Basic String escape

lexer/lexer.go

@@ -1,6 +1,9 @@
 package lexer
 
-import "monkey/token"
+import (
+	"monkey/token"
+	"strings"
+)
 
 type Lexer struct {
 	input        string
@@ -179,14 +182,20 @@ func (l *Lexer) skipWhitespace() {
 }
 
 func (l *Lexer) readString() string {
-	position := l.position + 1
+	b := &strings.Builder{}
 	for {
 		l.readChar()
-		if l.ch == '"' || l.ch == 0 {
-			break
+		if l.ch == '\\' && l.peekChar() == '"' {
+			l.readChar()
+		} else {
+			if l.ch == '"' || l.ch == 0 {
+				break
+			}
 		}
+
+		b.WriteByte(l.ch)
 	}
-	return l.input[position:l.position]
+	return b.String()
 }
 
 func (l *Lexer) readLine() string {

lexer/lexer_test.go

@@ -32,6 +32,7 @@ func TestNextToken(t *testing.T) {
 				"foo bar"
 				[1, 2];
 				{"foo": "bar"}
+				"foo \"bar\""
 			`
 
 	tests := []struct {
@@ -137,7 +138,7 @@ func TestNextToken(t *testing.T) {
 		{token.COLON, ":"},
 		{token.STRING, "bar"},
 		{token.RBRACE, "}"},
-
+		{token.STRING, "foo \"bar\""},
 		{token.EOF, ""},
 	}