elemental.xpath

Interface XPathEvaluator

All Known Implementing Classes:

JsXPathEvaluator

public interface XPathEvaluator

dom/interfaces/xpath/nsIDOMXPathEvaluator.idlScriptable

This interface is used to evaluate XPath expressions against a DOM node.

Inherits from: nsISupports Last changed in Gecko 1.7

Implemented by: @mozilla.org/dom/xpath-evaluator;1. To create an instance, use:

var domXPathEvaluator = Components.classes["@mozilla.org/dom/xpath-evaluator;1"]
                        .createInstance(Components.interfaces.nsIDOMXPathEvaluator);

Method Summary

Methods

Modifier and Type	Method and Description
XPathExpression	createExpression(String expression, XPathNSResolver resolver) Creates an nsIDOMXPathExpression which can then be used for (repeated) evaluations.
XPathNSResolver	createNSResolver(Node nodeResolver) Creates an nsIDOMXPathExpression which resolves name spaces with respect to the definitions in scope for a specified node.
XPathResult	evaluate(String expression, Node contextNode, XPathNSResolver resolver, int type, XPathResult inResult) Evaluate the specified XPath expression.

Method Detail

createExpression

XPathExpression createExpression(String expression,
                               XPathNSResolver resolver)

Creates an nsIDOMXPathExpression which can then be used for (repeated) evaluations.

Gecko 1.9 note

(Firefox 3)

Prior to Gecko 1.9, you could call this method on documents other than the one you planned to run the XPath against; starting with Gecko 1.9, however, you must call it on the same document.

Parameters

expression

A string representing the XPath to be created.

resolver

A name space resolver created by , or a user defined name space resolver. Read more on Implementing a User Defined Namespace Resolver if you wish to take the latter approach.

Return value

An XPath expression, as an nsIDOMXPathExpression object.

createNSResolver

XPathNSResolver createNSResolver(Node nodeResolver)

Creates an nsIDOMXPathExpression which resolves name spaces with respect to the definitions in scope for a specified node. It is used to resolve prefixes within the XPath itself, so that they can be matched with the document. null is common for HTML documents or when no name space prefixes are used.

Parameters

nodeResolver

The node to be used as a context for name space resolution.

Return value

A name space resolver.

evaluate

XPathResult evaluate(String expression,
                   Node contextNode,
                   XPathNSResolver resolver,
                   int type,
                   XPathResult inResult)

Evaluate the specified XPath expression.

Parameters

expression

A string representing the XPath to be evaluated.

contextNode

A DOM Node to evaluate the XPath expression against. To evaluate against a whole document, use the document.documentElement .

resolver

A name space resolver created by , or a user defined name space resolver. Read more on Implementing a User Defined Namespace Resolver if you wish to take the latter approach.

type

A number that corresponds to one of the type constants of nsIXPathResult .

result

An existing nsIXPathResult to use for the result. Using null will create a new nsIXPathResult .

Return value

An XPath result.