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- /***************************************************************************/
- /* */
- /* 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 <ft2build.h>
- #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 */
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