cachingregistry.hpp

/*
    KTech, Kaup's C++ 2D terminal game engine library.
    Copyright (C) 2023-2025 Ethan Kaufman (AKA Kaup)
 
    This file is part of KTech.
 
    KTech 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
    any later version.
 
    KTech 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 KTech. If not, see <https://www.gnu.org/licenses/>.
*/
 
#pragma once
 
#define KTECH_DEFINITION
#include "../ktech.hpp"
#undef KTECH_DEFINITION
 
#include <cstddef>
#include <vector>
 
template<typename T>
class KTech::CachingRegistry
{
public:
    auto operator[](const ID<T>& id) -> T*
    {
        if (!m_vec.empty())
        {
            for (size_t i = (id.m_i < m_vec.size() ? id.m_i : m_vec.size() - 1);; i--)
            {
                if (m_vec[i]->m_id == id)
                {
                    id.m_i = i;
                    return m_vec[i];
                }
                if (i == 0)
                {
                    break;
                }
            }
        }
        id.m_i = 0;
        return nullptr;
    }
 
    auto Exists(const ID<T>& id) -> bool
    {
        return IDToIndex(id) != m_vec.size();
    }
 
private:
    std::vector<T*> m_vec;
 
    // Adds the pointer to the container.
    // Automatically called by objects, layers, cameras and maps for themselves.
    // You shouldn't call this manually on a structure.
    auto Add(T* structure) -> ID<T>
    {
        structure->m_id.m_i = m_vec.size();
        m_vec.push_back(structure);
        return m_vec[m_vec.size() - 1]->m_id;
    }
 
    // Remove a structure from storage (doesn't delete it's memory).
    // Returns true if the structure was found and removed.
    // Returns false if the structure is missing.
    auto Remove(const ID<T>& id) -> bool
    {
        size_t toRemove = IDToIndex(id);
        if (toRemove == m_vec.size())
        {
            return false;
        }
        m_vec.erase(m_vec.begin() + toRemove);
        return true;
    }
 
    // Returns the valid index of the ID.
    // If the UUID is missing, return the size of the array making the index invalid.
    auto IDToIndex(const ID<T>& id) -> size_t
    {
        if (!m_vec.empty())
        {
            for (size_t i = (id.m_i < m_vec.size() ? id.m_i : m_vec.size() - 1);; i--)
            {
                if (m_vec[i]->m_id == id)
                {
                    id.m_i = i;
                    return i;
                }
                if (i == 0)
                {
                    break;
                }
            }
        }
        id.m_i = 0;
        return m_vec.size();
    }
 
    friend T;
    friend class Memory;
};