Bug 126004 – Implement ArrayBuffer.isView

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Brent Fulgham]

We need an implementation of ArrayBuffer.isView, added to the ECMA specification as of the May 14, 2013 draft:

15.13.5.4.2 ArrayBuffer.isView ( arg )
The isView function takes one argument arg, and performs the following steps are taken:
1. If Type(arg) is not Object, return false.
2. If arg is an exotic Array object, then return true.
3. If arg has a [[ViewedArrayBuffer]] internal data property, then return true.
4. Return false.

This is needed to fully comply with WebGL requirements.

[Brent Fulgham]

<rdar://problem/15201822>

[Brent Fulgham]

Created attachment 219690 [details]
Patch

[Oliver Hunt]

Comment on attachment 219690 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=219690&action=review

Almost there :)

> Source/JavaScriptCore/runtime/JSArrayBufferConstructor.cpp:56
> +    putDirectNativeFunction(vm, globalObject(), makeIdentifier(vm, ("isView")), 1, arrayBufferFuncIsView, NoIntrinsic, DontEnum |Function);

JSC_NATIVE_FUNCTION(vm.propertyNames->isView, arrayBufferFuncIsView, DontEnum, 1);

Add isView to CommonIdentifiers

[Brent Fulgham]

Comment on attachment 219690 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=219690&action=review

>> Source/JavaScriptCore/runtime/JSArrayBufferConstructor.cpp:56
>> +    putDirectNativeFunction(vm, globalObject(), makeIdentifier(vm, ("isView")), 1, arrayBufferFuncIsView, NoIntrinsic, DontEnum |Function);
> 
> JSC_NATIVE_FUNCTION(vm.propertyNames->isView, arrayBufferFuncIsView, DontEnum, 1);
> 
> Add isView to CommonIdentifiers

I tried using JSC_NATIVE_FUNCTION, but it assumes "globalObject" is defined in the current scope (except as a function), so the macro gives a syntax error.

[Filip Pizlo]

Comment on attachment 219690 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=219690&action=review

R=me unless Oliver has super strong opinions about that macro.

>>> Source/JavaScriptCore/runtime/JSArrayBufferConstructor.cpp:56
>>> +    putDirectNativeFunction(vm, globalObject(), makeIdentifier(vm, ("isView")), 1, arrayBufferFuncIsView, NoIntrinsic, DontEnum |Function);
>> 
>> JSC_NATIVE_FUNCTION(vm.propertyNames->isView, arrayBufferFuncIsView, DontEnum, 1);
>> 
>> Add isView to CommonIdentifiers
> 
> I tried using JSC_NATIVE_FUNCTION, but it assumes "globalObject" is defined in the current scope (except as a function), so the macro gives a syntax error.

Yeah, other places that use JSC_NATIVE_FUNCTION often have some pro-forma setup like:

JSGlobalObject* globalObject = prototype->globalObjects();

Or whatever is appropriate.

 I don't mind that you're calling putDirectNativeFunction directly.  But, you should add isView to CommonIdentifiers.  Then you'll access it by saying vm.propertyNames->isView.  This isn't a big deal, but it's nice to be consistent.

[Brent Fulgham]

Created attachment 219699 [details]
Patch

[Brent Fulgham]

Committed r160876: <http://trac.webkit.org/changeset/160876>