Hi Jake,
Jacob Kjome <[EMAIL PROTECTED]> wrote on 09/23/2006 02:44:20 AM:
<snip/>
> What do you think of this (below). It actually goes one step further
> by not necessarily counting on the parsing process to build up the
> "identifiers" map. It first checks super.getElementById() (which
> uses the "identifiers" map). If it finds the element, it returns it
> immediately. No unnecessary recursion. If it doesn't find it, it
> falls back to the pre-existing recursive behavior to find the
> element. If it is found, it populates the "identifiers" map with the
> element so the next call to getElementById() will be
> optimized. Finally, it returns the element.
>
> public synchronized Element getElementById( String elementId )
> {
> Element idElement = super.getElementById(elementId);
> if (idElement != null) {
> return idElement;
> }
> idElement = getElementById( elementId, this );
> if (idElement != null) {
> putIdentifier(elementId, idElement);
> }
> return idElement;
> }
>
> What do you think? With this in place, even if no parse-time
> solution is found for HTML documents to populate the "identifiers"
> map, there's still some optimization provided in the case that
> getElementById() is called more than once on the same Id. I know,
> it's kind of odd, but there are some situations where such a thing
> happens and it doesn't hurt anything to account for it. And with a
> parse-time solution, the less efficient recursion will never have to
> be run because "identifiers" map will already have been populated
> allowing for fully optimized access to elements with Ids.
I don't think that's going to work. If after caching the id in the
"identifiers" map the application changes the value of the id or removes
it from the element the "identifers" map won't get updated so a subsequent
call to getElementById() would return the wrong answer. Only modifications
to ID attributes [1] get reflected in this map.
> Now, hopefully I'll get a good answer from Andy so I can take full
> advantage of the optimization!
>
>
> later,
>
> Jake
>
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[1]
http://xerces.apache.org/xerces2-j/javadocs/api/org/w3c/dom/Attr.html#isId()
Michael Glavassevich
XML Parser Development
IBM Toronto Lab
E-mail: [EMAIL PROTECTED]
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