ResourceCache.hpp

/******************************************************************************
 
  nomlib - C++11 cross-platform game engine
 
Copyright (c) 2013, 2014 Jeffrey Carpenter <i8degrees@gmail.com>
All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
******************************************************************************/
#ifndef NOMLIB_SYSTEM_RESOURCE_CACHE_HPP
#define NOMLIB_SYSTEM_RESOURCE_CACHE_HPP
 
#include <string>
#include <map>
#include <memory>
#include <functional>
// #include <type_traits>
 
#include "nomlib/config.hpp"
#include "nomlib/system/File.hpp"
#include "nomlib/system/Path.hpp"
#include "nomlib/system/ResourceFile.hpp"
 
namespace nom {

template <typename ResourceType>
class ResourceCache
{
  public:
    typedef ResourceCache self_type;
 
    typedef self_type* raw_ptr;
    typedef std::unique_ptr<self_type> unique_ptr;
    typedef std::shared_ptr<self_type> shared_ptr;
 
    typedef std::function<void( const ResourceFile&, ResourceType& )> callback_type;

    ResourceCache( void )
    {
      // NOM_LOG_TRACE( NOM );
    }

    ~ResourceCache( void )
    {
      // NOM_LOG_TRACE( NOM );
 
      // Goodbye cruel world!
      this->resources_.clear();
    }

    nom::size_type size( void ) const
    {
      return this->resources_.size();
    }

    const ResourceFile& find_resource( const std::string& key ) const
    {
      auto res = this->resources_.find( ResourceFile( key ) );
 
      if( res != this->resources_.end() )
      {
        return res->first;
      }
 
      return ResourceFile::null;
    }

    void set_resource_handler( const callback_type& delegate )
    {
      this->callback_ = delegate;
    }

    bool append_resource( const ResourceFile& res )
    {
      File fp;
      ResourceFile member( res.name() );
 
      auto itr = this->resources_.find( member );
 
      // Duplicate resource entry; reject
      if( itr != this->resources_.end() )
      {
        // NOM_LOG_ERR( NOM, "Could not add resource: " + res.name() + " already exists." );
        return false;
      }
 
      if( res.exists() == false )
      {
        NOM_LOG_ERR( NOM, "Could not add resource: " + res.name() + " does not exist at " + res.path() );
        return false;
      }
 
      // Create the resource before insertion
      ResourceType res_type;
 
      // Initialize the resource when type is a pointer; this resolves a
      // compile-time warning: res_type is uninitialized when this condition is
      // false.
      // if( std::is_pointer<ResourceType>::value == true ) {
      //   res_type = nullptr;
      // }
 
      // Use the load handler callback helper for resource initialization, if
      // it has been set.
      if( this->callback_ != nullptr )
      {
        this->callback_( res, res_type );
      }
 
      this->resources_.insert( { res, std::make_shared<ResourceType>(res_type) } );
 
      return true;
    }

    ResourceType* load_resource( const std::string& key )
    {
      ResourceFile member( key );
 
      auto res = this->resources_.find( member );
 
      // Found a match
      if( res != this->resources_.end() )
      {
        // Load the resource only if it has not been yet
        if( res->first.loaded() == false )
        {
          // Err if the resource is invalid
          // if( res->second->valid() == false ) {
          if( res->second == nullptr ) {
            NOM_LOG_ERR( NOM, "Could not load resource: invalid resource." );
            return nullptr;
          }
 
          // Err if the resource cannot be loaded
          if( res->second.get()->load( res->first.path() ) == false )
          {
            NOM_LOG_ERR( NOM, "Could not load resource: file path does not exist at " + res->first.path() );
            return nullptr;
          }
 
          // res->first.set_loaded( true );
          res->first.loaded_ = true;
 
        } // end if not loaded
 
        return res->second.get();
 
      } // end if resource found
 
      // Err
      return nullptr;
    }

    void clear( void )
    {
      this->resources_.clear();
    }

    void erase( const std::string& key )
    {
      this->resources_.erase( key );
    }

    void dump( void )
    {
      for( auto itr = this->resources_.begin(); itr != this->resources_.end(); ++itr )
      {
        NOM_LOG_INFO( NOM, "Resource " + itr->first.name() + " at path: " + itr->first.path() + "." );
      }
    }
 
  private:
    std::map<ResourceFile, std::shared_ptr<ResourceType>> resources_;

    callback_type callback_;
};
 
} // namespace nom
 
#endif // include guard defined