Add all the files from the interpreter repo
Signed-off-by: jmug <u.g.a.mariano@gmail.com>
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34 changed files with 3784 additions and 0 deletions
160
pkg/lexer/lexer.go
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160
pkg/lexer/lexer.go
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package lexer
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import "code.jmug.me/jmug/interpreter-in-go/pkg/token"
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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) NextToken() token.Token {
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l.skipWhitespace()
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var tok token.Token
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switch l.ch {
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case '=':
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if l.peekChar() == '=' {
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ch := l.ch
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l.readChar()
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literal := string(ch) + string(l.ch)
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tok.Type = token.EQ
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tok.Literal = literal
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} else {
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tok = newToken(token.ASSIGN, l.ch)
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}
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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.MINUS, l.ch)
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case '!':
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if l.peekChar() == '=' {
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ch := l.ch
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l.readChar()
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literal := string(ch) + string(l.ch)
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tok.Type = token.NOT_EQ
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tok.Literal = literal
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} else {
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tok = newToken(token.BANG, l.ch)
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}
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case '*':
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tok = newToken(token.ASTERISK, l.ch)
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case '/':
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tok = newToken(token.SLASH, l.ch)
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case '<':
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tok = newToken(token.LT, l.ch)
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case '>':
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tok = newToken(token.GT, 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 ':':
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tok = newToken(token.COLON, 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.LBRACKET, l.ch)
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case ']':
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tok = newToken(token.RBRACKET, l.ch)
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case '"':
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tok.Type = token.STRING
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tok.Literal = l.readString()
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case 0:
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tok.Literal = ""
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tok.Type = token.EOF
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default:
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if isLetter(l.ch) {
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tok.Literal = l.readIdentifier()
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tok.Type = token.LookupIdent(tok.Literal)
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// Don't let it fall through because readIdentifier calls readChar.
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return tok
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} else if isDigit(l.ch) {
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tok.Literal = l.readNumber()
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tok.Type = token.INT
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// Don't let it fall through because readNumber calls readChar.
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return tok
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} else {
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tok = newToken(token.ILLEGAL, l.ch)
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}
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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 (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) peekChar() byte {
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if l.readPosition >= len(l.input) {
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return 0
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}
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return l.input[l.readPosition]
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}
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func (l *Lexer) readIdentifier() string {
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position := l.position
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for isLetter(l.ch) {
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l.readChar()
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}
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// Slicing until l.position instead of readPosition because the last read
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// char was not a letter.
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return l.input[position:l.position]
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}
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func (l *Lexer) readNumber() string {
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position := l.position
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for isDigit(l.ch) {
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l.readChar()
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}
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// Slicing until l.position instead of readPosition because the last read
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// char was not a letter.
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return l.input[position:l.position]
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}
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func (l *Lexer) readString() string {
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// Don't include the quotes in the literal.
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position := l.position + 1
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l.readChar()
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for l.ch != '"' && l.ch != 0 {
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l.readChar()
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}
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return l.input[position:l.position]
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}
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func (l *Lexer) skipWhitespace() {
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for l.ch == ' ' || l.ch == '\t' || l.ch == '\n' || l.ch == '\r' {
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l.readChar()
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}
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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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func isLetter(ch byte) bool {
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return ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z') || ch == '_'
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}
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func isDigit(ch byte) bool {
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return '0' <= ch && ch <= '9'
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}
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144
pkg/lexer/lexer_test.go
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144
pkg/lexer/lexer_test.go
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package lexer
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import (
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"testing"
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"code.jmug.me/jmug/interpreter-in-go/pkg/token"
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)
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func TestNextToken(t *testing.T) {
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input := `let five = 5;
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let ten = 10;
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let add = fn(x, y) {
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x + y;
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};
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let result = add(five, ten);
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!-/*5;
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5 < 10 > 5;
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if (5 < 10) {
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return true;
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} else {
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return false;
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}
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10 == 10;
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10 != 9;
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"foobar"
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"foo bar"
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[1, 2];
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{1: 2};
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`
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tests := []struct {
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expectedType token.TokenType
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expectedLiteral string
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}{
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{token.LET, "let"},
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{token.IDENT, "five"},
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{token.ASSIGN, "="},
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{token.INT, "5"},
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{token.SEMICOLON, ";"},
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{token.LET, "let"},
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{token.IDENT, "ten"},
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{token.ASSIGN, "="},
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{token.INT, "10"},
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{token.SEMICOLON, ";"},
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{token.LET, "let"},
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{token.IDENT, "add"},
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{token.ASSIGN, "="},
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{token.FUNCTION, "fn"},
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{token.LPAREN, "("},
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{token.IDENT, "x"},
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{token.COMMA, ","},
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{token.IDENT, "y"},
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{token.RPAREN, ")"},
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{token.LBRACE, "{"},
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{token.IDENT, "x"},
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{token.PLUS, "+"},
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{token.IDENT, "y"},
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{token.SEMICOLON, ";"},
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{token.RBRACE, "}"},
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{token.SEMICOLON, ";"},
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{token.LET, "let"},
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{token.IDENT, "result"},
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{token.ASSIGN, "="},
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{token.IDENT, "add"},
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{token.LPAREN, "("},
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{token.IDENT, "five"},
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{token.COMMA, ","},
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{token.IDENT, "ten"},
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{token.RPAREN, ")"},
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{token.SEMICOLON, ";"},
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{token.BANG, "!"},
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{token.MINUS, "-"},
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{token.SLASH, "/"},
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{token.ASTERISK, "*"},
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{token.INT, "5"},
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{token.SEMICOLON, ";"},
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{token.INT, "5"},
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{token.LT, "<"},
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{token.INT, "10"},
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{token.GT, ">"},
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{token.INT, "5"},
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{token.SEMICOLON, ";"},
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{token.IF, "if"},
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{token.LPAREN, "("},
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{token.INT, "5"},
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{token.LT, "<"},
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{token.INT, "10"},
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{token.RPAREN, ")"},
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{token.LBRACE, "{"},
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{token.RETURN, "return"},
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{token.TRUE, "true"},
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{token.SEMICOLON, ";"},
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{token.RBRACE, "}"},
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{token.ELSE, "else"},
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{token.LBRACE, "{"},
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{token.RETURN, "return"},
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{token.FALSE, "false"},
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{token.SEMICOLON, ";"},
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{token.RBRACE, "}"},
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{token.INT, "10"},
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{token.EQ, "=="},
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{token.INT, "10"},
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{token.SEMICOLON, ";"},
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{token.INT, "10"},
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{token.NOT_EQ, "!="},
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{token.INT, "9"},
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{token.SEMICOLON, ";"},
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{token.STRING, "foobar"},
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{token.STRING, "foo bar"},
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{token.LBRACKET, "["},
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{token.INT, "1"},
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{token.COMMA, ","},
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{token.INT, "2"},
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{token.RBRACKET, "]"},
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{token.SEMICOLON, ";"},
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{token.LBRACE, "{"},
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{token.INT, "1"},
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{token.COLON, ":"},
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{token.INT, "2"},
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{token.RBRACE, "}"},
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{token.SEMICOLON, ";"},
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{token.EOF, ""},
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}
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l := New(input)
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for i, tt := range tests {
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tok := l.NextToken()
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if tok.Type != tt.expectedType {
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t.Fatalf("tests[%d] - tokentype wrong. expected=%q, got=%q",
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i, tt.expectedType, tok.Type)
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}
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if tok.Literal != tt.expectedLiteral {
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t.Fatalf("tests[%d] - literal wrong. expected=%q, got=%q",
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i, tt.expectedLiteral, tok.Literal)
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}
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}
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}
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