cxml-devel May 2007

cxml-devel@common-lisp.net

3 participants
4 discussions

[cxml-devel] New release: cxml-rng
by David Lichteblau 26 May '07

26 May '07

Hi, the first release of cxml-rng is available for download at http://www.lichteblau.com/cxml-rng/ cxml-rng is an implementation of Relax NG schema validation, including support for compact syntax, DTD Compatibility, and the XSD type library. Make sure to upgrade to today's CXML release before trying cxml-rng. d.

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[cxml-devel] New release: cxml
by David Lichteblau 26 May '07

26 May '07

Hi, a new release tarball is available for download. * cxml.asd has been split up into cxml.asd for the XML parser and runes.asd for the runes package, in preparation of a complete split of the two systems. Future CXML releases will use separate tarballs for runes and cxml. * xml:base support (SAX and Klacks only, not yet used in DOM). * New class broadcast-handler as a generalization of the older sax-proxy. * New class tapping-source, a klacks source that relays events from an upstream klacks source unchanged, while also emitting them as SAX events to a user-specified handler at the same time. * Changed attributes to carry an lname even when occurring without a namespace. Added new functions attribute*, unparse-attribute, and macro with-element*, with-namespace* to the SAX generation wrapper API. * Klacks improvements: Incompatibly changed klacks:find-element and find-event to consider the current event as a result. Added klacks-error, klacks:expect, klacks:skip, klacks:expecting-element. Fixed serialize-event to generate start-prefix-mapping and end-prefix-mapping events. New function map-current-namespace-declarations. * fixed build with common-lisp-controller

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[cxml-devel] Bugs in namespace parsing.
by Peder Chr. Nørgaard 22 May '07

22 May '07

I think I have run into a pretty bad bug in namespace handling in Closure XML. Of course, I may just be using the code wrongly. I am using the 2007-02-18 tarball of cxml on a piece of XML code from RFC 4741 (netconf protocol): (defvar example "<rpc message-id=\"101\" xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\"> <my-own-method xmlns=\"http://example.net/me/my-own/1.0\"> <my-first-parameter>14</my-first-parameter> <another-parameter>fred</another-parameter> </my-own-method> </rpc>") I run (defvar p-example (cxml:parse-stream (make-string-input-stream example) cxml-xmls:make-xmls-builder))) This is the result: (("rpc" (("xmlns" "urn:ietf:params:xml:ns:netconf:base:1.0") ("message-id" "101")) " " ("my-own-method" (("xmlns" "http://example.net/me/my-own/1.0")) " " ("my-first-parameter" NIL "14") " " ("another-parameter" NIL "fred") " ") " ")) It should have been something like ((("rpc" . "urn:ietf:params:xml:ns:netconf:base:1.0") (("xmlns" "urn:ietf:params:xml:ns:netconf:base:1.0") (("message-id" . "urn:ietf:params:xml:ns:netconf:base:1.0") "101")) " " (("my-own-method" . "http://example.net/me/my-own/1.0") (("xmlns" "http://example.net/me/my-own/1.0")) " " (("my-first-parameter" . "http://example.net/me/my-own/1.0) NIL "14") " " (("another-parameter" . "http://example.net/me/my-own/1.0) NIL "fred") " ") " ")) There seems to be not one, but two problems. First, the parser or the builder ignores the rule that the scope of an xmlns attribute starts from the tag of the element in which it is included. Second, (and that is probably the builder) fail to apply the default namespace to internal elements. FYI, XMLS has the approximately the same kind of bug. So has the PXML suite from Franz. It is evidently something that is a bit tough to get right. Maybe because it involves two scans of a <> construction - you really don't know the namespace of tags and attributes until you have parsed the entire <> construction and located the zero-or-one "xmlns=" and the zero-one-or-many "xmlns:<name>=" attributes. best regards -- Peder Chr. Nørgaard e-mail: pcn(a)pogt.dk Gefionsvej 19 spejder-e-mail: hathi(a)gallerne.dk DK-8230 Åbyhøj tel: +45 87 44 11 99 Denmark mob: +45 30 91 84 31

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[cxml-devel] XPath in CXML
by Chas Emerick 13 May '07

13 May '07

Greetings, I noticed a post by David Lichteblau on c.l.l where it was mentioned that an XPath impl for CXML is on a todo list. This is something that I've had a run at, although my end point turned out to be far from the XPath standard. Rather than implementing XPath itself, I implemented a "lispy" element set addressing scheme. By lispy, I mean that rather than addressing nodesets using strings, a declarative DSL is used. Here's an example that yields the title element in an XHTML document: (xmatch :root "html" "head" "title") Here's one that yields all of the TD elements in an XHTML document that have a colspan attribute: (xmatch :root (:desc "td" (:@ "colspan"))) And here's one that yields the second TD element in each row of a table, only if it has a colspan of '1': (xmatch "tr" (:child "td" (:@value "colspan" "1"))) The first two examples are context-free, thanks to the :root directive; the third would need to be run on a table element (or list thereof). If it isn't already clear, xmatch is a macro that builds a closure that, when provided with an element, document, or list as context, returns the node-set that matches the XPath-esque definition. This makes it very similar in style and usage to cl-ppcre:create-scanner. It supports a subset of XPath predicates (such as :@, :@value, :index, and a few others) that I have needed in my application so far, but is by no means complete. I'm passing this information on, not because I have code I'm ready to contribute at the moment (although that could be arranged given some time), but because I think this approach (while not standards- compliant) is superior to any potential "direct" XPath implementation for CXML. Perhaps CXML could grow something like xmatch; in addition to it being used directly, a "proper" XPath implementation could be built on top of an xmatch-like facility. I don't want to belabor the point, but this approach is far more flexible, allows for a much richer set of predicates (and custom ones, at that), and doesn't confine the match definition to a flat string -- sexps are good here, for the same reasons why they are good elsewhere. For example, I have a couple of other macros that generate xmatch definitions themselves; XPath strings *can* be generated dynamically, but that is a Dark Path (at least by my standards). I hope I'm not suggesting anything patently obvious -- I'm functionally new to Lisp (again, this being my second tour of duty, after a long hiatus), so this may all be elementary to others. Thanks for your time, Chas Emerick Founder, Snowtide Informatics Systems Enterprise-class PDF content extraction cemerick(a)snowtide.com http://snowtide.com

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cxml-devel May 2007