[webkit-dev] Can node->renderer()->node() == node ever be false?

Dimitri Glazkov dglazkov at chromium.org
Tue Sep 14 19:19:42 PDT 2010


Sounds good, I will look into this. FWIW, when I remove this loop, I
see no regressions in layout tests, including the tests added with the
same commit as the loop.

:DG<

On Tue, Sep 14, 2010 at 5:55 PM, Maciej Stachowiak <mjs at apple.com> wrote:
>
> On Sep 14, 2010, at 5:41 PM, Dimitri Glazkov wrote:
>
>> Sorry, I meant node->renderer()->node() != 0. My bad. This loop will
>> always exit in in the first iteration.
>
> It definitely is possible for renderers to have a null result from node(). I do not know for sure that it's impossible for node->renderer()->node() to be null under any circumstances. Anonymous renderers and inline continuations are among the ways a null node pointers. It might be that in all such circumstances, the renderer won't be returned by any node's renderer() method. It would be worth some analysis.
>
>  - Maciej
>
>>
>> :DG<
>>
>> On Tue, Sep 14, 2010 at 4:45 PM, Adam Roben <aroben at apple.com> wrote:
>>> On Sep 14, 2010, at 6:46 PM, Dimitri Glazkov wrote:
>>>
>>>> I've been looking at this line here and it doesn't seem to make sense
>>>> to me: http://trac.webkit.org/browser/trunk/WebCore/page/EventHandler.cpp#L2153
>>>>
>>>> It looks like the loop in question will always exit early, because it
>>>> short-circuits to node->renderer()->node() == node, which seems like
>>>> it always will be true. At least, that's what the layout tests say
>>>> when I remove it.
>>>
>>> I don't see anything in that loop that is equivalent to node->renderer()->node() == node. All I see are null-checks. Note that line 2154 declares a new variable with the name "node".
>>>
>>> I don't know anything else about this code or what you're asking, though.
>>>
>>> -Adam
>>>
>>>
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>
>


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