362 lines
12 KiB
C++
362 lines
12 KiB
C++
/*
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* Copyright (C) 2005 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_STRONG_POINTER_H
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#define ANDROID_STRONG_POINTER_H
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#include <functional>
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#include <type_traits> // for common_type.
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// ---------------------------------------------------------------------------
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namespace android {
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template<typename T> class wp;
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// ---------------------------------------------------------------------------
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template<typename T>
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class sp {
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public:
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inline sp() : m_ptr(nullptr) { }
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// The old way of using sp<> was like this. This is bad because it relies
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// on implicit conversion to sp<>, which we would like to remove (if an
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// object is being managed some other way, this is double-ownership). We
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// want to move away from this:
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//
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// sp<Foo> foo = new Foo(...); // DO NOT DO THIS
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//
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// Instead, prefer to do this:
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//
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// sp<Foo> foo = sp<Foo>::make(...); // DO THIS
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//
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// Sometimes, in order to use this, when a constructor is marked as private,
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// you may need to add this to your class:
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//
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// friend class sp<Foo>;
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template <typename... Args>
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static inline sp<T> make(Args&&... args);
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// if nullptr, returns nullptr
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//
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// if a strong pointer is already available, this will retrieve it,
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// otherwise, this will abort
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static inline sp<T> fromExisting(T* other);
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// for more information about this macro and correct RefBase usage, see
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// the comment at the top of utils/RefBase.h
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#if defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
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sp(std::nullptr_t) : sp() {}
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#else
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sp(T* other); // NOLINT(implicit)
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template <typename U>
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sp(U* other); // NOLINT(implicit)
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sp& operator=(T* other);
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template <typename U>
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sp& operator=(U* other);
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#endif
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sp(const sp<T>& other);
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sp(sp<T>&& other) noexcept;
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template<typename U> sp(const sp<U>& other); // NOLINT(implicit)
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template<typename U> sp(sp<U>&& other); // NOLINT(implicit)
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// Cast a strong pointer directly from one type to another. Constructors
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// allow changing types, but only if they are pointer-compatible. This does
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// a static_cast internally.
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template <typename U>
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static inline sp<T> cast(const sp<U>& other);
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~sp();
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// Assignment
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sp& operator = (const sp<T>& other);
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sp& operator=(sp<T>&& other) noexcept;
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template<typename U> sp& operator = (const sp<U>& other);
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template<typename U> sp& operator = (sp<U>&& other);
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//! Special optimization for use by ProcessState (and nobody else).
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void force_set(T* other);
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// Reset
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void clear();
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// Accessors
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inline T& operator* () const { return *m_ptr; }
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inline T* operator-> () const { return m_ptr; }
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inline T* get() const { return m_ptr; }
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inline explicit operator bool () const { return m_ptr != nullptr; }
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// Punt these to the wp<> implementation.
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template<typename U>
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inline bool operator == (const wp<U>& o) const {
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return o == *this;
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}
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template<typename U>
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inline bool operator != (const wp<U>& o) const {
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return o != *this;
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}
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private:
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template<typename Y> friend class sp;
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template<typename Y> friend class wp;
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void set_pointer(T* ptr);
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T* m_ptr;
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};
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#define COMPARE_STRONG(_op_) \
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template <typename T, typename U> \
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static inline bool operator _op_(const sp<T>& t, const sp<U>& u) { \
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return t.get() _op_ u.get(); \
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} \
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template <typename T, typename U> \
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static inline bool operator _op_(const T* t, const sp<U>& u) { \
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return t _op_ u.get(); \
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} \
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template <typename T, typename U> \
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static inline bool operator _op_(const sp<T>& t, const U* u) { \
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return t.get() _op_ u; \
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} \
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template <typename T> \
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static inline bool operator _op_(const sp<T>& t, std::nullptr_t) { \
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return t.get() _op_ nullptr; \
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} \
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template <typename T> \
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static inline bool operator _op_(std::nullptr_t, const sp<T>& t) { \
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return nullptr _op_ t.get(); \
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}
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template <template <typename C> class comparator, typename T, typename U>
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static inline bool _sp_compare_(T* a, U* b) {
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return comparator<typename std::common_type<T*, U*>::type>()(a, b);
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}
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#define COMPARE_STRONG_FUNCTIONAL(_op_, _compare_) \
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template <typename T, typename U> \
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static inline bool operator _op_(const sp<T>& t, const sp<U>& u) { \
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return _sp_compare_<_compare_>(t.get(), u.get()); \
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} \
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template <typename T, typename U> \
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static inline bool operator _op_(const T* t, const sp<U>& u) { \
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return _sp_compare_<_compare_>(t, u.get()); \
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} \
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template <typename T, typename U> \
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static inline bool operator _op_(const sp<T>& t, const U* u) { \
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return _sp_compare_<_compare_>(t.get(), u); \
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} \
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template <typename T> \
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static inline bool operator _op_(const sp<T>& t, std::nullptr_t) { \
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return _sp_compare_<_compare_>(t.get(), nullptr); \
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} \
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template <typename T> \
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static inline bool operator _op_(std::nullptr_t, const sp<T>& t) { \
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return _sp_compare_<_compare_>(nullptr, t.get()); \
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}
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COMPARE_STRONG(==)
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COMPARE_STRONG(!=)
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COMPARE_STRONG_FUNCTIONAL(>, std::greater)
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COMPARE_STRONG_FUNCTIONAL(<, std::less)
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COMPARE_STRONG_FUNCTIONAL(<=, std::less_equal)
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COMPARE_STRONG_FUNCTIONAL(>=, std::greater_equal)
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#undef COMPARE_STRONG
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#undef COMPARE_STRONG_FUNCTIONAL
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// For code size reasons, we do not want these inlined or templated.
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void sp_report_race();
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// ---------------------------------------------------------------------------
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// No user serviceable parts below here.
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// TODO: Ideally we should find a way to increment the reference count before running the
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// constructor, so that generating an sp<> to this in the constructor is no longer dangerous.
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template <typename T>
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template <typename... Args>
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sp<T> sp<T>::make(Args&&... args) {
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T* t = new T(std::forward<Args>(args)...);
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sp<T> result;
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result.m_ptr = t;
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t->incStrong(t);
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return result;
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}
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template <typename T>
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sp<T> sp<T>::fromExisting(T* other) {
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if (other) {
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other->incStrongRequireStrong(other);
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sp<T> result;
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result.m_ptr = other;
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return result;
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}
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return nullptr;
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}
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#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
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template<typename T>
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sp<T>::sp(T* other)
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: m_ptr(other) {
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if (other) {
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other->incStrong(this);
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}
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}
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template <typename T>
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template <typename U>
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sp<T>::sp(U* other) : m_ptr(other) {
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if (other) {
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(static_cast<T*>(other))->incStrong(this);
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}
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}
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template <typename T>
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sp<T>& sp<T>::operator=(T* other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (other) {
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other->incStrong(this);
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}
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other;
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return *this;
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}
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#endif
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template<typename T>
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sp<T>::sp(const sp<T>& other)
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: m_ptr(other.m_ptr) {
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if (m_ptr)
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m_ptr->incStrong(this);
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}
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template <typename T>
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sp<T>::sp(sp<T>&& other) noexcept : m_ptr(other.m_ptr) {
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other.m_ptr = nullptr;
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}
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template<typename T> template<typename U>
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sp<T>::sp(const sp<U>& other)
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: m_ptr(other.m_ptr) {
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if (m_ptr)
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m_ptr->incStrong(this);
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}
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template<typename T> template<typename U>
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sp<T>::sp(sp<U>&& other)
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: m_ptr(other.m_ptr) {
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other.m_ptr = nullptr;
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}
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template <typename T>
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template <typename U>
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sp<T> sp<T>::cast(const sp<U>& other) {
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return sp<T>::fromExisting(static_cast<T*>(other.get()));
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}
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template<typename T>
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sp<T>::~sp() {
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if (m_ptr)
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m_ptr->decStrong(this);
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}
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template<typename T>
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sp<T>& sp<T>::operator =(const sp<T>& other) {
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// Force m_ptr to be read twice, to heuristically check for data races.
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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T* otherPtr(other.m_ptr);
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if (otherPtr) otherPtr->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = otherPtr;
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return *this;
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}
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template <typename T>
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sp<T>& sp<T>::operator=(sp<T>&& other) noexcept {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other.m_ptr;
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other.m_ptr = nullptr;
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return *this;
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}
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(const sp<U>& other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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T* otherPtr(other.m_ptr);
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if (otherPtr) otherPtr->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = otherPtr;
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return *this;
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}
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(sp<U>&& other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (m_ptr) m_ptr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other.m_ptr;
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other.m_ptr = nullptr;
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return *this;
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}
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#if !defined(ANDROID_UTILS_REF_BASE_DISABLE_IMPLICIT_CONSTRUCTION)
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template<typename T> template<typename U>
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sp<T>& sp<T>::operator =(U* other) {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (other) (static_cast<T*>(other))->incStrong(this);
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if (oldPtr) oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = other;
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return *this;
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}
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#endif
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template<typename T>
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void sp<T>::force_set(T* other) {
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other->forceIncStrong(this);
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m_ptr = other;
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}
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template<typename T>
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void sp<T>::clear() {
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T* oldPtr(*const_cast<T* volatile*>(&m_ptr));
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if (oldPtr) {
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oldPtr->decStrong(this);
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if (oldPtr != *const_cast<T* volatile*>(&m_ptr)) sp_report_race();
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m_ptr = nullptr;
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}
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}
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template<typename T>
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void sp<T>::set_pointer(T* ptr) {
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m_ptr = ptr;
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}
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} // namespace android
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// ---------------------------------------------------------------------------
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#endif // ANDROID_STRONG_POINTER_H
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