henrike@webrtc.org | f7795df | 2014-05-13 18:00:26 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2012 The WebRTC Project Authors. All rights reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | // Scopers help you manage ownership of a pointer, helping you easily manage the |
| 12 | // a pointer within a scope, and automatically destroying the pointer at the |
| 13 | // end of a scope. There are two main classes you will use, which correspond |
| 14 | // to the operators new/delete and new[]/delete[]. |
| 15 | // |
| 16 | // Example usage (scoped_ptr<T>): |
| 17 | // { |
| 18 | // scoped_ptr<Foo> foo(new Foo("wee")); |
| 19 | // } // foo goes out of scope, releasing the pointer with it. |
| 20 | // |
| 21 | // { |
| 22 | // scoped_ptr<Foo> foo; // No pointer managed. |
| 23 | // foo.reset(new Foo("wee")); // Now a pointer is managed. |
| 24 | // foo.reset(new Foo("wee2")); // Foo("wee") was destroyed. |
| 25 | // foo.reset(new Foo("wee3")); // Foo("wee2") was destroyed. |
| 26 | // foo->Method(); // Foo::Method() called. |
| 27 | // foo.get()->Method(); // Foo::Method() called. |
| 28 | // SomeFunc(foo.release()); // SomeFunc takes ownership, foo no longer |
| 29 | // // manages a pointer. |
| 30 | // foo.reset(new Foo("wee4")); // foo manages a pointer again. |
| 31 | // foo.reset(); // Foo("wee4") destroyed, foo no longer |
| 32 | // // manages a pointer. |
| 33 | // } // foo wasn't managing a pointer, so nothing was destroyed. |
| 34 | // |
| 35 | // Example usage (scoped_ptr<T[]>): |
| 36 | // { |
| 37 | // scoped_ptr<Foo[]> foo(new Foo[100]); |
| 38 | // foo.get()->Method(); // Foo::Method on the 0th element. |
| 39 | // foo[10].Method(); // Foo::Method on the 10th element. |
| 40 | // } |
| 41 | // |
| 42 | // These scopers also implement part of the functionality of C++11 unique_ptr |
| 43 | // in that they are "movable but not copyable." You can use the scopers in |
| 44 | // the parameter and return types of functions to signify ownership transfer |
| 45 | // in to and out of a function. When calling a function that has a scoper |
| 46 | // as the argument type, it must be called with the result of an analogous |
| 47 | // scoper's Pass() function or another function that generates a temporary; |
| 48 | // passing by copy will NOT work. Here is an example using scoped_ptr: |
| 49 | // |
| 50 | // void TakesOwnership(scoped_ptr<Foo> arg) { |
| 51 | // // Do something with arg |
| 52 | // } |
| 53 | // scoped_ptr<Foo> CreateFoo() { |
| 54 | // // No need for calling Pass() because we are constructing a temporary |
| 55 | // // for the return value. |
| 56 | // return scoped_ptr<Foo>(new Foo("new")); |
| 57 | // } |
| 58 | // scoped_ptr<Foo> PassThru(scoped_ptr<Foo> arg) { |
| 59 | // return arg.Pass(); |
| 60 | // } |
| 61 | // |
| 62 | // { |
| 63 | // scoped_ptr<Foo> ptr(new Foo("yay")); // ptr manages Foo("yay"). |
| 64 | // TakesOwnership(ptr.Pass()); // ptr no longer owns Foo("yay"). |
| 65 | // scoped_ptr<Foo> ptr2 = CreateFoo(); // ptr2 owns the return Foo. |
| 66 | // scoped_ptr<Foo> ptr3 = // ptr3 now owns what was in ptr2. |
| 67 | // PassThru(ptr2.Pass()); // ptr2 is correspondingly NULL. |
| 68 | // } |
| 69 | // |
| 70 | // Notice that if you do not call Pass() when returning from PassThru(), or |
| 71 | // when invoking TakesOwnership(), the code will not compile because scopers |
| 72 | // are not copyable; they only implement move semantics which require calling |
| 73 | // the Pass() function to signify a destructive transfer of state. CreateFoo() |
| 74 | // is different though because we are constructing a temporary on the return |
| 75 | // line and thus can avoid needing to call Pass(). |
| 76 | // |
| 77 | // Pass() properly handles upcast in initialization, i.e. you can use a |
| 78 | // scoped_ptr<Child> to initialize a scoped_ptr<Parent>: |
| 79 | // |
| 80 | // scoped_ptr<Foo> foo(new Foo()); |
| 81 | // scoped_ptr<FooParent> parent(foo.Pass()); |
| 82 | // |
| 83 | // PassAs<>() should be used to upcast return value in return statement: |
| 84 | // |
| 85 | // scoped_ptr<Foo> CreateFoo() { |
| 86 | // scoped_ptr<FooChild> result(new FooChild()); |
| 87 | // return result.PassAs<Foo>(); |
| 88 | // } |
| 89 | // |
| 90 | // Note that PassAs<>() is implemented only for scoped_ptr<T>, but not for |
| 91 | // scoped_ptr<T[]>. This is because casting array pointers may not be safe. |
| 92 | |
| 93 | #ifndef WEBRTC_BASE_SCOPED_PTR_H__ |
| 94 | #define WEBRTC_BASE_SCOPED_PTR_H__ |
| 95 | |
| 96 | #include <stddef.h> // for ptrdiff_t |
| 97 | #include <stdlib.h> // for free() decl |
| 98 | |
| 99 | #include <algorithm> // For std::swap(). |
| 100 | |
| 101 | #include "webrtc/base/common.h" // for ASSERT |
| 102 | #include "webrtc/base/compile_assert.h" // for COMPILE_ASSERT |
| 103 | #include "webrtc/base/move.h" // for TALK_MOVE_ONLY_TYPE_FOR_CPP_03 |
| 104 | #include "webrtc/base/template_util.h" // for is_convertible, is_array |
| 105 | |
| 106 | #ifdef WEBRTC_WIN |
| 107 | namespace std { using ::ptrdiff_t; }; |
| 108 | #endif // WEBRTC_WIN |
| 109 | |
| 110 | namespace rtc { |
| 111 | |
| 112 | // Function object which deletes its parameter, which must be a pointer. |
| 113 | // If C is an array type, invokes 'delete[]' on the parameter; otherwise, |
| 114 | // invokes 'delete'. The default deleter for scoped_ptr<T>. |
| 115 | template <class T> |
| 116 | struct DefaultDeleter { |
| 117 | DefaultDeleter() {} |
| 118 | template <typename U> DefaultDeleter(const DefaultDeleter<U>& other) { |
| 119 | // IMPLEMENTATION NOTE: C++11 20.7.1.1.2p2 only provides this constructor |
| 120 | // if U* is implicitly convertible to T* and U is not an array type. |
| 121 | // |
| 122 | // Correct implementation should use SFINAE to disable this |
| 123 | // constructor. However, since there are no other 1-argument constructors, |
| 124 | // using a COMPILE_ASSERT() based on is_convertible<> and requiring |
| 125 | // complete types is simpler and will cause compile failures for equivalent |
| 126 | // misuses. |
| 127 | // |
| 128 | // Note, the is_convertible<U*, T*> check also ensures that U is not an |
| 129 | // array. T is guaranteed to be a non-array, so any U* where U is an array |
| 130 | // cannot convert to T*. |
| 131 | enum { T_must_be_complete = sizeof(T) }; |
| 132 | enum { U_must_be_complete = sizeof(U) }; |
| 133 | COMPILE_ASSERT((rtc::is_convertible<U*, T*>::value), |
| 134 | U_ptr_must_implicitly_convert_to_T_ptr); |
| 135 | } |
| 136 | inline void operator()(T* ptr) const { |
| 137 | enum { type_must_be_complete = sizeof(T) }; |
| 138 | delete ptr; |
| 139 | } |
| 140 | }; |
| 141 | |
| 142 | // Specialization of DefaultDeleter for array types. |
| 143 | template <class T> |
| 144 | struct DefaultDeleter<T[]> { |
| 145 | inline void operator()(T* ptr) const { |
| 146 | enum { type_must_be_complete = sizeof(T) }; |
| 147 | delete[] ptr; |
| 148 | } |
| 149 | |
| 150 | private: |
| 151 | // Disable this operator for any U != T because it is undefined to execute |
| 152 | // an array delete when the static type of the array mismatches the dynamic |
| 153 | // type. |
| 154 | // |
| 155 | // References: |
| 156 | // C++98 [expr.delete]p3 |
| 157 | // http://cplusplus.github.com/LWG/lwg-defects.html#938 |
| 158 | template <typename U> void operator()(U* array) const; |
| 159 | }; |
| 160 | |
| 161 | template <class T, int n> |
| 162 | struct DefaultDeleter<T[n]> { |
| 163 | // Never allow someone to declare something like scoped_ptr<int[10]>. |
| 164 | COMPILE_ASSERT(sizeof(T) == -1, do_not_use_array_with_size_as_type); |
| 165 | }; |
| 166 | |
| 167 | // Function object which invokes 'free' on its parameter, which must be |
| 168 | // a pointer. Can be used to store malloc-allocated pointers in scoped_ptr: |
| 169 | // |
| 170 | // scoped_ptr<int, rtc::FreeDeleter> foo_ptr( |
| 171 | // static_cast<int*>(malloc(sizeof(int)))); |
| 172 | struct FreeDeleter { |
| 173 | inline void operator()(void* ptr) const { |
| 174 | free(ptr); |
| 175 | } |
| 176 | }; |
| 177 | |
| 178 | namespace internal { |
| 179 | |
| 180 | // Minimal implementation of the core logic of scoped_ptr, suitable for |
| 181 | // reuse in both scoped_ptr and its specializations. |
| 182 | template <class T, class D> |
| 183 | class scoped_ptr_impl { |
| 184 | public: |
| 185 | explicit scoped_ptr_impl(T* p) : data_(p) { } |
| 186 | |
| 187 | // Initializer for deleters that have data parameters. |
| 188 | scoped_ptr_impl(T* p, const D& d) : data_(p, d) {} |
| 189 | |
| 190 | // Templated constructor that destructively takes the value from another |
| 191 | // scoped_ptr_impl. |
| 192 | template <typename U, typename V> |
| 193 | scoped_ptr_impl(scoped_ptr_impl<U, V>* other) |
| 194 | : data_(other->release(), other->get_deleter()) { |
| 195 | // We do not support move-only deleters. We could modify our move |
| 196 | // emulation to have rtc::subtle::move() and |
| 197 | // rtc::subtle::forward() |
| 198 | // functions that are imperfect emulations of their C++11 equivalents, |
| 199 | // but until there's a requirement, just assume deleters are copyable. |
| 200 | } |
| 201 | |
| 202 | template <typename U, typename V> |
| 203 | void TakeState(scoped_ptr_impl<U, V>* other) { |
| 204 | // See comment in templated constructor above regarding lack of support |
| 205 | // for move-only deleters. |
| 206 | reset(other->release()); |
| 207 | get_deleter() = other->get_deleter(); |
| 208 | } |
| 209 | |
| 210 | ~scoped_ptr_impl() { |
| 211 | if (data_.ptr != NULL) { |
| 212 | // Not using get_deleter() saves one function call in non-optimized |
| 213 | // builds. |
| 214 | static_cast<D&>(data_)(data_.ptr); |
| 215 | } |
| 216 | } |
| 217 | |
| 218 | void reset(T* p) { |
| 219 | // This is a self-reset, which is no longer allowed: http://crbug.com/162971 |
| 220 | if (p != NULL && p == data_.ptr) |
| 221 | abort(); |
| 222 | |
| 223 | // Note that running data_.ptr = p can lead to undefined behavior if |
| 224 | // get_deleter()(get()) deletes this. In order to pevent this, reset() |
| 225 | // should update the stored pointer before deleting its old value. |
| 226 | // |
| 227 | // However, changing reset() to use that behavior may cause current code to |
| 228 | // break in unexpected ways. If the destruction of the owned object |
| 229 | // dereferences the scoped_ptr when it is destroyed by a call to reset(), |
| 230 | // then it will incorrectly dispatch calls to |p| rather than the original |
| 231 | // value of |data_.ptr|. |
| 232 | // |
| 233 | // During the transition period, set the stored pointer to NULL while |
| 234 | // deleting the object. Eventually, this safety check will be removed to |
| 235 | // prevent the scenario initially described from occuring and |
| 236 | // http://crbug.com/176091 can be closed. |
| 237 | T* old = data_.ptr; |
| 238 | data_.ptr = NULL; |
| 239 | if (old != NULL) |
| 240 | static_cast<D&>(data_)(old); |
| 241 | data_.ptr = p; |
| 242 | } |
| 243 | |
| 244 | T* get() const { return data_.ptr; } |
| 245 | |
| 246 | D& get_deleter() { return data_; } |
| 247 | const D& get_deleter() const { return data_; } |
| 248 | |
| 249 | void swap(scoped_ptr_impl& p2) { |
| 250 | // Standard swap idiom: 'using std::swap' ensures that std::swap is |
| 251 | // present in the overload set, but we call swap unqualified so that |
| 252 | // any more-specific overloads can be used, if available. |
| 253 | using std::swap; |
| 254 | swap(static_cast<D&>(data_), static_cast<D&>(p2.data_)); |
| 255 | swap(data_.ptr, p2.data_.ptr); |
| 256 | } |
| 257 | |
| 258 | T* release() { |
| 259 | T* old_ptr = data_.ptr; |
| 260 | data_.ptr = NULL; |
| 261 | return old_ptr; |
| 262 | } |
| 263 | |
| 264 | T** accept() { |
| 265 | reset(NULL); |
| 266 | return &(data_.ptr); |
| 267 | } |
| 268 | |
| 269 | T** use() { |
| 270 | return &(data_.ptr); |
| 271 | } |
| 272 | |
| 273 | private: |
| 274 | // Needed to allow type-converting constructor. |
| 275 | template <typename U, typename V> friend class scoped_ptr_impl; |
| 276 | |
| 277 | // Use the empty base class optimization to allow us to have a D |
| 278 | // member, while avoiding any space overhead for it when D is an |
| 279 | // empty class. See e.g. http://www.cantrip.org/emptyopt.html for a good |
| 280 | // discussion of this technique. |
| 281 | struct Data : public D { |
| 282 | explicit Data(T* ptr_in) : ptr(ptr_in) {} |
| 283 | Data(T* ptr_in, const D& other) : D(other), ptr(ptr_in) {} |
| 284 | T* ptr; |
| 285 | }; |
| 286 | |
| 287 | Data data_; |
| 288 | |
| 289 | DISALLOW_COPY_AND_ASSIGN(scoped_ptr_impl); |
| 290 | }; |
| 291 | |
| 292 | } // namespace internal |
| 293 | |
| 294 | // A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T> |
| 295 | // automatically deletes the pointer it holds (if any). |
| 296 | // That is, scoped_ptr<T> owns the T object that it points to. |
| 297 | // Like a T*, a scoped_ptr<T> may hold either NULL or a pointer to a T object. |
| 298 | // Also like T*, scoped_ptr<T> is thread-compatible, and once you |
| 299 | // dereference it, you get the thread safety guarantees of T. |
| 300 | // |
| 301 | // The size of scoped_ptr is small. On most compilers, when using the |
| 302 | // DefaultDeleter, sizeof(scoped_ptr<T>) == sizeof(T*). Custom deleters will |
| 303 | // increase the size proportional to whatever state they need to have. See |
| 304 | // comments inside scoped_ptr_impl<> for details. |
| 305 | // |
| 306 | // Current implementation targets having a strict subset of C++11's |
| 307 | // unique_ptr<> features. Known deficiencies include not supporting move-only |
| 308 | // deleteres, function pointers as deleters, and deleters with reference |
| 309 | // types. |
| 310 | template <class T, class D = rtc::DefaultDeleter<T> > |
| 311 | class scoped_ptr { |
| 312 | TALK_MOVE_ONLY_TYPE_FOR_CPP_03(scoped_ptr, RValue) |
| 313 | |
| 314 | public: |
| 315 | // The element and deleter types. |
| 316 | typedef T element_type; |
| 317 | typedef D deleter_type; |
| 318 | |
| 319 | // Constructor. Defaults to initializing with NULL. |
| 320 | scoped_ptr() : impl_(NULL) { } |
| 321 | |
| 322 | // Constructor. Takes ownership of p. |
| 323 | explicit scoped_ptr(element_type* p) : impl_(p) { } |
| 324 | |
| 325 | // Constructor. Allows initialization of a stateful deleter. |
| 326 | scoped_ptr(element_type* p, const D& d) : impl_(p, d) { } |
| 327 | |
| 328 | // Constructor. Allows construction from a scoped_ptr rvalue for a |
| 329 | // convertible type and deleter. |
| 330 | // |
| 331 | // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this constructor distinct |
| 332 | // from the normal move constructor. By C++11 20.7.1.2.1.21, this constructor |
| 333 | // has different post-conditions if D is a reference type. Since this |
| 334 | // implementation does not support deleters with reference type, |
| 335 | // we do not need a separate move constructor allowing us to avoid one |
| 336 | // use of SFINAE. You only need to care about this if you modify the |
| 337 | // implementation of scoped_ptr. |
| 338 | template <typename U, typename V> |
| 339 | scoped_ptr(scoped_ptr<U, V> other) : impl_(&other.impl_) { |
| 340 | COMPILE_ASSERT(!rtc::is_array<U>::value, U_cannot_be_an_array); |
| 341 | } |
| 342 | |
| 343 | // Constructor. Move constructor for C++03 move emulation of this type. |
| 344 | scoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) { } |
| 345 | |
| 346 | // operator=. Allows assignment from a scoped_ptr rvalue for a convertible |
| 347 | // type and deleter. |
| 348 | // |
| 349 | // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from |
| 350 | // the normal move assignment operator. By C++11 20.7.1.2.3.4, this templated |
| 351 | // form has different requirements on for move-only Deleters. Since this |
| 352 | // implementation does not support move-only Deleters, we do not need a |
| 353 | // separate move assignment operator allowing us to avoid one use of SFINAE. |
| 354 | // You only need to care about this if you modify the implementation of |
| 355 | // scoped_ptr. |
| 356 | template <typename U, typename V> |
| 357 | scoped_ptr& operator=(scoped_ptr<U, V> rhs) { |
| 358 | COMPILE_ASSERT(!rtc::is_array<U>::value, U_cannot_be_an_array); |
| 359 | impl_.TakeState(&rhs.impl_); |
| 360 | return *this; |
| 361 | } |
| 362 | |
| 363 | // Reset. Deletes the currently owned object, if any. |
| 364 | // Then takes ownership of a new object, if given. |
| 365 | void reset(element_type* p = NULL) { impl_.reset(p); } |
| 366 | |
| 367 | // Accessors to get the owned object. |
| 368 | // operator* and operator-> will assert() if there is no current object. |
| 369 | element_type& operator*() const { |
| 370 | ASSERT(impl_.get() != NULL); |
| 371 | return *impl_.get(); |
| 372 | } |
| 373 | element_type* operator->() const { |
| 374 | ASSERT(impl_.get() != NULL); |
| 375 | return impl_.get(); |
| 376 | } |
| 377 | element_type* get() const { return impl_.get(); } |
| 378 | |
| 379 | // Access to the deleter. |
| 380 | deleter_type& get_deleter() { return impl_.get_deleter(); } |
| 381 | const deleter_type& get_deleter() const { return impl_.get_deleter(); } |
| 382 | |
| 383 | // Allow scoped_ptr<element_type> to be used in boolean expressions, but not |
| 384 | // implicitly convertible to a real bool (which is dangerous). |
| 385 | // |
| 386 | // Note that this trick is only safe when the == and != operators |
| 387 | // are declared explicitly, as otherwise "scoped_ptr1 == |
| 388 | // scoped_ptr2" will compile but do the wrong thing (i.e., convert |
| 389 | // to Testable and then do the comparison). |
| 390 | private: |
| 391 | typedef rtc::internal::scoped_ptr_impl<element_type, deleter_type> |
| 392 | scoped_ptr::*Testable; |
| 393 | |
| 394 | public: |
| 395 | operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; } |
| 396 | |
| 397 | // Comparison operators. |
| 398 | // These return whether two scoped_ptr refer to the same object, not just to |
| 399 | // two different but equal objects. |
| 400 | bool operator==(const element_type* p) const { return impl_.get() == p; } |
| 401 | bool operator!=(const element_type* p) const { return impl_.get() != p; } |
| 402 | |
| 403 | // Swap two scoped pointers. |
| 404 | void swap(scoped_ptr& p2) { |
| 405 | impl_.swap(p2.impl_); |
| 406 | } |
| 407 | |
| 408 | // Release a pointer. |
| 409 | // The return value is the current pointer held by this object. |
| 410 | // If this object holds a NULL pointer, the return value is NULL. |
| 411 | // After this operation, this object will hold a NULL pointer, |
| 412 | // and will not own the object any more. |
| 413 | element_type* release() WARN_UNUSED_RESULT { |
| 414 | return impl_.release(); |
| 415 | } |
| 416 | |
| 417 | // Delete the currently held pointer and return a pointer |
| 418 | // to allow overwriting of the current pointer address. |
| 419 | element_type** accept() WARN_UNUSED_RESULT { |
| 420 | return impl_.accept(); |
| 421 | } |
| 422 | |
| 423 | // Return a pointer to the current pointer address. |
| 424 | element_type** use() WARN_UNUSED_RESULT { |
| 425 | return impl_.use(); |
| 426 | } |
| 427 | |
| 428 | // C++98 doesn't support functions templates with default parameters which |
| 429 | // makes it hard to write a PassAs() that understands converting the deleter |
| 430 | // while preserving simple calling semantics. |
| 431 | // |
| 432 | // Until there is a use case for PassAs() with custom deleters, just ignore |
| 433 | // the custom deleter. |
| 434 | template <typename PassAsType> |
| 435 | scoped_ptr<PassAsType> PassAs() { |
| 436 | return scoped_ptr<PassAsType>(Pass()); |
| 437 | } |
| 438 | |
| 439 | private: |
| 440 | // Needed to reach into |impl_| in the constructor. |
| 441 | template <typename U, typename V> friend class scoped_ptr; |
| 442 | rtc::internal::scoped_ptr_impl<element_type, deleter_type> impl_; |
| 443 | |
| 444 | // Forbidden for API compatibility with std::unique_ptr. |
| 445 | explicit scoped_ptr(int disallow_construction_from_null); |
| 446 | |
| 447 | // Forbid comparison of scoped_ptr types. If U != T, it totally |
| 448 | // doesn't make sense, and if U == T, it still doesn't make sense |
| 449 | // because you should never have the same object owned by two different |
| 450 | // scoped_ptrs. |
| 451 | template <class U> bool operator==(scoped_ptr<U> const& p2) const; |
| 452 | template <class U> bool operator!=(scoped_ptr<U> const& p2) const; |
| 453 | }; |
| 454 | |
| 455 | template <class T, class D> |
| 456 | class scoped_ptr<T[], D> { |
| 457 | TALK_MOVE_ONLY_TYPE_FOR_CPP_03(scoped_ptr, RValue) |
| 458 | |
| 459 | public: |
| 460 | // The element and deleter types. |
| 461 | typedef T element_type; |
| 462 | typedef D deleter_type; |
| 463 | |
| 464 | // Constructor. Defaults to initializing with NULL. |
| 465 | scoped_ptr() : impl_(NULL) { } |
| 466 | |
| 467 | // Constructor. Stores the given array. Note that the argument's type |
| 468 | // must exactly match T*. In particular: |
| 469 | // - it cannot be a pointer to a type derived from T, because it is |
| 470 | // inherently unsafe in the general case to access an array through a |
| 471 | // pointer whose dynamic type does not match its static type (eg., if |
| 472 | // T and the derived types had different sizes access would be |
| 473 | // incorrectly calculated). Deletion is also always undefined |
| 474 | // (C++98 [expr.delete]p3). If you're doing this, fix your code. |
| 475 | // - it cannot be NULL, because NULL is an integral expression, not a |
| 476 | // pointer to T. Use the no-argument version instead of explicitly |
| 477 | // passing NULL. |
| 478 | // - it cannot be const-qualified differently from T per unique_ptr spec |
| 479 | // (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting |
| 480 | // to work around this may use implicit_cast<const T*>(). |
| 481 | // However, because of the first bullet in this comment, users MUST |
| 482 | // NOT use implicit_cast<Base*>() to upcast the static type of the array. |
| 483 | explicit scoped_ptr(element_type* array) : impl_(array) { } |
| 484 | |
| 485 | // Constructor. Move constructor for C++03 move emulation of this type. |
| 486 | scoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) { } |
| 487 | |
| 488 | // operator=. Move operator= for C++03 move emulation of this type. |
| 489 | scoped_ptr& operator=(RValue rhs) { |
| 490 | impl_.TakeState(&rhs.object->impl_); |
| 491 | return *this; |
| 492 | } |
| 493 | |
| 494 | // Reset. Deletes the currently owned array, if any. |
| 495 | // Then takes ownership of a new object, if given. |
| 496 | void reset(element_type* array = NULL) { impl_.reset(array); } |
| 497 | |
| 498 | // Accessors to get the owned array. |
| 499 | element_type& operator[](size_t i) const { |
| 500 | ASSERT(impl_.get() != NULL); |
| 501 | return impl_.get()[i]; |
| 502 | } |
| 503 | element_type* get() const { return impl_.get(); } |
| 504 | |
| 505 | // Access to the deleter. |
| 506 | deleter_type& get_deleter() { return impl_.get_deleter(); } |
| 507 | const deleter_type& get_deleter() const { return impl_.get_deleter(); } |
| 508 | |
| 509 | // Allow scoped_ptr<element_type> to be used in boolean expressions, but not |
| 510 | // implicitly convertible to a real bool (which is dangerous). |
| 511 | private: |
| 512 | typedef rtc::internal::scoped_ptr_impl<element_type, deleter_type> |
| 513 | scoped_ptr::*Testable; |
| 514 | |
| 515 | public: |
| 516 | operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; } |
| 517 | |
| 518 | // Comparison operators. |
| 519 | // These return whether two scoped_ptr refer to the same object, not just to |
| 520 | // two different but equal objects. |
| 521 | bool operator==(element_type* array) const { return impl_.get() == array; } |
| 522 | bool operator!=(element_type* array) const { return impl_.get() != array; } |
| 523 | |
| 524 | // Swap two scoped pointers. |
| 525 | void swap(scoped_ptr& p2) { |
| 526 | impl_.swap(p2.impl_); |
| 527 | } |
| 528 | |
| 529 | // Release a pointer. |
| 530 | // The return value is the current pointer held by this object. |
| 531 | // If this object holds a NULL pointer, the return value is NULL. |
| 532 | // After this operation, this object will hold a NULL pointer, |
| 533 | // and will not own the object any more. |
| 534 | element_type* release() WARN_UNUSED_RESULT { |
| 535 | return impl_.release(); |
| 536 | } |
| 537 | |
| 538 | // Delete the currently held pointer and return a pointer |
| 539 | // to allow overwriting of the current pointer address. |
| 540 | element_type** accept() WARN_UNUSED_RESULT { |
| 541 | return impl_.accept(); |
| 542 | } |
| 543 | |
| 544 | // Return a pointer to the current pointer address. |
| 545 | element_type** use() WARN_UNUSED_RESULT { |
| 546 | return impl_.use(); |
| 547 | } |
| 548 | |
| 549 | private: |
| 550 | // Force element_type to be a complete type. |
| 551 | enum { type_must_be_complete = sizeof(element_type) }; |
| 552 | |
| 553 | // Actually hold the data. |
| 554 | rtc::internal::scoped_ptr_impl<element_type, deleter_type> impl_; |
| 555 | |
| 556 | // Disable initialization from any type other than element_type*, by |
| 557 | // providing a constructor that matches such an initialization, but is |
| 558 | // private and has no definition. This is disabled because it is not safe to |
| 559 | // call delete[] on an array whose static type does not match its dynamic |
| 560 | // type. |
| 561 | template <typename U> explicit scoped_ptr(U* array); |
| 562 | explicit scoped_ptr(int disallow_construction_from_null); |
| 563 | |
| 564 | // Disable reset() from any type other than element_type*, for the same |
| 565 | // reasons as the constructor above. |
| 566 | template <typename U> void reset(U* array); |
| 567 | void reset(int disallow_reset_from_null); |
| 568 | |
| 569 | // Forbid comparison of scoped_ptr types. If U != T, it totally |
| 570 | // doesn't make sense, and if U == T, it still doesn't make sense |
| 571 | // because you should never have the same object owned by two different |
| 572 | // scoped_ptrs. |
| 573 | template <class U> bool operator==(scoped_ptr<U> const& p2) const; |
| 574 | template <class U> bool operator!=(scoped_ptr<U> const& p2) const; |
| 575 | }; |
| 576 | |
| 577 | } // namespace rtc |
| 578 | |
| 579 | // Free functions |
| 580 | template <class T, class D> |
| 581 | void swap(rtc::scoped_ptr<T, D>& p1, rtc::scoped_ptr<T, D>& p2) { |
| 582 | p1.swap(p2); |
| 583 | } |
| 584 | |
| 585 | template <class T, class D> |
| 586 | bool operator==(T* p1, const rtc::scoped_ptr<T, D>& p2) { |
| 587 | return p1 == p2.get(); |
| 588 | } |
| 589 | |
| 590 | template <class T, class D> |
| 591 | bool operator!=(T* p1, const rtc::scoped_ptr<T, D>& p2) { |
| 592 | return p1 != p2.get(); |
| 593 | } |
| 594 | |
| 595 | #endif // #ifndef WEBRTC_BASE_SCOPED_PTR_H__ |