builtins/ArrayConstructor.js

   1 /*
   2  * Copyright (C) 2015 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 function of(/* items... */)
  27 {
  28     "use strict";
  29
  30     var length = arguments.length;
  31     // TODO: Need isConstructor(this) instead of typeof "function" check.
  32     var array = typeof this === 'function' ? new this(length) : new @Array(length);
  33     for (var k = 0; k < length; ++k)
  34         @putByValDirect(array, k, arguments[k]);
  35     array.length = length;
  36     return array;
  37 }
  38
  39 function from(items /*, mapFn, thisArg */) {
  40     "use strict";
  41
  42     var thisObj = this;
  43
  44     var mapFn = arguments.length > 1 ? arguments[1] : undefined;
  45
  46     var thisArg;
  47
  48     if (mapFn !== undefined) {
  49         if (typeof mapFn !== "function")
  50             throw new @TypeError("Array.from requires that the second argument, when provided, be a function");
  51
  52         if (arguments.length > 2)
  53             thisArg = arguments[2];
  54     }
  55
  56     if (items == null)
  57         throw new @TypeError("Array.from requires an array-like object - not null or undefined");
  58
  59     var iteratorMethod = items[@symbolIterator];
  60     if (iteratorMethod != null) {
  61         if (typeof iteratorMethod !== "function")
  62             throw new @TypeError("Array.from requires that the property of the first argument, items[Symbol.iterator], when exists, be a function");
  63
  64         // TODO: Need isConstructor(thisObj) instead of typeof "function" check.
  65         var result = (typeof thisObj === "function") ? @Object(new thisObj()) : [];
  66
  67         var k = 0;
  68         var iterator = iteratorMethod.@call(items);
  69
  70         // Since for-of loop once more looks up the @@iterator property of a given iterable,
  71         // it could be observable if the user defines a getter for @@iterator.
  72         // To avoid this situation, we define a wrapper object that @@iterator just returns a given iterator.
  73         var wrapper = {
  74             [@symbolIterator]() {
  75                 return iterator;
  76             }
  77         };
  78
  79         for (var value of wrapper) {
  80             if (mapFn)
  81                 @putByValDirect(result, k, thisArg === undefined ? mapFn(value, k) : mapFn.@call(thisArg, value, k));
  82             else
  83                 @putByValDirect(result, k, value);
  84             k += 1;
  85         }
  86
  87         result.length = k;
  88         return result;
  89     }
  90
  91     var arrayLike = @Object(items);
  92     var arrayLikeLength = @toLength(arrayLike.length);
  93
  94     // TODO: Need isConstructor(thisObj) instead of typeof "function" check.
  95     var result = (typeof thisObj === "function") ? @Object(new thisObj(arrayLikeLength)) : new @Array(arrayLikeLength);
  96
  97     var k = 0;
  98     while (k < arrayLikeLength) {
  99         var value = arrayLike[k];
 100         if (mapFn)
 101             @putByValDirect(result, k, thisArg === undefined ? mapFn(value, k) : mapFn.@call(thisArg, value, k));
 102         else
 103             @putByValDirect(result, k, value);
 104         k += 1;
 105     }
 106
 107     result.length = arrayLikeLength;
 108     return result;
 109 }