Changeset 227775 in webkit for trunk/Source/JavaScriptCore/parser/Lexer.cpp

Timestamp:

Jan 29, 2018, 11:34:44 PM (7 years ago)

Author:

Yusuke Suzuki

Message:

[JSC] Relax line terminators in String to make JSON subset of JS
​https://bugs.webkit.org/show_bug.cgi?id=182232

Reviewed by Keith Miller.

JSTests:

• ChakraCore/test/es5/Lex_u3.baseline-jsc:
• stress/relaxed-line-terminators-in-string.js: Added.

(shouldBe):

Source/JavaScriptCore:

"Subsume JSON" spec is now stage 3[1]. Before this spec change,
JSON can accept \u2028 / \u2029 in string while JS cannot do that.
It accidentally made JSON non subset of JS.

Now we extend our JS string to accept \u2028 / \u2029 to make JSON
subset of JS in this spec change.

[1]: ​https://github.com/tc39/proposal-json-superset

• parser/Lexer.cpp:

(JSC::Lexer<T>::parseStringSlowCase):

LayoutTests:

• sputnik/Conformance/07_Lexical_Conventions/7.3_Line_Terminators/S7.3_A2.3-expected.txt:
• sputnik/Conformance/07_Lexical_Conventions/7.3_Line_Terminators/S7.3_A2.3.html:
• sputnik/Conformance/07_Lexical_Conventions/7.3_Line_Terminators/S7.3_A2.4-expected.txt:
• sputnik/Conformance/07_Lexical_Conventions/7.3_Line_Terminators/S7.3_A2.4.html:

File:

• trunk/Source/JavaScriptCore/parser/Lexer.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/parser/Lexer.cpp

@@ -1356 +1356 @@
         }
         // Fast check for characters that require special handling.
-        // Catches 0, \n, \r, 0x2028, and 0x2029 as efficiently
-        // as possible, and lets through all common ASCII characters.
-        if (UNLIKELY(((static_cast<unsigned>(m_current) - 0xE) & 0x2000))) {
+        // Catches 0, \n, and \r as efficiently as possible, and lets through all common ASCII characters.
+        static_assert(std::is_unsigned<T>::value, "Lexer expects an unsigned character type");
+        if (UNLIKELY(m_current < 0xE)) {
             // New-line or end of input is not allowed
-            if (atEnd() || isLineTerminator(m_current)) {
+            if (atEnd() || m_current == '\r' || m_current == '\n') {
                 m_lexErrorMessage = ASCIILiteral("Unexpected EOF");
                 return atEnd() ? StringUnterminated : StringCannotBeParsed;