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/*
* This file is part of OpenTTD.
* OpenTTD 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, version 2.
* OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file saveload_filter.h Declaration of filters used for saving and loading savegames. */
#ifndef SAVELOAD_FILTER_H
#define SAVELOAD_FILTER_H
/** Interface for filtering a savegame till it is loaded. */
struct LoadFilter {
/** Chained to the (savegame) filters. */
LoadFilter *chain;
/**
* Initialise this filter.
* @param chain The next filter in this chain.
*/
LoadFilter(LoadFilter *chain) : chain(chain)
{
}
/** Make sure the writers are properly closed. */
virtual ~LoadFilter()
{
delete this->chain;
}
/**
* Read a given number of bytes from the savegame.
* @param buf The bytes to read.
* @param len The number of bytes to read.
* @return The number of actually read bytes.
*/
virtual size_t Read(byte *buf, size_t len) = 0;
/**
* Reset this filter to read from the beginning of the file.
*/
virtual void Reset()
{
this->chain->Reset();
}
};
/**
* Instantiator for a load filter.
* @param chain The next filter in this chain.
* @tparam T The type of load filter to create.
*/
template <typename T> LoadFilter *CreateLoadFilter(LoadFilter *chain)
{
return new T(chain);
}
/** Interface for filtering a savegame till it is written. */
struct SaveFilter {
/** Chained to the (savegame) filters. */
SaveFilter *chain;
/**
* Initialise this filter.
* @param chain The next filter in this chain.
*/
SaveFilter(SaveFilter *chain) : chain(chain)
{
}
/** Make sure the writers are properly closed. */
virtual ~SaveFilter()
{
delete this->chain;
}
/**
* Write a given number of bytes into the savegame.
* @param buf The bytes to write.
* @param len The number of bytes to write.
*/
virtual void Write(byte *buf, size_t len) = 0;
/**
* Prepare everything to finish writing the savegame.
*/
virtual void Finish()
{
if (this->chain != nullptr) this->chain->Finish();
}
};
/**
* Instantiator for a save filter.
* @param chain The next filter in this chain.
* @param compression_level The requested level of compression.
* @tparam T The type of save filter to create.
*/
template <typename T> SaveFilter *CreateSaveFilter(SaveFilter *chain, byte compression_level)
{
return new T(chain, compression_level);
}
#endif /* SAVELOAD_FILTER_H */
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