25931 2009-05-21 07:06:36 -0700 XPath' position() fails to match elements 2009-05-27 06:07:42 -0700 1 1 1 Unclassified WebKit XML 528+ (Nightly build) Mac OS X 10.5 RESOLVED INVALID http://yura.thinkweb2.com/cft/#IS_XPATH_POSITION_FUNCTION_BUGGY P2 Normal --- 1 kangax ap fearphage+bugmail oldest_to_newest 122348 0 kangax 2009-05-21 07:06:36 -0700 Please, see attached url with a testcase. Only Firefox 3.0.x gets this right so far. I just checked it with latest WebKit nightly (r43887) and the test still fails. Thank you. 122711 1 30586 ap 2009-05-22 11:48:47 -0700 Created attachment 30586 test case Actually, I do not think that Firefox gets this nearly right. Here is what I think the expression in your test means: //*[position() = 2] is an abbreviated syntax for /descendant-or-self::node()/child:*[position() = 2]. It is an absolute path, so the context you pass in Document.evaluate() will be completely ignored (thus, document.evaluate(xpath, el, ...) is exactly the same as document.evaluate(xpath, document, ...)). The first step of this location path, obviously, selects all nodes in a document, including the document node itself. The next step selects all element children that have position 2 within their respective containers (NOT the second element in the document, and definitely not the second element in the test <div>). Since the position is computed respecting Text and other non-element nodes, it is entirely possible that no element will have position 2, even in a large container. Note the following example in XPath 1.0 specification: "The location path //para[1] does not mean the same as the location path /descendant::para[1]. The latter selects the first descendant para element; the former selects all descendant para elements that are the first para children of their parents." So, I think that your test case actually shows a bug in Firefox XPath implementation - namely, the absolute path there is treated as if it were relative. Attaching a larger test I made while investigating this. I cannot explain some of WebKit's results on this test, so I need to look at this test deeper. 122741 2 kangax 2009-05-22 15:28:22 -0700 Alexey, thanks for an explanation; It definitely makes sense. I see that both - WebKit and Opera (10a) - return proper results when given a relative expression - "*[position()=2]". I'm not sure if this is a bug per se (and if I should file it with them), or if Firefox just tries to be "unobtrusively helpful" by treating absolute expressions as relative ones when evaluating in a non-global context. 122806 3 ap 2009-05-22 23:14:10 -0700 Please file a bug with Mozilla - if that's intentional, we'll learn the reasons, and would consider matching Firefox to make life easier for developers. I'm going to keep this bug open to investigate the apparent mysteries in the attached test case (but to avoid confusion, I'll need to open new bugs if I find real problems). 123008 4 ap 2009-05-24 23:31:45 -0700 (In reply to comment #1) > Since the position is computed respecting Text and other > non-element nodes, it is entirely possible that no element will have position > 2, even in a large container. I was wrong here - the node set as seen in predicates is one after applying the node filter. 123018 5 ap 2009-05-25 00:35:44 -0700 Filed bug 26005 for a problem I found with my test, closing as INVALID since the originally reported issue is not a bug. Please post a Mozilla bug URL here for future reference if you decide to file one. 123104 6 kangax 2009-05-25 22:09:37 -0700 Filed with Mozilla - <https://bugzilla.mozilla.org/show_bug.cgi?id=494842> 123281 7 30707 fearphage+bugmail 2009-05-27 06:07:08 -0700 Created attachment 30707 test case showing before and after dom append As best I can discern the spec http://www.w3.org/TR/xpath#path-abbrev : "//para selects all the para descendants of the document root and thus selects all para elements in the same document as the context node" There exist no parent document for the context node in the original URL, thus there should be no answer (null). Firefox 2 returned null and Opera currently returns null in this case. However once it is appended to the document, the answer refers to the root element as it should. The bug here is that you are executing from the current document root regardless of whether the context node exist in the document or not. 30586 2009-05-22 11:48:47 -0700 2009-05-22 11:48:47 -0700 test case position.html text/html 4891 ap PCFET0NUWVBFIGh0bWw+CjxodG1sPgo8aGVhZD4KPGJhc2UgaHJlZj0iaHR0cDovL3RyYWMud2Vi a2l0Lm9yZy9leHBvcnQvNDQwNDkvdHJ1bmsvTGF5b3V0VGVzdHMvZmFzdC94cGF0aC9wb3NpdGlv bi5odG1sIj4KPGxpbmsgcmVsPSJzdHlsZXNoZWV0IiBocmVmPSIuLi9qcy9yZXNvdXJjZXMvanMt dGVzdC1zdHlsZS5jc3MiPgo8c2NyaXB0IHNyYz0iLi4vanMvcmVzb3VyY2VzL2pzLXRlc3QtcHJl LmpzIj48L3NjcmlwdD4KPHNjcmlwdCBzcmM9InhwYXRoLXRlc3QtcHJlLmpzIj48L3NjcmlwdD4K PC9oZWFkPgo8Ym9keT4KPGI+VGhlc2UgcmVzdWx0cyBhcmUgdGFrZW4gZnJvbSBGaXJlZm94LCB3 aGljaCBJIHRoaW5rIGlzIHdyb25nLjwvYj4KPGRpdiBpZD0iY29uc29sZSI+PC9kaXY+Cgo8c2Ny aXB0PgoKdmFyIFJPT1QgPSBkb2N1bWVudC5jcmVhdGVFbGVtZW50KCdkaXYnKTsKUk9PVC5pbm5l ckhUTUwgPSAnPHA+YTwvcD48ZGl2PmI8c3Bhbj48L3NwYW4+PC9kaXY+JzsKdmFyIENISUxEMSA9 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