问题
I've tried to use the XPath 2.0
exp //span/string(.)
in libxml2
, but it doesn't work.
So, my question is: does libxml2
support XPath 2.0
or not?
回答1:
As far as I know -- not. The prevailing majority of XPath 2.0 implementations are part of XSLT 2.0 processors or XQuery processors.
回答2:
According to this 2007 email from the maintainer of libxml2, libxml2 does not, and will not, support XPath 2.0.
回答3:
you might be interested in an XPath 2.0 extension to libxml2 - however, 2 caveats apply: it's work in progress and it's free for non-commercial use only.
hope this helps,
best regards, carsten
ps: i am neither affiliated with the guys working on libx nor have i any personal experience on using it or knowledge beyond the info from their website.
回答4:
Libxml2 implements a number of existing standards related to markup languages:
the XML standard: http://www.w3.org/TR/REC-xml Namespaces in XML: http://www.w3.org/TR/REC-xml-names/ XML Base: http://www.w3.org/TR/xmlbase/ RFC 2396 : Uniform Resource Identifiers http://www.ietf.org/rfc/rfc2396.txt XML Path Language (XPath) 1.0: http://www.w3.org/TR/xpath HTML4 parser: http://www.w3.org/TR/html401/ XML Pointer Language (XPointer) Version 1.0: http://www.w3.org/TR/xptr XML Inclusions (XInclude) Version 1.0: http://www.w3.org/TR/xinclude/ ISO-8859-x encodings, as well as rfc2044 [UTF-8] and rfc2781 [UTF-16] Unicode encodings, and more if using iconv support part of SGML Open Technical Resolution TR9401:1997 XML Catalogs Working Draft 06 August 2001: http://www.oasis-open.org/committees/entity/spec-2001-08-06.html Canonical XML Version 1.0: http://www.w3.org/TR/xml-c14n and the Exclusive XML Canonicalization CR draft http://www.w3.org/TR/xml-exc-c14n Relax NG, ISO/IEC 19757-2:2003, http://www.oasis-open.org/committees/relax-ng/spec-20011203.html W3C XML Schemas Part 2: Datatypes REC 02 May 2001 W3C xml:id Working Draft 7 April 2004
Since libxml2 supports XPath 1.0, the syntax is incorrect:
//span/string(.)
Should be:
string(//span/.)
For clarification, the string
method is part of XPath 1.0 as well. For future reference:
libxml2 supports XPath 1.0
Objective-C supports XPath 2.0 via the
nodesForXPath
method of NSXMLNode in GNUStep/NextStep
The Cocoa implementation uses XPath 2.0, which is a World Wide Web Consortium recommendation.
References
NSXML Concepts: XML Glossary
NSXML Concepts: Querying an XML Document
NSXMLNode: nodesForXPath
GNUStep: NSXMLNode Class Documentation
GalaXquery
PsychoPathXPathProcessor
CoreServicesLayer
libxml, a.k.a. gnome-xml
来源:https://stackoverflow.com/questions/6586896/does-libxml2-support-xpath-2-0-or-not