[webkit-dev] JavaScriptCore Binding Problem
I've got a new IDL class I'm working of for some "experiments in XML"
and I've run into an interesting snag. I have a call to a "parse"
method from Javascript where the string argument seems to be getting
mangled. The IDL for the method looks like:
boolean parse(in DOMString str);
and the call from javascript looks like:
reader.parse("I am a document");
Everything else about this interface & implementation works fine.
Unfortunately, for the above method, the string of XML to parse comes
in as "empty". It looks to me like things are mangled in some way but
I can't determine why.
The generated code from the IDL is:
EncodedJSValue JSC_HOST_CALL jsXMLReaderPrototypeFunctionParse(ExecState* exec)
{
JSValue thisValue = exec->hostThisValue();
if (!thisValue.inherits(&JSXMLReader::s_info))
return throwVMTypeError(exec);
JSXMLReader* castedThis = static_cast(asObject(thisValue));
XMLReader* imp = static_cast(castedThis->impl());
const String& str = ustringToString(exec->argument(0).toString(exec));
if (exec->hadException())
return JSValue::encode(jsUndefined());
JSC::JSValue result = jsBoolean(imp->parse(str));
return JSValue::encode(result);
}
The 'str' object in the debugger is empty and the argument from which
it is converted has a strange string of length 1 character.
Any ideas how this could get mangled? Something is obviously stepping
on some object but I can't see where. The other possibility is
something related to JIT compiling in the Javascript environment but
that is a pure guess at this point. The backtrace shows some JIT
compile code in the stack.
--
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."
Bertrand Russell in a footnote of Principles of Mathematics
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Re: [webkit-dev] JavaScriptCore Binding Problem
On Wed, Jan 5, 2011 at 7:38 PM, Alex Milowski wrote:
> I've got a new IDL class I'm working of for some "experiments in XML"
> and I've run into an interesting snag. I have a call to a "parse"
> method from Javascript where the string argument seems to be getting
> mangled. The IDL for the method looks like:
>
> boolean parse(in DOMString str);
>
> and the call from javascript looks like:
>
> reader.parse("I am a document");
>
> Everything else about this interface & implementation works fine.
> Unfortunately, for the above method, the string of XML to parse comes
> in as "empty". It looks to me like things are mangled in some way but
> I can't determine why.
Just as an experiment, I set a breakpoint in the Javascript debugger
inside Safari and found another interesting data point. The code in
the test case goes from the source:
window.onload = function() {
var xml = "";
reader.parse(xml);
}
to this displayed in the inspector when the breakpoint is hit:
window.onload = function() {
var xml = "";
reader.parse(xml);
}
That's very strange. Any ideas of what to look at here? Could the
JIT compiler for JavascriptCore be dropping/mangling the string
constant somehow?
--
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."
Bertrand Russell in a footnote of Principles of Mathematics
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Re: [webkit-dev] JavaScriptCore Binding Problem
Completely embarrassing ... but it is an XHTML file and so the markup in the string gets parsed unless I escape it ... *sigh* Too many hours wasted in the debugger on this one. :( So, it is a non-issue. Thanks to Evan Martin for pointed that out. -- --Alex Milowski "The excellence of grammar as a guide is proportional to the paucity of the inflexions, i.e. to the degree of analysis effected by the language considered." Bertrand Russell in a footnote of Principles of Mathematics ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
