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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // This defines a set of argument wrappers and related factory methods that | 5 // This defines a set of argument wrappers and related factory methods that |
6 // can be used specify the refcounting and reference semantics of arguments | 6 // can be used specify the refcounting and reference semantics of arguments |
7 // that are bound by the Bind() function in base/bind.h. | 7 // that are bound by the Bind() function in base/bind.h. |
8 // | 8 // |
9 // The public functions are base::Unretained() and base::ConstRef(). | 9 // The public functions are base::Unretained() and base::ConstRef(). |
10 // Unretained() allows Bind() to bind a non-refcounted class. | 10 // Unretained() allows Bind() to bind a non-refcounted class. |
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116 // exist, then &C::TargetFunc is not ambiguous, and the overload resolution | 116 // exist, then &C::TargetFunc is not ambiguous, and the overload resolution |
117 // will prefer GoodCheck(Helper<&C::TargetFunc>*). | 117 // will prefer GoodCheck(Helper<&C::TargetFunc>*). |
118 // | 118 // |
119 // This method of SFINAE will correctly probe for inherited names, but it cannot | 119 // This method of SFINAE will correctly probe for inherited names, but it cannot |
120 // typecheck those names. It's still a good enough sanity check though. | 120 // typecheck those names. It's still a good enough sanity check though. |
121 // | 121 // |
122 // Works on gcc-4.2, gcc-4.4, and Visual Studio 2008. | 122 // Works on gcc-4.2, gcc-4.4, and Visual Studio 2008. |
123 // | 123 // |
124 // TODO(ajwong): Move to ref_counted.h or template_util.h when we've vetted | 124 // TODO(ajwong): Move to ref_counted.h or template_util.h when we've vetted |
125 // this works well. | 125 // this works well. |
| 126 // |
| 127 // TODO(ajwong): Make this check for Release() as well. |
| 128 // See http://crbug.com/82038. |
126 template <typename T> | 129 template <typename T> |
127 class SupportsAddRefAndRelease { | 130 class SupportsAddRefAndRelease { |
128 typedef char Yes[1]; | 131 typedef char Yes[1]; |
129 typedef char No[2]; | 132 typedef char No[2]; |
130 | 133 |
131 struct BaseMixin { | 134 struct BaseMixin { |
132 void AddRef(); | 135 void AddRef(); |
133 void Release(); | |
134 }; | 136 }; |
135 | 137 |
136 // MSVC warns when you try to use Base if T has a private destructor, the | 138 // MSVC warns when you try to use Base if T has a private destructor, the |
137 // common pattern for refcounted types. It does this even though no attempt to | 139 // common pattern for refcounted types. It does this even though no attempt to |
138 // instantiate Base is made. We disable the warning for this definition. | 140 // instantiate Base is made. We disable the warning for this definition. |
139 #if defined(OS_WIN) | 141 #if defined(OS_WIN) |
140 #pragma warning(disable:4624) | 142 #pragma warning(disable:4624) |
141 #endif | 143 #endif |
142 struct Base : public T, public BaseMixin { | 144 struct Base : public T, public BaseMixin { |
143 }; | 145 }; |
144 #if defined(OS_WIN) | 146 #if defined(OS_WIN) |
145 #pragma warning(default:4624) | 147 #pragma warning(default:4624) |
146 #endif | 148 #endif |
147 | 149 |
148 template <void(BaseMixin::*)(void)> struct Helper {}; | 150 template <void(BaseMixin::*)(void)> struct Helper {}; |
149 | 151 |
150 template <typename C> | 152 template <typename C> |
151 static No& Check(Helper<&C::AddRef>*, Helper<&C::Release>*); | 153 static No& Check(Helper<&C::AddRef>*); |
152 | 154 |
153 template <typename > | 155 template <typename > |
154 static Yes& Check(...); | 156 static Yes& Check(...); |
155 | 157 |
156 public: | 158 public: |
157 static const bool value = sizeof(Check<Base>(0,0)) == sizeof(Yes); | 159 static const bool value = sizeof(Check<Base>(0)) == sizeof(Yes); |
158 }; | 160 }; |
159 | 161 |
160 | 162 |
161 // Helpers to assert that arguments of a recounted type are bound with a | 163 // Helpers to assert that arguments of a recounted type are bound with a |
162 // scoped_refptr. | 164 // scoped_refptr. |
163 template <bool IsClasstype, typename T> | 165 template <bool IsClasstype, typename T> |
164 struct UnsafeBindtoRefCountedArgHelper : false_type { | 166 struct UnsafeBindtoRefCountedArgHelper : false_type { |
165 }; | 167 }; |
166 | 168 |
167 template <typename T> | 169 template <typename T> |
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254 } | 256 } |
255 | 257 |
256 template <typename T> | 258 template <typename T> |
257 inline internal::ConstRefWrapper<T> ConstRef(const T& o) { | 259 inline internal::ConstRefWrapper<T> ConstRef(const T& o) { |
258 return internal::ConstRefWrapper<T>(o); | 260 return internal::ConstRefWrapper<T>(o); |
259 } | 261 } |
260 | 262 |
261 } // namespace base | 263 } // namespace base |
262 | 264 |
263 #endif // BASE_BIND_HELPERS_H_ | 265 #endif // BASE_BIND_HELPERS_H_ |
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