cv/mgflib/lookup.h

/* Copyright (c) 1994 Regents of the University of California */

/* SCCSid "$SunId$ LBL" */

/*
 * Header file for general associative table lookup routines
 */

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

typedef struct {
        long    (*hashf)();     /* key hash function */
        int     (*keycmp)();    /* key comparison function */
        void    (*freek)();     /* free a key */
        void    (*freed)();     /* 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.
 *
 * 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.
 */

#ifdef NOPROTO
extern int      lu_init();
extern LUENT    *lu_find();
extern void     lu_delete();
extern void     lu_done();
extern long     lu_shash();
#else
extern int      lu_init(LUTAB *, int);
extern LUENT    *lu_find(LUTAB *, char *);
extern void     lu_delete(LUTAB *, char *);
extern void     lu_done(LUTAB *);
extern long     lu_shash(char *);
#endif

extern int      strcmp();
Revision:	1.4
Committed:	Sat Jun 25 16:34:50 1994 UTC (29 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.3:	+30 -18 lines
Log Message:	enhancements for general (non-string) associations
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1994 Regents of the University of California */
2
3			/* SCCSid "$SunId$ LBL" */
4
5			/*
6	greg	1.4	* Header file for general associative table lookup routines
7	greg	1.1	*/
8
9			typedef struct {
10	greg	1.4	char key; / key name */
11			long hval; /* key hash value (for efficiency) */
12	greg	1.1	char data; / pointer to client data */
13			} LUENT;
14
15			typedef struct {
16	greg	1.4	long (hashf)(); / key hash function */
17			int (keycmp)(); / key comparison function */
18			void (freek)(); / free a key */
19			void (freed)(); / free the data */
20	greg	1.1	int tsiz; /* current table size */
21			LUENT tabl; / table, if allocated */
22	greg	1.2	int ndel; /* number of deleted entries */
23	greg	1.1	} LUTAB;
24
25	greg	1.4	#define LU_SINIT(fk,fd) {lu_shash,strcmp,(void (*)())(fk),\
26			(void (*)())(fd),0,NULL,0}
27	greg	1.2
28	greg	1.1	/*
29			* The lu_init routine is called to initialize a table. The number of
30			* elements passed is not a limiting factor, as a table can grow to
31			* any size permitted by memory. However, access will be more efficient
32			* if this number strikes a reasonable balance between default memory use
33			* and the expected (minimum) table size. The value returned is the
34			* actual allocated table size (or zero if there was insufficient memory).
35			*
36	greg	1.4	* The hashf, keycmp, freek and freed member functions must be assigned
37			* separately. If the hash value is sufficient to guarantee equality
38			* between keys, then the keycmp pointer may be NULL. Otherwise, it
39			* should return 0 if the two passed keys match. If it is not necessary
40			* (or possible) to free the key and/or data values, then the freek and/or
41			* freed member functions may be NULL.
42	greg	1.1	*
43	greg	1.4	* It isn't fully necessary to call lu_init to initialize the LUTAB structure.
44			* If tsiz is 0, then the first call to lu_find will allocate a minimal table.
45			* The LU_SINIT macro provides a convenient static declaration for character
46			* string keys.
47			*
48	greg	1.1	* The lu_find routine returns the entry corresponding to the given
49	greg	1.4	* key. If the entry does not exist, the corresponding key field will
50			* be NULL. If the entry has been previously deleted but not yet freed,
51			* then only the data field will be NULL. It is the caller's
52			* responsibility to (allocate and) assign the key and data fields when
53			* creating a new entry. The only case where lu_find returns NULL is when
54			* the system has run out of memory.
55	greg	1.1	*
56	greg	1.2	* The lu_delete routine frees an entry's data (if any) by calling
57			* the freed member function, but does not free the key field. This
58			* will be freed later during (or instead of) table reallocation.
59			*
60	greg	1.1	* The lu_done routine calls the given free function once for each
61			* assigned table entry (i.e. each entry with an assigned key value).
62	greg	1.3	* The user must define these routines to free the key and the data
63	greg	1.2	* in the LU_TAB structure. The final action of lu_done is to free the
64	greg	1.1	* allocated table itself.
65			*/
66
67			#ifdef NOPROTO
68			extern int lu_init();
69			extern LUENT *lu_find();
70	greg	1.2	extern void lu_delete();
71	greg	1.1	extern void lu_done();
72	greg	1.4	extern long lu_shash();
73	greg	1.1	#else
74			extern int lu_init(LUTAB *, int);
75			extern LUENT lu_find(LUTAB , char *);
76	greg	1.2	extern void lu_delete(LUTAB , char );
77			extern void lu_done(LUTAB *);
78	greg	1.4	extern long lu_shash(char *);
79	greg	1.1	#endif
80	greg	1.4
81			extern int strcmp();