
}
l.next()
if l.peek() != ']' {
break
}
l.next()
l.emit(tokenDoubleRightBracket)
return l.lexVoid
case '[':
return l.errorf("table array key cannot contain ']'")
default:
l.next()
}
}
return l.errorf("unclosed table array key")
}
// Parse the key till "]" but only bare keys are supported
func (l *tomlLexer) lexInsideTableKey() tomlLexStateFn {
for r := l.peek(); r != eof; r = l.peek() {
switch r {
case ']':
if l.currentTokenStop > l.currentTokenStart {
l.emit(tokenKeyGroup)
}
l.next()
l.emit(tokenRightBracket)
return l.lexVoid
case '[':
return l.errorf("table key cannot contain ']'")
default:
l.next()
}
}
return l.errorf("unclosed table key")
}
func (l *tomlLexer) lexRightBracket() tomlLexStateFn {
l.next()
l.emit(tokenRightBracket)
return l.lexRvalue
}
type validRuneFn func(r rune) bool
func isValidHexRune(r rune) bool {
return r >= 'a' && r <= 'f' ||
r >= 'A' && r <= 'F' ||
r >= '0' && r <= '9' ||
r == '_'
}
func isValidOctalRune(r rune) bool {
return r >= '0' && r <= '7' || r == '_'
}
func isValidBinaryRune(r rune) bool {
return r == '0' || r == '1' || r == '_'
}
func (l *tomlLexer) lexNumber() tomlLexStateFn {
r := l.peek()
if r == '0' {
follow := l.peekString(2)
if len(follow) == 2 {
var isValidRune validRuneFn
switch follow[1] {
case 'x':
isValidRune = isValidHexRune
case 'o':
isValidRune = isValidOctalRune
case 'b':
isValidRune = isValidBinaryRune
default:
if follow[1] >= 'a' && follow[1] <= 'z' || follow[1] >= 'A' && follow[1] <= 'Z' {
return l.errorf("unknown number base: %s. possible options are x (hex) o (octal) b (binary)", string(follow[1]))
}
}
if isValidRune != nil {
l.next()
l.next()
digitSeen := false
for {
next := l.peek()
if !isValidRune(next) {
break
}
digitSeen = true
l.next()
}
if !digitSeen {
return l.errorf("number needs at least one digit")
}
l.emit(tokenInteger)
return l.lexRvalue
}
}
}
if r == '+' || r == '-' {
l.next()
if l.follow("inf") {
return l.lexInf
}
if l.follow("nan") {
return l.lexNan
}
}
pointSeen := false
expSeen := false
digitSeen := false
for {
next := l.peek()
if next == '.' {
if pointSeen {
return l.errorf("cannot have two dots in one float")
}
l.next()
if !isDigit(l.peek()) {
return l.errorf("float cannot end with a dot")
}
pointSeen = true
} else if next == 'e' || next == 'E' {
expSeen = true
l.next()
r := l.peek()
if r == '+' || r == '-' {
l.next()
}
} else if isDigit(next) {
digitSeen = true
l.next()
} else if next == '_' {
l.next()
} else {
break
}
if pointSeen && !digitSeen {
return l.errorf("cannot start float with a dot")
}
}
if !digitSeen {
return l.errorf("no digit in that number")
}
if pointSeen || expSeen {
l.emit(tokenFloat)
} else {
l.emit(tokenInteger)
}
return l.lexRvalue
}
func (l *tomlLexer) run() {
for state := l.lexVoid; state != nil; {
state = state()
}
}
func init() {
dateRegexp = regexp.MustCompile(`^\d{1,4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d{1,9})?(Z|[+-]\d{2}:\d{2})`)
}
// Entry point
func lexToml(inputBytes []byte) []token {
runes := bytes.Runes(inputBytes)
l := &tomlLexer{
input: runes,
tokens: make([]token, 0, 256),
line: 1,
col: 1,
endbufferLine: 1,
endbufferCol: 1,
}
l.run()
return l.tokens
}