InstancePool.h

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/****************************************************************************/
// Eclipse SUMO, Simulation of Urban MObility; see https://eclipse.dev/sumo
// Copyright (C) 2001-2024 German Aerospace Center (DLR) and others.
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0/
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License 2.0 are satisfied: GNU General Public License, version 2
// or later which is available at
// https://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
/****************************************************************************/
// A pool of resuable instances
/****************************************************************************/
#pragma once
#include <config.h>
#include <vector>
#include <algorithm>
 
 
// ===========================================================================
// class definitions
// ===========================================================================
template<typename T>
class InstancePool {
public:
    InstancePool(bool deleteOnQuit) : myDeleteOnQuit(deleteOnQuit) { }
 
 
    ~InstancePool() {
        typedef typename std::vector<T*>::iterator It;
        if (myDeleteOnQuit) {
            for (It i = myFreeInstances.begin(); i != myFreeInstances.end(); i++) {
                delete *i;
            }
        }
    }
 
 
    T* getFreeInstance() {
        if (myFreeInstances.size() == 0) {
            return 0;
        } else {
            T* instance = myFreeInstances.back();
            myFreeInstances.pop_back();
            return instance;
        }
    }
 
 
    void addFreeInstance(T* instance) {
        myFreeInstances.push_back(instance);
    }
 
 
    void addFreeInstances(const std::vector<T*> instances) {
        std::copy(instances.begin(), instances.end(),
                  std::back_inserter(myFreeInstances));
    }
 
 
private:
    std::vector<T*> myFreeInstances;
 
    bool myDeleteOnQuit;
 
 
};