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New program to make fixed tables for universal hashing.
[mLib] / sym.h
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1/* -*-c-*-
2 *
3 * $Id: sym.h,v 1.12 2001/01/20 11:49:37 mdw Exp $
4 *
5 * Symbol table management
6 *
7 * (c) 1998 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: sym.h,v $
33 * Revision 1.12 2001/01/20 11:49:37 mdw
34 * Export tuning parameters from header file, for the benefit of other
35 * hashtable implementations. Change the storage of symbol names: store
36 * the name after the allocated symbol block in all cases. This replaces
37 * the previous complicated and slightly wasteful arrangement.
38 *
39 * Revision 1.11 2000/06/17 10:37:39 mdw
40 * Add support for arena management.
41 *
42 * Revision 1.10 1999/12/10 23:42:04 mdw
43 * Change header file guard names.
44 *
45 * Revision 1.9 1999/08/02 16:53:48 mdw
46 * Improve type safety for sym_iter objects.
47 *
48 * Revision 1.8 1999/08/02 14:45:48 mdw
49 * Break low-level hashtable code out from sym.
50 *
51 * Revision 1.7 1999/06/01 09:49:33 mdw
52 * Allow things to be looked up by just their caller-supplied hashes. This
53 * actually needs to be thought through better.
54 *
55 * Revision 1.6 1999/05/26 21:08:31 mdw
56 * Rename symbols in line with newer conventions.
57 *
58 * Revision 1.5 1999/05/13 22:48:37 mdw
59 * Change `-ise' to `-ize' throughout.
60 *
61 * Revision 1.4 1999/05/06 19:51:35 mdw
62 * Reformatted the LGPL notice a little bit.
63 *
64 * Revision 1.3 1999/05/05 18:50:31 mdw
65 * Change licensing conditions to LGPL.
66 *
67 * Revision 1.2 1998/11/26 19:27:34 mdw
68 * Move SYM_NAME into the header file. Fix bugs.
69 *
70 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
71 * Initial version of mLib
72 *
73 */
74
75#ifndef MLIB_SYM_H
76#define MLIB_SYM_H
77
78#ifdef __cplusplus
79 extern "C" {
80#endif
81
82/*----- Required headers --------------------------------------------------*/
83
84#include <stddef.h>
85
86#ifndef MLIB_BITS_H
87# include "bits.h"
88#endif
89
90#ifndef MLIB_HASH_H
91# include "hash.h"
92#endif
93
94#ifndef MLIB_SUB_H
95# include "sub.h"
96#endif
97
98/*----- Tuning parameters -------------------------------------------------*/
99
100/* --- Initial hash table size --- *
101 *
102 * This is the initial @mask@ value. It must be of the form %$2^n - 1$%,
103 * so that it can be used to mask of the bottom bits of a hash value.
104 */
105
106#define SYM_INITSZ 32 /* Size of a new hash table */
107
108/* --- Maximum load factor --- *
109 *
110 * This parameter controls how much the table has to be loaded before the
111 * table is extended. The number of elements %$n$%, the number of bins %$b$%
112 * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
113 * added to the table and this relation is found to be false, the table is
114 * doubled in size.
115 */
116
117#define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */
118
119/*----- Type definitions --------------------------------------------------*/
120
121/* --- Symbol table --- *
122 *
123 * A @sym_table@ contains the information needed to manage a symbol table.
124 * Users shouldn't fiddle with this information directly, but it needs to be
125 * here so that objects of the correct type can be created.
126 */
127
128typedef struct sym_table {
129 hash_table t;
130 subarena *s;
131 size_t load;
132} sym_table;
133
134/* --- A symbol table entry --- *
135 *
136 * I don't care what actually gets stored in symbol entries because I don't
137 * create them: that's the responsibility of my client. All I care about
138 * here is that whatever gets passed to me is a structure whose first member
139 * is a @sym_base@. The ANSI guarantees about structure layout are
140 * sufficient to allow me to manipulate such objects.
141 */
142
143typedef struct sym_base {
144 hash_base b; /* Base structure */
145 char *name; /* Pointer to name string */
146 size_t len; /* Length of the symbol's name */
147} sym_base;
148
149/* --- Macros for picking out useful information --- *
150 *
151 * Note that @SYM_LEN@ returns the size of the symbol key. For textual keys,
152 * this will include the terminating null.
153 */
154
155#define SYM_NAME(sy) ((const char *)(((sym_base *)(sy))->name))
156#define SYM_LEN(sy) (((sym_base *)(sy))->len + 0)
157#define SYM_HASH(sy) (((sym_base *)(sy))->b.hash + 0)
158
159/* --- An iterator block --- */
160
161typedef struct { hash_iter i; } sym_iter;
162
163/*----- External functions ------------------------------------------------*/
164
165/* --- @sym_create@ --- *
166 *
167 * Arguments: @sym_table *t@ = symbol table to initialize
168 *
169 * Returns: ---
170 *
171 * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if
172 * there isn't enough memory.
173 */
174
175extern void sym_create(sym_table */*t*/);
176
177/* --- @sym_destroy@ --- *
178 *
179 * Arguments: @sym_table *t@ = pointer to symbol table in question
180 *
181 * Returns: ---
182 *
183 * Use: Destroys a symbol table, freeing all the memory it used to
184 * occupy.
185 */
186
187extern void sym_destroy(sym_table */*t*/);
188
189/* --- @sym_find@ --- *
190 *
191 * Arguments: @sym_table *t@ = pointer to symbol table in question
192 * @const char *n@ = pointer to symbol table to look up
193 * @long l@ = length of the name string or negative to measure
194 * @size_t sz@ = size of desired symbol object, or zero
195 * @unsigned *f@ = pointer to a flag, or null.
196 *
197 * Returns: The address of a @sym_base@ structure, or null if not found
198 * and @sz@ is zero.
199 *
200 * Use: Looks up a symbol in a given symbol table. The name is
201 * passed by the address of its first character. The length
202 * may be given, in which case the name may contain arbitrary
203 * binary data, or it may be given as a negative number, in
204 * which case the length of the name is calculated as
205 * @strlen(n) + 1@.
206 *
207 * The return value is the address of a pointer to a @sym_base@
208 * block (which may have other things on the end, as above). If
209 * the symbol could be found, the return value points to the
210 * symbol block. If the symbol wasn't there, then if @sz@ is
211 * nonzero, a new symbol is created and its address is returned;
212 * otherwise a null pointer is returned. The exception
213 * @EXC_NOMEM@ is raised if the block can't be allocated.
214 *
215 * The value of @*f@ indicates whether a new symbol entry was
216 * created: a nonzero value indicates that an old value was
217 * found.
218 */
219
220extern void *sym_find(sym_table */*t*/, const char */*n*/, long /*l*/,
221 size_t /*sz*/, unsigned */*f*/);
222
223/* --- @sym_remove@ --- *
224 *
225 * Arguments: @sym_table *t@ = pointer to a symbol table object
226 * @void *b@ = pointer to symbol table entry
227 *
228 * Returns: ---
229 *
230 * Use: Removes the object from the symbol table. The space occupied
231 * by the object and its name is freed; anything else attached
232 * to the entry should already be gone by this point.
233 */
234
235extern void sym_remove(sym_table */*t*/, void */*b*/);
236
237/* --- @sym_mkiter@ --- *
238 *
239 * Arguments: @sym_iter *i@ = pointer to an iterator object
240 * @sym_table *t@ = pointer to a symbol table object
241 *
242 * Returns: ---
243 *
244 * Use: Creates a new symbol table iterator which may be used to
245 * iterate through a symbol table.
246 */
247
248#define SYM_MKITER(i_, t_) HASH_MKITER(&(i_)->i, &(t_)->t)
249
250extern void sym_mkiter(sym_iter */*i*/, sym_table */*t*/);
251
252/* --- @sym_next@ --- *
253 *
254 * Arguments: @sym_iter *i@ = pointer to iterator object
255 *
256 * Returns: Pointer to the next symbol found, or null when finished.
257 *
258 * Use: Returns the next symbol from the table. Symbols are not
259 * returned in any particular order.
260 */
261
262#define SYM_NEXT(i_, p) do { \
263 hash_base *_q; \
264 HASH_NEXT(&(i_)->i, _q); \
265 (p) = (void *)_q; \
266} while (0)
267
268extern void *sym_next(sym_iter */*i*/);
269
270/*----- That's all, folks -------------------------------------------------*/
271
272#ifdef __cplusplus
273 }
274#endif
275
276#endif