Add castRest, flatRest, and overRest helpers.

lodash.js

@@ -3829,24 +3829,7 @@
      * @returns {Function} Returns the new function.
      */
     function baseRest(func, start) {
-      start = nativeMax(start === undefined ? (func.length - 1) : start, 0);
+      return setToString(overRest(func, start, identity), func + '');
-      return setToString(function() {
-        var args = arguments,
-            index = -1,
-            length = nativeMax(args.length - start, 0),
-            array = Array(length);
-
-        while (++index < length) {
-          array[index] = args[start + index];
-        }
-        index = -1;
-        var otherArgs = Array(start + 1);
-        while (++index < start) {
-          otherArgs[index] = args[index];
-        }
-        otherArgs[start] = array;
-        return apply(func, this, otherArgs);
-      }, func + '');
     }
 
     /**
@@ -4316,6 +4299,17 @@
       return isArray(value) ? value : stringToPath(value);
     }
 
+    /**
+     * A `baseRest` alias which can be replaced with `identity` by module
+     * replacement plugins.
+     *
+     * @private
+     * @type {Function}
+     * @param {Function} func The function to apply a rest parameter to.
+     * @returns {Function} Returns the new function.
+     */
+    var castRest = baseRest;
+
     /**
      * Casts `array` to a slice if it's needed.
      *
@@ -4929,9 +4923,7 @@
      * @returns {Function} Returns the new flow function.
      */
     function createFlow(fromRight) {
-      return baseRest(function(funcs) {
+      return flatRest(function(funcs) {
-        funcs = baseFlatten(funcs, 1);
-
         var length = funcs.length,
             index = length,
             prereq = LodashWrapper.prototype.thru;
@@ -5114,11 +5106,8 @@
      * @returns {Function} Returns the new over function.
      */
     function createOver(arrayFunc) {
-      return baseRest(function(iteratees) {
+      return flatRest(function(iteratees) {
-        iteratees = (iteratees.length == 1 && isArray(iteratees[0]))
+        iteratees = arrayMap(iteratees, baseUnary(getIteratee()));
-          ? arrayMap(iteratees[0], baseUnary(getIteratee()))
-          : arrayMap(baseFlatten(iteratees, 1), baseUnary(getIteratee()));
-
         return baseRest(function(args) {
           var thisArg = this;
           return arrayFunc(iteratees, function(iteratee) {
@@ -5643,6 +5632,17 @@
       return result;
     }
 
+    /**
+     * A specialized version of `baseRest` which flattens the rest array.
+     *
+     * @private
+     * @param {Function} func The function to apply a rest parameter to.
+     * @returns {Function} Returns the new function.
+     */
+    function flatRest(func) {
+      return setToString(overRest(func, undefined, flatten), func + '');
+    }
+
     /**
      * Creates an array of own enumerable property names and symbols of `object`.
      *
@@ -6290,6 +6290,36 @@
       return result;
     }
 
+    /**
+     * A specialized version of `baseRest` which transforms the rest array.
+     *
+     * @private
+     * @param {Function} func The function to apply a rest parameter to.
+     * @param {number} [start=func.length-1] The start position of the rest parameter.
+     * @param {Function} transform The rest array transform.
+     * @returns {Function} Returns the new function.
+     */
+    function overRest(func, start, transform) {
+      start = nativeMax(start === undefined ? (func.length - 1) : start, 0);
+      return function() {
+        var args = arguments,
+            index = -1,
+            length = nativeMax(args.length - start, 0),
+            array = Array(length);
+
+        while (++index < length) {
+          array[index] = args[start + index];
+        }
+        index = -1;
+        var otherArgs = Array(start + 1);
+        while (++index < start) {
+          otherArgs[index] = args[index];
+        }
+        otherArgs[start] = transform(array);
+        return apply(func, this, otherArgs);
+      };
+    }
+
     /**
      * Gets the parent value at `path` of `object`.
      *
@@ -7487,9 +7517,7 @@
      * console.log(pulled);
      * // => ['b', 'd']
      */
-    var pullAt = baseRest(function(array, indexes) {
+    var pullAt = flatRest(function(array, indexes) {
-      indexes = baseFlatten(indexes, 1);
-
       var length = array ? array.length : 0,
           result = baseAt(array, indexes);
 
@@ -8505,8 +8533,7 @@
      * _(object).at(['a[0].b.c', 'a[1]']).value();
      * // => [3, 4]
      */
-    var wrapperAt = baseRest(function(paths) {
+    var wrapperAt = flatRest(function(paths) {
-      paths = baseFlatten(paths, 1);
       var length = paths.length,
           start = length ? paths[0] : 0,
           value = this.__wrapped__,
@@ -10366,7 +10393,7 @@
      * func(10, 5);
      * // => [100, 10]
      */
-    var overArgs = baseRest(function(func, transforms) {
+    var overArgs = castRest(function(func, transforms) {
       transforms = (transforms.length == 1 && isArray(transforms[0]))
         ? arrayMap(transforms[0], baseUnary(getIteratee()))
         : arrayMap(baseFlatten(transforms, 1), baseUnary(getIteratee()));
@@ -10480,8 +10507,8 @@
      * rearged('b', 'c', 'a')
      * // => ['a', 'b', 'c']
      */
-    var rearg = baseRest(function(func, indexes) {
+    var rearg = flatRest(function(func, indexes) {
-      return createWrap(func, REARG_FLAG, undefined, undefined, undefined, baseFlatten(indexes, 1));
+      return createWrap(func, REARG_FLAG, undefined, undefined, undefined, indexes);
     });
 
     /**
@@ -12429,9 +12456,7 @@
      * _.at(object, ['a[0].b.c', 'a[1]']);
      * // => [3, 4]
      */
-    var at = baseRest(function(object, paths) {
+    var at = flatRest(baseAt);
-      return baseAt(object, baseFlatten(paths, 1));
-    });
 
     /**
      * Creates an object that inherits from the `prototype` object. If a
@@ -13166,11 +13191,11 @@
      * _.omit(object, ['a', 'c']);
      * // => { 'b': '2' }
      */
-    var omit = baseRest(function(object, props) {
+    var omit = flatRest(function(object, props) {
       if (object == null) {
         return {};
       }
-      props = arrayMap(baseFlatten(props, 1), toKey);
+      props = arrayMap(props, toKey);
       return basePick(object, baseDifference(getAllKeysIn(object), props));
     });
 
@@ -13215,8 +13240,8 @@
      * _.pick(object, ['a', 'c']);
      * // => { 'a': 1, 'c': 3 }
      */
-    var pick = baseRest(function(object, props) {
+    var pick = flatRest(function(object, props) {
-      return object == null ? {} : basePick(object, arrayMap(baseFlatten(props, 1), toKey));
+      return object == null ? {} : basePick(object, arrayMap(props, toKey));
     });
 
     /**
@@ -14923,8 +14948,8 @@
      * jQuery(element).on('click', view.click);
      * // => Logs 'clicked docs' when clicked.
      */
-    var bindAll = baseRest(function(object, methodNames) {
+    var bindAll = flatRest(function(object, methodNames) {
-      arrayEach(baseFlatten(methodNames, 1), function(key) {
+      arrayEach(methodNames, function(key) {
         key = toKey(key);
         baseAssignValue(object, key, bind(object[key], object));
       });