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IteratorHelpers.js
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94 lines (81 loc) · 3.51 KB
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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* 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.
*/
@linkTimeConstant
function performIteration(iterable)
{
"use strict";
// This is performing a spread operation on the iterable passed in,
// and returning the result in an array.
// https://tc39.github.io/ecma262/#sec-runtime-semantics-arrayaccumulation
var result = [];
if (@isUndefinedOrNull(iterable))
@throwTypeError('Spread syntax requires ...iterable not be null or undefined');
var iteratorMethod = iterable.@@iterator;
if (!@isCallable(iteratorMethod))
@throwTypeError('Spread syntax requires ...iterable[Symbol.iterator] to be a function');
var iterator = iteratorMethod.@call(iterable);
var next = iterator.next;
var item;
var index = 0;
while (true) {
item = next.@call(iterator);
if (!@isObject(item))
@throwTypeError("Iterator result interface is not an object");
if (item.done)
return result;
@putByValDirect(result, index++, item.value);
}
}
@linkTimeConstant
function wrappedIterator(iterator)
{
let wrapper = @Object.@create(null);
wrapper.@@iterator = function() { return iterator; }
return wrapper;
}
@linkTimeConstant
function builtinSetIterable(set)
{
"use strict";
if (!@isSet(set))
@throwTypeError("builtinSetIterable called with non-Set object.");
// Using the private @@iterator only guarantees that the symbol itself has not been modified, but does not protect
// against the iterator itself having been replaced. For Sets, `@values` has a copy of the function originally
// placed at `Symbol.iterator`.
let iteratorFunction = set.@values;
return @wrappedIterator(iteratorFunction.@call(set));
}
@linkTimeConstant
function builtinMapIterable(map)
{
"use strict";
if (!@isMap(map))
@throwTypeError("builtinMapIterable called with non-Map object.");
// Using the private @@iterator only guarantees that the symbol itself has not been modified, but does not protect
// against the iterator itself having been replaced. For Maps, `@entries` has a copy of the function originally
// placed at `Symbol.iterator`.
let iteratorFunction = map.@entries;
return @wrappedIterator(iteratorFunction.@call(map));
}