80 lines
1.2 KiB
Go
80 lines
1.2 KiB
Go
package runner
|
|
|
|
type Scanner struct {
|
|
source string
|
|
|
|
// State.
|
|
tokens []Token
|
|
start int
|
|
current int
|
|
line int
|
|
}
|
|
|
|
func NewScanner(source string) *Scanner {
|
|
return &Scanner{
|
|
source: source,
|
|
tokens: []Token{},
|
|
|
|
start: 0,
|
|
current: 0,
|
|
line: 1,
|
|
}
|
|
}
|
|
|
|
func (s *Scanner) ScanTokens() []Token {
|
|
for !s.isAtEnd() {
|
|
s.start = s.current
|
|
s.scanToken()
|
|
}
|
|
|
|
s.tokens = append(s.tokens, NewToken(EOF, "", nil, s.line))
|
|
return s.tokens
|
|
}
|
|
|
|
func (s *Scanner) scanToken() {
|
|
c := s.advance()
|
|
switch c {
|
|
case '(':
|
|
s.addToken(LPAREN)
|
|
case ')':
|
|
s.addToken(RPAREN)
|
|
case '{':
|
|
s.addToken(LBRACE)
|
|
case '}':
|
|
s.addToken(RBRACE)
|
|
case ',':
|
|
s.addToken(COMMA)
|
|
case '.':
|
|
s.addToken(DOT)
|
|
case '-':
|
|
s.addToken(MINUS)
|
|
case '+':
|
|
s.addToken(PLUS)
|
|
case ';':
|
|
s.addToken(SEMI)
|
|
case '*':
|
|
s.addToken(STAR)
|
|
}
|
|
}
|
|
|
|
func (s *Scanner) advance() byte {
|
|
idx := s.current
|
|
s.current += 1
|
|
return s.source[idx]
|
|
}
|
|
|
|
func (s *Scanner) addToken(typ TokenType) {
|
|
s.addTokenWithLiteral(typ, nil)
|
|
}
|
|
|
|
func (s *Scanner) addTokenWithLiteral(typ TokenType, literal interface{}) {
|
|
lexme := s.source[s.start:s.current]
|
|
s.tokens = append(
|
|
s.tokens,
|
|
NewToken(typ, lexme, literal, s.line),
|
|
)
|
|
}
|
|
|
|
func (s *Scanner) isAtEnd() bool {
|
|
return s.current >= len(s.source)
|
|
}
|