README

-*- outline -*-

* Dependencies
The XPath-plugin depends on following libraries and programs:

** dlvhex
Naturally, dlvhex must already be installed on the system.

** libxml2
http://xmlsoft.org/

* Building and installing dlvhex-xpathplugin

** Prerequisites

*** dlvhex
For instructions how to install dlvhex, see the respective README there.

** Configuration
Run "configure" to create the necessary Makefiles. If you want to install the
plugin locally in your home, use the configure-switch --enable-userinstall
(then, the plugin will be installed in ~/.dlvhex/plugins, where dlvhex will
find it). Otherwise, the default installation is automatically determined from
the configuration of dlvhex (usually /usr/local/lib/dlvhex/plugins or similar).

** Installation
Run "make install" to install the plugin. It will be placed at a location
determined by configure.

* Using the XPath-plugin
The XPath-plugin provides a single atom, &xpath, to read atomic values from
a given XML file using XPath queries:

	&xpath[uri,xpath_query](X).
	
The input constant "uri" denotes the location of the XML file. It could either
be the path to a local file or to a web address.
The input constant xpath_query can be every XPath query that returns atomic values
(values and attribute values).
Please note: The XPath-plugin does not handle results that contain non-atomic values.