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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 Utility functions for mathml and mathjax rule store.
*/
goog.provide('cvox.MathmlStoreUtil');
goog.require('cvox.MathUtil');
goog.require('cvox.TraverseMath');
/**
* Retrieves MathML sub element with same id as MathJax node.
* @param {!Node} inner A node internal to a MathJax node.
* @return {Node} The internal MathML node corresponding to the MathJax node.
*/
cvox.MathmlStoreUtil.matchMathjaxToMathml = function(inner) {
var mml = cvox.TraverseMath.getInstance().activeMathmlHost;
return mml.querySelector('#' + inner.id);
};
/**
* Retrieve an extender symbol for a given node.
* @param {!Node} jax The MathJax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.retrieveMathjaxExtender = function(jax) {
var ext = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
if (ext) {
return [ext];
}
return [];
};
/**
* Retrieve an extender symbol for a given node.
* @param {!Node} jax The MathJax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.retrieveMathjaxLeaf = function(jax) {
var leaf = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
if (leaf) {
return [leaf];
}
return [];
};
/**
* For a given MathJax node it returns the equivalent MathML node,
* if it is of the right tag.
* @param {!Node} jax The Mathjax node.
* @param {!string} tag The required tag.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.checkMathjaxTag = function(jax, tag) {
var node = cvox.MathmlStoreUtil.matchMathjaxToMathml(jax);
if (node && node.tagName.toUpperCase() == tag) {
return [node];
}
return [];
};
/**
* Returns MathML node if MathJax is munder.
* @param {!Node} jax The Mathjax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.checkMathjaxMunder = function(jax) {
return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MUNDER');
};
/**
* Returns MathML node if MathJax is mover.
* @param {!Node} jax The Mathjax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.checkMathjaxMover = function(jax) {
return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MOVER');
};
/**
* Returns MathML node if MathJax is msub.
* @param {!Node} jax The Mathjax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.checkMathjaxMsub = function(jax) {
return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MSUB');
};
/**
* Returns MathML node if MathJax is msup.
* @param {!Node} jax The Mathjax node.
* @return {Array<Node>} The resulting node list.
*/
cvox.MathmlStoreUtil.checkMathjaxMsup = function(jax) {
return cvox.MathmlStoreUtil.checkMathjaxTag(jax, 'MSUP');
};
/**
* Constructs a closure that returns separators for an MathML mfenced
* expression.
* Separators in MathML are represented by a list and used up one by one
* until the final element is used as the default.
* Example: a b c d e and separators [+,-,*]
* would result in a + b - c * d * e.
* @param {string} separators String representing a list of mfenced separators.
* @return {function(): string|null} A closure that returns the next separator
* for an mfenced expression starting with the first node in nodes.
*/
cvox.MathmlStoreUtil.nextSeparatorFunction = function(separators) {
if (separators) {
// Mathjax does not expand empty separators.
if (separators.match(/^\s+$/)) {
return null;
} else {
var sepList = separators.replace(/\s/g, '')
.split('')
.filter(function(x) {return x;});
}
} else {
// When no separator is given MathML uses comma as default.
var sepList = [','];
}
return function() {
if (sepList.length > 1) {
return sepList.shift();
}
return sepList[0];
};
};
/**
* Computes the correct separators for each node.
* @param {Array<Node>} nodes A node array.
* @param {string} context A context string.
* @return {function(): string} A closure that returns the next separator for an
* mfenced expression starting with the first node in nodes.
*/
cvox.MathmlStoreUtil.mfencedSeparators = function(nodes, context) {
var nextSeparator = cvox.MathmlStoreUtil.nextSeparatorFunction(context);
return function() {
return nextSeparator ? nextSeparator() : '';
};
};
/**
* Iterates over the list of content nodes of the parent of the given nodes.
* @param {Array<Node>} nodes A node array.
* @param {string} context A context string.
* @return {function(): string} A closure that returns the content of the next
* content node. Returns only context string if list is exhausted.
*/
cvox.MathmlStoreUtil.contentIterator = function(nodes, context) {
if (nodes.length > 0) {
var contentNodes = cvox.XpathUtil.evalXPath('../../content/*', nodes[0]);
} else {
var contentNodes = [];
}
return function() {
var content = contentNodes.shift();
return context + (content ? content.textContent : '');
};
};
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