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SXPath - SXML Query Language

SXPath is a query language for SXML. It treats a location path as a composite query over an XPath tree or its branch. A single step is a combination of a projection, selection or a transitive closure. Multiple steps are combined via join and union operations.

Lower-level SXPath consists of a set of predicates, filters, selectors and combinators, and higher-level abbreviated SXPath functions which are implemented in terms of lower-level functions.

Higher level SXPath functions are dealing with XPath expressions which may be represented as a list of steps in the location path ("native" SXPath):
(sxpath '(table (tr 3) td @ align))
or as a textual representation of XPath expressions which is compatible with W3C XPath recommendation ("textual" SXPath):
(sxpath "table/tr[3]/td/@align")

An arbitrary converter implemented as a Scheme function may be used as a step in location path of "native" SXPath, which makes it extremely powerful and flexible tool. On other hand, a lot of W3C Recommendations such as XSLT, XPointer, XLink depends on a textual XPath expressions.

It is possible to combine "native" and "textual" location paths and location step functions in one query, constructing an arbitrary XML query far beyond capabilities of XPath. For example, the query
(sxpath `("document/chapter[3]" ,relevant-links @ author)
makes a use of location step function relevant-links which implements an arbitrary algorithm in Scheme.

SXPath may be considered as a compiler from abbreviated XPath (extended with native SXPath and location step functions) to SXPath primitives.


Tutorial and examples

SSAX-SXML at SourceForge
SXPath is a part of this project

Oleg Kiselyov's page on SXPath

ILC'2002 Paper
XML, XPath, XSLT implementations as SXML, SXPath, and SXSLT
Presentation transcript


SourceForge CVS

Test fixture

PLT Collection

Bigloo package
maintained by D. Lizorkin

Gauche module
maintained by Shiro Kawai

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