154 lines
3.9 KiB
Go
154 lines
3.9 KiB
Go
package lexer
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import "strconv"
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import "github.com/sashakoshka/arf/file"
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// tokenizeString tokenizes a string or rune literal.
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func (lexer *LexingOperation) tokenizeString (isRuneLiteral bool) (err error) {
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err = lexer.nextRune()
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if err != nil { return }
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got := ""
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for {
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// TODO: add hexadecimal escape codes
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if lexer.char == '\\' {
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err = lexer.nextRune()
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if err != nil { return }
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var actual rune
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actual, err = lexer.getEscapeSequence()
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if err != nil { return }
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got += string(actual)
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} else {
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got += string(lexer.char)
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err = lexer.nextRune()
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if err != nil { return }
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}
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if isRuneLiteral {
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if lexer.char == '\'' { break }
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} else {
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if lexer.char == '"' { break }
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}
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}
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err = lexer.nextRune()
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if err != nil { return }
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token := Token { }
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if isRuneLiteral {
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if len(got) > 1 {
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err = file.NewError (
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lexer.file.Location(), len(got) - 1,
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"excess data in rune literal",
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file.ErrorKindError)
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return
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}
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token.kind = TokenKindRune
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token.value = rune([]rune(got)[0])
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} else {
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token.kind = TokenKindString
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token.value = got
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}
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lexer.addToken(token)
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return
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}
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// escapeSequenceMap contains basic escape sequences and how they map to actual
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// runes.
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var escapeSequenceMap = map[rune] rune {
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'a': '\x07',
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'b': '\x08',
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'f': '\x0c',
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'n': '\x0a',
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'r': '\x0d',
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't': '\x09',
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'v': '\x0b',
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'\'': '\'',
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'"': '"',
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'\\': '\\',
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}
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// getEscapeSequence reads an escape sequence in a string or rune literal.
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func (lexer *LexingOperation) getEscapeSequence () (result rune, err error) {
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result, exists := escapeSequenceMap[lexer.char]
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if exists {
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err = lexer.nextRune()
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return
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} else if lexer.char >= '0' && lexer.char <= '7' {
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// octal escape sequence
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number := string(lexer.char)
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err = lexer.nextRune()
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if err != nil { return }
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for len(number) < 3 {
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if lexer.char < '0' || lexer.char > '7' { break }
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number += string(lexer.char)
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err = lexer.nextRune()
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if err != nil { return }
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}
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if len(number) < 3 {
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err = file.NewError (
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lexer.file.Location(), 1,
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"octal escape sequence too short",
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file.ErrorKindError)
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return
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}
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parsedNumber, _ := strconv.ParseInt(number, 8, 8)
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result = rune(parsedNumber)
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} else if lexer.char == 'x' || lexer.char == 'u' || lexer.char == 'U' {
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// hexidecimal escape sequence
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want := 2
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if lexer.char == 'u' { want = 4 }
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if lexer.char == 'U' { want = 8 }
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number := ""
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err = lexer.nextRune()
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if err != nil { return }
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for len(number) < want {
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notLower := lexer.char < 'a' || lexer.char > 'f'
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notUpper := lexer.char < 'A' || lexer.char > 'F'
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notNum := lexer.char < '0' || lexer.char > '9'
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if notLower && notUpper && notNum { break }
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number += string(lexer.char)
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err = lexer.nextRune()
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if err != nil { return }
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}
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if len(number) < want {
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err = file.NewError (
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lexer.file.Location(), 1,
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"hex escape sequence too short ",
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file.ErrorKindError)
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return
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}
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parsedNumber, _ := strconv.ParseInt(number, 16, want * 4)
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result = rune(parsedNumber)
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} else {
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err = file.NewError (
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lexer.file.Location(), 1,
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"unknown escape character " +
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string(lexer.char), file.ErrorKindError)
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return
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}
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return
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}
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