Pool.h

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#pragma once
 
#include <vector>
 
#include <tdme/tdme.h>
#include <tdme/utilities/fwd-tdme.h>
 
using std::vector;
 
namespace tdme {
namespace utilities {
 
/**
 * Pool template class
 * @author Andreas Drewke
 * @param<E>
 */
template<typename T>
class Pool
{
private:
    vector<T*> freeElements;
    vector<T*> usedElements;
 
protected:
    /**
     * Instantiate element
     * @return instantiates a new element
     */
    virtual T* instantiate() = 0;
 
public:
    // forbid class copy
    FORBID_CLASS_COPY(Pool)
 
    /**
     * Public constructor
     */
    Pool() {
    }
 
    virtual ~Pool() {
        for (auto element: usedElements) {
            delete element;
        }
        for (auto element: freeElements) {
            delete element;
        }
    }
 
    /**
     * Allocate a new element from pool
     * @return element
     */
    T* allocate() {
        if (freeElements.empty() == false) {
            auto element = freeElements[freeElements.size() - 1];
            freeElements.erase(freeElements.begin() + freeElements.size() - 1);
            usedElements.push_back(element);
            return element;
        }
        auto element = instantiate();
        usedElements.push_back(element);
        return element;
    }
 
    /**
     * Release element in pool for being reused
     * @param element element
     */
    void release(T* element) {
        for (auto i = 0; i < usedElements.size(); i++) {
            if (usedElements[i] == element) {
                usedElements.erase(usedElements.begin() + i);
                freeElements.push_back(element);
                return;
            }
        }
    }
 
    /**
     * @return element capacity
     */
    int32_t capacity() {
        return usedElements.size() + freeElements.size();
    }
 
    /**
     * @return elements in use
     */
    int32_t size() {
        return usedElements.size();
    }
 
    /**
     * Reset this pool
     */
    void reset() {
        for (auto i = 0; i < usedElements.size(); i++) {
            freeElements.push_back(usedElements[i]);
        }
        usedElements.clear();
    }
 
};
 
};
};