chrome/browser/resources/chromeos/chromevox/common/xpath_util.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview A collection of JavaScript utilities used to simplify working
   7  * with xpaths.
   8  */
   9
  10
  11 goog.provide('cvox.XpathUtil');
  12
  13
  14 /**
  15  * Utilities for simplifying working with xpaths
  16  * @constructor
  17  */
  18 cvox.XpathUtil = function() {
  19  };
  20
  21
  22 /**
  23  * Mapping for some default namespaces.
  24  * @const
  25  * @private
  26  */
  27 cvox.XpathUtil.nameSpaces_ = {
  28   'xhtml' : 'http://www.w3.org/1999/xhtml',
  29   'mathml': 'http://www.w3.org/1998/Math/MathML'
  30 };
  31
  32
  33 /**
  34  * Resolve some default name spaces.
  35  * @param {string} prefix Namespace prefix.
  36  * @return {string} The corresponding namespace URI.
  37  */
  38 cvox.XpathUtil.resolveNameSpace = function(prefix) {
  39   return cvox.XpathUtil.nameSpaces_[prefix] || null;
  40 };
  41
  42
  43 /**
  44  * Given an XPath expression and rootNode, it returns an array of children nodes
  45  * that match. The code for this function was taken from Mihai Parparita's GMail
  46  * Macros Greasemonkey Script.
  47  * http://gmail-greasemonkey.googlecode.com/svn/trunk/scripts/gmail-new-macros.user.js
  48  * @param {string} expression The XPath expression to evaluate.
  49  * @param {Node} rootNode The HTML node to start evaluating the XPath from.
  50  * @return {Array} The array of children nodes that match.
  51  */
  52 cvox.XpathUtil.evalXPath = function(expression, rootNode) {
  53   try {
  54     var xpathIterator = rootNode.ownerDocument.evaluate(
  55       expression,
  56       rootNode,
  57       cvox.XpathUtil.resolveNameSpace,
  58       XPathResult.ORDERED_NODE_ITERATOR_TYPE,
  59       null); // no existing results
  60   } catch (err) {
  61     return [];
  62   }
  63   var results = [];
  64   // Convert result to JS array
  65   for (var xpathNode = xpathIterator.iterateNext();
  66        xpathNode;
  67        xpathNode = xpathIterator.iterateNext()) {
  68     results.push(xpathNode);
  69   }
  70   return results;
  71 };
  72
  73 /**
  74  * Given a rootNode, it returns an array of all its leaf nodes.
  75  * @param {Node} rootNode The node to get the leaf nodes from.
  76  * @return {Array} The array of leaf nodes for the given rootNode.
  77  */
  78 cvox.XpathUtil.getLeafNodes = function(rootNode) {
  79   try {
  80     var xpathIterator = rootNode.ownerDocument.evaluate(
  81       './/*[count(*)=0]',
  82       rootNode,
  83       null, // no namespace resolver
  84       XPathResult.ORDERED_NODE_ITERATOR_TYPE,
  85       null); // no existing results
  86   } catch (err) {
  87     return [];
  88   }
  89   var results = [];
  90   // Convert result to JS array
  91   for (var xpathNode = xpathIterator.iterateNext();
  92        xpathNode;
  93        xpathNode = xpathIterator.iterateNext()) {
  94     results.push(xpathNode);
  95   }
  96   return results;
  97 };
  98
  99 /**
 100  * Returns whether or not xpath is supported.
 101  * @return {boolean} True if xpath is supported.
 102  */
 103 cvox.XpathUtil.xpathSupported = function() {
 104   if (typeof(XPathResult) == 'undefined') {
 105     return false;
 106   }
 107   return true;
 108 };
 109
 110
 111 /**
 112  * Given an XPath expression and rootNode, it evaluates the XPath expression as
 113  * a boolean type and returns the result.
 114  * @param {string} expression The XPath expression to evaluate.
 115  * @param {Node} rootNode The HTML node to start evaluating the XPath from.
 116  * @return {boolean} The result of evaluating the xpath expression.
 117  */
 118 cvox.XpathUtil.evaluateBoolean = function(expression, rootNode) {
 119   try {
 120     var xpathResult = rootNode.ownerDocument.evaluate(
 121         expression,
 122         rootNode,
 123         cvox.XpathUtil.resolveNameSpace,
 124         XPathResult.BOOLEAN_TYPE,
 125         null); // no existing results
 126   } catch (err) {
 127     return false;
 128   }
 129   return xpathResult.booleanValue;
 130 };
 131
 132
 133 /**
 134  * Given an XPath expression and rootNode, it evaluates the XPath expression as
 135  * a string type and returns the result.
 136  * @param {string} expression The XPath expression to evaluate.
 137  * @param {Node} rootNode The HTML node to start evaluating the XPath from.
 138  * @return {string} The result of evaluating the Xpath expression.
 139  */
 140 cvox.XpathUtil.evaluateString = function(expression, rootNode) {
 141   try {
 142     var xpathResult = rootNode.ownerDocument.evaluate(
 143         expression,
 144         rootNode,
 145         cvox.XpathUtil.resolveNameSpace,
 146         XPathResult.STRING_TYPE,
 147         null); // no existing results
 148   } catch (err) {
 149     return '';
 150   }
 151   return xpathResult.stringValue;
 152 };