Added quoted string scanner

scanners.go

@@ -23,3 +23,24 @@ func ScanAlphaNum(l *Lexer) bool {
 	l.AcceptWhile(alpha + digits)
 	return true
 }
+
+// ScanQuotedString returns true if next input tokens is quoted string. Can be used with any type of quotes.
+func ScanQuotedString(l *Lexer, quote rune) bool {
+	start := l.Pos
+	if l.Next() != quote {
+		l.Back()
+		return false
+	}
+	for {
+		ch := l.Next()
+		switch ch {
+		case EOF:
+			l.Pos = start // Return position to start
+			return false  // Unclosed quote string?
+		case '\\':
+			l.Next() // Skip next char
+		case quote:
+			return true // Closing quote
+		}
+	}
+}

scanners_test.go

@@ -51,3 +51,25 @@ func TestScanAlphaNum(t *testing.T) {
 		}
 	}
 }
+
+func TestScanQuotedString(t *testing.T) {
+	testCases := []struct {
+		Input    string
+		Expected bool
+		Pos      int
+	}{
+		{`asd`, false, 0},
+		{`"asd`, false, 0},
+		{`"asd"qwe`, true, 5},
+	}
+	for _, tc := range testCases {
+		l := New(tc.Input)
+		actual := ScanQuotedString(l, '"')
+		if actual != tc.Expected {
+			t.Errorf("Input: %s expected scan result: %v actual: %v", tc.Input, tc.Expected, actual)
+		}
+		if l.Pos != tc.Pos {
+			t.Errorf("Input: %s expected scan position: %d actual: %d", tc.Input, tc.Pos, l.Pos)
+		}
+	}
+}