src/saveload/saveload_filter.h

   1 /* $Id: saveload_filter.h 21395 2010-12-05 14:41:34Z rubidium $ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file saveload_filter.h Declaration of filters used for saving and loading savegames. */
  11
  12 #ifndef SAVELOAD_FILTER_H
  13 #define SAVELOAD_FILTER_H
  14
  15 /** Interface for filtering a savegame till it is loaded. */
  16 struct LoadFilter {
  17         /** Chained to the (savegame) filters. */
  18         LoadFilter *chain;
  19
  20         /**
  21          * Initialise this filter.
  22          * @param chain The next filter in this chain.
  23          */
  24         LoadFilter(LoadFilter *chain) : chain(chain)
  25         {
  26         }
  27
  28         /** Make sure the writers are properly closed. */
  29         virtual ~LoadFilter()
  30         {
  31                 delete this->chain;
  32         }
  33
  34         /**
  35          * Read a given number of bytes from the savegame.
  36          * @param buf The bytes to read.
  37          * @param len The number of bytes to read.
  38          * @return The number of actually read bytes.
  39          */
  40         virtual size_t Read(byte *buf, size_t len) = 0;
  41
  42         /**
  43          * Reset this filter to read from the beginning of the file.
  44          */
  45         virtual void Reset()
  46         {
  47                 this->chain->Reset();
  48         }
  49 };
  50
  51 /**
  52  * Instantiator for a load filter.
  53  * @param chain The next filter in this chain.
  54  * @tparam T    The type of load filter to create.
  55  */
  56 template <typename T> LoadFilter *CreateLoadFilter(LoadFilter *chain)
  57 {
  58         return new T(chain);
  59 }
  60
  61 /** Interface for filtering a savegame till it is written. */
  62 struct SaveFilter {
  63         /** Chained to the (savegame) filters. */
  64         SaveFilter *chain;
  65
  66         /**
  67          * Initialise this filter.
  68          * @param chain The next filter in this chain.
  69          */
  70         SaveFilter(SaveFilter *chain) : chain(chain)
  71         {
  72         }
  73
  74         /** Make sure the writers are properly closed. */
  75         virtual ~SaveFilter()
  76         {
  77                 delete this->chain;
  78         }
  79
  80         /**
  81          * Write a given number of bytes into the savegame.
  82          * @param buf The bytes to write.
  83          * @param len The number of bytes to write.
  84          */
  85         virtual void Write(byte *buf, size_t len) = 0;
  86
  87         /**
  88          * Prepare everything to finish writing the savegame.
  89          */
  90         virtual void Finish()
  91         {
  92                 if (this->chain != nullptr) this->chain->Finish();
  93         }
  94 };
  95
  96 /**
  97  * Instantiator for a save filter.
  98  * @param chain             The next filter in this chain.
  99  * @param compression_level The requested level of compression.
 100  * @tparam T                The type of save filter to create.
 101  */
 102 template <typename T> SaveFilter *CreateSaveFilter(SaveFilter *chain, byte compression_level)
 103 {
 104         return new T(chain, compression_level);
 105 }
 106
 107 #endif /* SAVELOAD_FILTER_H */