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mathMLTree.js (2702B)

      1 /**
      2  * These objects store data about MathML nodes. This is the MathML equivalent
      3  * of the types in domTree.js. Since MathML handles its own rendering, and
      4  * since we're mainly using MathML to improve accessibility, we don't manage
      5  * any of the styling state that the plain DOM nodes do.
      6  *
      7  * The `toNode` and `toMarkup` functions work simlarly to how they do in
      8  * domTree.js, creating namespaced DOM nodes and HTML text markup respectively.
      9  */
     10 
     11 const utils = require("./utils");
     12 
     13 /**
     14  * This node represents a general purpose MathML node of any type. The
     15  * constructor requires the type of node to create (for example, `"mo"` or
     16  * `"mspace"`, corresponding to `<mo>` and `<mspace>` tags).
     17  */
     18 function MathNode(type, children) {
     19     this.type = type;
     20     this.attributes = {};
     21     this.children = children || [];
     22 }
     23 
     24 /**
     25  * Sets an attribute on a MathML node. MathML depends on attributes to convey a
     26  * semantic content, so this is used heavily.
     27  */
     28 MathNode.prototype.setAttribute = function(name, value) {
     29     this.attributes[name] = value;
     30 };
     31 
     32 /**
     33  * Converts the math node into a MathML-namespaced DOM element.
     34  */
     35 MathNode.prototype.toNode = function() {
     36     const node = document.createElementNS(
     37         "http://www.w3.org/1998/Math/MathML", this.type);
     38 
     39     for (const attr in this.attributes) {
     40         if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
     41             node.setAttribute(attr, this.attributes[attr]);
     42         }
     43     }
     44 
     45     for (let i = 0; i < this.children.length; i++) {
     46         node.appendChild(this.children[i].toNode());
     47     }
     48 
     49     return node;
     50 };
     51 
     52 /**
     53  * Converts the math node into an HTML markup string.
     54  */
     55 MathNode.prototype.toMarkup = function() {
     56     let markup = "<" + this.type;
     57 
     58     // Add the attributes
     59     for (const attr in this.attributes) {
     60         if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
     61             markup += " " + attr + "=\"";
     62             markup += utils.escape(this.attributes[attr]);
     63             markup += "\"";
     64         }
     65     }
     66 
     67     markup += ">";
     68 
     69     for (let i = 0; i < this.children.length; i++) {
     70         markup += this.children[i].toMarkup();
     71     }
     72 
     73     markup += "</" + this.type + ">";
     74 
     75     return markup;
     76 };
     77 
     78 /**
     79  * This node represents a piece of text.
     80  */
     81 function TextNode(text) {
     82     this.text = text;
     83 }
     84 
     85 /**
     86  * Converts the text node into a DOM text node.
     87  */
     88 TextNode.prototype.toNode = function() {
     89     return document.createTextNode(this.text);
     90 };
     91 
     92 /**
     93  * Converts the text node into HTML markup (which is just the text itself).
     94  */
     95 TextNode.prototype.toMarkup = function() {
     96     return utils.escape(this.text);
     97 };
     98 
     99 module.exports = {
    100     MathNode: MathNode,
    101     TextNode: TextNode,
    102 };