xml::xpath_context Class Reference

Context in which XPath expressions can be evaluated. More...

#include <xpath.h>

Public Member Functions
	xpath_context (const xml::document &doc)
	Create XPath context for the given document. More...
void	register_namespace (const std::string &prefix, const std::string &href)
	Register a namespace with prefix. More...
const_nodes_view	evaluate (const std::string &expr, error_handler &on_error=throw_on_error)
	Execute an XPath query in the document scope. More...
const_nodes_view	evaluate (const std::string &expr, const xml::node &n, error_handler &on_error=throw_on_error)
	Execute an XPath query in the scope of XML node n. More...
nodes_view	evaluate (const std::string &expr, xml::node &n, error_handler &on_error=throw_on_error)
	Execute an XPath query in the scope of XML node n. More...

Detailed Description

Context in which XPath expressions can be evaluated.

The context object can (and indeed, should) be reused for multiple XPath queries on the same document.

Since

0.8.0

Constructor & Destructor Documentation

xpath_context()

xml::xpath_context::xpath_context

(

const xml::document &

doc

)

Create XPath context for the given document.

Parameters

doc	Document for the context to work with. The lifetime of the document must be greater than the context object's.

Member Function Documentation

evaluate() [1/3]

const_nodes_view xml::xpath_context::evaluate	(	const std::string &	expr,
		error_handler &	on_error = throw_on_error
	)

Execute an XPath query in the document scope.

Calling this function is exactly equivalent to using the overload taking an xml::node argument with xml::document::get_root_node().

In particular, this implies that if you need to modify nodes in the returned set, you can simple use the non-const overload taking xml::node& argument and pass xml::document::get_root_node() result to it.

evaluate() [2/3]

const_nodes_view xml::xpath_context::evaluate	(	const std::string &	expr,
		const xml::node &	n,
		error_handler &	on_error = throw_on_error
	)

Execute an XPath query in the scope of XML node n.

Parameters

expr	XPath expression.
n	The context node for the expression.
on_error	Error handler throwing an exception if an error occurs during the expression evaluation. Notice that absence of matches isn't considered to be an error, in this case the function just returns an empty set.

Returns

Const set of matching nodes.

evaluate() [3/3]

nodes_view xml::xpath_context::evaluate	(	const std::string &	expr,
		xml::node &	n,
		error_handler &	on_error = throw_on_error
	)

Execute an XPath query in the scope of XML node n.

This overload is identical to the one taking const n argument, except that it returns a set of nodes that can be modified.

register_namespace()

void xml::xpath_context::register_namespace	(	const std::string &	prefix,
		const std::string &	href
	)

Register a namespace with prefix.

This function has to be called in order to be able to evaluate XPath expressions that match nodes in a non-default namespace. Must be called before evaluate().

Parameters

prefix	The prefix used in XPath expressions for the namespace. (Notice that it doesn't have to be the same prefix as used in the XML document.)
href	URI of the namespace used in the document.

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The documentation for this class was generated from the following file:

• xmlwrapp/xpath.h