Ex: enwiki:Light, enwiki:MathML
----- JS:[34267, 34347] -----
<math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x+5}">
+++++ PHP:[34181, 34218] +++++
<math alttext="{\displaystyle x+5}">Description
Description
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| Status | Subtype | Assigned | Task | ||
|---|---|---|---|---|---|
| Resolved | ssastry | T229015 Tracking: Direct live production traffic at Parsoid/PHP | |||
| Resolved | cscott | T235295 MathML tags are missing xmlns attribute |
Event Timeline
Comment Actions
RemexHTML seems to be dropping the xmlns attribute (see output when I added a log output to ExtensionHandler.php)
[subbu@earth:~/work/wmf/parsoid] echo '<math>1</math>' | php bin/parse.php --body_only --dump extoutput
HTML STRING: <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 1}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mn>1</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle 1}</annotation>
</semantics>
</math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/92d98b82a3778f043108d4e20960a9193df57cbf" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:1.162ex; height:2.176ex;" alt="1"/></span>
[dump/extoutput] ================================================================================
[dump/extoutput] EXTENSION INPUT: <math>1</math>
[dump/extoutput] ================================================================================
[dump/extoutput] EXTENSION OUTPUT (outerHTML of body of parsed html doc):
[dump/extoutput] <body><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math alttext="{\displaystyle 1}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>1</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 1}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/92d98b82a3778f043108d4e20960a9193df57cbf" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:1.162ex; height:2.176ex;" alt="1"/></span></body>
[dump/extoutput] --------------------------------------------------------------------------------Comment Actions
I bet the culprit is the workaround for T217708 (Remex commit 33de7ba9746fce0aaaeb9314a7a78460f2a28122), although that was *supposed* to affect only HTML elements, not xmlns="http://www.w3.org/1998/Math/MathML".
Comment Actions
Hm. Apparently the PHP DOM just ignores setAttribute and setAttributeNS when the name is xmlns. This is regardless of whether the element is created with createElement or createElementNS. I haven't figured out a workaround yet.
Grumble grumble PHP DOM grumble grumble.
Comment Actions
Change 548913 had a related patch set uploaded (by C. Scott Ananian; owner: C. Scott Ananian):
[mediawiki/libs/RemexHtml@master] WIP: Hack Remex to work around PHP DOM "special case" of xmlns attributes
Comment Actions
Change 548937 had a related patch set uploaded (by C. Scott Ananian; owner: C. Scott Ananian):
[mediawiki/services/parsoid@master] Workaround for missing xmlns attributes on DOMElement
Comment Actions
Change 548913 abandoned by C. Scott Ananian:
WIP: Hack Remex to work around PHP DOM "special case" of xmlns attributes
Reason:
Abandoned in favor of I7ef44ad9c1996749e9cf4306ac4d89cc5b8cc6e0
Comment Actions
Change 548937 merged by jenkins-bot:
[mediawiki/services/parsoid@master] Workaround for missing xmlns attributes on DOMElement
Comment Actions
Change 549132 had a related patch set uploaded (by Subramanya Sastry; owner: Subramanya Sastry):
[mediawiki/services/parsoid@master] Remove T235295 normalization from html diffing script
Comment Actions
Change 549132 merged by jenkins-bot:
[mediawiki/services/parsoid@master] Remove T235295 normalization from html diffing script
Comment Actions
Change 549619 had a related patch set uploaded (by C. Scott Ananian; owner: C. Scott Ananian):
[mediawiki/services/parsoid@master] Put the 'fake' xmlns attribute first, in an attempt to better match JS
Comment Actions
Change 549655 had a related patch set uploaded (by C. Scott Ananian; owner: C. Scott Ananian):
[mediawiki/services/parsoid@master] Reorder attributes in Parsoid/JS to put xmlns first
Comment Actions
Change 549619 merged by jenkins-bot:
[mediawiki/services/parsoid@master] Put the 'fake' xmlns attribute first, in an attempt to better match JS
Comment Actions
Change 549655 abandoned by C. Scott Ananian:
Reorder attributes in Parsoid/JS to put xmlns first
Reason:
Not worth doing.
Comment Actions
I think PHP's behaviour is defensible. According to the XHTML serialization part of the HTML spec, if there is "an Attr node with no namespace whose local name is the lowercase string "xmlns"", the serializer is required to throw.
The W3C DOM Parsing and Serialization draft specifies that when serializing an element that is in a different namespace to the default, an xmlns attribute should be emitted. If an xmlns attribute actually existed in the DOM, you would end up with a duplicate xmlns attribute and an invalid resulting document. So you can see why it would make sense to throw an exception in that case.
The HTML spec states that when coercing an HTML document to an XML infoset,
If the XML API doesn't support attributes in no namespace that are named "xmlns", attributes whose names start with "xmlns:", or attributes in the XMLNS namespace, then the tool may drop such attributes.
So PHP's behaviour is explicitly permitted.
The correct way to serialize an element to XML is by emitting an xmlns attribute at serialization time if the namespace of the element requires it. Parsoid's XMLSerializer was incorrect in attempting to simply iterate over $element->attributes.
So I see DOMCompat::attributes() is a hack to work around Parsoid's incorrect XML namespace serialization, not as a workaround for a PHP bug.
Comment Actions
Change 734058 had a related patch set uploaded (by Tim Starling; author: Tim Starling):
[mediawiki/services/parsoid@master] Make DOMCompat::attributes() return string[]
Comment Actions
Change 734058 merged by jenkins-bot:
[mediawiki/services/parsoid@master] Replace DOMCompat::attributes() with DOMUtils::attributes()