ResourceCache.hpp

/*
Copyright (C) 2016-2018,2025,2026 Rodrigo Jose Hernandez Cordoba
 
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
 
http://www.apache.org/licenses/LICENSE-2.0
 
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef AEONGAMES_RESOURCECACHE_H
#define AEONGAMES_RESOURCECACHE_H
#include <cstdint>
#include <functional>
#include "aeongames/Platform.hpp"
#include "aeongames/UniqueAnyPtr.hpp"
 
namespace AeonGames
{
    class ResourceId;
#if 0
    template<class B, class K, class D = B, typename... Args>
    const std::shared_ptr<B> Get ( const K& key, Args... args )
    {
        static std::unordered_map<K, std::weak_ptr<B >> cache;
        static std::mutex m;
        std::lock_guard<std::mutex> hold ( m );
        auto iter = cache.find ( key );
        if ( iter == cache.end() )
        {
            auto retval = std::shared_ptr<B> ( std::make_unique<D> ( args... ).release(), [key] ( B * t )
            {
                delete ( t );
                cache.erase ( cache.find ( key ) );
            } );
            cache[key] = retval;
            return retval;
        }
        return iter->second.lock();
    }
//----------------------------------------------------------------------------------------
    template<class K, class B>
    class ResourceCache
    {
    public:
        ResourceCache() = default;
        ~ResourceCache() = default;
        ResourceCache ( const ResourceCache& ) = delete;
        ResourceCache ( ResourceCache&& ) = delete;
        ResourceCache& operator= ( const ResourceCache& ) = delete;
        ResourceCache& operator= ( ResourceCache&& ) = delete;
        template<class D = B, typename... Args>
        static const std::shared_ptr<B> Get ( const K& aKey, Args... args )
        {
            std::lock_guard<std::mutex> hold ( mMutex );
            auto iter = mCache.find ( aKey );
            if ( iter == mCache.end() )
            {
                auto retval = std::shared_ptr<B> ( std::make_unique<D> ( args... ).release(), [aKey] ( B * t )
                {
                    delete ( t );
                    mCache.erase ( mCache.find ( aKey ) );
                } );
                mCache[aKey] = retval;
                return retval;
            }
            return iter->second.lock();
        }
        static const K& GetKey ( const std::shared_ptr<B>& aValue )
        {
            std::lock_guard<std::mutex> hold ( mMutex );
            auto i = std::find_if ( mCache.begin(), mCache.end(), [&aValue] ( const std::pair<const K, std::weak_ptr<B >> & aPair )
            {
                return aPair.second.lock() == aValue;
            } );
            if ( i != mCache.end() )
            {
                return i->first;
            }
            throw std::runtime_error ( "Resource not found in cache." );
        }
 
    private:
        static std::unordered_map<K, std::weak_ptr<B >> mCache;
        static std::mutex mMutex;
    };
    template<class K, class B>
    std::unordered_map<K, std::weak_ptr<B >> ResourceCache<K, B>::mCache;
    template<class K, class B>
    std::mutex ResourceCache<K, B>::mMutex;
#endif
    DLL void ClearAllResources();
    DLL void EnumerateResources ( const std::function<bool ( uint32_t, const UniqueAnyPtr& ) >& aEnumerator );
    DLL const UniqueAnyPtr& StoreResource ( uint32_t aKey, UniqueAnyPtr&& pointer );
    DLL UniqueAnyPtr DisposeResource ( uint32_t aKey );
    DLL const UniqueAnyPtr& GetResource ( uint32_t aKey );
    DLL const UniqueAnyPtr& GetResource ( const ResourceId& aResourceId );
}
#endif