Extend the text format parser to allow concatenation of string literals in single quotes.

Signed-off-by: David Symonds <dsymonds@golang.org>

proto/text_parser.go

@@ -119,6 +119,14 @@ func isWhitespace(c byte) bool {
 	return false
 }
 
+func isQuote(c byte) bool {
+	switch c {
+	case '"', '\'':
+		return true
+	}
+	return false
+}
+
 func (p *textParser) skipWhitespace() {
 	i := 0
 	for i < len(p.s) && (isWhitespace(p.s[i]) || p.s[i] == '#') {
@@ -333,13 +341,13 @@ func (p *textParser) next() *token {
 	p.advance()
 	if p.done {
 		p.cur.value = ""
-	} else if len(p.cur.value) > 0 && p.cur.value[0] == '"' {
+	} else if len(p.cur.value) > 0 && isQuote(p.cur.value[0]) {
 		// Look for multiple quoted strings separated by whitespace,
 		// and concatenate them.
 		cat := p.cur
 		for {
 			p.skipWhitespace()
-			if p.done || p.s[0] != '"' {
+			if p.done || !isQuote(p.s[0]) {
 				break
 			}
 			p.advance()

proto/text_parser_test.go

@@ -95,7 +95,7 @@ var unMarshalTextTests = []UnmarshalTextTest{
 		},
 	},
 
-	// Quoted string concatenation
+	// Quoted string concatenation with double quotes
 	{
 		in: `count:42 name: "My name is "` + "\n" + `"elsewhere"`,
 		out: &MyMessage{
@@ -104,6 +104,31 @@ var unMarshalTextTests = []UnmarshalTextTest{
 		},
 	},
 
+	// Quoted string concatenation with single quotes
+	{
+		in: "count:42 name: 'My name is '\n'elsewhere'",
+		out: &MyMessage{
+			Count: Int32(42),
+			Name:  String("My name is elsewhere"),
+		},
+	},
+
+	// Quoted string concatenations with mixed quotes
+	{
+		in: "count:42 name: 'My name is '\n\"elsewhere\"",
+		out: &MyMessage{
+			Count: Int32(42),
+			Name:  String("My name is elsewhere"),
+		},
+	},
+	{
+		in: "count:42 name: \"My name is \"\n'elsewhere'",
+		out: &MyMessage{
+			Count: Int32(42),
+			Name:  String("My name is elsewhere"),
+		},
+	},
+
 	// Quoted string with escaped apostrophe
 	{
 		in: `count:42 name: "HOLIDAY - New Year\'s Day"`,