caddyfile: Support backticks as quotes (closes #2591) (#3242)

caddyconfig/caddyfile/lexer.go

@@ -73,7 +73,7 @@ func (l *lexer) load(input io.Reader) error {
 // a token was loaded; false otherwise.
 func (l *lexer) next() bool {
 	var val []rune
-	var comment, quoted, escaped bool
+	var comment, quoted, btQuoted, escaped bool
 
 	makeToken := func() bool {
 		l.token.Text = string(val)
@@ -92,13 +92,13 @@ func (l *lexer) next() bool {
 			panic(err)
 		}
 
-		if !escaped && ch == '\\' {
+		if !escaped && !btQuoted && ch == '\\' {
 			escaped = true
 			continue
 		}
 
-		if quoted {
-			if escaped {
+		if quoted || btQuoted {
+			if quoted && escaped {
 				// all is literal in quoted area,
 				// so only escape quotes
 				if ch != '"' {
@@ -106,7 +106,10 @@ func (l *lexer) next() bool {
 				}
 				escaped = false
 			} else {
-				if ch == '"' {
+				if quoted && ch == '"' {
+					return makeToken()
+				}
+				if btQuoted && ch == '`' {
 					return makeToken()
 				}
 			}
@@ -151,6 +154,10 @@ func (l *lexer) next() bool {
 				quoted = true
 				continue
 			}
+			if ch == '`' {
+				btQuoted = true
+				continue
+			}
 		}
 
 		if escaped {

caddyconfig/caddyfile/lexer_test.go

@@ -199,6 +199,38 @@ func TestLexer(t *testing.T) {
 				{Line: 1, Text: ":8080"},
 			},
 		},
+		{
+			input: "simple `backtick quoted` string",
+			expected: []Token{
+				{Line: 1, Text: `simple`},
+				{Line: 1, Text: `backtick quoted`},
+				{Line: 1, Text: `string`},
+			},
+		},
+		{
+			input: "multiline `backtick\nquoted\n` string",
+			expected: []Token{
+				{Line: 1, Text: `multiline`},
+				{Line: 1, Text: "backtick\nquoted\n"},
+				{Line: 3, Text: `string`},
+			},
+		},
+		{
+			input: "nested `\"quotes inside\" backticks` string",
+			expected: []Token{
+				{Line: 1, Text: `nested`},
+				{Line: 1, Text: `"quotes inside" backticks`},
+				{Line: 1, Text: `string`},
+			},
+		},
+		{
+			input: "reverse-nested \"`backticks` inside\" quotes",
+			expected: []Token{
+				{Line: 1, Text: `reverse-nested`},
+				{Line: 1, Text: "`backticks` inside"},
+				{Line: 1, Text: `quotes`},
+			},
+		},
 	}
 
 	for i, testCase := range testCases {