Adds escape sequence tracking to acceptUntilUnescaped; fixes #25

Author: tomnomnom

ungron.go

@@ -162,15 +162,23 @@ func (l *lexer) acceptUntil(delims string) {
 // rune contained in the provided string, unless that rune was
 // escaped with a backslash
 func (l *lexer) acceptUntilUnescaped(delims string) {
+
 	// Read until we hit an unescaped rune or the end of the input
+	inEscape := false
 	for {
-		if strings.ContainsRune(delims, l.next()) && l.prev != '\\' {
+		r := l.next()
+		if r == '\\' && !inEscape {
+			inEscape = true
+			continue
+		}
+		if strings.ContainsRune(delims, r) && !inEscape {
 			l.backup()
 			return
 		}
 		if l.cur == utf8.RuneError {
 			return
 		}
+		inEscape = false
 	}
 }
 

ungron_test.go

@@ -46,6 +46,27 @@ func TestLex(t *testing.T) {
 			{`;`, typSemi},
 		}},
 
+		{`json = "\\";`, []token{
+			{`json`, typBare},
+			{`=`, typEquals},
+			{`"\\"`, typString},
+			{`;`, typSemi},
+		}},
+
+		{`json = "\\\\";`, []token{
+			{`json`, typBare},
+			{`=`, typEquals},
+			{`"\\\\"`, typString},
+			{`;`, typSemi},
+		}},
+
+		{`json = "f\oo\\";`, []token{
+			{`json`, typBare},
+			{`=`, typEquals},
+			{`"f\oo\\"`, typString},
+			{`;`, typSemi},
+		}},
+
 		{`json.value = "\u003c ;";`, []token{
 			{`json`, typBare},
 			{`.`, typDot},