Add _.isMap, _.isSet, _.isWeakMap, & _.isWeakSet.

lodash.js

@@ -81,7 +81,8 @@
       setTag = '[object Set]',
       stringTag = '[object String]',
       symbolTag = '[object Symbol]',
-      weakMapTag = '[object WeakMap]';
+      weakMapTag = '[object WeakMap]',
+      weakSetTag = '[object WeakSet]';
 
   var arrayBufferTag = '[object ArrayBuffer]',
       float32Tag = '[object Float32Array]',
@@ -1339,9 +1340,10 @@
     /** Used to store function metadata. */
     var metaMap = WeakMap && new WeakMap;
 
-    /** Used to detect maps and sets. */
+    /** Used to detect maps, sets, and weakmaps. */
     var mapCtorString = Map ? funcToString.call(Map) : '',
-        setCtorString = Set ? funcToString.call(Set) : '';
+        setCtorString = Set ? funcToString.call(Set) : '',
+        weakMapCtorString = WeakMap ? funcToString.call(WeakMap) : '';
 
     /** Used to convert symbols to primitives and strings. */
     var symbolProto = Symbol ? Symbol.prototype : undefined,
@@ -4875,19 +4877,20 @@
       return objectToString.call(value);
     }
 
-    // Fallback for IE 11 providing `toStringTag` values for maps and sets.
-    if ((Map && getTag(new Map) != mapTag) || (Set && getTag(new Set) != setTag)) {
+    // Fallback for IE 11 providing `toStringTag` values for maps, sets, and weakmaps.
+    if ((Map && getTag(new Map) != mapTag) ||
+        (Set && getTag(new Set) != setTag) ||
+        (WeakMap && getTag(new WeakMap) != weakMapTag)) {
       getTag = function(value) {
         var result = objectToString.call(value),
             Ctor = result == objectTag ? value.constructor : null,
             ctorString = typeof Ctor == 'function' ? funcToString.call(Ctor) : '';
 
         if (ctorString) {
-          if (ctorString == mapCtorString) {
-            return mapTag;
-          }
-          if (ctorString == setCtorString) {
-            return setTag;
+          switch (ctorString) {
+            case mapCtorString: return mapTag;
+            case setCtorString: return setTag;
+            case weakMapCtorString: return weakMapTag;
           }
         }
         return result;
@@ -9901,6 +9904,26 @@
       return !!value && typeof value == 'object';
     }
 
+    /**
+     * Checks if `value` is classified as a `Map` object.
+     *
+     * @static
+     * @memberOf _
+     * @category Lang
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
+     * @example
+     *
+     * _.isMap(new Map);
+     * // => true
+     *
+     * _.isMap(new WeakMap);
+     * // => false
+     */
+    function isMap(value) {
+      return isObjectLike(value) && getTag(value) == mapTag;
+    }
+
     /**
      * Performs a deep comparison between `object` and `source` to determine if
      * `object` contains equivalent property values.
@@ -10186,6 +10209,26 @@
       return isInteger(value) && value >= -MAX_SAFE_INTEGER && value <= MAX_SAFE_INTEGER;
     }
 
+    /**
+     * Checks if `value` is classified as a `Set` object.
+     *
+     * @static
+     * @memberOf _
+     * @category Lang
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
+     * @example
+     *
+     * _.isSet(new Set);
+     * // => true
+     *
+     * _.isSet(new WeakSet);
+     * // => false
+     */
+    function isSet(value) {
+      return isObjectLike(value) && getTag(value) == setTag;
+    }
+
     /**
      * Checks if `value` is classified as a `String` primitive or object.
      *
@@ -10268,6 +10311,46 @@
       return value === undefined;
     }
 
+    /**
+     * Checks if `value` is classified as a `WeakMap` object.
+     *
+     * @static
+     * @memberOf _
+     * @category Lang
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
+     * @example
+     *
+     * _.isWeakMap(new WeakMap);
+     * // => true
+     *
+     * _.isWeakMap(new Map);
+     * // => false
+     */
+    function isWeakMap(value) {
+      return isObjectLike(value) && getTag(value) == weakMapTag;
+    }
+
+    /**
+     * Checks if `value` is classified as a `WeakSet` object.
+     *
+     * @static
+     * @memberOf _
+     * @category Lang
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
+     * @example
+     *
+     * _.isWeakSet(new WeakSet);
+     * // => true
+     *
+     * _.isWeakSet(new Set);
+     * // => false
+     */
+    function isWeakSet(value) {
+      return isObjectLike(value) && objectToString.call(value) == weakSetTag;
+    }
+
     /**
      * Checks if `value` is less than `other`.
      *
@@ -14290,6 +14373,7 @@
     lodash.isFunction = isFunction;
     lodash.isInteger = isInteger;
     lodash.isLength = isLength;
+    lodash.isMap = isMap;
     lodash.isMatch = isMatch;
     lodash.isMatchWith = isMatchWith;
     lodash.isNaN = isNaN;
@@ -14302,10 +14386,13 @@
     lodash.isPlainObject = isPlainObject;
     lodash.isRegExp = isRegExp;
     lodash.isSafeInteger = isSafeInteger;
+    lodash.isSet = isSet;
     lodash.isString = isString;
     lodash.isSymbol = isSymbol;
     lodash.isTypedArray = isTypedArray;
     lodash.isUndefined = isUndefined;
+    lodash.isWeakMap = isWeakMap;
+    lodash.isWeakSet = isWeakSet;
     lodash.join = join;
     lodash.kebabCase = kebabCase;
     lodash.last = last;