Allow argCount to be omitted an not default to 3, and cleanup createBound.

Former-commit-id: cbafeaa441aae1ef28268bc2614b1a6e038acfe1

lodash.js

@@ -485,7 +485,6 @@
     /** Native method shortcuts */
     var ceil = Math.ceil,
         clearTimeout = context.clearTimeout,
-        concat = arrayRef.concat,
         defineProperty = reNative.test(defineProperty = Object.defineProperty) && defineProperty,
         floor = Math.floor,
         fnToString = Function.prototype.toString,
@@ -495,7 +494,8 @@
         propertyIsEnumerable = objectProto.propertyIsEnumerable,
         setImmediate = context.setImmediate,
         setTimeout = context.setTimeout,
-        toString = objectProto.toString;
+        toString = objectProto.toString,
+        unshift = arrayRef.unshift;
 
     /* Native method shortcuts for methods with the same name as other `lodash` methods */
     var nativeBind = reNative.test(nativeBind = toString.bind) && nativeBind,
@@ -954,7 +954,7 @@
     /** Reusable iterator options shared by `each`, `forIn`, and `forOwn` */
     var eachIteratorOptions = {
       'args': 'collection, callback, thisArg',
-      'top': "callback = callback && typeof thisArg == 'undefined' ? callback : lodash.createCallback(callback, thisArg)",
+      'top': "callback = callback && typeof thisArg == 'undefined' ? callback : lodash.createCallback(callback, thisArg, 3)",
       'array': "typeof length == 'number'",
       'loop': 'if (callback(iterable[index], index, collection) === false) return result'
     };
@@ -1393,9 +1393,7 @@
       if (!isFunc && !isBindKey) {
         throw new TypeError;
       }
-      var args = func.__bindData__,
-          key = thisArg;
-
+      var args = func.__bindData__;
       if (args) {
         push.apply(args[2], partialArgs);
         push.apply(args[3], partialRightArgs);
@@ -1408,17 +1406,12 @@
         }
         return createBound.apply(null, args);
       }
-      // take a snapshot of `arguments` before juggling
-      args = nativeSlice.call(arguments);
-
-      // juggle arguments for `_.bindKey` behavior
-      if (isBindKey) {
-        thisArg = func;
-      }
       // use `Function#bind` if it exists and is fast
       // (in V8 `Function#bind` is slower except when partially applied)
       if (!isPartial && !isAlt && !partialRightArgs.length && (support.fastBind || (nativeBind && partialArgs.length))) {
-        var bound = nativeBind.call.apply(nativeBind, concat.call(arrayRef, func, thisArg, partialArgs));
+        args = [func, thisArg];
+        push.apply(args, partialArgs);
+        var bound = nativeBind.call.apply(nativeBind, args);
       }
       else {
         bound = function() {
@@ -1431,7 +1424,7 @@
             func = thisArg[key];
           }
           if (partialArgs.length || partialRightArgs.length) {
-            args = concat.apply(partialArgs, args);
+            unshift.apply(args, partialArgs);
             push.apply(args, partialRightArgs);
           }
           if (this instanceof bound) {
@@ -1446,6 +1439,12 @@
           return func.apply(thisBinding, args);
         };
       }
+      // take a snapshot of `arguments` before juggling
+      args = nativeSlice.call(arguments);
+      if (isBindKey) {
+        var key = thisArg;
+        thisArg = func;
+      }
       setBindData(bound, args);
       return bound;
     }
@@ -1930,7 +1929,7 @@
      */
     function findKey(object, callback, thisArg) {
       var result;
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
       forOwn(object, function(value, key, object) {
         if (callback(value, key, object)) {
           result = key;
@@ -2552,7 +2551,7 @@
           result = {};
 
       if (isFunc) {
-        callback = lodash.createCallback(callback, thisArg);
+        callback = lodash.createCallback(callback, thisArg, 3);
       } else {
         var props = baseFlatten(arguments, true, false, 1);
       }
@@ -2634,7 +2633,7 @@
           }
         }
       } else {
-        callback = lodash.createCallback(callback, thisArg);
+        callback = lodash.createCallback(callback, thisArg, 3);
         forIn(object, function(value, key, object) {
           if (callback(value, key, object)) {
             result[key] = value;
@@ -2842,7 +2841,7 @@
      */
     function countBy(collection, callback, thisArg) {
       var result = {};
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       forEach(collection, function(value, key, collection) {
         key = String(callback(value, key, collection));
@@ -2894,7 +2893,7 @@
      */
     function every(collection, callback, thisArg) {
       var result = true;
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       if (isArray(collection)) {
         var index = -1,
@@ -2955,7 +2954,7 @@
      */
     function filter(collection, callback, thisArg) {
       var result = [];
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       if (isArray(collection)) {
         var index = -1,
@@ -3021,7 +3020,7 @@
      * // => { 'name': 'banana', 'organic': true, 'type': 'fruit' }
      */
     function find(collection, callback, thisArg) {
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       if (isArray(collection)) {
         var index = -1,
@@ -3119,7 +3118,7 @@
      */
     function groupBy(collection, callback, thisArg) {
       var result = {};
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       forEach(collection, function(value, key, collection) {
         key = String(callback(value, key, collection));
@@ -3207,7 +3206,7 @@
           length = collection ? collection.length : 0,
           result = Array(typeof length == 'number' ? length : 0);
 
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
       if (isArray(collection)) {
         while (++index < length) {
           result[index] = callback(collection[index], index, collection);
@@ -3276,7 +3275,7 @@
       } else {
         callback = (!callback && isString(collection))
           ? charAtCallback
-          : lodash.createCallback(callback, thisArg);
+          : lodash.createCallback(callback, thisArg, 3);
 
         baseEach(collection, function(value, index, collection) {
           var current = callback(value, index, collection);
@@ -3345,7 +3344,7 @@
       } else {
         callback = (!callback && isString(collection))
           ? charAtCallback
-          : lodash.createCallback(callback, thisArg);
+          : lodash.createCallback(callback, thisArg, 3);
 
         baseEach(collection, function(value, index, collection) {
           var current = callback(value, index, collection);
@@ -3514,7 +3513,7 @@
      * // => [{ 'name': 'carrot', 'organic': true, 'type': 'vegetable' }]
      */
     function reject(collection, callback, thisArg) {
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
       return filter(collection, function(value, index, collection) {
         return !callback(value, index, collection);
       });
@@ -3616,7 +3615,7 @@
      */
     function some(collection, callback, thisArg) {
       var result;
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
 
       if (isArray(collection)) {
         var index = -1,
@@ -3675,7 +3674,7 @@
           length = collection ? collection.length : 0,
           result = Array(typeof length == 'number' ? length : 0);
 
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
       forEach(collection, function(value, key, collection) {
         var object = result[++index] = getObject();
         object.criteria = callback(value, key, collection);
@@ -3841,7 +3840,7 @@
       var index = -1,
           length = array ? array.length : 0;
 
-      callback = lodash.createCallback(callback, thisArg);
+      callback = lodash.createCallback(callback, thisArg, 3);
       while (++index < length) {
         if (callback(array[index], index, array)) {
           return index;
@@ -3914,7 +3913,7 @@
 
         if (typeof callback != 'number' && callback != null) {
           var index = -1;
-          callback = lodash.createCallback(callback, thisArg);
+          callback = lodash.createCallback(callback, thisArg, 3);
           while (++index < length && callback(array[index], index, array)) {
             n++;
           }
@@ -4082,7 +4081,7 @@
 
       if (typeof callback != 'number' && callback != null) {
         var index = length;
-        callback = lodash.createCallback(callback, thisArg);
+        callback = lodash.createCallback(callback, thisArg, 3);
         while (index-- && callback(array[index], index, array)) {
           n++;
         }
@@ -4215,7 +4214,7 @@
 
         if (typeof callback != 'number' && callback != null) {
           var index = length;
-          callback = lodash.createCallback(callback, thisArg);
+          callback = lodash.createCallback(callback, thisArg, 3);
           while (index-- && callback(array[index], index, array)) {
             n++;
           }
@@ -4375,7 +4374,7 @@
             index = -1,
             length = array ? array.length : 0;
 
-        callback = lodash.createCallback(callback, thisArg);
+        callback = lodash.createCallback(callback, thisArg, 3);
         while (++index < length && callback(array[index], index, array)) {
           n++;
         }
@@ -4519,7 +4518,7 @@
         isSorted = false;
       }
       if (callback != null) {
-        callback = lodash.createCallback(callback, thisArg);
+        callback = lodash.createCallback(callback, thisArg, 3);
       }
       return baseUniq(array, isSorted, callback);
     }
@@ -4779,7 +4778,7 @@
      * @category Functions
      * @param {Mixed} [func=identity] The value to convert to a callback.
      * @param {Mixed} [thisArg] The `this` binding of the created callback.
-     * @param {Number} [argCount=3] The number of arguments the callback accepts.
+     * @param {Number} [argCount] The number of arguments the callback accepts.
      * @returns {Function} Returns a callback function.
      * @example
      *
@@ -4863,23 +4862,22 @@
         // created by `_.partial` or `_.partialRight`
         return bindData[4] ? bind(func, thisArg) : func;
       }
-      if (argCount === 1) {
-        return function(value) {
+      switch (argCount) {
+        case 1: return function(value) {
           return func.call(thisArg, value);
         };
-      }
-      if (argCount === 2) {
-        return function(a, b) {
+        case 2: return function(a, b) {
           return func.call(thisArg, a, b);
         };
-      }
-      if (argCount === 4) {
-        return function(accumulator, value, index, collection) {
+        case 3: return function(value, index, collection) {
+          return func.call(thisArg, value, index, collection);
+        };
+        case 4: return function(accumulator, value, index, collection) {
           return func.call(thisArg, accumulator, value, index, collection);
         };
       }
-      return function(value, index, collection) {
-        return func.call(thisArg, value, index, collection);
+      return function() {
+        return func.apply(thisArg, arguments);
       };
     }