Add support for single quotes

this fixes #18

README.md

@@ -26,6 +26,7 @@ global = "global value";
 # Primary section
 primary {
   string = "primary string value";
+  single = 'single quotes are allowed too';
   integer = 500;
   float = 80.80;
   boolean = true;

forge.go

@@ -32,7 +32,7 @@
 //     NULL: 'null'
 //     INTEGER: ('-')? NUMBERS
 //     FLOAT: ('-')? NUMBERS '.' NUMBERS
-//     STRING: '"' .* '"'
+//     STRING: ['"] .* ['"]
 //     REFERENCE: (IDENTIFIER)? ('.' IDENTIFIER)+
 //     VALUE: BOOL | NULL | INTEGER | FLOAT | STRING | REFERENCE
 //
@@ -46,8 +46,8 @@
 //
 // Values
 //  * String:
-//      Any value enclosed in double quotes (single quotes not allowed) (e.g. "string").
-//      Double quotes and backslashes can be escaped with backslashes (e.g. "\"quoted\"" and "\\<--backslash")
+//      Any value enclosed in double or single quotes (e.g. "string" or 'string').
+//      Double quotes, single quotes, and backslashes can be escaped with backslashes (e.g. "\"quoted\"", '\'quoted\'', and "\\<--backslash")
 //  * Integer:
 //      Any number without decimal places (e.g. 500)
 //  * Float:

forge_test.go

@@ -15,6 +15,8 @@ global = "global value";
 primary {
   string = "primary string value";
   string_with_quote = "some \"quoted\" str\\ing";
+  single = 'hello world';
+  single_with_quote = '\'hello\' "world"';
   integer = 500;
   float = 80.80;
   negative = -50;
@@ -56,6 +58,8 @@ func assertDirectives(values map[string]interface{}, t *testing.T) {
 	primary := values["primary"].(map[string]interface{})
 	assertEqual(primary["string"], "primary string value", t)
 	assertEqual(primary["string_with_quote"], "some \"quoted\" str\\ing", t)
+	assertEqual(primary["single"], "hello world", t)
+	assertEqual(primary["single_with_quote"], "'hello' \"world\"", t)
 	assertEqual(primary["integer"], int64(500), t)
 	assertEqual(primary["float"], float64(80.80), t)
 	assertEqual(primary["negative"], int64(-50), t)

scanner.go

@@ -14,10 +14,6 @@ func isLetter(ch rune) bool {
 	return ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z')
 }
 
-func isEscapeCharacter(ch rune) bool {
-	return ch == '\\' || ch == '"'
-}
-
 func isDigit(ch rune) bool {
 	return ('0' <= ch && ch <= '9')
 }
@@ -124,11 +120,18 @@ func (scanner *Scanner) parseNumber(negative bool) {
 	}
 }
 
-func (scanner *Scanner) parseString() {
+func (scanner *Scanner) parseString(delimiter rune) {
 	scanner.curTok.ID = token.STRING
-	scanner.curTok.Literal = string(scanner.curCh)
+	scanner.curTok.Literal = ""
 	// Whether or not we are trying to escape a character
 	escape := false
+
+	// If the first character is an escape
+	if scanner.curCh == '\\' {
+		escape = true
+	} else {
+		scanner.curTok.Literal = string(scanner.curCh)
+	}
 	for {
 		scanner.readRune()
 		if escape == false {
@@ -137,16 +140,18 @@ func (scanner *Scanner) parseString() {
 				// A new backslash
 				escape = true
 				continue
-			} else if scanner.curCh == '"' {
+			} else if scanner.curCh == delimiter {
 				// An unescaped quote, time to bail out
 				break
 			}
-		} else if isEscapeCharacter(scanner.curCh) {
+			// Continue as normal, no escaping necessary
+		} else if scanner.curCh == '\\' || scanner.curCh == delimiter {
 			// A valid escape character, continue as normal
 			escape = false
 		} else {
 			// We had a backslash, but an invalid escape character
 			// TODO: "Unsupported escape character found"
+			break
 		}
 		scanner.curTok.Literal += string(scanner.curCh)
 	}
@@ -204,8 +209,8 @@ func (scanner *Scanner) NextToken() token.Token {
 		switch ch {
 		case '=':
 			scanner.curTok.ID = token.EQUAL
-		case '"':
-			scanner.parseString()
+		case '"', '\'':
+			scanner.parseString(ch)
 		case '{':
 			scanner.curTok.ID = token.LBRACKET
 		case '}':

test.cfg

@@ -4,6 +4,8 @@ global = "global value";
 primary {
   string = "primary string value";
   string_with_quote = "some \"quoted\" str\\ing";
+  single = 'hello world';
+  single_with_quote = '\'hello\' "world"';
   integer = 500;
   float = 80.80;
   negative = -50;