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      1 // Copyright (c) 2012 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 This is a simple template engine inspired by JsTemplates
      7  * optimized for i18n.
      8  *
      9  * It currently supports three handlers:
     10  *
     11  *   * i18n-content which sets the textContent of the element.
     12  *
     13  *     <span i18n-content="myContent"></span>
     14  *
     15  *   * i18n-options which generates <option> elements for a <select>.
     16  *
     17  *     <select i18n-options="myOptionList"></select>
     18  *
     19  *   * i18n-values is a list of attribute-value or property-value pairs.
     20  *     Properties are prefixed with a '.' and can contain nested properties.
     21  *
     22  *     <span i18n-values="title:myTitle;.style.fontSize:fontSize"></span>
     23  *
     24  * This file is a copy of i18n_template.js, with minor tweaks to support using
     25  * load_time_data.js. It should replace i18n_template.js eventually.
     26  */
     27 
     28 var i18nTemplate = (function() {
     29   /**
     30    * This provides the handlers for the templating engine. The key is used as
     31    * the attribute name and the value is the function that gets called for every
     32    * single node that has this attribute.
     33    * @type {Object}
     34    */
     35   var handlers = {
     36     /**
     37      * This handler sets the textContent of the element.
     38      * @param {HTMLElement} element The node to modify.
     39      * @param {string} key The name of the value in the dictionary.
     40      * @param {LoadTimeData} dictionary The dictionary of strings to draw from.
     41      */
     42     'i18n-content': function(element, key, dictionary) {
     43       element.textContent = dictionary.getString(key);
     44     },
     45 
     46     /**
     47      * This handler adds options to a <select> element.
     48      * @param {HTMLElement} select The node to modify.
     49      * @param {string} key The name of the value in the dictionary. It should
     50      *     identify an array of values to initialize an <option>. Each value,
     51      *     if a pair, represents [content, value]. Otherwise, it should be a
     52      *     content string with no value.
     53      * @param {LoadTimeData} dictionary The dictionary of strings to draw from.
     54      */
     55     'i18n-options': function(select, key, dictionary) {
     56       var options = dictionary.getValue(key);
     57       options.forEach(function(optionData) {
     58         var option = typeof optionData == 'string' ?
     59             new Option(optionData) :
     60             new Option(optionData[1], optionData[0]);
     61         select.appendChild(option);
     62       });
     63     },
     64 
     65     /**
     66      * This is used to set HTML attributes and DOM properties. The syntax is:
     67      *   attributename:key;
     68      *   .domProperty:key;
     69      *   .nested.dom.property:key
     70      * @param {HTMLElement} element The node to modify.
     71      * @param {string} attributeAndKeys The path of the attribute to modify
     72      *     followed by a colon, and the name of the value in the dictionary.
     73      *     Multiple attribute/key pairs may be separated by semicolons.
     74      * @param {LoadTimeData} dictionary The dictionary of strings to draw from.
     75      */
     76     'i18n-values': function(element, attributeAndKeys, dictionary) {
     77       var parts = attributeAndKeys.replace(/\s/g, '').split(/;/);
     78       parts.forEach(function(part) {
     79         if (!part)
     80           return;
     81 
     82         var attributeAndKeyPair = part.match(/^([^:]+):(.+)$/);
     83         if (!attributeAndKeyPair)
     84           throw new Error('malformed i18n-values: ' + attributeAndKeys);
     85 
     86         var propName = attributeAndKeyPair[1];
     87         var propExpr = attributeAndKeyPair[2];
     88 
     89         var value = dictionary.getValue(propExpr);
     90 
     91         // Allow a property of the form '.foo.bar' to assign a value into
     92         // element.foo.bar.
     93         if (propName[0] == '.') {
     94           var path = propName.slice(1).split('.');
     95           var targetObject = element;
     96           while (targetObject && path.length > 1) {
     97             targetObject = targetObject[path.shift()];
     98           }
     99           if (targetObject) {
    100             targetObject[path] = value;
    101             // In case we set innerHTML (ignoring others) we need to
    102             // recursively check the content.
    103             if (path == 'innerHTML')
    104               process(element, dictionary);
    105           }
    106         } else {
    107           element.setAttribute(propName, value);
    108         }
    109       });
    110     }
    111   };
    112 
    113   var attributeNames = Object.keys(handlers);
    114   var selector = '[' + attributeNames.join('],[') + ']';
    115 
    116   /**
    117    * Processes a DOM tree with the {@code dictionary} map.
    118    * @param {HTMLElement} node The root of the DOM tree to process.
    119    * @param {LoadTimeData} dictionary The dictionary to draw from.
    120    */
    121   function process(node, dictionary) {
    122     var elements = node.querySelectorAll(selector);
    123     for (var element, i = 0; element = elements[i]; i++) {
    124       for (var j = 0; j < attributeNames.length; j++) {
    125         var name = attributeNames[j];
    126         var attribute = element.getAttribute(name);
    127         if (attribute != null)
    128           handlers[name](element, attribute, dictionary);
    129       }
    130     }
    131   }
    132 
    133   return {
    134     process: process
    135   };
    136 }());
    137