completed lexer and tokens for the language spec

mcapell · Aug 22, 2024 · 9ed1b70 · 9ed1b70
1 parent 9ca8248
commit 9ed1b70
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Showing 3 changed files with 108 additions and 8 deletions.
diff --git a/lexer/lexer.go b/lexer/lexer.go
@@ -35,7 +35,33 @@ func (l *Lexer) NextToken() token.Token {
 
 	switch l.ch {
 	case '=':
-		tok = newToken(token.ASSIGN, l.ch)
+		if l.peekChar() == '=' {
+			ch := l.ch
+			l.readChar()
+			tok = token.Token{Type: token.EQ, Literal: string(ch) + string(l.ch)}
+		} else {
+			tok = newToken(token.ASSIGN, l.ch)
+		}
+	case '+':
+		tok = newToken(token.PLUS, l.ch)
+	case '-':
+		tok = newToken(token.MINUS, l.ch)
+	case '!':
+		if l.peekChar() == '=' {
+			ch := l.ch
+			l.readChar()
+			tok = token.Token{Type: token.NOT_EQ, Literal: string(ch) + string(l.ch)}
+		} else {
+			tok = newToken(token.BANG, l.ch)
+		}
+	case '/':
+		tok = newToken(token.SLASH, l.ch)
+	case '*':
+		tok = newToken(token.ASTERISK, l.ch)
+	case '<':
+		tok = newToken(token.LT, l.ch)
+	case '>':
+		tok = newToken(token.GT, l.ch)
 	case ';':
 		tok = newToken(token.SEMICOLON, l.ch)
 	case '(':
@@ -44,8 +70,6 @@ func (l *Lexer) NextToken() token.Token {
 		tok = newToken(token.RPAREN, l.ch)
 	case ',':
 		tok = newToken(token.COMMA, l.ch)
-	case '+':
-		tok = newToken(token.PLUS, l.ch)
 	case '{':
 		tok = newToken(token.LBRACE, l.ch)
 	case '}':
@@ -90,6 +114,14 @@ func (l *Lexer) readNumber() string {
 	return l.input[position:l.position]
 }
 
+func (l *Lexer) peekChar() byte {
+	if l.readPosition >= len(l.input) {
+		return 0
+	}
+
+	return l.input[l.readPosition]
+}
+
 func (l *Lexer) skipWhitespace() {
 	for l.ch == ' ' || l.ch == '\t' || l.ch == '\n' || l.ch == '\r' {
 		l.readChar()

diff --git a/lexer/lexer_test.go b/lexer/lexer_test.go
@@ -14,7 +14,19 @@ let add = fn(x, y) {
 	x + y;
 };
 
-let result = add(five, ten);`
+let result = add(five, ten);
+!-/*5;
+5 < 10 > 5;
+
+if (5 < 10) {
+	return true;
+} else {
+	return false;
+}
+
+10 == 10;
+10 != 9;
+`
 
 	tests := []struct {
 		expectedType    token.TokenType
@@ -56,6 +68,43 @@ let result = add(five, ten);`
 		{token.IDENT, "ten"},
 		{token.RPAREN, ")"},
 		{token.SEMICOLON, ";"},
+		{token.BANG, "!"},
+		{token.MINUS, "-"},
+		{token.SLASH, "/"},
+		{token.ASTERISK, "*"},
+		{token.INT, "5"},
+		{token.SEMICOLON, ";"},
+		{token.INT, "5"},
+		{token.LT, "<"},
+		{token.INT, "10"},
+		{token.GT, ">"},
+		{token.INT, "5"},
+		{token.SEMICOLON, ";"},
+		{token.IF, "if"},
+		{token.LPAREN, "("},
+		{token.INT, "5"},
+		{token.LT, "<"},
+		{token.INT, "10"},
+		{token.RPAREN, ")"},
+		{token.LBRACE, "{"},
+		{token.RETURN, "return"},
+		{token.TRUE, "true"},
+		{token.SEMICOLON, ";"},
+		{token.RBRACE, "}"},
+		{token.ELSE, "else"},
+		{token.LBRACE, "{"},
+		{token.RETURN, "return"},
+		{token.FALSE, "false"},
+		{token.SEMICOLON, ";"},
+		{token.RBRACE, "}"},
+		{token.INT, "10"},
+		{token.EQ, "=="},
+		{token.INT, "10"},
+		{token.SEMICOLON, ";"},
+		{token.INT, "10"},
+		{token.NOT_EQ, "!="},
+		{token.INT, "9"},
+		{token.SEMICOLON, ";"},
 		{token.EOF, ""},
 	}
 

diff --git a/token/token.go b/token/token.go
@@ -16,8 +16,17 @@ const (
 	INT   = "INT"   // Integer
 
 	// Operators
-	ASSIGN = "="
-	PLUS   = "+"
+	ASSIGN   = "="
+	PLUS     = "+"
+	MINUS    = "-"
+	BANG     = "!"
+	ASTERISK = "*"
+	SLASH    = "/"
+
+	LT     = "<"
+	GT     = ">"
+	EQ     = "=="
+	NOT_EQ = "!="
 
 	// Delimiters
 	COMMA     = ","
@@ -31,11 +40,21 @@ const (
 	// Keywords
 	FUNCTION = "FUNCTION"
 	LET      = "LET"
+	TRUE     = "TRUE"
+	FALSE    = "FALSE"
+	IF       = "IF"
+	ELSE     = "ELSE"
+	RETURN   = "RETURN"
 )
 
 var keywords = map[string]TokenType{
-	"fn":  FUNCTION,
-	"let": LET,
+	"fn":     FUNCTION,
+	"let":    LET,
+	"true":   TRUE,
+	"false":  FALSE,
+	"if":     IF,
+	"else":   ELSE,
+	"return": RETURN,
 }
 
 func LookupIdent(ident string) TokenType {