From 97fb05dd4abd4af01b5d0a41d65d4db8130d6eda Mon Sep 17 00:00:00 2001
From: Fatih Arslan <ftharsln@gmail.com>
Date: Sun, 4 Oct 2015 00:20:26 +0300
Subject: [PATCH] lexer: scan strings

---
 parser/lexer.go      | 27 +++++++++++++++++++++++-
 parser/lexer_test.go | 50 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/parser/lexer.go b/parser/lexer.go
index e14fb39..2677647 100644
--- a/parser/lexer.go
+++ b/parser/lexer.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"io"
 	"io/ioutil"
+	"log"
 	"unicode"
 )
 
@@ -77,8 +78,8 @@ func (s *Scanner) Scan() (tok Token, lit string) {
 
 	// identifier
 	if isLetter(ch) {
-		s.scanIdentifier()
 		tok = IDENT
+		s.scanIdentifier()
 	}
 
 	if isDigit(ch) {
@@ -88,6 +89,10 @@ func (s *Scanner) Scan() (tok Token, lit string) {
 	switch ch {
 	case eof:
 		tok = EOF
+	case '"':
+		tok = STRING
+		s.scanString()
+		s.next() // move forward so we finalize the string
 	}
 
 	s.tokEnd = s.pos.Offset - s.lastCharLen
@@ -95,6 +100,26 @@ func (s *Scanner) Scan() (tok Token, lit string) {
 	return tok, s.TokenLiteral()
 }
 
+func (s *Scanner) scanString() {
+	// '"' opening already consumed
+	ch := s.next() // read character after quote
+	for ch != '"' {
+		if ch == '\n' || ch < 0 {
+			log.Println("[ERROR] literal not terminated")
+			return
+		}
+
+		if ch == '\\' {
+			// scanEscape
+			return
+		} else {
+			ch = s.next()
+		}
+	}
+
+	return
+}
+
 func (s *Scanner) scanIdentifier() {
 	for isLetter(s.ch) || isDigit(s.ch) {
 		s.next()
diff --git a/parser/lexer_test.go b/parser/lexer_test.go
index e48c117..e69dbb6 100644
--- a/parser/lexer_test.go
+++ b/parser/lexer_test.go
@@ -6,6 +6,8 @@ import (
 	"testing"
 )
 
+var f100 = "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
+
 type token struct {
 	tok  Token
 	text string
@@ -54,3 +56,51 @@ func TestIdent(t *testing.T) {
 
 	}
 }
+
+func TestString(t *testing.T) {
+	var identList = []token{
+		{STRING, `" "`},
+		{STRING, `"a"`},
+		{STRING, `"本"`},
+		// {STRING, `"\a"`},
+		// {STRING, `"\b"`},
+		// {STRING, `"\f"`},
+		// {STRING, `"\n"`},
+		// {STRING, `"\r"`},
+		// {STRING, `"\t"`},
+		// {STRING, `"\v"`},
+		// {STRING, `"\""`},
+		// {STRING, `"\000"`},
+		// {STRING, `"\777"`},
+		// {STRING, `"\x00"`},
+		// {STRING, `"\xff"`},
+		// {STRING, `"\u0000"`},
+		// {STRING, `"\ufA16"`},
+		// {STRING, `"\U00000000"`},
+		// {STRING, `"\U0000ffAB"`},
+		// {STRING, `"` + f100 + `"`},
+	}
+
+	// create artifical source code
+	buf := new(bytes.Buffer)
+	for _, ident := range identList {
+		fmt.Fprintf(buf, " \t%s\n", ident.text)
+	}
+
+	l, err := NewLexer(buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, ident := range identList {
+		tok, lit := l.Scan()
+		if tok != ident.tok {
+			t.Errorf("tok = %s want %s for %s\n", tok, ident.tok, ident.text)
+		}
+
+		if lit != ident.text {
+			t.Errorf("text = %s want %s", lit, ident.text)
+		}
+
+	}
+}