// If the next token is a keyword with the given value, return that token after
// advancing the parser. Otherwise, do not change the parser state and return false.
func expectKeyWord(parser *Parser, value string) (lexer.Token, error) {
token := parser.Token
if token.Kind == lexer.TokenKind[lexer.NAME] && token.Value == value {
err := advance(parser)
return token, err
}
descp := fmt.Sprintf("Expected \"%s\", found %s", value, lexer.GetTokenDesc(token))
return token, gqlerrors.NewSyntaxError(parser.Source, token.Start, descp)
}
// If the next token is of the given kind, return that token after advancing
// the parser. Otherwise, do not change the parser state and return error.
func expect(parser *Parser, kind int) (lexer.Token, error) {
token := parser.Token
if token.Kind == kind {
err := advance(parser)
return token, err
}
descp := fmt.Sprintf("Expected %s, found %s", lexer.GetTokenKindDesc(kind), lexer.GetTokenDesc(token))
return token, gqlerrors.NewSyntaxError(parser.Source, token.Start, descp)
}
// Reads a number token from the source file, either a float
// or an int depending on whether a decimal point appears.
// Int: -?(0|[1-9][0-9]*)
// Float: -?(0|[1-9][0-9]*)(\.[0-9]+)?((E|e)(+|-)?[0-9]+)?
func readNumber(s *source.Source, start int, firstCode rune, codeLength int) (Token, error) {
code := firstCode
body := s.Body
position := start
isFloat := false
if code == '-' { // -
position += codeLength
code, codeLength = runeAt(body, position)
}
if code == '0' { // 0
position += codeLength
code, codeLength = runeAt(body, position)
if code >= '0' && code <= '9' {
description := fmt.Sprintf("Invalid number, unexpected digit after 0: %v.", printCharCode(code))
return Token{}, gqlerrors.NewSyntaxError(s, position, description)
}
} else {
p, err := readDigits(s, position, code, codeLength)
if err != nil {
return Token{}, err
}
position = p
code, codeLength = runeAt(body, position)
}
if code == '.' { // .
isFloat = true
position += codeLength
code, codeLength = runeAt(body, position)
p, err := readDigits(s, position, code, codeLength)
if err != nil {
return Token{}, err
}
position = p
code, codeLength = runeAt(body, position)
}
if code == 'E' || code == 'e' { // E e
isFloat = true
position += codeLength
code, codeLength = runeAt(body, position)
if code == '+' || code == '-' { // + -
position += codeLength
code, codeLength = runeAt(body, position)
}
p, err := readDigits(s, position, code, codeLength)
if err != nil {
return Token{}, err
}
position = p
}
kind := TokenKind[INT]
if isFloat {
kind = TokenKind[FLOAT]
}
return makeToken(kind, start, position, string(body[start:position])), nil
}
// Helper function for creating an error when an unexpected lexed token
// is encountered.
func unexpected(parser *Parser, atToken lexer.Token) error {
var token lexer.Token
if (atToken == lexer.Token{}) {
token = parser.Token
} else {
token = parser.Token
}
description := fmt.Sprintf("Unexpected %v", lexer.GetTokenDesc(token))
return gqlerrors.NewSyntaxError(parser.Source, token.Start, description)
}
// Returns the new position in the source after reading digits.
func readDigits(s *source.Source, start int, firstCode rune, codeLength int) (int, error) {
body := s.Body
position := start
code := firstCode
if code >= '0' && code <= '9' { // 0 - 9
for {
if code >= '0' && code <= '9' { // 0 - 9
position += codeLength
code, codeLength = runeAt(body, position)
continue
} else {
break
}
}
return position, nil
}
var description string
description = fmt.Sprintf("Invalid number, expected digit but got: %v.", printCharCode(code))
return position, gqlerrors.NewSyntaxError(s, position, description)
}
func readToken(s *source.Source, fromPosition int) (Token, error) {
body := s.Body
bodyLength := len(body)
position, runePosition := positionAfterWhitespace(body, fromPosition)
if position >= bodyLength {
return makeToken(TokenKind[EOF], position, position, ""), nil
}
code, codeLength := runeAt(body, position)
// SourceCharacter
if code < 0x0020 && code != 0x0009 && code != 0x000A && code != 0x000D {
return Token{}, gqlerrors.NewSyntaxError(s, runePosition, fmt.Sprintf(`Invalid character %v`, printCharCode(code)))
}
switch code {
// !
case '!':
return makeToken(TokenKind[BANG], position, position+1, ""), nil
// $
case '$':
return makeToken(TokenKind[DOLLAR], position, position+1, ""), nil
// (
case '(':
return makeToken(TokenKind[PAREN_L], position, position+1, ""), nil
// )
case ')':
return makeToken(TokenKind[PAREN_R], position, position+1, ""), nil
// .
case '.':
next1, _ := runeAt(body, position+1)
next2, _ := runeAt(body, position+2)
if next1 == '.' && next2 == '.' {
return makeToken(TokenKind[SPREAD], position, position+3, ""), nil
}
break
// :
case ':':
return makeToken(TokenKind[COLON], position, position+1, ""), nil
// =
case '=':
return makeToken(TokenKind[EQUALS], position, position+1, ""), nil
// @
case '@':
return makeToken(TokenKind[AT], position, position+1, ""), nil
// [
case '[':
return makeToken(TokenKind[BRACKET_L], position, position+1, ""), nil
// ]
case ']':
return makeToken(TokenKind[BRACKET_R], position, position+1, ""), nil
// {
case '{':
return makeToken(TokenKind[BRACE_L], position, position+1, ""), nil
// |
case '|':
return makeToken(TokenKind[PIPE], position, position+1, ""), nil
// }
case '}':
return makeToken(TokenKind[BRACE_R], position, position+1, ""), nil
// A-Z
case 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z':
return readName(s, position, runePosition), nil
// _
// a-z
case '_', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z':
return readName(s, position, runePosition), nil
// -
// 0-9
case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
token, err := readNumber(s, position, code, codeLength)
if err != nil {
return token, err
}
return token, nil
// "
case '"':
token, err := readString(s, position)
if err != nil {
return token, err
}
return token, nil
}
description := fmt.Sprintf("Unexpected character %v.", printCharCode(code))
return Token{}, gqlerrors.NewSyntaxError(s, runePosition, description)
}
func readString(s *source.Source, start int) (Token, error) {
body := s.Body
position := start + 1
runePosition := start + 1
chunkStart := position
var code rune
var n int
var valueBuffer bytes.Buffer
for {
code, n = runeAt(body, position)
if position < len(body) &&
// not LineTerminator
code != 0x000A && code != 0x000D &&
// not Quote (")
code != '"' {
// SourceCharacter
if code < 0x0020 && code != 0x0009 {
return Token{}, gqlerrors.NewSyntaxError(s, runePosition, fmt.Sprintf(`Invalid character within String: %v.`, printCharCode(code)))
}
position += n
runePosition++
if code == '\\' { // \
valueBuffer.Write(body[chunkStart : position-1])
code, n = runeAt(body, position)
switch code {
case '"':
valueBuffer.WriteRune('"')
break
case '/':
valueBuffer.WriteRune('/')
break
case '\\':
valueBuffer.WriteRune('\\')
break
case 'b':
valueBuffer.WriteRune('\b')
break
case 'f':
valueBuffer.WriteRune('\f')
break
case 'n':
valueBuffer.WriteRune('\n')
break
case 'r':
valueBuffer.WriteRune('\r')
break
case 't':
valueBuffer.WriteRune('\t')
break
case 'u':
// Check if there are at least 4 bytes available
if len(body) <= position+4 {
return Token{}, gqlerrors.NewSyntaxError(s, runePosition,
fmt.Sprintf("Invalid character escape sequence: "+
"\\u%v", string(body[position+1:])))
}
charCode := uniCharCode(
rune(body[position+1]),
rune(body[position+2]),
rune(body[position+3]),
rune(body[position+4]),
)
if charCode < 0 {
return Token{}, gqlerrors.NewSyntaxError(s, runePosition,
fmt.Sprintf("Invalid character escape sequence: "+
"\\u%v", string(body[position+1:position+5])))
}
valueBuffer.WriteRune(charCode)
position += 4
runePosition += 4
break
default:
return Token{}, gqlerrors.NewSyntaxError(s, runePosition,
fmt.Sprintf(`Invalid character escape sequence: \\%c.`, code))
}
position += n
runePosition++
chunkStart = position
}
continue
} else {
break
}
}
if code != '"' { // quote (")
return Token{}, gqlerrors.NewSyntaxError(s, runePosition, "Unterminated string.")
}
stringContent := body[chunkStart:position]
valueBuffer.Write(stringContent)
value := valueBuffer.String()
return makeToken(TokenKind[STRING], start, position+1, value), nil
}