json: true, false, null lex [GH-22]

json/lex.go

@@ -74,9 +74,49 @@ func (x *jsonLex) Lex(yylval *jsonSymType) int {
 		case '"':
 			return x.lexString(yylval)
 		default:
-			x.createErr(fmt.Sprintf("unexpected character: %c", c))
+			x.backup()
+			return x.lexId(yylval)
+		}
+	}
+}
+
+// lexId lexes an identifier
+func (x *jsonLex) lexId(yylval *jsonSymType) int {
+	var b bytes.Buffer
+	first := true
+	for {
+		c := x.next()
+		if c == lexEOF {
+			break
+		}
+
+		if !unicode.IsDigit(c) && !unicode.IsLetter(c) && c != '_' && c != '-' {
+			x.backup()
+
+			if first {
+				x.createErr("Invalid identifier")
 				return lexEOF
 			}
+
+			break
+		}
+
+		first = false
+		if _, err := b.WriteRune(c); err != nil {
+			return lexEOF
+		}
+	}
+
+	switch v := b.String(); v {
+	case "true":
+		return TRUE
+	case "false":
+		return FALSE
+	case "null":
+		return NULL
+	default:
+		x.createErr(fmt.Sprintf("Invalid identifier: %s", v))
+		return lexEOF
 	}
 }
 

json/test-fixtures/types.json

@@ -3,5 +3,8 @@
 	"bar": 7,
 	"baz": [1,2,3],
 	"foo": -12,
-	"bar": 3.14159
+	"bar": 3.14159,
+    "foo": true,
+    "bar": false,
+    "foo": null
 }