Last Comment Bug 388415 - document.evaluate throws error if context is an empty text node.
: document.evaluate throws error if context is an empty text node.
Product: Core
Classification: Components
Component: DOM (show other bugs)
: unspecified
: All All
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Assigned To: Nobody; OK to take it and work on it
: Andrew Overholt [:overholt]
Depends on:
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Reported: 2007-07-17 04:16 PDT by Mark Wubben
Modified: 2007-07-17 05:52 PDT (History)
3 users (show)
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Description User image Mark Wubben 2007-07-17 04:16:57 PDT
User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en; rv: Gecko/20070711 Camino/1.6a1pre (like Firefox/
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.9a7pre) Gecko/2007071604 Minefield/3.0a7pre

Evaluating an XPATH expression using document.evaluate() throws an error if the contextNode is an empty text node.

Error thrown:

Error: uncaught exception: [Exception... "Operation is not supported"  code: "9" nsresult: "0x80530009 (NS_ERROR_DOM_NOT_SUPPORTED_ERR)"  location: " Line: 20"]

The line number corresponds with the result argument.

Reproducible: Always

Steps to Reproduce:
1. Open Firefox
2. Open the error console, make sure it's cleared
3. Go to the test case:
Actual Results:  

Expected Results:  
No error is thrown. "[Object HTMLSpanElement]" is alerted.

This problem also occurs in Firefox 2.0.
Comment 1 User image Mark Wubben 2007-07-17 04:26:43 PDT
Firefox 2.0 gives the following exception:

Error: uncaught exception: [Exception... "Object cannot be created in this context"  code: "9" nsresult: "0x80530009 (NS_ERROR_DOM_NOT_SUPPORTED_ERR)"  location: " Line: 22"]
Comment 2 User image Olli Pettay [:smaug] (pto-ish for couple of days) 2007-07-17 04:40:24 PDT
This looks like intended behavior. Peter, could you explain why?
Is it because of ?
Comment 3 User image Sjoerd Visscher 2007-07-17 05:31:41 PDT
The xpath implementation does no text node normalization, so is not the reason.

In Xopus I catch these errors, and work around it by making the parent element the context node, and prefixing the xpath expression with "node()[x]/" where x is the number of preceding siblings of the text node. Then everything works as expected.

So I think this test should just go, as empty text nodes as context will probably work just fine.
Comment 4 User image Peter Van der Beken [:peterv] 2007-07-17 05:48:06 PDT
This is because the DOM and the XPath data model differ: XPath doesn't have empty text nodes. We don't enforce that everywhere in Transformiix, but probably should do more of these checks instead of less. We could just not throw in this case and return an empty result.
Comment 5 User image Peter Van der Beken [:peterv] 2007-07-17 05:50:09 PDT

"If the context node is a Text or a CDATASection, ..., unless the node is empty in which case it may not serve as the XPath context."
Comment 6 User image Sjoerd Visscher 2007-07-17 05:52:43 PDT
The same goes for document fragments.
This test fails for document fragments, but if I start at a child of the document fragment and add "../" to the xpath expression, everything works fine.

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