package toml import ( "fmt" "reflect" "runtime" "strings" "unicode" "unicode/utf8" ) type itemType int const ( itemError itemType = iota itemNIL // used in the parser to indicate no type itemEOF itemText itemString itemRawString itemMultilineString itemRawMultilineString itemBool itemInteger itemFloat itemDatetime itemArray // the start of an array itemArrayEnd itemTableStart itemTableEnd itemArrayTableStart itemArrayTableEnd itemKeyStart itemKeyEnd itemCommentStart itemInlineTableStart itemInlineTableEnd ) const ( eof = 0 comma = ',' tableStart = '[' tableEnd = ']' arrayTableStart = '[' arrayTableEnd = ']' tableSep = '.' keySep = '=' arrayStart = '[' arrayEnd = ']' commentStart = '#' stringStart = '"' stringEnd = '"' rawStringStart = '\'' rawStringEnd = '\'' inlineTableStart = '{' inlineTableEnd = '}' ) type stateFn func(lx *lexer) stateFn type lexer struct { input string start int pos int line int state stateFn items chan item // Allow for backing up up to four runes. // This is necessary because TOML contains 3-rune tokens (""" and '''). prevWidths [4]int nprev int // how many of prevWidths are in use // If we emit an eof, we can still back up, but it is not OK to call // next again. atEOF bool // A stack of state functions used to maintain context. // The idea is to reuse parts of the state machine in various places. // For example, values can appear at the top level or within arbitrarily // nested arrays. The last state on the stack is used after a value has // been lexed. Similarly for comments. stack []stateFn } type item struct { typ itemType val string line int } func (lx *lexer) nextItem() item { for { select { case item := <-lx.items: return item default: lx.state = lx.state(lx) //fmt.Printf(" STATE %-24s current: %-10q stack: %s\n", lx.state, lx.current(), lx.stack) } } } func lex(input string) *lexer { lx := &lexer{ input: input, state: lexTop, line: 1, items: make(chan item, 10), stack: make([]stateFn, 0, 10), } return lx } func (lx *lexer) push(state stateFn) { lx.stack = append(lx.stack, state) } func (lx *lexer) pop() stateFn { if len(lx.stack) == 0 { return lx.errorf("BUG in lexer: no states to pop") } last := lx.stack[len(lx.stack)-1] lx.stack = lx.stack[0 : len(lx.stack)-1] return last } func (lx *lexer) current() string { return lx.input[lx.start:lx.pos] } func (lx *lexer) emit(typ itemType) { lx.items <- item{typ, lx.current(), lx.line} lx.start = lx.pos } func (lx *lexer) emitTrim(typ itemType) { lx.items <- item{typ, strings.TrimSpace(lx.current()), lx.line} lx.start = lx.pos } func (lx *lexer) next() (r rune) { if lx.atEOF { panic("BUG in lexer: next called after EOF") } if lx.pos >= len(lx.input) { lx.atEOF = true return eof } if lx.input[lx.pos] == '\n' { lx.line++ } lx.prevWidths[3] = lx.prevWidths[2] lx.prevWidths[2] = lx.prevWidths[1] lx.prevWidths[1] = lx.prevWidths[0] if lx.nprev < 4 { lx.nprev++ } r, w := utf8.DecodeRuneInString(lx.input[lx.pos:]) if r == utf8.RuneError { lx.errorf("invalid UTF-8 byte at position %d (line %d): 0x%02x", lx.pos, lx.line, lx.input[lx.pos]) return utf8.RuneError } lx.prevWidths[0] = w lx.pos += w return r } // ignore skips over the pending input before this point. func (lx *lexer) ignore() { lx.start = lx.pos } // backup steps back one rune. Can be called 4 times between calls to next. func (lx *lexer) backup() { if lx.atEOF { lx.atEOF = false return } if lx.nprev < 1 { panic("BUG in lexer: backed up too far") } w := lx.prevWidths[0] lx.prevWidths[0] = lx.prevWidths[1] lx.prevWidths[1] = lx.prevWidths[2] lx.prevWidths[2] = lx.prevWidths[3] lx.nprev-- lx.pos -= w if lx.pos < len(lx.input) && lx.input[lx.pos] == '\n' { lx.line-- } } // accept consumes the next rune if it's equal to `valid`. func (lx *lexer) accept(valid rune) bool { if lx.next() == valid { return true } lx.backup() return false } // peek returns but does not consume the next rune in the input. func (lx *lexer) peek() rune { r := lx.next() lx.backup() return r } // skip ignores all input that matches the given predicate. func (lx *lexer) skip(pred func(rune) bool) { for { r := lx.next() if pred(r) { continue } lx.backup() lx.ignore() return } } // errorf stops all lexing by emitting an error and returning `nil`. // Note that any value that is a character is escaped if it's a special // character (newlines, tabs, etc.). func (lx *lexer) errorf(format string, values ...interface{}) stateFn { lx.items <- item{ itemError, fmt.Sprintf(format, values...), lx.line, } return nil } // lexTop consumes elements at the top level of TOML data. func lexTop(lx *lexer) stateFn { r := lx.next() if isWhitespace(r) || isNL(r) { return lexSkip(lx, lexTop) } switch r { case commentStart: lx.push(lexTop) return lexCommentStart case tableStart: return lexTableStart case eof: if lx.pos > lx.start { return lx.errorf("unexpected EOF") } lx.emit(itemEOF) return nil } // At this point, the only valid item can be a key, so we back up // and let the key lexer do the rest. lx.backup() lx.push(lexTopEnd) return lexKeyStart } // lexTopEnd is entered whenever a top-level item has been consumed. (A value // or a table.) It must see only whitespace, and will turn back to lexTop // upon a newline. If it sees EOF, it will quit the lexer successfully. func lexTopEnd(lx *lexer) stateFn { r := lx.next() switch { case r == commentStart: // a comment will read to a newline for us. lx.push(lexTop) return lexCommentStart case isWhitespace(r): return lexTopEnd case isNL(r): lx.ignore() return lexTop case r == eof: lx.emit(itemEOF) return nil } return lx.errorf( "expected a top-level item to end with a newline, comment, or EOF, but got %q instead", r) } // lexTable lexes the beginning of a table. Namely, it makes sure that // it starts with a character other than '.' and ']'. // It assumes that '[' has already been consumed. // It also handles the case that this is an item in an array of tables. // e.g., '[[name]]'. func lexTableStart(lx *lexer) stateFn { if lx.peek() == arrayTableStart { lx.next() lx.emit(itemArrayTableStart) lx.push(lexArrayTableEnd) } else { lx.emit(itemTableStart) lx.push(lexTableEnd) } return lexTableNameStart } func lexTableEnd(lx *lexer) stateFn { lx.emit(itemTableEnd) return lexTopEnd } func lexArrayTableEnd(lx *lexer) stateFn { if r := lx.next(); r != arrayTableEnd { return lx.errorf( "expected end of table array name delimiter %q, but got %q instead", arrayTableEnd, r) } lx.emit(itemArrayTableEnd) return lexTopEnd } func lexTableNameStart(lx *lexer) stateFn { lx.skip(isWhitespace) switch r := lx.peek(); { case r == tableEnd || r == eof: return lx.errorf("unexpected end of table name (table names cannot be empty)") case r == tableSep: return lx.errorf("unexpected table separator (table names cannot be empty)") case r == stringStart || r == rawStringStart: lx.ignore() lx.push(lexTableNameEnd) return lexQuotedName default: lx.push(lexTableNameEnd) return lexBareName } } // lexTableNameEnd reads the end of a piece of a table name, optionally // consuming whitespace. func lexTableNameEnd(lx *lexer) stateFn { lx.skip(isWhitespace) switch r := lx.next(); { case isWhitespace(r): return lexTableNameEnd case r == tableSep: lx.ignore() return lexTableNameStart case r == tableEnd: return lx.pop() default: return lx.errorf("expected '.' or ']' to end table name, but got %q instead", r) } } // lexBareName lexes one part of a key or table. // // It assumes that at least one valid character for the table has already been // read. // // Lexes only one part, e.g. only 'a' inside 'a.b'. func lexBareName(lx *lexer) stateFn { r := lx.next() if isBareKeyChar(r) { return lexBareName } lx.backup() lx.emit(itemText) return lx.pop() } // lexBareName lexes one part of a key or table. // // It assumes that at least one valid character for the table has already been // read. // // Lexes only one part, e.g. only '"a"' inside '"a".b'. func lexQuotedName(lx *lexer) stateFn { r := lx.next() switch { case isWhitespace(r): return lexSkip(lx, lexValue) case r == stringStart: lx.ignore() // ignore the '"' return lexString case r == rawStringStart: lx.ignore() // ignore the "'" return lexRawString case r == eof: return lx.errorf("unexpected EOF; expected value") default: return lx.errorf("expected value but found %q instead", r) } } // lexKeyStart consumes all key parts until a '='. func lexKeyStart(lx *lexer) stateFn { lx.skip(isWhitespace) switch r := lx.peek(); { case r == '=' || r == eof: return lx.errorf("unexpected '=': key name appears blank") case r == '.': return lx.errorf("unexpected '.': keys cannot start with a '.'") case r == stringStart || r == rawStringStart: lx.ignore() fallthrough default: // Bare key lx.emit(itemKeyStart) return lexKeyNameStart } } func lexKeyNameStart(lx *lexer) stateFn { lx.skip(isWhitespace) switch r := lx.peek(); { case r == '=' || r == eof: return lx.errorf("unexpected '='") case r == '.': return lx.errorf("unexpected '.'") case r == stringStart || r == rawStringStart: lx.ignore() lx.push(lexKeyEnd) return lexQuotedName default: lx.push(lexKeyEnd) return lexBareName } } // lexKeyEnd consumes the end of a key and trims whitespace (up to the key // separator). func lexKeyEnd(lx *lexer) stateFn { lx.skip(isWhitespace) switch r := lx.next(); { case isWhitespace(r): return lexSkip(lx, lexKeyEnd) case r == eof: return lx.errorf("unexpected EOF; expected key separator %q", keySep) case r == '.': lx.ignore() return lexKeyNameStart case r == '=': lx.emit(itemKeyEnd) return lexSkip(lx, lexValue) default: return lx.errorf("expected '.' or '=', but got %q instead", r) } } // lexValue starts the consumption of a value anywhere a value is expected. // lexValue will ignore whitespace. // After a value is lexed, the last state on the next is popped and returned. func lexValue(lx *lexer) stateFn { // We allow whitespace to precede a value, but NOT newlines. // In array syntax, the array states are responsible for ignoring newlines. r := lx.next() switch { case isWhitespace(r): return lexSkip(lx, lexValue) case isDigit(r): lx.backup() // avoid an extra state and use the same as above return lexNumberOrDateStart } switch r { case arrayStart: lx.ignore() lx.emit(itemArray) return lexArrayValue case inlineTableStart: lx.ignore() lx.emit(itemInlineTableStart) return lexInlineTableValue case stringStart: if lx.accept(stringStart) { if lx.accept(stringStart) { lx.ignore() // Ignore """ return lexMultilineString } lx.backup() } lx.ignore() // ignore the '"' return lexString case rawStringStart: if lx.accept(rawStringStart) { if lx.accept(rawStringStart) { lx.ignore() // Ignore """ return lexMultilineRawString } lx.backup() } lx.ignore() // ignore the "'" return lexRawString case '.': // special error case, be kind to users return lx.errorf("floats must start with a digit, not '.'") case 'i', 'n': if (lx.accept('n') && lx.accept('f')) || (lx.accept('a') && lx.accept('n')) { lx.emit(itemFloat) return lx.pop() } case '-', '+': return lexDecimalNumberStart } if unicode.IsLetter(r) { // Be permissive here; lexBool will give a nice error if the // user wrote something like // x = foo // (i.e. not 'true' or 'false' but is something else word-like.) lx.backup() return lexBool } if r == eof { return lx.errorf("unexpected EOF; expected value") } return lx.errorf("expected value but found %q instead", r) } // lexArrayValue consumes one value in an array. It assumes that '[' or ',' // have already been consumed. All whitespace and newlines are ignored. func lexArrayValue(lx *lexer) stateFn { r := lx.next() switch { case isWhitespace(r) || isNL(r): return lexSkip(lx, lexArrayValue) case r == commentStart: lx.push(lexArrayValue) return lexCommentStart case r == comma: return lx.errorf("unexpected comma") case r == arrayEnd: // NOTE(caleb): The spec isn't clear about whether you can have // a trailing comma or not, so we'll allow it. return lexArrayEnd } lx.backup() lx.push(lexArrayValueEnd) return lexValue } // lexArrayValueEnd consumes everything between the end of an array value and // the next value (or the end of the array): it ignores whitespace and newlines // and expects either a ',' or a ']'. func lexArrayValueEnd(lx *lexer) stateFn { r := lx.next() switch { case isWhitespace(r) || isNL(r): return lexSkip(lx, lexArrayValueEnd) case r == commentStart: lx.push(lexArrayValueEnd) return lexCommentStart case r == comma: lx.ignore() return lexArrayValue // move on to the next value case r == arrayEnd: return lexArrayEnd } return lx.errorf( "expected a comma or array terminator %q, but got %s instead", arrayEnd, runeOrEOF(r)) } // lexArrayEnd finishes the lexing of an array. // It assumes that a ']' has just been consumed. func lexArrayEnd(lx *lexer) stateFn { lx.ignore() lx.emit(itemArrayEnd) return lx.pop() } // lexInlineTableValue consumes one key/value pair in an inline table. // It assumes that '{' or ',' have already been consumed. Whitespace is ignored. func lexInlineTableValue(lx *lexer) stateFn { r := lx.next() switch { case isWhitespace(r): return lexSkip(lx, lexInlineTableValue) case isNL(r): return lx.errorf("newlines not allowed within inline tables") case r == commentStart: lx.push(lexInlineTableValue) return lexCommentStart case r == comma: return lx.errorf("unexpected comma") case r == inlineTableEnd: return lexInlineTableEnd } lx.backup() lx.push(lexInlineTableValueEnd) return lexKeyStart } // lexInlineTableValueEnd consumes everything between the end of an inline table // key/value pair and the next pair (or the end of the table): // it ignores whitespace and expects either a ',' or a '}'. func lexInlineTableValueEnd(lx *lexer) stateFn { switch r := lx.next(); { case isWhitespace(r): return lexSkip(lx, lexInlineTableValueEnd) case isNL(r): return lx.errorf("newlines not allowed within inline tables") case r == commentStart: lx.push(lexInlineTableValueEnd) return lexCommentStart case r == comma: lx.ignore() lx.skip(isWhitespace) if lx.peek() == '}' { return lx.errorf("trailing comma not allowed in inline tables") } return lexInlineTableValue case r == inlineTableEnd: return lexInlineTableEnd default: return lx.errorf( "expected a comma or an inline table terminator %q, but got %s instead", inlineTableEnd, runeOrEOF(r)) } } func runeOrEOF(r rune) string { if r == eof { return "end of file" } return "'" + string(r) + "'" } // lexInlineTableEnd finishes the lexing of an inline table. // It assumes that a '}' has just been consumed. func lexInlineTableEnd(lx *lexer) stateFn { lx.ignore() lx.emit(itemInlineTableEnd) return lx.pop() } // lexString consumes the inner contents of a string. It assumes that the // beginning '"' has already been consumed and ignored. func lexString(lx *lexer) stateFn { r := lx.next() switch { case r == eof: return lx.errorf(`unexpected EOF; expected '"'`) case isControl(r) || r == '\r': return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) case isNL(r): return lx.errorf("strings cannot contain newlines") case r == '\\': lx.push(lexString) return lexStringEscape case r == stringEnd: lx.backup() lx.emit(itemString) lx.next() lx.ignore() return lx.pop() } return lexString } // lexMultilineString consumes the inner contents of a string. It assumes that // the beginning '"""' has already been consumed and ignored. func lexMultilineString(lx *lexer) stateFn { r := lx.next() switch r { case eof: return lx.errorf(`unexpected EOF; expected '"""'`) case '\r': if lx.peek() != '\n' { return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) } return lexMultilineString case '\\': return lexMultilineStringEscape case stringEnd: /// Found " → try to read two more "". if lx.accept(stringEnd) { if lx.accept(stringEnd) { /// Peek ahead: the string can contain " and "", including at the /// end: """str""""" /// 6 or more at the end, however, is an error. if lx.peek() == stringEnd { /// Check if we already lexed 5 's; if so we have 6 now, and /// that's just too many man! if strings.HasSuffix(lx.current(), `"""""`) { return lx.errorf(`unexpected '""""""'`) } lx.backup() lx.backup() return lexMultilineString } lx.backup() /// backup: don't include the """ in the item. lx.backup() lx.backup() lx.emit(itemMultilineString) lx.next() /// Read over ''' again and discard it. lx.next() lx.next() lx.ignore() return lx.pop() } lx.backup() } } if isControl(r) { return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) } return lexMultilineString } // lexRawString consumes a raw string. Nothing can be escaped in such a string. // It assumes that the beginning "'" has already been consumed and ignored. func lexRawString(lx *lexer) stateFn { r := lx.next() switch { case r == eof: return lx.errorf(`unexpected EOF; expected "'"`) case isControl(r) || r == '\r': return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) case isNL(r): return lx.errorf("strings cannot contain newlines") case r == rawStringEnd: lx.backup() lx.emit(itemRawString) lx.next() lx.ignore() return lx.pop() } return lexRawString } // lexMultilineRawString consumes a raw string. Nothing can be escaped in such // a string. It assumes that the beginning "'''" has already been consumed and // ignored. func lexMultilineRawString(lx *lexer) stateFn { r := lx.next() switch r { case eof: return lx.errorf(`unexpected EOF; expected "'''"`) case '\r': if lx.peek() != '\n' { return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) } return lexMultilineRawString case rawStringEnd: /// Found ' → try to read two more ''. if lx.accept(rawStringEnd) { if lx.accept(rawStringEnd) { /// Peek ahead: the string can contain ' and '', including at the /// end: '''str''''' /// 6 or more at the end, however, is an error. if lx.peek() == rawStringEnd { /// Check if we already lexed 5 's; if so we have 6 now, and /// that's just too many man! if strings.HasSuffix(lx.current(), "'''''") { return lx.errorf(`unexpected "''''''"`) } lx.backup() lx.backup() return lexMultilineRawString } lx.backup() /// backup: don't include the ''' in the item. lx.backup() lx.backup() lx.emit(itemRawMultilineString) lx.next() /// Read over ''' again and discard it. lx.next() lx.next() lx.ignore() return lx.pop() } lx.backup() } } if isControl(r) { return lx.errorf("control characters are not allowed inside strings: '0x%02x'", r) } return lexMultilineRawString } // lexMultilineStringEscape consumes an escaped character. It assumes that the // preceding '\\' has already been consumed. func lexMultilineStringEscape(lx *lexer) stateFn { // Handle the special case first: if isNL(lx.next()) { return lexMultilineString } lx.backup() lx.push(lexMultilineString) return lexStringEscape(lx) } func lexStringEscape(lx *lexer) stateFn { r := lx.next() switch r { case 'b': fallthrough case 't': fallthrough case 'n': fallthrough case 'f': fallthrough case 'r': fallthrough case '"': fallthrough case ' ', '\t': // Inside """ .. """ strings you can use \ to escape newlines, and any // amount of whitespace can be between the \ and \n. fallthrough case '\\': return lx.pop() case 'u': return lexShortUnicodeEscape case 'U': return lexLongUnicodeEscape } return lx.errorf("invalid escape character %q; only the following escape characters are allowed: "+ `\b, \t, \n, \f, \r, \", \\, \uXXXX, and \UXXXXXXXX`, r) } func lexShortUnicodeEscape(lx *lexer) stateFn { var r rune for i := 0; i < 4; i++ { r = lx.next() if !isHexadecimal(r) { return lx.errorf( `expected four hexadecimal digits after '\u', but got %q instead`, lx.current()) } } return lx.pop() } func lexLongUnicodeEscape(lx *lexer) stateFn { var r rune for i := 0; i < 8; i++ { r = lx.next() if !isHexadecimal(r) { return lx.errorf( `expected eight hexadecimal digits after '\U', but got %q instead`, lx.current()) } } return lx.pop() } // lexNumberOrDateStart processes the first character of a value which begins // with a digit. It exists to catch values starting with '0', so that // lexBaseNumberOrDate can differentiate base prefixed integers from other // types. func lexNumberOrDateStart(lx *lexer) stateFn { r := lx.next() switch r { case '0': return lexBaseNumberOrDate } if !isDigit(r) { // The only way to reach this state is if the value starts // with a digit, so specifically treat anything else as an // error. return lx.errorf("expected a digit but got %q", r) } return lexNumberOrDate } // lexNumberOrDate consumes either an integer, float or datetime. func lexNumberOrDate(lx *lexer) stateFn { r := lx.next() if isDigit(r) { return lexNumberOrDate } switch r { case '-', ':': return lexDatetime case '_': return lexDecimalNumber case '.', 'e', 'E': return lexFloat } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexDatetime consumes a Datetime, to a first approximation. // The parser validates that it matches one of the accepted formats. func lexDatetime(lx *lexer) stateFn { r := lx.next() if isDigit(r) { return lexDatetime } switch r { case '-', ':', 'T', 't', ' ', '.', 'Z', 'z', '+': return lexDatetime } lx.backup() lx.emitTrim(itemDatetime) return lx.pop() } // lexHexInteger consumes a hexadecimal integer after seeing the '0x' prefix. func lexHexInteger(lx *lexer) stateFn { r := lx.next() if isHexadecimal(r) { return lexHexInteger } switch r { case '_': return lexHexInteger } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexOctalInteger consumes an octal integer after seeing the '0o' prefix. func lexOctalInteger(lx *lexer) stateFn { r := lx.next() if isOctal(r) { return lexOctalInteger } switch r { case '_': return lexOctalInteger } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexBinaryInteger consumes a binary integer after seeing the '0b' prefix. func lexBinaryInteger(lx *lexer) stateFn { r := lx.next() if isBinary(r) { return lexBinaryInteger } switch r { case '_': return lexBinaryInteger } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexDecimalNumber consumes a decimal float or integer. func lexDecimalNumber(lx *lexer) stateFn { r := lx.next() if isDigit(r) { return lexDecimalNumber } switch r { case '.', 'e', 'E': return lexFloat case '_': return lexDecimalNumber } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexDecimalNumber consumes the first digit of a number beginning with a sign. // It assumes the sign has already been consumed. Values which start with a sign // are only allowed to be decimal integers or floats. // // The special "nan" and "inf" values are also recognized. func lexDecimalNumberStart(lx *lexer) stateFn { r := lx.next() // Special error cases to give users better error messages switch r { case 'i': if !lx.accept('n') || !lx.accept('f') { return lx.errorf("invalid float: '%s'", lx.current()) } lx.emit(itemFloat) return lx.pop() case 'n': if !lx.accept('a') || !lx.accept('n') { return lx.errorf("invalid float: '%s'", lx.current()) } lx.emit(itemFloat) return lx.pop() case '0': p := lx.peek() switch p { case 'b', 'o', 'x': return lx.errorf("cannot use sign with non-decimal numbers: '%s%c'", lx.current(), p) } case '.': return lx.errorf("floats must start with a digit, not '.'") } if isDigit(r) { return lexDecimalNumber } return lx.errorf("expected a digit but got %q", r) } // lexBaseNumberOrDate differentiates between the possible values which // start with '0'. It assumes that before reaching this state, the initial '0' // has been consumed. func lexBaseNumberOrDate(lx *lexer) stateFn { r := lx.next() // Note: All datetimes start with at least two digits, so we don't // handle date characters (':', '-', etc.) here. if isDigit(r) { return lexNumberOrDate } switch r { case '_': // Can only be decimal, because there can't be an underscore // between the '0' and the base designator, and dates can't // contain underscores. return lexDecimalNumber case '.', 'e', 'E': return lexFloat case 'b': r = lx.peek() if !isBinary(r) { lx.errorf("not a binary number: '%s%c'", lx.current(), r) } return lexBinaryInteger case 'o': r = lx.peek() if !isOctal(r) { lx.errorf("not an octal number: '%s%c'", lx.current(), r) } return lexOctalInteger case 'x': r = lx.peek() if !isHexadecimal(r) { lx.errorf("not a hexidecimal number: '%s%c'", lx.current(), r) } return lexHexInteger } lx.backup() lx.emit(itemInteger) return lx.pop() } // lexFloat consumes the elements of a float. It allows any sequence of // float-like characters, so floats emitted by the lexer are only a first // approximation and must be validated by the parser. func lexFloat(lx *lexer) stateFn { r := lx.next() if isDigit(r) { return lexFloat } switch r { case '_', '.', '-', '+', 'e', 'E': return lexFloat } lx.backup() lx.emit(itemFloat) return lx.pop() } // lexBool consumes a bool string: 'true' or 'false. func lexBool(lx *lexer) stateFn { var rs []rune for { r := lx.next() if !unicode.IsLetter(r) { lx.backup() break } rs = append(rs, r) } s := string(rs) switch s { case "true", "false": lx.emit(itemBool) return lx.pop() } return lx.errorf("expected value but found %q instead", s) } // lexCommentStart begins the lexing of a comment. It will emit // itemCommentStart and consume no characters, passing control to lexComment. func lexCommentStart(lx *lexer) stateFn { lx.ignore() lx.emit(itemCommentStart) return lexComment } // lexComment lexes an entire comment. It assumes that '#' has been consumed. // It will consume *up to* the first newline character, and pass control // back to the last state on the stack. func lexComment(lx *lexer) stateFn { switch r := lx.next(); { case isNL(r) || r == eof: lx.backup() lx.emit(itemText) return lx.pop() case isControl(r): return lx.errorf("control characters are not allowed inside comments: '0x%02x'", r) default: return lexComment } } // lexSkip ignores all slurped input and moves on to the next state. func lexSkip(lx *lexer, nextState stateFn) stateFn { lx.ignore() return nextState } // isWhitespace returns true if `r` is a whitespace character according // to the spec. func isWhitespace(r rune) bool { return r == '\t' || r == ' ' } func isNL(r rune) bool { return r == '\n' || r == '\r' } // Control characters except \n, \t func isControl(r rune) bool { switch r { case '\t', '\r', '\n': return false default: return (r >= 0x00 && r <= 0x1f) || r == 0x7f } } func isDigit(r rune) bool { return r >= '0' && r <= '9' } func isHexadecimal(r rune) bool { return (r >= '0' && r <= '9') || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F') } func isOctal(r rune) bool { return r >= '0' && r <= '7' } func isBinary(r rune) bool { return r == '0' || r == '1' } func isBareKeyChar(r rune) bool { return (r >= 'A' && r <= 'Z') || (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '_' || r == '-' } func (s stateFn) String() string { name := runtime.FuncForPC(reflect.ValueOf(s).Pointer()).Name() if i := strings.LastIndexByte(name, '.'); i > -1 { name = name[i+1:] } if s == nil { name = "" } return name + "()" } func (itype itemType) String() string { switch itype { case itemError: return "Error" case itemNIL: return "NIL" case itemEOF: return "EOF" case itemText: return "Text" case itemString, itemRawString, itemMultilineString, itemRawMultilineString: return "String" case itemBool: return "Bool" case itemInteger: return "Integer" case itemFloat: return "Float" case itemDatetime: return "DateTime" case itemTableStart: return "TableStart" case itemTableEnd: return "TableEnd" case itemKeyStart: return "KeyStart" case itemKeyEnd: return "KeyEnd" case itemArray: return "Array" case itemArrayEnd: return "ArrayEnd" case itemCommentStart: return "CommentStart" case itemInlineTableStart: return "InlineTableStart" case itemInlineTableEnd: return "InlineTableEnd" } panic(fmt.Sprintf("BUG: Unknown type '%d'.", int(itype))) } func (item item) String() string { return fmt.Sprintf("(%s, %s)", item.typ.String(), item.val) }