feature: support raw string with char `

Author: zhuliquan

parser/lexer/lexer.go

@@ -219,3 +219,16 @@ func (l *lexer) scanString(quote rune) (n int) {
 	}
 	return
 }
+
+func (l *lexer) scanRawString(quote rune) (n int) {
+	ch := l.next() // read character after quote
+	for ch != quote {
+		if ch == eof {
+			l.error("literal not terminated")
+			return
+		}
+		ch = l.next()
+		n++
+	}
+	return
+}

parser/lexer/state.go

@@ -1,6 +1,7 @@
 package lexer
 
 import (
+	"strconv"
 	"strings"
 )
 
@@ -21,6 +22,14 @@ func root(l *lexer) stateFn {
 			l.error("%v", err)
 		}
 		l.emitValue(String, str)
+	case r == '`': // raw string case
+		l.scanRawString(r)
+		n := len(l.word())
+		str, err := unescape(strconv.Quote(l.word()[1 : n-1]))
+		if err != nil {
+			l.error("%v", err)
+		}
+		l.emitValue(String, str)
 	case '0' <= r && r <= '9':
 		l.backup()
 		return number

parser/parser_test.go

@@ -444,6 +444,24 @@ func TestParse(t *testing.T) {
 				Left:  &IdentifierNode{Value: "foo"},
 				Right: &CallNode{Callee: &IdentifierNode{Value: "bar"}}},
 		},
+		{
+			"`" + `foo\n\rbar\\` + "`",
+			&StringNode{Value: `foo\n\rbar\\`},
+		},
+		{
+			"`" + `foo\
+\n` + "`",
+			&StringNode{Value: "foo\\\n\\n"},
+		},
+		{
+			"`foo\\n\\rbar\\\\`", // because quoted by ", must add '\' to '\'
+			&StringNode{Value: `foo\n\rbar\\`},
+		},
+		{
+			"\"" + `foo\nbar\\` + "\"",
+			&StringNode{Value: `foo
+bar\`},
+		},
 	}
 	for _, test := range parseTests {
 		actual, err := parser.Parse(test.input)
@@ -538,6 +556,15 @@ func TestParse_error(t *testing.T) {
 	}
 }
 
+func TestParseRawString_error(t *testing.T) {
+	_, err := parser.Parse("`foo")
+	if err == nil {
+		t.Errorf("expect to get error")
+	} else {
+		t.Logf("got err: %+v", err)
+	}
+}
+
 func TestParse_optional_chaining(t *testing.T) {
 	parseTests := []struct {
 		input    string