Changeset 270005 in webkit

Timestamp:

Nov 18, 2020, 6:32:56 PM (4 years ago)

Author:

Ross Kirsling

Message:

[JSC] Reinstate String#at
​https://bugs.webkit.org/show_bug.cgi?id=219124

Reviewed by Yusuke Suzuki.

JSTests:

• stress/at-method.js: Re-add tests.
• test262/config.yaml: Re-enable feature.
• test262/expectations.yaml:

"at/prop-desc.js" failures are due to a typo; will be fixed in ​https://github.com/tc39/test262/pull/2908.

Source/JavaScriptCore:

At this week's TC39 meeting, consensus was achieved on renaming item() *and* keeping it for strings too.
Accordingly, this patch reinstates String.prototype.at behind the existing useAtMethod runtime option.

• builtins/StringPrototype.js:

(at):

• runtime/StringPrototype.cpp:

(JSC::StringPrototype::finishCreation):

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/stress/at-method.js (modified) (1 diff)
• JSTests/test262/config.yaml (modified) (2 diffs)
• JSTests/test262/expectations.yaml (modified) (1 diff)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/builtins/StringPrototype.js (modified) (1 diff)
• Source/JavaScriptCore/runtime/StringPrototype.cpp (modified) (1 diff)

trunk/JSTests/ChangeLog

@@ +1 @@
+2020-11-18  Ross Kirsling  <ross.kirsling@sony.com>
+
+        [JSC] Reinstate String#at
+        https://bugs.webkit.org/show_bug.cgi?id=219124
+
+        Reviewed by Yusuke Suzuki.
+
+        * stress/at-method.js: Re-add tests.
+        * test262/config.yaml: Re-enable feature.
+        * test262/expectations.yaml:
+        "at/prop-desc.js" failures are due to a typo; will be fixed in https://github.com/tc39/test262/pull/2908.
+
 2020-11-17  Yusuke Suzuki  <ysuzuki@apple.com>
 

trunk/JSTests/stress/at-method.js

@@ -50 +50 @@
   shouldBe(ta.at({ valueOf: () => -1 }), ta[ta.length - 1]);
 }
+
+shouldBe(String.prototype.at.length, 1);  
+shouldThrowTypeError(() => String.prototype.at.call(undefined));  
+shouldThrowTypeError(() => String.prototype.at.call(null)); 
+
+const string = 'abc'; 
+// intentionally go one too far to ensure that we get undefined instead of wrapping 
+for (let i = 0; i <= string.length; i++) {  
+  shouldBe(string.at(i), string[i]);  
+  shouldBe(string.at(-i - 1), string[string.length - i - 1]); 
+} 
+shouldBe(string.at(), string[0]); 
+shouldBe(string.at(null), string[0]); 
+shouldBe(string.at({ valueOf: () => -1 }), string[string.length - 1]);  
+
+const emojiPseudoString = { toString: () => '😅' };  
+shouldBe(String.prototype.at.call(emojiPseudoString, 0), '\u{d83d}'); 
+shouldBe(String.prototype.at.call(emojiPseudoString, -1), '\u{de05}');

trunk/JSTests/test262/config.yaml

@@ -11 +11 @@
   Array.prototype.at: useAtMethod
   TypedArray.prototype.at: useAtMethod
+  String.prototype.at: useAtMethod
 skip:
   features:
@@ -28 +29 @@
     - top-level-await
     - Intl.ListFormat
-
-    - String.prototype.at
   paths:
     - test/built-ins/DataView/prototype/getBigInt64

trunk/JSTests/test262/expectations.yaml

@@ -824 +824 @@
   default: 'SyntaxError: Invalid regular expression: number too large in {} quantifier'
   strict mode: 'SyntaxError: Invalid regular expression: number too large in {} quantifier'
+test/built-ins/String/prototype/at/prop-desc.js:
+  default: 'Test262Error: descriptor should be writable'
+  strict mode: 'Test262Error: descriptor should be writable'
 test/built-ins/TypedArray/prototype/at/prop-desc.js:
   default: 'Test262Error: descriptor should be writable'

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2020-11-18  Ross Kirsling  <ross.kirsling@sony.com>
+
+        [JSC] Reinstate String#at
+        https://bugs.webkit.org/show_bug.cgi?id=219124
+
+        Reviewed by Yusuke Suzuki.
+
+        At this week's TC39 meeting, consensus was achieved on renaming item() *and* keeping it for strings too.
+        Accordingly, this patch reinstates String.prototype.at behind the existing useAtMethod runtime option.
+
+        * builtins/StringPrototype.js:
+        (at):
+        * runtime/StringPrototype.cpp:
+        (JSC::StringPrototype::finishCreation):
+
 2020-11-17  Yusuke Suzuki  <ysuzuki@apple.com>
 

trunk/Source/JavaScriptCore/builtins/StringPrototype.js

@@ -341 +341 @@
 }
 
+// FIXME: This is extremely similar to charAt, so we should optimize it accordingly.    
+//        https://bugs.webkit.org/show_bug.cgi?id=217139    
+function at(index)    
+{   
+    "use strict";   
+
+    if (@isUndefinedOrNull(this))   
+        @throwTypeError("String.prototype.at requires that |this| not be null or undefined"); 
+
+    var string = @toString(this);   
+    var length = string.length; 
+
+    var k = @toInteger(index);  
+    if (k < 0)  
+        k += length;    
+
+    return (k >= 0 && k < length) ? string[k] : @undefined; 
+}
+
 @globalPrivate
 function createHTML(func, string, tag, attribute, value)

trunk/Source/JavaScriptCore/runtime/StringPrototype.cpp

@@ -151 +151 @@
     JSC_NATIVE_FUNCTION_WITHOUT_TRANSITION("normalize", stringProtoFuncNormalize, static_cast<unsigned>(PropertyAttribute::DontEnum), 0);
     JSC_NATIVE_INTRINSIC_FUNCTION_WITHOUT_TRANSITION(vm.propertyNames->builtinNames().charCodeAtPrivateName(), stringProtoFuncCharCodeAt, static_cast<unsigned>(PropertyAttribute::DontEnum), 1, CharCodeAtIntrinsic);
+
+    if (Options::useAtMethod())
+        JSC_BUILTIN_FUNCTION_WITHOUT_TRANSITION(vm.propertyNames->builtinNames().atPublicName(), stringPrototypeAtCodeGenerator, static_cast<unsigned>(PropertyAttribute::DontEnum));
 
     JSFunction* trimStartFunction = JSFunction::create(vm, globalObject, 0, "trimStart"_s, stringProtoFuncTrimStart, NoIntrinsic);