www.pudn.com > freetype.rar > ftlru.h
/***************************************************************************/
/* */
/* 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. */
/* */
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/********* *********/
/********* WARNING, THIS IS BETA CODE. *********/
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#ifndef __FTLRU_H__
#define __FTLRU_H__
#include "ft2build.h"
#include "freetype/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 */