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// Copyright 2014 The Chromium 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 MOJO_PUBLIC_CPP_BINDINGS_LIB_SHARED_DATA_H_
#define MOJO_PUBLIC_CPP_BINDINGS_LIB_SHARED_DATA_H_
#include "mojo/public/cpp/system/macros.h"
namespace mojo {
namespace internal {
// Used to allocate an instance of T that can be shared via reference counting.
template <typename T>
class SharedData {
public:
~SharedData() { holder_->Release(); }
SharedData() : holder_(new Holder()) {}
explicit SharedData(const T& value) : holder_(new Holder(value)) {}
SharedData(const SharedData<T>& other) : holder_(other.holder_) {
holder_->Retain();
}
SharedData<T>& operator=(const SharedData<T>& other) {
if (other.holder_ == holder_)
return *this;
holder_->Release();
holder_ = other.holder_;
holder_->Retain();
return *this;
}
void reset() {
holder_->Release();
holder_ = new Holder();
}
void reset(const T& value) {
holder_->Release();
holder_ = new Holder(value);
}
void set_value(const T& value) { holder_->value = value; }
T* mutable_value() { return &holder_->value; }
const T& value() const { return holder_->value; }
private:
class Holder {
public:
Holder() : value(), ref_count_(1) {}
Holder(const T& value) : value(value), ref_count_(1) {}
void Retain() { ++ref_count_; }
void Release() {
if (--ref_count_ == 0)
delete this;
}
T value;
private:
int ref_count_;
MOJO_DISALLOW_COPY_AND_ASSIGN(Holder);
};
Holder* holder_;
};
} // namespace internal
} // namespace mojo
#endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_SHARED_DATA_H_
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