apis.js

'use strict';


/**
 * Computes a hash of an 'obj'.
 * Hash of a:
 *  string is string
 *  number is number as string
 *  object is either result of calling $$hashKey function on the object or uniquely generated id,
 *         that is also assigned to the $$hashKey property of the object.
 *
 * @param obj
 * @returns {string} hash string such that the same input will have the same hash string.
 *         The resulting string key is in 'type:hashKey' format.
 */
function hashKey(obj) {
  var objType = typeof obj,
      key;

  if (objType == 'object' && obj !== null) {
    if (typeof (key = obj.$$hashKey) == 'function') {
      // must invoke on object to keep the right this
      key = obj.$$hashKey();
    } else if (key === undefined) {
      key = obj.$$hashKey = nextUid();
    }
  } else {
    key = obj;
  }

  return objType + ':' + key;
}

/**
 * HashMap which can use objects as keys
 */
function HashMap(array){
  forEach(array, this.put, this);
}
HashMap.prototype = {
  /**
   * Store key value pair
   * @param key key to store can be any type
   * @param value value to store can be any type
   */
  put: function(key, value) {
    this[hashKey(key)] = value;
  },

  /**
   * @param key
   * @returns the value for the key
   */
  get: function(key) {
    return this[hashKey(key)];
  },

  /**
   * Remove the key/value pair
   * @param key
   */
  remove: function(key) {
    var value = this[key = hashKey(key)];
    delete this[key];
    return value;
  }
};

/**
 * A map where multiple values can be added to the same key such that they form a queue.
 * @returns {HashQueueMap}
 */
function HashQueueMap() {}
HashQueueMap.prototype = {
  /**
   * Same as array push, but using an array as the value for the hash
   */
  push: function(key, value) {
    var array = this[key = hashKey(key)];
    if (!array) {
      this[key] = [value];
    } else {
      array.push(value);
    }
  },

  /**
   * Same as array shift, but using an array as the value for the hash
   */
  shift: function(key) {
    var array = this[key = hashKey(key)];
    if (array) {
      if (array.length == 1) {
        delete this[key];
        return array[0];
      } else {
        return array.shift();
      }
    }
  },
  
  /**
   * return the first item without deleting it
   */
  peek: function(key) {
    var array = this[key = hashKey(key)];
    if (array) {
    return array[0];
    }
  }
};