nasin/internal/styles/tss/lex.go

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package tss
import "io"
import "bufio"
import "unicode"
import "unicode/utf8"
import "git.tebibyte.media/sashakoshka/goparse"
const (
Comment parse.TokenKind = iota
LBrace
RBrace
LBracket
RBracket
Equals
Colon
Comma
Semicolon
Star
Dot
Dollar
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Slash
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Color
Ident
Number
String
)
var tokenNames = map[parse.TokenKind] string {
parse.EOF: "EOF",
Comment: "Comment",
LBrace: "LBrace",
RBrace: "RBrace",
LBracket: "LBracket",
RBracket: "RBracket",
Equals: "Equals",
Colon: "Colon",
Comma: "Comma",
Semicolon: "Semicolon",
Star: "Star",
Dot: "Dot",
Dollar: "Dollar",
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Slash: "Slash",
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Color: "Color",
Ident: "Ident",
Number: "Number",
String: "String",
}
type lexer struct {
filename string
lineScanner *bufio.Scanner
rune rune
line string
lineFood string
offset int
row int
column int
eof bool
}
func Lex (filename string, reader io.Reader) parse.Lexer {
lex := &lexer {
filename: filename,
lineScanner: bufio.NewScanner(reader),
}
lex.nextRune()
return lex
}
func (this *lexer) Next () (parse.Token, error) {
for {
token, err := this.next()
if err == io.EOF { return token, this.errUnexpectedEOF() }
if err != nil { return token, err }
if !token.Is(Comment) {
return token, err
}
}
}
func (this *lexer) next () (token parse.Token, err error) {
err = this.skipWhitespace()
token.Position = this.pos()
if this.eof {
token.Kind = parse.EOF
err = nil
return
}
if err != nil { return }
appendRune := func () {
token.Value += string(this.rune)
err = this.nextRune()
}
skipRune := func () {
err = this.nextRune()
}
defer func () {
newPos := this.pos()
newPos.End --
token.Position = token.Position.Union(newPos)
} ()
switch {
case this.rune == '/':
token.Kind = Comment
skipRune()
if err != nil { return }
if this.rune == '/' {
for this.rune != '\n' {
skipRune()
if err != nil { return }
}
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} else {
token.Kind = Slash
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}
if this.eof { err = nil; return }
case this.rune == '{':
token.Kind = LBrace
appendRune()
if this.eof { err = nil; return }
case this.rune == '}':
token.Kind = RBrace
appendRune()
if this.eof { err = nil; return }
case this.rune == '[':
token.Kind = LBracket
appendRune()
if this.eof { err = nil; return }
case this.rune == ']':
token.Kind = RBracket
appendRune()
if this.eof { err = nil; return }
case this.rune == '=':
token.Kind = Equals
appendRune()
if this.eof { err = nil; return }
case this.rune == ':':
token.Kind = Colon
appendRune()
if this.eof { err = nil; return }
case this.rune == ',':
token.Kind = Comma
appendRune()
if this.eof { err = nil; return }
case this.rune == ';':
token.Kind = Semicolon
appendRune()
if this.eof { err = nil; return }
case this.rune == '*':
token.Kind = Star
appendRune()
if this.eof { err = nil; return }
case this.rune == '.':
token.Kind = Dot
appendRune()
if this.eof { err = nil; return }
case this.rune == '$':
token.Kind = Dollar
appendRune()
if this.eof { err = nil; return }
case this.rune == '#':
token.Kind = Color
skipRune()
if err != nil { return }
for isHexDigit(this.rune) {
appendRune()
if this.eof { err = nil; return }
}
if this.eof { err = nil; return }
case unicode.IsLetter(this.rune):
token.Kind = Ident
for unicode.IsLetter(this.rune) || unicode.IsNumber(this.rune) {
appendRune()
if this.eof { err = nil; return }
}
if this.eof { err = nil; return }
case this.rune == '-':
token.Kind = Number
appendRune()
for isDigit(this.rune) {
appendRune()
if this.eof { err = nil; return }
}
if this.eof { err = nil; return }
case isDigit(this.rune):
token.Kind = Number
for isDigit(this.rune) {
appendRune()
if this.eof { err = nil; return }
}
if this.eof { err = nil; return }
case this.rune == '\'', this.rune == '"':
stringDelimiter := this.rune
token.Kind = String
err = this.nextRune()
if err != nil { return }
for this.rune != stringDelimiter {
if this.rune == '\\' {
var result rune
result, err = this.escapeSequence(stringDelimiter)
if err != nil { return }
token.Value += string(result)
} else {
appendRune()
if this.eof { err = nil; return }
if err != nil { return }
}
}
err = this.nextRune()
if this.eof { err = nil; return }
if err != nil { return }
default:
err = parse.Errorf (
this.pos(), "unexpected rune %U",
this.rune)
}
return
}
func (this *lexer) nextRune () error {
if this.lineFood == "" {
ok := this.lineScanner.Scan()
if ok {
this.line = this.lineScanner.Text()
this.lineFood = this.line
this.rune = '\n'
this.column = 0
this.row ++
} else {
err := this.lineScanner.Err()
if err == nil {
this.eof = true
return io.EOF
} else {
return err
}
}
} else {
var ch rune
var size int
for ch == 0 && this.lineFood != "" {
ch, size = utf8.DecodeRuneInString(this.lineFood)
this.lineFood = this.lineFood[size:]
}
this.rune = ch
this.column ++
}
return nil
}
func (this *lexer) escapeSequence (stringDelimiter rune) (rune, error) {
err := this.nextRune()
if err != nil { return 0, err }
if isDigit(this.rune) {
var number rune
for index := 0; index < 3; index ++ {
if !isDigit(this.rune) { break }
number *= 8
number += this.rune - '0'
err = this.nextRune()
if err != nil { return 0, err }
}
return number, nil
}
defer this.nextRune()
switch this.rune {
case '\\', '\n', stringDelimiter:
return this.rune, nil
case 'a': return '\a', nil
case 'b': return '\b', nil
case 't': return '\t', nil
case 'n': return '\n', nil
case 'v': return '\v', nil
case 'f': return '\f', nil
case 'r': return '\r', nil
default: return 0, this.errBadEscapeSequence()
}
}
func (this *lexer) skipWhitespace () error {
for isWhitespace(this.rune) {
err := this.nextRune()
if err != nil { return err }
}
return nil
}
func (this *lexer) pos () parse.Position {
return parse.Position {
File: this.filename,
Line: this.lineScanner.Text(),
Row: this.row - 1,
Start: this.column - 1,
End: this.column,
}
}
func (this *lexer) errUnexpectedEOF () error {
return parse.Errorf(this.pos(), "unexpected EOF")
}
func (this *lexer) errBadEscapeSequence () error {
return parse.Errorf(this.pos(), "bad escape sequence")
}
func isWhitespace (char rune) bool {
switch char {
case ' ', '\t', '\r', '\n': return true
default: return false
}
}
func isSymbol (char rune) bool {
switch char {
case
'~', '!', '@', '#', '$', '%', '^', '&', '-', '_', '=', '+',
'\\', '|', ';', ',', '<', '>', '/', '?':
return true
default:
return false
}
}
func isDigit (char rune) bool {
return char >= '0' && char <= '9'
}
func isHexDigit (char rune) bool {
return isDigit(char) ||
char >= 'a' && char <= 'f' ||
char >= 'A' && char <= 'F'
}