62 lines
1.1 KiB
Go
62 lines
1.1 KiB
Go
package lexer
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import (
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"gitlab.com/Tyrel/monkey/token"
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)
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type Lexer struct {
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input string
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position int
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readPosition int
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ch byte
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}
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func New(input string) *Lexer {
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l := &Lexer{input: input}
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l.readChar()
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return l
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}
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func (l *Lexer) readChar() {
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if l.readPosition >= len(l.input) {
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l.ch = 0
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} else {
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l.ch = l.input[l.readPosition]
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}
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l.position = l.readPosition
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l.readPosition += 1
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}
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func (l *Lexer) NextToken() token.Token {
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var tok token.Token
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switch l.ch {
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case '=':
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tok = newToken(token.ASSIGN, l.ch)
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case '+':
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tok = newToken(token.PLUS, l.ch)
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case '(':
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tok = newToken(token.LPAREN, l.ch)
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case ')':
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tok = newToken(token.RPAREN, l.ch)
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case '{':
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tok = newToken(token.LBRACE, l.ch)
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case '}':
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tok = newToken(token.RBRACE, l.ch)
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case ',':
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tok = newToken(token.COMMA, l.ch)
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case ';':
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tok = newToken(token.SEMICOLON, l.ch)
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case 0:
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tok.Literal = ""
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tok.Type = token.EOF
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}
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l.readChar()
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return tok
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}
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func newToken(tokenType token.TokenType, ch byte) token.Token {
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return token.Token{Type: tokenType, Literal: string(ch)}
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}
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