3 * $Id: sym.c,v 1.11 2000/06/17 10:37:39 mdw Exp $
5 * Symbol table management
7 * (c) 1998 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.11 2000/06/17 10:37:39 mdw
34 * Add support for arena management.
36 * Revision 1.10 1999/12/10 23:42:04 mdw
37 * Change header file guard names.
39 * Revision 1.9 1999/10/22 22:36:37 mdw
40 * New test structure for symbol tables.
42 * Revision 1.8 1999/08/02 14:45:48 mdw
43 * Break low-level hashtable code out from sym.
45 * Revision 1.7 1999/06/01 09:49:08 mdw
46 * Allow things to be looked up by just their caller-supplied hashes. This
47 * actually needs to be thought through better.
49 * Revision 1.6 1999/05/26 21:08:31 mdw
50 * Rename symbols in line with newer conventions.
52 * Revision 1.5 1999/05/13 22:48:37 mdw
53 * Twiddle the extension threshold. Change `-ise' to `-ize' throughout.
55 * Revision 1.4 1999/05/06 19:51:35 mdw
56 * Reformatted the LGPL notice a little bit.
58 * Revision 1.3 1999/05/05 18:50:31 mdw
59 * Change licensing conditions to LGPL.
61 * Revision 1.2 1998/11/26 19:27:33 mdw
62 * Move SYM_NAME into the header file. Fix bugs.
64 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
65 * Initial version of mLib
69 /*----- Header files ------------------------------------------------------*/
71 /* --- ANSI headers --- */
77 /* --- Local headers --- */
88 /*----- Tuning parameters -------------------------------------------------*/
90 /* --- Initial hash table size --- *
92 * This is the initial @mask@ value. It must be of the form %$2^n - 1$%,
93 * so that it can be used to mask of the bottom bits of a hash value.
96 #define SYM_INITSZ 64 /* Size of a new hash table */
98 /* --- Maximum load factor --- *
100 * This parameter controls how much the table has to be loaded before the
101 * table is extended. The number of elements %$n$%, the number of bins %$b$%
102 * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
103 * added to the table and this relation is found to be false, the table is
107 #define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */
109 /*----- Main code ---------------------------------------------------------*/
111 /* --- @sym_create@ --- *
113 * Arguments: @sym_table *t@ = symbol table to initialize
117 * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if
118 * there isn't enough memory.
121 void sym_create(sym_table *t)
123 hash_create(&t->t, SYM_INITSZ);
125 t->load = SYM_LIMIT(SYM_INITSZ);
128 /* --- @sym_destroy@ --- *
130 * Arguments: @sym_table *t@ = pointer to symbol table in question
134 * Use: Destroys a symbol table, freeing all the memory it used to
138 void sym_destroy(sym_table *t)
148 if (p->len > SYM_BUFSZ)
149 subarena_free(t->s, p->name.p, p->len);
155 /* --- @sym_find@ --- *
157 * Arguments: @sym_table *t@ = pointer to symbol table in question
158 * @const char *n@ = pointer to symbol table to look up
159 * @long l@ = length of the name string or negative to measure
160 * @size_t sz@ = size of desired symbol object, or zero
161 * @unsigned *f@ = pointer to a flag, or null.
163 * Returns: The address of a @sym_base@ structure, or null if not found
166 * Use: Looks up a symbol in a given symbol table. The name is
167 * passed by the address of its first character. The length
168 * may be given, in which case the name may contain arbitrary
169 * binary data, or it may be given as a negative number, in
170 * which case the length of the name is calculated as
173 * The return value is the address of a pointer to a @sym_base@
174 * block (which may have other things on the end, as above). If
175 * the symbol could be found, the return value points to the
176 * symbol block. If the symbol wasn't there, then if @sz@ is
177 * nonzero, a new symbol is created and its address is returned;
178 * otherwise a null pointer is returned. The exception
179 * @EXC_NOMEM@ is raised if the block can't be allocated.
181 * The value of @*f@ indicates whether a new symbol entry was
182 * created: a nonzero value indicates that an old value was
186 void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
190 hash_base **bin, **p;
193 /* --- Find the correct bin --- */
195 len = l < 0 ? strlen(n) + 1 : l;
196 CRC32(hash, 0, n, len);
197 bin = HASH_BIN(&t->t, hash);
199 /* --- Search the bin list --- */
201 for (p = bin; *p; p = &(*p)->next) {
203 if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) {
205 /* --- Found a match --- *
207 * As a minor, and probably pointless, tweak, move the item to the
208 * front of its bin list.
215 /* --- Return the block --- */
222 /* --- Couldn't find the item there --- */
227 /* --- Create a new symbol block and initialize it --- */
229 q = x_alloc(t->t.a, sz);
234 if (len <= SYM_BUFSZ)
235 memcpy(q->name.b, n, len);
237 q->name.p = subarena_alloc(t->s, len);
238 memcpy(q->name.p, n, len);
244 /* --- Consider growing the array --- */
248 if (!t->load && hash_extend(&t->t))
249 t->load = SYM_LIMIT(t->t.mask / 2 + 1);
251 /* --- Finished that, so return the new symbol block --- */
256 /* --- @sym_remove@ --- *
258 * Arguments: @sym_table *t@ = pointer to a symbol table object
259 * @void *p@ = pointer to symbol table entry
263 * Use: Removes the object from the symbol table. The space occupied
264 * by the object and its name is freed; anything else attached
265 * to the entry should already be gone by this point.
268 void sym_remove(sym_table *t, void *p)
271 hash_remove(&t->t, &q->b);
272 if (q->len > SYM_BUFSZ)
273 subarena_free(t->s, q->name.p, q->len);
278 /* --- @sym_mkiter@ --- *
280 * Arguments: @sym_iter *i@ = pointer to an iterator object
281 * @sym_table *t@ = pointer to a symbol table object
285 * Use: Creates a new symbol table iterator which may be used to
286 * iterate through a symbol table.
289 void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); }
291 /* --- @sym_next@ --- *
293 * Arguments: @sym_iter *i@ = pointer to iterator object
295 * Returns: Pointer to the next symbol found, or null when finished.
297 * Use: Returns the next symbol from the table. Symbols are not
298 * returned in any particular order.
301 void *sym_next(sym_iter *i)
308 /*----- That's all, folks -------------------------------------------------*/