I see. Thanks. On Mon, Mar 2, 2009 at 7:28 PM, Zoltan Herczeg <[email protected]>wrote:
> Why do you want to use the original context pointer? The context is > something like "current machine state". It is important for JS function > return, exception handling, and many other things. It is not a global > pointer, like JSGlobalData (JSContextGroupRef), it points to the current > context. > > Zoltan > > > Thanks for your answer. Then, in the callback function (such as > > GetPropertyCallback), is it ok to use the original context pointer > created > > at beginning? Or the ctx passed to the callback must be used instead? > > > > Regards > > James Su > > > > On Mon, Mar 2, 2009 at 4:52 PM, Zoltan Herczeg > > <[email protected]>wrote: > > > >> Hi, > >> > >> that is intended, since the context pointer is the current > >> CallFrame/ExecState. WebKit creates its own stack (called RegisterFile) > >> to > >> run JavaScript. The stack base of the current function is pointed by > >> CallFrame (similar to ebp in x86, or fp in ARM architectures). When you > >> call a JS function, several important pointers are stored on the top of > >> the stack, like return value, current code block, previous call frame, > >> and > >> these values are accessed through the CallFrame pointer. It is essential > >> for JavaScriptCore, there is no workaround. > >> > >> Zoltan > >> > >> > Hi, > >> > Recently, I'm writing an application which uses JavaScriptCore to > >> > execute > >> > javascript code. I just encountered a problem when using > >> JSEvaluateScript > >> > function to evaluate a piece of script. When executing the script, > >> some > >> > callbacks provided by my code will be called, but I found that the > >> context > >> > received by callbacks are different than the context I created and > >> passed > >> > to > >> > JSEvaluateScript function. > >> > > >> > Attached is a test program. > >> > Below is the output of this program on my system (ubuntu 8.04 64bit > >> with > >> > latest webkit svn): > >> > > >> > Create context 0x7faf5d567e88, global object 0x7faf5d530000 > >> > InitializeCallback(ctx=0x7faf5d567e88, obj=0x7faf5d532400) > >> > HasPropertyCallback(ctx=0x7faf50c4b048, obj=0x7faf5d532400, > >> > prop=prototype) > >> > CallAsConstructorCallback(ctx=0x7faf50c4b0c0, obj=0x7faf5d532400) > >> > InitializeCallback(ctx=0x7faf50c4b0c0, obj=0x7faf5d532440) > >> > SetPropertyCallback(ctx=0x7faf50c4b048, obj=0x7faf5d532440, > >> prop=prop1) > >> > HasPropertyCallback(ctx=0x7faf50c4b048, obj=0x7faf5d532440, > >> prop=prop1) > >> > FinalizeCallback(obj=0x7faf5d532400) > >> > FinalizeCallback(obj=0x7faf5d532440) > >> > > >> > You can see that, the callback functions received several different > >> > context > >> > pointers comparing to the one created at first beginning. > >> > > >> > Is it an intend behavior or a bug of webkit? And how can I avoid or > >> > workaround this problem? > >> > > >> > Thanks a lot. > >> > > >> > James Su > >> > _______________________________________________ > >> > webkit-dev mailing list > >> > [email protected] > >> > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev > >> > > >> > >> > >> _______________________________________________ > >> webkit-dev mailing list > >> [email protected] > >> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev > >> > > _______________________________________________ > > webkit-dev mailing list > > [email protected] > > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev > > > > _______________________________________________ > webkit-dev mailing list > [email protected] > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev >
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