cv/mgflib/lookup.h

/* RCSid: $Id: lookup.h,v 1.10 2003/02/28 20:11:29 greg Exp $ */
/*
 * Header file for general associative table lookup routines
 */
#ifndef _MGF_LOOKUP_H_
#define _MGF_LOOKUP_H_
#ifdef __cplusplus
extern "C" {
#endif


typedef struct {
        char    *key;           /* key name */
        long    hval;           /* key hash value (for efficiency) */
        char    *data;          /* pointer to client data */
} LUENT;

typedef struct {
        unsigned long   (*hashf)(char *);       /* key hash function */
        int     (*keycmp)(const char *, const char *);  /* key comparison function */
        void    (*freek)(char *);       /* free a key */
        void    (*freed)(char *);       /* free the data */
        int     tsiz;           /* current table size */
        LUENT   *tabl;          /* table, if allocated */
        int     ndel;           /* number of deleted entries */
} LUTAB;

#define LU_SINIT(fk,fd)         {lu_shash,strcmp,(void (*)())(fk),\
                                (void (*)())(fd),0,NULL,0}

/*
 * The lu_init routine is called to initialize a table.  The number of
 * elements passed is not a limiting factor, as a table can grow to
 * any size permitted by memory.  However, access will be more efficient
 * if this number strikes a reasonable balance between default memory use
 * and the expected (minimum) table size.  The value returned is the
 * actual allocated table size (or zero if there was insufficient memory).
 *
 * The hashf, keycmp, freek and freed member functions must be assigned
 * separately.  If the hash value is sufficient to guarantee equality
 * between keys, then the keycmp pointer may be NULL.  Otherwise, it
 * should return 0 if the two passed keys match.  If it is not necessary
 * (or possible) to free the key and/or data values, then the freek and/or
 * freed member functions may be NULL.
 *
 * It isn't fully necessary to call lu_init to initialize the LUTAB structure.
 * If tsiz is 0, then the first call to lu_find will allocate a minimal table.
 * The LU_SINIT macro provides a convenient static declaration for character
 * string keys.
 *
 * The lu_find routine returns the entry corresponding to the given
 * key.  If the entry does not exist, the corresponding key field will
 * be NULL.  If the entry has been previously deleted but not yet freed,
 * then only the data field will be NULL.  It is the caller's
 * responsibility to (allocate and) assign the key and data fields when
 * creating a new entry.  The only case where lu_find returns NULL is when
 * the system has run out of memory.
 *
 * The lu_delete routine frees an entry's data (if any) by calling
 * the freed member function, but does not free the key field.  This
 * will be freed later during (or instead of) table reallocation.
 * It is therefore an error to reuse or do anything with the key
 * field after calling lu_delete.
 *
 * The lu_done routine calls the given free function once for each
 * assigned table entry (i.e. each entry with an assigned key value).
 * The user must define these routines to free the key and the data
 * in the LU_TAB structure.  The final action of lu_done is to free the
 * allocated table itself.
 */

extern int      lu_init(LUTAB *, int);
extern LUENT    *lu_find(LUTAB *, char *);
extern void     lu_delete(LUTAB *, char *);
extern void     lu_done(LUTAB *);
extern unsigned long    lu_shash(char *);


#ifdef __cplusplus
}
#endif
#endif /* _MGF_LOOKUP_H_ */

Revision:	1.11
Committed:	Sat Jun 7 01:11:17 2003 UTC (20 years, 10 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 1.10:	+13 -20 lines
Log Message:	Instrumented headers against multiple inclusion and for use from C++. Removed NOPROTO sections.
#	User	Rev	Content
1	schorsch	1.11	/* RCSid: $Id: lookup.h,v 1.10 2003/02/28 20:11:29 greg Exp $ */
2	greg	1.1	/*
3	greg	1.4	* Header file for general associative table lookup routines
4	greg	1.1	*/
5	schorsch	1.11	#ifndef _MGF_LOOKUP_H_
6			#define _MGF_LOOKUP_H_
7			#ifdef __cplusplus
8			extern "C" {
9			#endif
10
11	greg	1.1
12			typedef struct {
13	greg	1.4	char key; / key name */
14			long hval; /* key hash value (for efficiency) */
15	greg	1.1	char data; / pointer to client data */
16			} LUENT;
17
18	greg	1.6	typedef struct {
19	gwlarson	1.9	unsigned long (hashf)(char ); /* key hash function */
20	greg	1.6	int (keycmp)(const char , const char ); / key comparison function */
21			void (freek)(char ); /* free a key */
22			void (freed)(char ); /* free the data */
23			int tsiz; /* current table size */
24			LUENT tabl; / table, if allocated */
25			int ndel; /* number of deleted entries */
26			} LUTAB;
27	greg	1.1
28	greg	1.4	#define LU_SINIT(fk,fd) {lu_shash,strcmp,(void (*)())(fk),\
29			(void (*)())(fd),0,NULL,0}
30	greg	1.2
31	greg	1.1	/*
32			* The lu_init routine is called to initialize a table. The number of
33			* elements passed is not a limiting factor, as a table can grow to
34			* any size permitted by memory. However, access will be more efficient
35			* if this number strikes a reasonable balance between default memory use
36			* and the expected (minimum) table size. The value returned is the
37			* actual allocated table size (or zero if there was insufficient memory).
38			*
39	greg	1.4	* The hashf, keycmp, freek and freed member functions must be assigned
40			* separately. If the hash value is sufficient to guarantee equality
41			* between keys, then the keycmp pointer may be NULL. Otherwise, it
42			* should return 0 if the two passed keys match. If it is not necessary
43			* (or possible) to free the key and/or data values, then the freek and/or
44			* freed member functions may be NULL.
45	greg	1.1	*
46	greg	1.4	* It isn't fully necessary to call lu_init to initialize the LUTAB structure.
47			* If tsiz is 0, then the first call to lu_find will allocate a minimal table.
48			* The LU_SINIT macro provides a convenient static declaration for character
49			* string keys.
50			*
51	greg	1.1	* The lu_find routine returns the entry corresponding to the given
52	greg	1.4	* key. If the entry does not exist, the corresponding key field will
53			* be NULL. If the entry has been previously deleted but not yet freed,
54			* then only the data field will be NULL. It is the caller's
55			* responsibility to (allocate and) assign the key and data fields when
56			* creating a new entry. The only case where lu_find returns NULL is when
57			* the system has run out of memory.
58	greg	1.1	*
59	greg	1.2	* The lu_delete routine frees an entry's data (if any) by calling
60			* the freed member function, but does not free the key field. This
61			* will be freed later during (or instead of) table reallocation.
62	greg	1.5	* It is therefore an error to reuse or do anything with the key
63			* field after calling lu_delete.
64	greg	1.2	*
65	greg	1.1	* The lu_done routine calls the given free function once for each
66			* assigned table entry (i.e. each entry with an assigned key value).
67	greg	1.3	* The user must define these routines to free the key and the data
68	greg	1.2	* in the LU_TAB structure. The final action of lu_done is to free the
69	greg	1.1	* allocated table itself.
70			*/
71
72			extern int lu_init(LUTAB *, int);
73			extern LUENT lu_find(LUTAB , char *);
74	greg	1.2	extern void lu_delete(LUTAB , char );
75			extern void lu_done(LUTAB *);
76	gwlarson	1.9	extern unsigned long lu_shash(char *);
77	schorsch	1.11
78
79			#ifdef __cplusplus
80			}
81	greg	1.1	#endif
82	schorsch	1.11	#endif /* _MGF_LOOKUP_H_ */
83