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/* vim: set sw=4 sts=4 et foldmethod=syntax : */

/*
 * Copyright (c) 2011 Ciaran McCreesh
 *
 * This file is part of the Paludis package manager. Paludis is free software;
 * you can redistribute it and/or modify it under the terms of the GNU General
 * Public License version 2, as published by the Free Software Foundation.
 *
 * Paludis 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef PALUDIS_GUARD_PALUDIS_UTIL_POOL_IMPL_HH
#define PALUDIS_GUARD_PALUDIS_UTIL_POOL_IMPL_HH 1

#include <paludis/util/pool.hh>
#include <paludis/util/mutex.hh>
#include <paludis/util/hashes.hh>
#include <unordered_map>
#include <memory>

namespace paludis
{
    template <typename Arg_, typename... Args_>
    void
    PoolKeys::add(const Arg_ & arg, const Args_ & ... args)
    {
        add_one(std::make_shared<ConcretePoolKey<Arg_> >(arg));
        add(args...);
    }

    template <typename T_>
    struct Imp<Pool<T_> >
    {
        mutable Mutex mutex;
        mutable std::unordered_map<PoolKeys, std::shared_ptr<const T_>, PoolKeysHasher, PoolKeysComparator> store;
    };

    template <typename T_>
    Pool<T_>::Pool() :
        _imp()
    {
    }

    template <typename T_>
    Pool<T_>::~Pool() = default;

    template <typename T_>
    struct PreventConversion
    {
        const T_ & ref;

        PreventConversion(const T_ & r) :
            ref(r)
        {
        }

        operator const T_ & ()
        {
            return ref;
        }
    };

    template <typename T_>
    template <typename... Args_>
    const std::shared_ptr<const T_>
    Pool<T_>::create(Args_ ... args) const
    {
        PoolKeys keys;
        keys.add(args...);

        Lock lock(_imp->mutex);
        auto i(_imp->store.find(keys));
        if (i == _imp->store.end())
            i = _imp->store.insert(std::make_pair(keys, std::make_shared<const T_>(PreventConversion<Args_>(args)...))).first;

        return i->second;
    }

    template <typename T_>
    ConcretePoolKey<T_>::ConcretePoolKey(const T_ & t) :
        PoolKey(PoolKeyTypeCodes::get<T_>()),
        _value(t)
    {
    }

    template <typename T_>
    ConcretePoolKey<T_>::~ConcretePoolKey() = default;

    template <typename T_>
    std::size_t
    ConcretePoolKey<T_>::hash() const
    {
        return Hash<T_>()(_value);
    }

    template <typename T_>
    bool
    ConcretePoolKey<T_>::same_value(const PoolKey & other) const
    {
        return _value == static_cast<const ConcretePoolKey<T_> &>(other)._value;
    }

    template <typename T_>
    int
    PoolKeyTypeCodes::get()
    {
        static int result(next());
        return result;
    }
}

#endif