chrome/browser/resources/chromeos/chromevox/speech_rules/mathml_store_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 Utility functions for mathml and mathjax rule store.
   7  */
   8
   9 goog.provide('cvox.MathmlStoreUtil');
  10
  11 goog.require('cvox.MathUtil');
  12 goog.require('cvox.TraverseMath');
  13
  14
  15 /**
  16  * Retrieves MathML sub element with same id as MathJax node.
  17  * @param {!Node} inner A node internal to a MathJax node.
  18  * @return {Node} The internal MathML node corresponding to the MathJax node.
  19  */
  20 cvox.MathmlStoreUtil.matchMathjaxToMathml = function(inner) {
  21   var mml = cvox.TraverseMath.getInstance().activeMathmlHost;
  22   return mml.querySelector('#' + inner.id);
  23 };
  24
  25
  26 /**
  27  * Retrieve an extender symbol for a given node.
  28  * @param {!Node} jax The MathJax node.
  29  * @return {Array<Node>} The resulting node list.
  30  */
  31 cvox.MathmlStoreUtil.retrieveMathjaxExtender = function(jax) {
  32   var ext = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
  33   if (ext) {
  34     return [ext];
  35   }
  36   return [];
  37 };
  38
  39
  40 /**
  41  * Retrieve an extender symbol for a given node.
  42  * @param {!Node} jax The MathJax node.
  43  * @return {Array<Node>} The resulting node list.
  44  */
  45 cvox.MathmlStoreUtil.retrieveMathjaxLeaf = function(jax) {
  46   var leaf = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
  47   if (leaf) {
  48     return [leaf];
  49   }
  50   return [];
  51 };
  52
  53
  54 /**
  55  * For a given MathJax node it returns the equivalent MathML node,
  56  * if it is of the right tag.
  57  * @param {!Node} jax The Mathjax node.
  58  * @param {!string} tag The required tag.
  59  * @return {Array<Node>} The resulting node list.
  60  */
  61 cvox.MathmlStoreUtil.checkMathjaxTag = function(jax, tag) {
  62   var node = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
  63   if (node && node.tagName.toUpperCase() == tag) {
  64     return [node];
  65   }
  66   return [];
  67 };
  68
  69
  70 /**
  71  * Returns MathML node if MathJax is munder.
  72  * @param {!Node} jax The Mathjax node.
  73  * @return {Array<Node>} The resulting node list.
  74  */
  75 cvox.MathmlStoreUtil.checkMathjaxMunder = function(jax) {
  76   return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MUNDER');
  77 };
  78
  79
  80 /**
  81  * Returns MathML node if MathJax is mover.
  82  * @param {!Node} jax The Mathjax node.
  83  * @return {Array<Node>} The resulting node list.
  84  */
  85 cvox.MathmlStoreUtil.checkMathjaxMover = function(jax) {
  86   return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MOVER');
  87 };
  88
  89
  90 /**
  91  * Returns MathML node if MathJax is msub.
  92  * @param {!Node} jax The Mathjax node.
  93  * @return {Array<Node>} The resulting node list.
  94  */
  95 cvox.MathmlStoreUtil.checkMathjaxMsub = function(jax) {
  96   return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MSUB');
  97 };
  98
  99
 100 /**
 101  * Returns MathML node if MathJax is msup.
 102  * @param {!Node} jax The Mathjax node.
 103  * @return {Array<Node>} The resulting node list.
 104  */
 105 cvox.MathmlStoreUtil.checkMathjaxMsup = function(jax) {
 106   return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MSUP');
 107 };
 108
 109
 110 /**
 111  * Constructs a closure that returns separators for an MathML mfenced
 112  * expression.
 113  * Separators in MathML are represented by a list and used up one by one
 114  * until the final element is used as the default.
 115  * Example: a b c d e  and separators [+,-,*]
 116  * would result in a + b - c * d * e.
 117  * @param {string} separators String representing a list of mfenced separators.
 118  * @return {function(): string|null} A closure that returns the next separator
 119  * for an mfenced expression starting with the first node in nodes.
 120  */
 121 cvox.MathmlStoreUtil.nextSeparatorFunction = function(separators) {
 122   if (separators) {
 123     // Mathjax does not expand empty separators.
 124     if (separators.match(/^\s+$/)) {
 125       return null;
 126     } else {
 127       var sepList = separators.replace(/\s/g, '')
 128           .split('')
 129               .filter(function(x) {return x;});
 130     }
 131   } else {
 132     // When no separator is given MathML uses comma as default.
 133     var sepList = [','];
 134   }
 135
 136   return function() {
 137     if (sepList.length > 1) {
 138       return sepList.shift();
 139     }
 140     return sepList[0];
 141   };
 142 };
 143
 144
 145 /**
 146  * Computes the correct separators for each node.
 147  * @param {Array<Node>} nodes A node array.
 148  * @param {string} context A context string.
 149  * @return {function(): string} A closure that returns the next separator for an
 150  * mfenced expression starting with the first node in nodes.
 151  */
 152 cvox.MathmlStoreUtil.mfencedSeparators = function(nodes, context) {
 153   var nextSeparator = cvox.MathmlStoreUtil.nextSeparatorFunction(context);
 154   return function() {
 155     return nextSeparator ? nextSeparator() : '';
 156   };
 157 };
 158
 159
 160 /**
 161  * Iterates over the list of content nodes of the parent of the given nodes.
 162  * @param {Array<Node>} nodes A node array.
 163  * @param {string} context A context string.
 164  * @return {function(): string} A closure that returns the content of the next
 165  *     content node. Returns only context string if list is exhausted.
 166  */
 167 cvox.MathmlStoreUtil.contentIterator = function(nodes, context) {
 168   if (nodes.length > 0) {
 169     var contentNodes = cvox.XpathUtil.evalXPath('../../content/*', nodes[0]);
 170   } else {
 171     var contentNodes = [];
 172   }
 173   return function() {
 174     var content = contentNodes.shift();
 175     return context + (content ? content.textContent : '');
 176   };
 177 };