Pool.h

/*
 *  MoMEMta: a modular implementation of the Matrix Element Method
 *  Copyright (C) 2016  Universite catholique de Louvain (UCL), Belgium
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#pragma once

#include <assert.h>
#include <memory>
#include <unordered_map>

#include <momemta/any.h>
#include <momemta/impl/InputTag_fwd.h>
#include <momemta/Value.h>

// A simple memory pool

struct PoolContent {
    momemta::any ptr; 
    bool valid; 
};

class Pool {
    public:
        Pool() = default;

        template<typename T, typename... Args> std::shared_ptr<T> put(const InputTag& tag, Args&&... args);

        template<typename T> Value<T> get(const InputTag& tag) const;

        void alias(const InputTag& from, const InputTag& to);

        bool exists(const InputTag& tag) const;

    private:
        friend class MoMEMta;
        friend class Module;

        template <typename U>
        friend class ValueProxy;

        using PoolStorage = std::unordered_map<InputTag, PoolContent>;

        friend struct InputTag;

        void remove(const InputTag&, bool force = true);
        void remove_if_invalid(const InputTag&);

        momemta::any reserve(const InputTag&);

        template<typename T> std::shared_ptr<const T> raw_get(const InputTag& tag) const;

        template<typename T, typename... Args> PoolStorage::iterator create(const InputTag& tag,
                bool valid, Args&&... args) const;

    public:
        class tag_not_found_error: public std::runtime_error {
            using std::runtime_error::runtime_error;
        };

        class duplicated_tag_error: public std::runtime_error {
            using std::runtime_error::runtime_error;
        };

        class constructor_tag_error: public std::runtime_error {
            using std::runtime_error::runtime_error;
        };


private:

        virtual void freeze() final;

        Pool(const Pool&) = delete;
        Pool& operator=(const Pool&) = delete;

        bool m_frozen = false; 

        mutable PoolStorage m_storage;
};

using PoolPtr = std::shared_ptr<Pool>;