WebKit/Source/JavaScriptCore/builtins/MapConstructor.js at main · WebKit/WebKit · GitHub

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* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions

* are met:

* 1. Redistributions of source code must retain the above copyright

* notice, this list of conditions and the following disclaimer.

* 2. Redistributions in binary form must reproduce the above copyright

* notice, this list of conditions and the following disclaimer in the

* documentation and/or other materials provided with the distribution.

* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY

* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR

* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

function groupBy(items, callback)

{

"use strict";

if (@isUndefinedOrNull(items))

@throwTypeError("Map.groupBy requires that the first argument not be null or undefined");

if (!@isCallable(callback))

@throwTypeError("Map.groupBy requires that the second argument must be a function");

var iteratorMethod = items.@@iterator;

if (!@isCallable(iteratorMethod))

@throwTypeError("Map.groupBy requires that the property of the first argument, items[Symbol.iterator] be a function");

var groups = new @Map;

var k = 0;

var iterator = iteratorMethod.@call(items);

// Since for-of loop once more looks up the @@iterator property of a given iterable,

// it could be observable if the user defines a getter for @@iterator.

// To avoid this situation, we define a wrapper object that @@iterator just returns a given iterator.

var wrapper = {

@@iterator: function () { return iterator; }

};

for (var item of wrapper) {

if (k >= @MAX_SAFE_INTEGER)

@throwTypeError("The number of iterations exceeds 2**53 - 1");

var key = callback.@call(@undefined, item, k);

var group = groups.@get(key);

if (!group) {

group = [];

groups.@set(key, group);

}

@putByValDirect(group, group.length, item);

++k;

}

return groups;

}

WebKit/Source/JavaScriptCore/builtins/MapConstructor.js at main · WebKit/WebKit · GitHub

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