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// Copyright (c) 2011 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 CHROME_BROWSER_SYNC_SHARED_VALUE_H_
#define CHROME_BROWSER_SYNC_SHARED_VALUE_H_
#pragma once
#include "base/memory/ref_counted.h"
namespace browser_sync {
// Forward declaration for SharedValueTraits.
template <class ValueType>
class SharedValue;
// VS2005 workaround taken from base/observer_list_threadsafe.h.
template <class ValueType>
struct SharedValueTraits {
static void Destruct(const SharedValue<ValueType>* x) {
delete x;
}
};
// A ref-counted thread-safe wrapper around an immutable value.
//
// ValueType should be a subclass of Value that has a Swap() method.
template <class ValueType>
class SharedValue
: public base::RefCountedThreadSafe<
SharedValue<ValueType>, SharedValueTraits<ValueType> > {
public:
SharedValue() {}
// Takes over the data in |value|, leaving |value| empty.
explicit SharedValue(ValueType* value) {
value_.Swap(value);
}
const ValueType& Get() const {
return value_;
}
private:
~SharedValue() {}
friend struct SharedValueTraits<ValueType>;
ValueType value_;
};
} // namespace browser_sync
#endif // CHROME_BROWSER_SYNC_SHARED_VALUE_H_
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