added unit testing, and started implementing unit tests...phew

node_modules/async/memoize.js

@@ -0,0 +1,101 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = memoize;
+
+var _identity = require('lodash/identity');
+
+var _identity2 = _interopRequireDefault(_identity);
+
+var _slice = require('./internal/slice');
+
+var _slice2 = _interopRequireDefault(_slice);
+
+var _setImmediate = require('./internal/setImmediate');
+
+var _setImmediate2 = _interopRequireDefault(_setImmediate);
+
+var _initialParams = require('./internal/initialParams');
+
+var _initialParams2 = _interopRequireDefault(_initialParams);
+
+var _wrapAsync = require('./internal/wrapAsync');
+
+var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+function has(obj, key) {
+    return key in obj;
+}
+
+/**
+ * Caches the results of an async function. When creating a hash to store
+ * function results against, the callback is omitted from the hash and an
+ * optional hash function can be used.
+ *
+ * If no hash function is specified, the first argument is used as a hash key,
+ * which may work reasonably if it is a string or a data type that converts to a
+ * distinct string. Note that objects and arrays will not behave reasonably.
+ * Neither will cases where the other arguments are significant. In such cases,
+ * specify your own hash function.
+ *
+ * The cache of results is exposed as the `memo` property of the function
+ * returned by `memoize`.
+ *
+ * @name memoize
+ * @static
+ * @memberOf module:Utils
+ * @method
+ * @category Util
+ * @param {AsyncFunction} fn - The async function to proxy and cache results from.
+ * @param {Function} hasher - An optional function for generating a custom hash
+ * for storing results. It has all the arguments applied to it apart from the
+ * callback, and must be synchronous.
+ * @returns {AsyncFunction} a memoized version of `fn`
+ * @example
+ *
+ * var slow_fn = function(name, callback) {
+ *     // do something
+ *     callback(null, result);
+ * };
+ * var fn = async.memoize(slow_fn);
+ *
+ * // fn can now be used as if it were slow_fn
+ * fn('some name', function() {
+ *     // callback
+ * });
+ */
+function memoize(fn, hasher) {
+    var memo = Object.create(null);
+    var queues = Object.create(null);
+    hasher = hasher || _identity2.default;
+    var _fn = (0, _wrapAsync2.default)(fn);
+    var memoized = (0, _initialParams2.default)(function memoized(args, callback) {
+        var key = hasher.apply(null, args);
+        if (has(memo, key)) {
+            (0, _setImmediate2.default)(function () {
+                callback.apply(null, memo[key]);
+            });
+        } else if (has(queues, key)) {
+            queues[key].push(callback);
+        } else {
+            queues[key] = [callback];
+            _fn.apply(null, args.concat(function () /*args*/{
+                var args = (0, _slice2.default)(arguments);
+                memo[key] = args;
+                var q = queues[key];
+                delete queues[key];
+                for (var i = 0, l = q.length; i < l; i++) {
+                    q[i].apply(null, args);
+                }
+            }));
+        }
+    });
+    memoized.memo = memo;
+    memoized.unmemoized = fn;
+    return memoized;
+}
+module.exports = exports['default'];