93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
// Copyright 2016 PDFium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
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#ifndef CORE_FXCRT_WEAK_PTR_H_
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#define CORE_FXCRT_WEAK_PTR_H_
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#include <cstddef>
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#include <memory>
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#include <utility>
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#include "core/fxcrt/fx_system.h"
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#include "core/fxcrt/retain_ptr.h"
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namespace fxcrt {
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template <class T, class D = std::default_delete<T>>
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class WeakPtr {
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public:
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WeakPtr() = default;
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WeakPtr(const WeakPtr& that) : m_pHandle(that.m_pHandle) {}
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WeakPtr(WeakPtr&& that) noexcept { Swap(that); }
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explicit WeakPtr(std::unique_ptr<T, D> pObj)
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: m_pHandle(new Handle(std::move(pObj))) {}
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// Deliberately implicit to allow passing nullptr.
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// NOLINTNEXTLINE(runtime/explicit)
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WeakPtr(std::nullptr_t arg) {}
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explicit operator bool() const { return m_pHandle && !!m_pHandle->Get(); }
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bool HasOneRef() const { return m_pHandle && m_pHandle->HasOneRef(); }
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T* operator->() { return m_pHandle->Get(); }
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const T* operator->() const { return m_pHandle->Get(); }
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WeakPtr& operator=(const WeakPtr& that) {
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m_pHandle = that.m_pHandle;
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return *this;
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}
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bool operator==(const WeakPtr& that) const {
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return m_pHandle == that.m_pHandle;
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}
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bool operator!=(const WeakPtr& that) const { return !(*this == that); }
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T* Get() const { return m_pHandle ? m_pHandle->Get() : nullptr; }
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void DeleteObject() {
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if (m_pHandle) {
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m_pHandle->Clear();
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m_pHandle.Reset();
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}
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}
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void Reset() { m_pHandle.Reset(); }
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void Reset(std::unique_ptr<T, D> pObj) {
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m_pHandle.Reset(new Handle(std::move(pObj)));
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}
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void Swap(WeakPtr& that) { m_pHandle.Swap(that.m_pHandle); }
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private:
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class Handle {
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public:
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explicit Handle(std::unique_ptr<T, D> ptr) : m_pObj(std::move(ptr)) {}
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void Reset(std::unique_ptr<T, D> ptr) { m_pObj = std::move(ptr); }
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void Clear() { // Now you're all weak ptrs ...
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m_pObj.reset(); // unique_ptr nulls first before invoking delete.
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}
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T* Get() const { return m_pObj.get(); }
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T* Retain() {
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++m_nCount;
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return m_pObj.get();
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}
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void Release() {
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if (--m_nCount == 0)
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delete this;
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}
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bool HasOneRef() const { return m_nCount == 1; }
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private:
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~Handle() = default;
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intptr_t m_nCount = 0;
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std::unique_ptr<T, D> m_pObj;
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};
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RetainPtr<Handle> m_pHandle;
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};
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} // namespace fxcrt
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using fxcrt::WeakPtr;
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#endif // CORE_FXCRT_WEAK_PTR_H_
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