/usr/include/mircommon/mir/cached_ptr.h is in libmircommon-dev 0.26.3+16.04.20170605-0ubuntu1.1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | /*
* Copyright © 2013 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Authored by: Robert Carr <robert.carr@canonical.com>
*/
#ifndef MIR_CACHED_PTR_H_
#define MIR_CACHED_PTR_H_
#include <functional>
#include <memory>
namespace mir
{
template<typename Type>
class CachedPtr
{
std::weak_ptr<Type> cache;
CachedPtr(CachedPtr const&) = delete;
CachedPtr& operator=(CachedPtr const&) = delete;
public:
CachedPtr() = default;
std::shared_ptr<Type> operator()(std::function<std::shared_ptr<Type>()> make)
{
auto result = cache.lock();
if (!result)
{
cache = result = make();
}
return result;
}
};
} // namespace mir
#endif // MIR_CACHED_PTR_H_
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