Source: provider/abstractProviderByFile.js

  1. /**
  2.  * @author Sloan Seaman 
  3.  * @copyright 2016 and on
  4.  * @version .1
  5.  * @license https://www.apache.org/licenses/LICENSE-2.0 Apache License 2.0
  6.  */
  8. /** @private */
  10. /**
  11.  * Provides items by single file with multiple items defined in the file
  12.  * 
  13.  * items are loaded asynchronously but if a item is requested before being loaded 
  14.  * it will be immediately loaded and then skipped by the asychronous processing.
  15.  *
  16.  * @abstract
  17.  * @constructor
  18.  * @implements {Provider}
  19.  * @implements {ItemProcessor}
  20.  * @param {String} file The file to read all items from
  21.  * @param {Object.<String, Object>} options Options for configuration. This can also be used as a map to pass to the itemProcessor
  22.  *        if the implementing class wants to pass information into the itemProcessor method
  23.  * @param {Boolean} [options.preload=false] Should the file be preloaded or only loaded when a item is requested
  24.  * @param {String} [options.fileEncoding=utf8] The file encoding to use when reading files and directories
  25.  * @param {Object.<String, Object>} [options.itemMap] A map that may be passed in to prime the internal map with.
  26.  */
  27. function AbstractProviderByFile(file, options) {
  28. 	if (!file) throw Error('file required');
  30. 	this._file = file;
  31. 	this._options = options;
  33. 	this._fileEncoding = (options && options.fileEncoding)
  34. 		? options.fileEncoding
  35. 		: 'utf8';
  37. 	this._preload = (options && options.preload) 
  38. 		? options.preload
  39. 		: false;
  41. 	this._items = (options && options.itemMap) 
  42. 		? options.itemMap
  43. 		: {};
  45. 	this._fileLoaded = false;
  47. 	if (this._preload) { // this is a blocking call as it is sync
  48. 		var processed = this.processItems(this._items, file, this._options);
  49. 		for (var i=0;i<processed.length;i++) {
  50. 			this._items[processed[i].itemId] = processed[i].item;
  51. 		}
  52. 		this._fileLoaded = true;
  53. 	}
  54. }
  56. /**
  57.  * Returns the item based on the itemId
  58.  *
  59.  * @function
  60.  * @param  {String} itemId The id of the item to retrieve. If the file is not already loaded, it will load it to look for the item
  61.  * @return {item}  The item.  Null if no item is found
  62.  */
  63. AbstractProviderByFile.prototype.getItem = function(itemId) {
  64. 	var item = this._items[itemId];
  65. 	if (!item && !this._fileLoaded) {
  66. 		this.processItem(this._items, itemId, this._file, this._options); // didn't find it and haven't looked for it
  67. 		this._fileLoaded = true;
  68. 		item = this._items[itemId];
  69. 	}
  70. 	return item;
  71. };
  73. /**
  74.  * Returns all items that were loaded
  75.  *
  76.  * @function
  77.  * @return {Map} Map of the items where the Key is the itemId and the Value is the item itself
  78.  */
  79. AbstractProviderByFile.prototype.getItems = function() {
  80. 	return this._items;
  81. };
  83. /**
  84.  * Processes the specific item and returns the result
  85.  * 
  86.  * @function
  87.  * @abstract
  88.  * @param {Map} items Map of the items being processed
  89.  * @param {String} itemId The Id of the item to process
  90.  * @param {String} fileName The name of the file being processed
  91.  * @param {Object} options Any options that are being passed to the ItemProcessor (can be null)
  92.  */
  93. AbstractProviderByFile.prototype.processItem = function(items, itemId, fileName, options) {
  94. 	/*eslint no-unused-vars: ["error", { "args": "none" }]*/
  95. 	throw new Error('Must be implemented by subclass');
  96. };
  98. /**
  99.  * Processes multiple items at once
  100.  * 
  101.  * @function
  102.  * @abstract
  103.  * @param {Map} items Map of the items being processeds
  104.  * @param {String} fileName The name of the file being processed
  105.  * @param {Object} options Any options that are being passed to the ItemProcessor (can be null)
  106.  */
  107. AbstractProviderByFile.prototype.processItems = function(items, fileName, options) {
  108. 	/*eslint no-unused-vars: ["error", { "args": "none" }]*/
  109. 	throw new Error('Must be implemented by subclass');
  110. };
  112. module.exports = AbstractProviderByFile;