| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #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 |