// Copyright 2016 PDFium Authors. All rights reserved.
|
// Use of this source code is governed by a BSD-style license that can be
|
// found in the LICENSE file.
|
|
#ifndef CORE_FXCRT_MAYBE_OWNED_H_
|
#define CORE_FXCRT_MAYBE_OWNED_H_
|
|
#include <algorithm>
|
#include <memory>
|
#include <utility>
|
|
#include "core/fxcrt/fx_memory.h"
|
#include "core/fxcrt/fx_system.h"
|
|
namespace fxcrt {
|
|
// A template that can hold either owned or unowned references, and cleans up
|
// appropriately. Possibly the most pernicious anti-pattern imaginable, but
|
// it crops up throughout the codebase due to a desire to avoid copying-in
|
// objects or data.
|
template <typename T, typename D = std::default_delete<T>>
|
class MaybeOwned {
|
public:
|
MaybeOwned() : m_pObj(nullptr) {}
|
explicit MaybeOwned(T* ptr) : m_pObj(ptr) {}
|
explicit MaybeOwned(std::unique_ptr<T, D> ptr)
|
: m_pOwnedObj(std::move(ptr)), m_pObj(m_pOwnedObj.get()) {}
|
|
MaybeOwned(const MaybeOwned& that) = delete;
|
MaybeOwned(MaybeOwned&& that) noexcept
|
: m_pOwnedObj(that.m_pOwnedObj.release()), m_pObj(that.m_pObj) {
|
that.m_pObj = nullptr;
|
}
|
|
void Reset(std::unique_ptr<T, D> ptr) {
|
m_pOwnedObj = std::move(ptr);
|
m_pObj = m_pOwnedObj.get();
|
}
|
void Reset(T* ptr = nullptr) {
|
m_pOwnedObj.reset();
|
m_pObj = ptr;
|
}
|
|
bool IsOwned() const { return !!m_pOwnedObj; }
|
T* Get() const { return m_pObj; }
|
std::unique_ptr<T, D> Release() {
|
ASSERT(IsOwned());
|
return std::move(m_pOwnedObj);
|
}
|
|
MaybeOwned& operator=(const MaybeOwned& that) = delete;
|
MaybeOwned& operator=(MaybeOwned&& that) {
|
m_pOwnedObj = std::move(that.m_pOwnedObj);
|
m_pObj = that.m_pObj;
|
that.m_pObj = nullptr;
|
return *this;
|
}
|
MaybeOwned& operator=(T* ptr) {
|
Reset(ptr);
|
return *this;
|
}
|
MaybeOwned& operator=(std::unique_ptr<T, D> ptr) {
|
Reset(std::move(ptr));
|
return *this;
|
}
|
|
bool operator==(const MaybeOwned& that) const { return Get() == that.Get(); }
|
bool operator==(const std::unique_ptr<T, D>& ptr) const {
|
return Get() == ptr.get();
|
}
|
bool operator==(T* ptr) const { return Get() == ptr; }
|
|
bool operator!=(const MaybeOwned& that) const { return !(*this == that); }
|
bool operator!=(const std::unique_ptr<T, D> ptr) const {
|
return !(*this == ptr);
|
}
|
bool operator!=(T* ptr) const { return !(*this == ptr); }
|
|
explicit operator bool() const { return !!m_pObj; }
|
T& operator*() const { return *m_pObj; }
|
T* operator->() const { return m_pObj; }
|
|
private:
|
std::unique_ptr<T, D> m_pOwnedObj;
|
T* m_pObj;
|
};
|
|
} // namespace fxcrt
|
|
using fxcrt::MaybeOwned;
|
|
#endif // CORE_FXCRT_MAYBE_OWNED_H_
|
