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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview A collection of JavaScript utilities used to simplify working
* with xpaths.
*/
goog.provide('cvox.XpathUtil');
/**
* Utilities for simplifying working with xpaths
* @constructor
*/
cvox.XpathUtil = function() {
};
/**
* Mapping for some default namespaces.
* @const
* @private
*/
cvox.XpathUtil.nameSpaces_ = {
'xhtml' : 'http://www.w3.org/1999/xhtml',
'mathml': 'http://www.w3.org/1998/Math/MathML'
};
/**
* Resolve some default name spaces.
* @param {string} prefix Namespace prefix.
* @return {string} The corresponding namespace URI.
*/
cvox.XpathUtil.resolveNameSpace = function(prefix) {
return cvox.XpathUtil.nameSpaces_[prefix] || null;
};
/**
* Given an XPath expression and rootNode, it returns an array of children nodes
* that match. The code for this function was taken from Mihai Parparita's GMail
* Macros Greasemonkey Script.
* http://gmail-greasemonkey.googlecode.com/svn/trunk/scripts/gmail-new-macros.user.js
* @param {string} expression The XPath expression to evaluate.
* @param {Node} rootNode The HTML node to start evaluating the XPath from.
* @return {Array} The array of children nodes that match.
*/
cvox.XpathUtil.evalXPath = function(expression, rootNode) {
try {
var xpathIterator = rootNode.ownerDocument.evaluate(
expression,
rootNode,
cvox.XpathUtil.resolveNameSpace,
XPathResult.ORDERED_NODE_ITERATOR_TYPE,
null); // no existing results
} catch (err) {
return [];
}
var results = [];
// Convert result to JS array
for (var xpathNode = xpathIterator.iterateNext();
xpathNode;
xpathNode = xpathIterator.iterateNext()) {
results.push(xpathNode);
}
return results;
};
/**
* Given a rootNode, it returns an array of all its leaf nodes.
* @param {Node} rootNode The node to get the leaf nodes from.
* @return {Array} The array of leaf nodes for the given rootNode.
*/
cvox.XpathUtil.getLeafNodes = function(rootNode) {
try {
var xpathIterator = rootNode.ownerDocument.evaluate(
'.//*[count(*)=0]',
rootNode,
null, // no namespace resolver
XPathResult.ORDERED_NODE_ITERATOR_TYPE,
null); // no existing results
} catch (err) {
return [];
}
var results = [];
// Convert result to JS array
for (var xpathNode = xpathIterator.iterateNext();
xpathNode;
xpathNode = xpathIterator.iterateNext()) {
results.push(xpathNode);
}
return results;
};
/**
* Returns whether or not xpath is supported.
* @return {boolean} True if xpath is supported.
*/
cvox.XpathUtil.xpathSupported = function() {
if (typeof(XPathResult) == 'undefined') {
return false;
}
return true;
};
/**
* Given an XPath expression and rootNode, it evaluates the XPath expression as
* a boolean type and returns the result.
* @param {string} expression The XPath expression to evaluate.
* @param {Node} rootNode The HTML node to start evaluating the XPath from.
* @return {boolean} The result of evaluating the xpath expression.
*/
cvox.XpathUtil.evaluateBoolean = function(expression, rootNode) {
try {
var xpathResult = rootNode.ownerDocument.evaluate(
expression,
rootNode,
cvox.XpathUtil.resolveNameSpace,
XPathResult.BOOLEAN_TYPE,
null); // no existing results
} catch (err) {
return false;
}
return xpathResult.booleanValue;
};
/**
* Given an XPath expression and rootNode, it evaluates the XPath expression as
* a string type and returns the result.
* @param {string} expression The XPath expression to evaluate.
* @param {Node} rootNode The HTML node to start evaluating the XPath from.
* @return {string} The result of evaluating the Xpath expression.
*/
cvox.XpathUtil.evaluateString = function(expression, rootNode) {
try {
var xpathResult = rootNode.ownerDocument.evaluate(
expression,
rootNode,
cvox.XpathUtil.resolveNameSpace,
XPathResult.STRING_TYPE,
null); // no existing results
} catch (err) {
return '';
}
return xpathResult.stringValue;
};
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