/***************************************************************************/ /* */ /* ftlru.h */ /* */ /* Simple LRU list-cache (specification). */ /* */ /* Copyright 2000-2001 by */ /* David Turner, Robert Wilhelm, and Werner Lemberg. */ /* */ /* This file is part of the FreeType project, and may only be used, */ /* modified, and distributed under the terms of the FreeType project */ /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ /* this file you indicate that you have read the license and */ /* understand and accept it fully. */ /* */ /***************************************************************************/ /*************************************************************************/ /* */ /* An LRU is a list that cannot hold more than a certain number of */ /* elements (`max_elements'). All elements in the list are sorted in */ /* least-recently-used order, i.e., the `oldest' element is at the tail */ /* of the list. */ /* */ /* When doing a lookup (either through `Lookup()' or `Lookup_Node()'), */ /* the list is searched for an element with the corresponding key. If */ /* it is found, the element is moved to the head of the list and is */ /* returned. */ /* */ /* If no corresponding element is found, the lookup routine will try to */ /* obtain a new element with the relevant key. If the list is already */ /* full, the oldest element from the list is discarded and replaced by a */ /* new one; a new element is added to the list otherwise. */ /* */ /* Note that it is possible to pre-allocate the element list nodes. */ /* This is handy if `max_elements' is sufficiently small, as it saves */ /* allocations/releases during the lookup process. */ /* */ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /********* *********/ /********* WARNING, THIS IS BETA CODE. *********/ /********* *********/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ #ifndef __FTLRU_H__ #define __FTLRU_H__ #include #include FT_FREETYPE_H FT_BEGIN_HEADER /* generic list key type */ typedef FT_Pointer FT_LruKey; /* a list list handle */ typedef struct FT_LruListRec_* FT_LruList; /* a list class handle */ typedef const struct FT_LruList_ClassRec_* FT_LruList_Class; /* a list node handle */ typedef struct FT_LruNodeRec_* FT_LruNode; /* the list node structure */ typedef struct FT_LruNodeRec_ { FT_LruNode next; FT_LruKey key; } FT_LruNodeRec; /* the list structure */ typedef struct FT_LruListRec_ { FT_Memory memory; FT_LruList_Class clazz; FT_LruNode nodes; FT_UInt max_nodes; FT_UInt num_nodes; FT_Pointer data; } FT_LruListRec; /* initialize a list list */ typedef FT_Error (*FT_LruList_InitFunc)( FT_LruList list ); /* finalize a list list */ typedef void (*FT_LruList_DoneFunc)( FT_LruList list ); /* this method is used to initialize a new list element node */ typedef FT_Error (*FT_LruNode_InitFunc)( FT_LruNode node, FT_LruKey key, FT_Pointer data ); /* this method is used to finalize a given list element node */ typedef void (*FT_LruNode_DoneFunc)( FT_LruNode node, FT_Pointer data ); /* If defined, this method is called when the list if full */ /* during the lookup process -- it is used to change the contents */ /* of a list element node instead of calling `done_element()', */ /* then `init_element()'. Set it to 0 for default behaviour. */ typedef FT_Error (*FT_LruNode_FlushFunc)( FT_LruNode node, FT_LruKey new_key, FT_Pointer data ); /* If defined, this method is used to compare a list element node */ /* with a given key during a lookup. If set to 0, the `key' */ /* fields will be directly compared instead. */ typedef FT_Bool (*FT_LruNode_CompareFunc)( FT_LruNode node, FT_LruKey key, FT_Pointer data ); /* A selector is used to indicate whether a given list element node */ /* is part of a selection for FT_LruList_Remove_Selection(). The */ /* functrion must return true (i.e., non-null) to indicate that the */ /* node is part of it. */ typedef FT_Bool (*FT_LruNode_SelectFunc)( FT_LruNode node, FT_Pointer data, FT_Pointer list_data ); /* LRU class */ typedef struct FT_LruList_ClassRec_ { FT_UInt list_size; FT_LruList_InitFunc list_init; /* optional */ FT_LruList_DoneFunc list_done; /* optional */ FT_UInt node_size; FT_LruNode_InitFunc node_init; /* MANDATORY */ FT_LruNode_DoneFunc node_done; /* optional */ FT_LruNode_FlushFunc node_flush; /* optional */ FT_LruNode_CompareFunc node_compare; /* optional */ } FT_LruList_ClassRec; /* The following functions must be exported in the case where */ /* applications would want to write their own cache classes. */ FT_EXPORT( FT_Error ) FT_LruList_New( FT_LruList_Class clazz, FT_UInt max_elements, FT_Pointer user_data, FT_Memory memory, FT_LruList *alist ); FT_EXPORT( void ) FT_LruList_Reset( FT_LruList list ); FT_EXPORT( void ) FT_LruList_Destroy ( FT_LruList list ); FT_EXPORT( FT_Error ) FT_LruList_Lookup( FT_LruList list, FT_LruKey key, FT_LruNode *anode ); FT_EXPORT( void ) FT_LruList_Remove( FT_LruList list, FT_LruNode node ); FT_EXPORT( void ) FT_LruList_Remove_Selection( FT_LruList list, FT_LruNode_SelectFunc select_func, FT_Pointer select_data ); /* */ FT_END_HEADER #endif /* __FTLRU_H__ */ /* END */