| /* |
| * |
| * Copyright 2015, Google 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: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * 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. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "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 THE COPYRIGHT |
| * OWNER 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. |
| * |
| */ |
| |
| #import "GRXNSFastEnumerator.h" |
| |
| @implementation GRXNSFastEnumerator { |
| id<NSFastEnumeration> _container; |
| NSFastEnumerationState _state; |
| // Number of elements of the container currently in the _state.itemsPtr array. |
| NSUInteger _count; |
| // The index of the next object to return from the _state.itemsPtr array. |
| NSUInteger _index; |
| // A "buffer of one element," for the containers that enumerate their elements one by one. Those |
| // will set _state.itemsPtr to point to this. |
| // The NSFastEnumeration protocol requires it to be __unsafe_unretained, but that's alright |
| // because the only use we'd make of its value is to return it immediately as the result of |
| // nextObject. |
| __unsafe_unretained id _bufferValue; |
| // Neither NSEnumerator nor NSFastEnumeration instances are required to work correctly when the |
| // underlying container is mutated during iteration. The expectation is that an exception is |
| // thrown when that happens. So we check for mutations. |
| unsigned long _mutationFlag; |
| BOOL _mutationFlagIsSet; |
| } |
| |
| - (instancetype)init { |
| return [self initWithContainer:nil]; |
| } |
| |
| // Designated initializer. |
| - (instancetype)initWithContainer:(id<NSFastEnumeration>)container { |
| if ((self = [super init])) { |
| _container = container; |
| } |
| return self; |
| } |
| |
| - (id)nextObject { |
| if (_index == _count) { |
| _index = 0; |
| _count = [_container countByEnumeratingWithState:&_state objects:&_bufferValue count:1]; |
| if (_count == 0) { |
| // Enumeration is over. |
| _container = nil; |
| return nil; |
| } |
| if (_mutationFlagIsSet) { |
| NSAssert(_mutationFlag == *(_state.mutationsPtr), |
| @"container was mutated while being enumerated"); |
| } else { |
| _mutationFlag = *(_state.mutationsPtr); |
| _mutationFlagIsSet = YES; |
| } |
| } |
| return _state.itemsPtr[_index++]; |
| } |
| @end |