newgrf_storage.h

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00001 /* $Id: newgrf_storage.h 15568 2009-02-24 20:59:17Z smatz $ */
00002 
00005 #ifndef NEWGRF_STORAGE_H
00006 #define NEWGRF_STORAGE_H
00007 
00008 #include "core/alloc_func.hpp"
00009 
00014 struct BaseStorageArray
00015 {
00017   virtual ~BaseStorageArray() {}
00018 
00026   virtual void ClearChanges(bool keep_changes) = 0;
00027 
00033   virtual void Store(uint pos, uint32 value) = 0;
00034 };
00035 
00042 template <typename TYPE, uint SIZE>
00043 struct PersistentStorageArray : BaseStorageArray {
00044   TYPE storage[SIZE]; 
00045   TYPE *prev_storage; 
00046 
00048   PersistentStorageArray() : prev_storage(NULL)
00049   {
00050     memset(this->storage, 0, sizeof(this->storage));
00051   }
00052 
00054   ~PersistentStorageArray()
00055   {
00056     free(this->prev_storage);
00057   }
00058 
00066   void Store(uint pos, uint32 value)
00067   {
00068     /* Out of the scope of the array */
00069     if (pos >= SIZE) return;
00070 
00071     /* The value hasn't changed, so we pretend nothing happened.
00072      * Saves a few cycles and such and it's pretty easy to check. */
00073     if (this->storage[pos] == value) return;
00074 
00075     /* We do not have made a backup; lets do so */
00076     if (this->prev_storage != NULL) {
00077       this->prev_storage = MallocT<TYPE>(SIZE);
00078       memcpy(this->prev_storage, this->storage, sizeof(this->storage));
00079 
00080       /* We only need to register ourselves when we made the backup
00081        * as that is the only time something will have changed */
00082       AddChangedStorage(this);
00083     }
00084 
00085     this->storage[pos] = value;
00086   }
00087 
00093   TYPE Get(uint pos) const
00094   {
00095     /* Out of the scope of the array */
00096     if (pos >= SIZE) return 0;
00097 
00098     return this->storage[pos];
00099   }
00100 
00101   void ClearChanges(bool keep_changes)
00102   {
00103     assert(this->prev_storage != NULL);
00104 
00105     if (!keep_changes) {
00106       memcpy(this->storage, this->prev_storage, sizeof(this->storage));
00107     }
00108     free(this->prev_storage);
00109   }
00110 };
00111 
00112 
00119 template <typename TYPE, uint SIZE>
00120 struct TemporaryStorageArray : BaseStorageArray {
00121   TYPE storage[SIZE]; 
00122 
00124   TemporaryStorageArray()
00125   {
00126     memset(this->storage, 0, sizeof(this->storage));
00127   }
00128 
00134   void Store(uint pos, uint32 value)
00135   {
00136     /* Out of the scope of the array */
00137     if (pos >= SIZE) return;
00138 
00139     this->storage[pos] = value;
00140     AddChangedStorage(this);
00141   }
00142 
00148   TYPE Get(uint pos) const
00149   {
00150     /* Out of the scope of the array */
00151     if (pos >= SIZE) return 0;
00152 
00153     return this->storage[pos];
00154   }
00155 
00156   void ClearChanges(bool keep_changes)
00157   {
00158     memset(this->storage, 0, sizeof(this->storage));
00159   }
00160 };
00161 
00168 void AddChangedStorage(BaseStorageArray *storage);
00169 
00170 
00181 void ClearStorageChanges(bool keep_changes);
00182 
00183 #endif /* NEWGRF_STORAGE_H */

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