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/***************************************************************************/
/* */
/* ftlru.h */
/* */
/* Simple LRU list-cache (specification). */
/* */
/* Copyright 2000 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 on 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 ALPHA CODE, THIS API *********/
/********* IS DUE TO CHANGE UNTIL STRICTLY NOTIFIED BY THE *********/
/********* FREETYPE DEVELOPMENT TEAM *********/
/********* *********/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
#ifndef FTLRU_H
#define FTLRU_H
#include <freetype/freetype.h>
#ifdef __cplusplus
extern "C" {
#endif
/* generic key type */
typedef FT_Pointer FT_LruKey;
/* an lru node -- root.data points to the element */
typedef struct FT_LruNodeRec_
{
FT_ListNodeRec root;
FT_LruKey key;
} FT_LruNodeRec, *FT_LruNode;
/* forward declaration */
typedef struct FT_LruRec_* FT_Lru;
/* LRU clazz */
typedef struct FT_Lru_Class_
{
FT_UInt lru_size; /* object size in bytes */
/* this method is used to initialize a new list element node */
FT_Error (*init_element)( FT_Lru lru,
FT_LruNode node );
/* this method is used to finalize a given list element node */
void (*done_element)( FT_Lru lru,
FT_LruNode node );
/* 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. */
FT_Error (*flush_element)( FT_Lru lru,
FT_LruNode node,
FT_LruKey new_key );
/* 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. */
FT_Bool (*compare_element)( FT_LruNode node,
FT_LruKey key );
} FT_Lru_Class;
/* A selector is used to indicate whether a given list element node */
/* is part of a selection for FT_Lru_Remove_Selection(). The function */
/* must return true (i.e., non-null) to indicate that the node is part */
/* of it. */
typedef FT_Bool (*FT_Lru_Selector)( FT_Lru lru,
FT_LruNode node,
FT_Pointer data );
typedef struct FT_LruRec_
{
FT_Lru_Class* clazz;
FT_UInt max_elements;
FT_UInt num_elements;
FT_ListRec elements;
FT_Memory memory;
FT_Pointer user_data;
/* the following fields are only meaningful for static lru containers */
FT_ListRec free_nodes;
FT_LruNode nodes;
} FT_LruRec;
FT_EXPORT( FT_Error ) FT_Lru_New( const FT_Lru_Class* clazz,
FT_UInt max_elements,
FT_Pointer user_data,
FT_Memory memory,
FT_Bool pre_alloc,
FT_Lru* alru );
FT_EXPORT( void ) FT_Lru_Reset( FT_Lru lru );
FT_EXPORT( void ) FT_Lru_Done ( FT_Lru lru );
FT_EXPORT( FT_Error ) FT_Lru_Lookup_Node( FT_Lru lru,
FT_LruKey key,
FT_LruNode* anode );
FT_EXPORT( FT_Error ) FT_Lru_Lookup( FT_Lru lru,
FT_LruKey key,
FT_Pointer* aobject );
FT_EXPORT( void ) FT_Lru_Remove_Node( FT_Lru lru,
FT_LruNode node );
FT_EXPORT( void ) FT_Lru_Remove_Selection( FT_Lru lru,
FT_Lru_Selector selector,
FT_Pointer data );
#ifdef __cplusplus
}
#endif
#endif /* FTLRU_H */
/* END */
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