Vitali,
Thanks for taking this on. I've been meaning to do it for ages, but haven't
had time. I haven't had a chance to look over the patch in detail yet, but
the general approach sounds good.

To answer your earlier question about DOMImplMozilla[Old], the "old" one
(not the best name, I know) maps to the user-agent "gecko", which is the
fallback for pre-gecko-1.8. Gecko 1.8 is basically Firefox 1.5 and 2.0, and
is also used to support later versions (e.g., Firefox 3 is Gecko 1.9). Older
versions of Gecko don't exist in any browser you're likely to encounter in
the wild, but is used by the hosted-mode browser on Linux. As soon as we
move to out-of-process hosted mode (GWT 2.0 in all likelihood), we'll be
able to ditch support for old Geckos (yay!).

A couple of procedural things:
- Have you had a chance to sign a CLA yet? It's just a minor procedural
thing, but necessary.
  (http://code.google.com/webtoolkit/makinggwtbetter.html#committers)
- Could I get you to create an issue to track this?
- Also, if you could upload this patch to
http://gwt-code-reviews.appspot.com/ it would make it easier for everyone to
view and discuss.
  (Make sure to add [email protected] to the
CC list)

Thanks again,
joel.

On Sun, Apr 19, 2009 at 6:11 AM, Vitali Lovich <[email protected]> wrote:

> Oops - missed some compile errors in the JSNI code.  This is meant to be
> applied over top of the previous patches.  I've verified that if
> getElementsByClassName is not used then no code related to it appears in the
> output (compiled the GWT samples & grepped for getElementsByClassName).
>
> I still need to test whether or not the implementations work & write unit
> tests.
>
> Just for easy reference for myself, [].slice.call(nodeList, 0); is the
> code to convert a nodelist into an array.
>
>
> On Sun, Apr 19, 2009 at 5:47 AM, Vitali Lovich <[email protected]> wrote:
>
>> Here's my second attempt at the patch (2 of 2 is just a documentation
>> adjustment).
>>
>> One caveat I forgot to mention is that there is slightly different
>> cross-platform behaviour right now.  The native implementations return
>> NodeLists which are live whereas the Javascript implementations simply
>> return arrays.
>>
>> The question is should I change it so that a JsArray is always returned
>> (i.e. copy the node list into an array) so that semantics are constant
>> across browsers or leave as is for performance with maybe a caveat that the
>> user should be careful when using with FF3, Safari 3.1 or Opera 9.5 & copy
>> into an array if they need array semantics?
>>
>> Changes from first patch:
>> getElementsByClassName should now display the HTML5 behaviour in quirks
>> mode if the browser supports the native implementation or doesn't provide
>> XPath (IE or really really old versions of FF, Safari & friends).  I'm not
>> sure how to get case insensitive string matching with XPath (so quirks mode
>> won't work according to the HTML5 spec in FF2, Safari 3, Opera 9.4 or
>> earlier).  Is it even possible to do, or should I just fall back to using
>> the DOM implementation in quirks mode & make a note that performance could
>> be improved drastically if quirks mode is turned off on browsers that
>> support XPath?  Or just leave as is - it'll certainly have the same
>> behaviour as all the other JS libraries out there.
>>
>> Only DOMImpl, DOMImplStandard, & DOMImplSafari now require code changes.
>>
>> DOMImpl: contains a native implementation using DOM.  By default this
>> gets called.
>> DOMImplStandard now defines getElementsByXPath.  The fastest approach is
>> assigned* to getElementsByClassName in the Element prototype & document.
>> overrides getElementsByClassName
>> DOMImplSafari: getElementsByXPath calls the native one supplied by
>> Safari.  I'm assuming that document._getElementsByXPath & document.evaluate
>> came in with the same version of Safari (the one that implemented
>> XPath).  If that's not the case, then I'll have to rework the code a bit.
>> Document: added isBackCompat().  Could use !isCSS1Compat() for now, but
>> this ensures no code change required if other compat modes are added in the
>> future ('cause !quirks is all we care about).
>>
>> *I'm assuming that the way I wrote it ensures that if the developer
>> doesn't use getElementsByClassName, then there's 0-cost: the function is
>> never registered because the GWT compiler will recognize the dead code.
>>
>> If it is used, then there's only the overhead of performing the
>> implementation selection once on startup.
>>
>> Thank you,
>> Vitali
>>
>>
>> On 4/18/09, Vitali Lovich <[email protected]> wrote:
>> > Also, what's the difference between DOMImplMozilla & DOMImplMozillaOld
>> >  in terms of Firefox versions?
>> >
>> >  And what versions of each browser are supported?  Are all versions of
>> >  Safari, FF, & Opera supported as much as possible?  Is there a minimum
>> >  version for any of them?
>> >
>> >
>> >  On Sat, Apr 18, 2009 at 4:05 AM, Vitali Lovich <[email protected]>
>> wrote:
>> >  > If I put the check in a static block, then the check is only done
>> once
>> >  > on startup, right?  Is this acceptable, or is it frowned upon because
>> >  > it adds a slight penalty to the startup even if the developer never
>> >  > uses the function.
>> >  >
>> >  > Something like,
>> >  >
>> >  > static {
>> >  >  ensureGetElementsByClassNameRegistered();
>> >  > }
>> >  >
>> >  > private static native void ensureGetElementsByClassNameRegistered() {
>> >  >   if (!document.getElementsByClassName) {
>> >  >      document.getElementsByClassName = function(element, class) {
>> >  >             // etc
>> >  >      }
>> >  >   }
>> >  > }
>> >  >
>> >  > On Sat, Apr 18, 2009 at 3:54 AM, Ray Cromwell <[email protected]>
>> wrote:
>> >  >>
>> >  >> You don't want to create a separate property just for native
>> >  >> getElementsByClassName() as that would almost double the number of
>> >  >> permutations (except IE where is it known not to exist)  What you
>> >  >> could provide is 3 implementations. IE gets raw DOM version,
>> >  >> Safari/Firefox/Opera get a version that checks
>> >  >> if(document.getElementsByClassName) exists, and if not, falls back
>> to
>> >  >> document.evaluate.
>> >  >>
>> >  >> -Ray
>> >  >>
>> >  >>
>> >  >> On Fri, Apr 17, 2009 at 11:03 PM, Vitali Lovich <[email protected]>
>> wrote:
>> >  >>>
>> >  >>> Do you have any suggestions regarding how to do the proper deferred
>> >  >>> binding for the various versions?  Should I just put the typical JS
>> >  >>> check that regular libraries use? (i.e. if
>> >  >>> (!document.getElementsByClassName) { // provide fallback }.  I
>> thought
>> >  >>> the whole point of deferred binding was to get around that.
>> >  >>>
>> >  >>> What is the list of officially supported browsers?  In particular
>> the
>> >  >>> specific minimum version for each?
>> >  >>>
>> >  >>> I guess I'm going to have to install a virtual machine for this
>> >  >>> because Safari refuses to work in wine 1.0.19 - chrome is useable
>> >  >>> although no HTTPS sites.
>> >  >>>
>> >  >>> Is there a guide somewhere on writing & integrating the tests into
>> >  >>> GWT, or just look at existing ones in the source.
>> >  >>>
>> >  >>> On Sat, Apr 18, 2009 at 1:49 AM, Miroslav Pokorny
>> >  >>> <[email protected]> wrote:
>> >  >>>>
>> >  >>>> Provide some tests and make sure it works on all officially
>> supported
>> >  >>>> browsers even if the implementation is suboptimal. There are many
>> js
>> >  >>>> libs out there so it's not hard to find the best way to do it fir
>> the
>> >  >>>> various browsers...
>> >  >>>>
>> >  >>>> On 18/04/2009, at 12:39 PM, Vitali Lovich <[email protected]>
>> wrote:
>> >  >>>>
>> >  >>>>> Just my first attempt at adding some initial support for
>> >  >>>>> getElementsByClassName.  This is by no means tested or
>> >  >>>>>
>> >  >>>>> Newer browsers support getElementsByClassName.  This is my
>> attempt
>> >  >>>>> at a patch.
>> >  >>>>>
>> >  >>>>> Caveats:
>> >  >>>>> There's a "bug" in that quirks mode doesn't behave properly (I
>> don't
>> >  >>>>> know how to detect it in the deferred binding) for IE & Firefox2
>> &
>> >  >>>>> earlier.  According to the HTML5 spec, it's supposed to be case
>> >  >>>>> insensitive in quirks mode.  However, this "bug" behaves the
>> exact
>> >  >>>>> same way as all the javascript wrappers do (since I based the
>> XPath &
>> >  >>>>> RegExp code paths roughly around the implementations floating out
>> >  >>>>> there).
>> >  >>>>>
>> >  >>>>> I'm also not sure if I added the support correctly for Firefox.
>> >  >>>>> getElementsByClassName only came in with FF3 & requires the xpath
>> >  >>>>> workaround for FF2 & earlier (I believe I read xpath was
>> introduced
>> >  >>>>> with FF 1.5).  I placed the xpath code in DOMImplMozillaOld for
>> now
>> >  >>>>> (not sure whether or not gecko1_8 represents FF2).
>> >  >>>>>
>> >  >>>>> There's also no mention of the versions of Safari & Opera that
>> are
>> >  >>>>> supported by GWT, so they're defaulting to using the native
>> version
>> >  >>>>> (which will not work if they don't provide it).
>> >  >>>>>
>> >  >>>>> Safari in particular got it with version 3.1.  if earlier
>> versions are
>> >  >>>>> supported, it's not too much work.  Simply grab the expression
>> built
>> >  >>>>> in the FF xpath  & pass it to document._getElementsByXPath(query,
>> >  >>>>> parent) for Safari versions that have xpath (not sure which those
>> >  >>>>> are).  Not sure how to distinguish Safari pre3.1 & post3.1 in
>> deferred
>> >  >>>>> binding.
>> >  >>>>>
>> >  >>>>> Opera got it with 9.5.  Not sure when xPath support got into
>> Opera
>> >  >>>>> (should be a straightfoward copy of the mozilla code).  Not sure
>> how
>> >  >>>>> to distinguish the two in the deferred binding.
>> >  >>>>>
>> >  >>>>> Feedback would be appreciated.
>> >  >>>>>
>> >  >>>>> Should this go as an enhancement request in the issue tracker?
>> >  >>>>>
>> >  >>>>> >
>> >  >>>>> diff --git a/user/src/com/google/gwt/dom/client/DOMImpl.java
>> b/user/
>> >  >>>>> src/com/google/gwt/dom/client/DOMImpl.java index 1d7e39b..581764b
>> >  >>>>> 100644 --- a/user/src/com/google/gwt/dom/client/DOMImpl.java +++
>> b/
>> >  >>>>> user/src/com/google/gwt/dom/client/DOMImpl.java @@ -176,6 +176,8
>> @@
>> >  >>>>> abstract class DOMImpl { return 0; }-*/; + public abstract
>> NodeList
>> >  >>>>> getElementsByClassName(Element parent, String className); +
>> public
>> >  >>>>> native Element getFirstChildElement(Element elem) /*-{ var child
>> =
>> >  >>>>> elem.firstChild; while (child && child.nodeType != 1) diff --git
>> a/
>> >  >>>>> user/src/com/google/gwt/dom/client/DOMImplIE6.java
>> b/user/src/com/
>> >  >>>>> google/gwt/dom/client/DOMImplIE6.java index 04c205a..8c24a6c
>> 100644
>> >  >>>>> --- a/user/src/com/google/gwt/dom/client/DOMImplIE6.java +++
>> b/user/
>> >  >>>>> src/com/google/gwt/dom/client/DOMImplIE6.java @@ -15,6 +15,8 @@
>> */
>> >  >>>>> package com.google.gwt.dom.client; +import
>> >  >>>>> com.google.gwt.core.client.JsArray; +  /** * Internet Explorer 6
>> >  >>>>> implementation of * {...@link
>> com.google.gwt.user.client.impl.DOMImpl}.
>> >  >>>>> @@ -184,6 +186,31 @@ class DOMImplIE6 extends DOMImpl { }
>> @Override
>> >  >>>>> + public NodeList getElementsByClassName(Element parent, String
>> >  >>>>> className) { + // TODO: detect quirks mode so that the regexps do
>> a
>> >  >>>>> case insensitive match as per the + // spec. when quirks mode
>> >  >>>>> detected, pass "i" as the flags parameter + return
>> >  >>>>> getElementsByClassName(parent, className.split(" "), "").cast();
>> + }
>> >  >>>>> + +  private native JsArray getElementsByClassName(Element
>> parent,
>> >  >>>>> String [] classes, String flags) /*-{ + var i, j, e, c, elements
>> =
>> >  >>>>> parent.all || parent.getElementsByTagName("*"); + var regexps =
>> [],
>> >  >>>>> result = []; + for (i = classes.length - 1; i >= 0; i--) { + c =
>> >  >>>>> classes[i].replace(/^\s+|\s+$/g, ""); + if (c.length) +
>> >  >>>>> regexps.push(new RegExp(new Array("(?:^|\\s)", c, "(?:\\s|
>> >  >>>>> $)").join(""), flags); + } + if (regexps.length) { + for (i = 0,
>> c =
>> >  >>>>> elements.length; i < c; i++) { + e = elements[i]; + for (j =
>> >  >>>>> regexps.length - 1; j >= 0 && regexps[j].test(e); j--) {} + j ==
>> -1
>> >  >>>>> && result.push(e); + } + } + return result; + }-*/; + + @Override
>> >  >>>>> public native String getInnerText(Element elem) /*-{ return
>> >  >>>>> elem.innerText; }-*/; diff --git a/user/src/com/google/gwt/dom/
>> >  >>>>> client/DOMImplMozillaOld.java
>> b/user/src/com/google/gwt/dom/client/
>> >  >>>>> DOMImplMozillaOld.java index ecf52fb..5fd7312 100644 ---
>> a/user/src/
>> >  >>>>> com/google/gwt/dom/client/DOMImplMozillaOld.java +++
>> b/user/src/com/
>> >  >>>>> google/gwt/dom/client/DOMImplMozillaOld.java @@ -15,6 +15,8 @@ */
>> >  >>>>> package com.google.gwt.dom.client; +import
>> >  >>>>> com.google.gwt.core.client.JsArray; +  /** * DOM implementation
>> >  >>>>> differences for older version of Mozilla (mostly the * hosted
>> mode
>> >  >>>>> browser on linux). The main difference is due to changes in @@
>> >  >>>>> -114,4 +116,23 @@ package com.google.gwt.dom.client; return top +
>> >  >>>>> viewport.scrollTop; }-*/; + + @Override + public NodeList
>> >  >>>>> getElementsByClassName(Element parent, String className) { + //
>> the
>> >  >>>>> cast should be safe since both it & JsArray access the underlying
>> >  >>>>> object the same way + // and NodeList is immutable (constraints
>> >  >>>>> added, not removed) + return getElementsByClassName(parent,
>> >  >>>>> className.split(" ")).cast(); + } + + private native JsArray
>> >  >>>>> getElementsByClassName(Element parent, String [] classes) /*-{ +
>> var
>> >  >>>>> result, i, xpathResult, classExpr = ".//*"; + for (i =
>> >  >>>>> classes.length - 1; i >= 0; i--) { + classExpr +=
>> >  >>>>> "[contains(concat(' ', @class, ' '), ' " + classes[i] + " ')]"; +
>> }
>> >  >>>>> + xpathResult = document.evaluate(classExpr, parent, null, 0,
>> null);
>> >  >>>>> + while ((i = xpathResult.iterateNext())) { + result.push(i); + }
>> +
>> >  >>>>> return result; + }-*/; } diff --git
>> a/user/src/com/google/gwt/dom/
>> >  >>>>> client/DOMImplStandard.java b/user/src/com/google/gwt/dom/client/
>> >  >>>>> DOMImplStandard.java index 90d2e89..be29fe1 100644 ---
>> a/user/src/
>> >  >>>>> com/google/gwt/dom/client/DOMImplStandard.java +++
>> b/user/src/com/
>> >  >>>>> google/gwt/dom/client/DOMImplStandard.java @@ -114,6 +114,11 @@
>> >  >>>>> abstract class DOMImplStandard extends DOMImpl { }-*/; @Override
>> +
>> >  >>>>> public native NodeList getElementsByClassName(Element parent,
>> String
>> >  >>>>> className) /*-{ + return
>> parent.getElementsByClassName(className);
>> >  >>>>> + }-*/; + + @Override public native boolean isOrHasChild(Element
>> >  >>>>> parent, Element child) /*-{ return parent.contains(child); }-*/;
>> >  >>>>> diff --git a/user/src/com/google/gwt/dom/client/Document.java
>> b/user/
>> >  >>>>> src/com/google/gwt/dom/client/Document.java index
>> 209b1b9..23d6daf
>> >  >>>>> 100644 --- a/user/src/com/google/gwt/dom/client/Document.java +++
>> b/
>> >  >>>>> user/src/com/google/gwt/dom/client/Document.java @@ -1125,6
>> +1125,18
>> >  >>>>> @@ public class Document extends Node { }-*/; /** + * Returns a
>> >  >>>>> {...@link NodeList} of all the {...@link Element Elements} with a 
>> > given
>> +
>> >  >>>>> * class name in the order in which they are encountered in a
>> >  >>>>> preorder traversal + * of the document tree. + * + * @param
>> >  >>>>> className the space-separated name of the classes to match on + *
>> >  >>>>> @return a list containing all the matched elements. + */ + public
>> >  >>>>> final NodeList getElementsByClassName(String className) { +
>> return
>> >  >>>>> DOMImpl.impl.getElementsByClassName(this.cast(), className); + }
>> +
>> >  >>>>> + /** * Returns the {...@link Element} whose id is given by
>> elementId.
>> >  >>>>> If no such * element exists, returns null. Behavior is not
>> defined
>> >  >>>>> if more than one * element has this id. diff --git
>> a/user/src/com/
>> >  >>>>> google/gwt/dom/client/Element.java b/user/src/com/google/gwt/dom/
>> >  >>>>> client/Element.java index a0bf9f2..d64b83e 100644 ---
>> a/user/src/com/
>> >  >>>>> google/gwt/dom/client/Element.java +++
>> b/user/src/com/google/gwt/dom/
>> >  >>>>> client/Element.java @@ -149,6 +149,18 @@ public class Element
>> >  >>>>> extends Node { }-*/; /** + * Returns a {...@link NodeList} of all
>> the
>> >  >>>>> {...@link Element Elements} with a given + * class name in the order
>> in
>> >  >>>>> which they are encountered in a preorder traversal + * of this
>> >  >>>>> elements children. + * + * @param className the space-separated
>> >  >>>>> names of the classes to match on + * @return a list containing
>> all
>> >  >>>>> the matched elements. + */ + public final NodeList
>> >  >>>>> getElementsByClassName(String className) { + return
>> >  >>>>> DOMImpl.impl.getElementsByClassName(this, className); + } + + /**
>> *
>> >  >>>>> Returns a NodeList of all descendant Elements with a given tag
>> name,
>> >  >>>>> in the * order in which they are encountered in a preorder
>> traversal
>> >  >>>>> of this Element * tree.
>> >  >>>>
>> >  >>>> >
>> >  >>>>
>> >  >>>
>> >  >>> >
>> >  >>>
>> >  >>
>> >  >> >  >>
>> >  >>
>> >  >
>> >
>>
>
>
> >
>

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