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| 1 // Copyright 2017 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #import "ios/shared/chrome/browser/tabs/web_state_list_fast_enumeration_helper.h
" |
| 6 |
| 7 #include <algorithm> |
| 8 #include <cstdint> |
| 9 #include <memory> |
| 10 |
| 11 #include "base/logging.h" |
| 12 #include "base/memory/ptr_util.h" |
| 13 #import "ios/shared/chrome/browser/tabs/web_state_list.h" |
| 14 #import "ios/shared/chrome/browser/tabs/web_state_list_observer_bridge.h" |
| 15 |
| 16 #if !defined(__has_feature) || !__has_feature(objc_arc) |
| 17 #error "This file requires ARC support." |
| 18 #endif |
| 19 |
| 20 #pragma mark - WebStateListFastEnumerationHelperObserver |
| 21 |
| 22 // Observer for WebStateListFastEnumerationHelper that will increment the |
| 23 // mutation counter provided in the constructor every time the WebStateList |
| 24 // it is tracking is modified. |
| 25 @interface WebStateListFastEnumerationHelperObserver |
| 26 : NSObject<WebStateListObserving> |
| 27 |
| 28 // Initializes the observer with a pointer to the mutation counter to increment |
| 29 // when the WebStateList is mutated. |
| 30 - (instancetype)initWithMutationCounter:(unsigned long*)mutationCounter |
| 31 NS_DESIGNATED_INITIALIZER; |
| 32 |
| 33 - (instancetype)init NS_UNAVAILABLE; |
| 34 |
| 35 @end |
| 36 |
| 37 @implementation WebStateListFastEnumerationHelperObserver { |
| 38 // Pointer to the mutation counter to increment when the WebStateList is |
| 39 // mutated. |
| 40 unsigned long* _mutationCounter; |
| 41 } |
| 42 |
| 43 - (instancetype)initWithMutationCounter:(unsigned long*)mutationCounter { |
| 44 DCHECK(mutationCounter); |
| 45 if ((self = [super init])) |
| 46 _mutationCounter = mutationCounter; |
| 47 return self; |
| 48 } |
| 49 |
| 50 #pragma mark WebStateListObserving |
| 51 |
| 52 - (void)webStateList:(WebStateList*)webStateList |
| 53 didInsertWebState:(web::WebState*)webState |
| 54 atIndex:(int)index { |
| 55 ++*_mutationCounter; |
| 56 } |
| 57 |
| 58 - (void)webStateList:(WebStateList*)webStateList |
| 59 didMoveWebState:(web::WebState*)webState |
| 60 fromIndex:(int)fromIndex |
| 61 toIndex:(int)toIndex { |
| 62 ++*_mutationCounter; |
| 63 } |
| 64 |
| 65 - (void)webStateList:(WebStateList*)webStateList |
| 66 didReplaceWebState:(web::WebState*)oldWebState |
| 67 byWebState:(web::WebState*)newWebState |
| 68 atIndex:(int)index { |
| 69 ++*_mutationCounter; |
| 70 } |
| 71 |
| 72 - (void)webStateList:(WebStateList*)webStateList |
| 73 didDetachWebState:(web::WebState*)webState |
| 74 atIndex:(int)index { |
| 75 ++*_mutationCounter; |
| 76 } |
| 77 |
| 78 @end |
| 79 |
| 80 #pragma mark - WebStateListFastEnumerationHelper |
| 81 |
| 82 @implementation WebStateListFastEnumerationHelper { |
| 83 // The wrapped WebStateList. |
| 84 WebStateList* _webStateList; |
| 85 |
| 86 // Helper that returns Objective-C proxies for WebState objects. |
| 87 id<WebStateProxyFactory> _proxyFactory; |
| 88 |
| 89 // WebStateListObserverBridge forwarding the events of WebStateList to self. |
| 90 std::unique_ptr<WebStateListObserverBridge> _observerBridge; |
| 91 |
| 92 // Counter incremented each time the WebStateList is mutated. |
| 93 unsigned long _mutationCounter; |
| 94 } |
| 95 |
| 96 - (instancetype)initWithWebStateList:(WebStateList*)webStateList |
| 97 proxyFactory:(id<WebStateProxyFactory>)proxyFactory { |
| 98 DCHECK(webStateList); |
| 99 DCHECK(proxyFactory); |
| 100 if ((self = [super init])) { |
| 101 _webStateList = webStateList; |
| 102 _proxyFactory = proxyFactory; |
| 103 _observerBridge = base::MakeUnique<WebStateListObserverBridge>( |
| 104 [[WebStateListFastEnumerationHelperObserver alloc] |
| 105 initWithMutationCounter:&_mutationCounter]); |
| 106 _webStateList->AddObserver(_observerBridge.get()); |
| 107 } |
| 108 return self; |
| 109 } |
| 110 |
| 111 - (void)dealloc { |
| 112 _webStateList->RemoveObserver(_observerBridge.get()); |
| 113 } |
| 114 |
| 115 #pragma mark NSFastEnumeration |
| 116 |
| 117 - (NSUInteger)countByEnumeratingWithState:(NSFastEnumerationState*)state |
| 118 objects:(id __unsafe_unretained*)buffer |
| 119 count:(NSUInteger)len { |
| 120 // The number of objects already returned is stored in |state->state|. For |
| 121 // the first iteration, the counter will be zero and the rest of the state |
| 122 // structure need to be initialised. |
| 123 DCHECK_LE(state->state, static_cast<unsigned long>(INT_MAX)); |
| 124 const int offset = state->state; |
| 125 if (offset == 0) |
| 126 state->mutationsPtr = &_mutationCounter; |
| 127 |
| 128 if (len > static_cast<unsigned long>(INT_MAX)) |
| 129 len = static_cast<unsigned long>(INT_MAX); |
| 130 |
| 131 DCHECK_LE(offset, _webStateList->count()); |
| 132 const int count = |
| 133 std::min(static_cast<int>(len), _webStateList->count() - offset); |
| 134 |
| 135 for (int index = 0; index < count; ++index) { |
| 136 web::WebState* webState = _webStateList->GetWebStateAt(offset + index); |
| 137 __autoreleasing id wrapper = [_proxyFactory proxyForWebState:webState]; |
| 138 buffer[index] = wrapper; |
| 139 } |
| 140 |
| 141 state->state += count; |
| 142 state->itemsPtr = buffer; |
| 143 |
| 144 return static_cast<NSUInteger>(count); |
| 145 } |
| 146 |
| 147 @end |
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