3 * $Id: sym.c,v 1.14 2003/12/15 20:53:47 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 1.14 2003/12/15 20:53:47 mdw
34 * Add global unihash table; use universal hashing instead of CRC.
36 * Revision 1.13 2001/01/25 21:14:49 mdw
37 * Always add a terminating null, and don't count it in the length.
39 * Revision 1.12 2001/01/20 11:49:37 mdw
40 * Export tuning parameters from header file, for the benefit of other
41 * hashtable implementations. Change the storage of symbol names: store
42 * the name after the allocated symbol block in all cases. This replaces
43 * the previous complicated and slightly wasteful arrangement.
45 * Revision 1.11 2000/06/17 10:37:39 mdw
46 * Add support for arena management.
48 * Revision 1.10 1999/12/10 23:42:04 mdw
49 * Change header file guard names.
51 * Revision 1.9 1999/10/22 22:36:37 mdw
52 * New test structure for symbol tables.
54 * Revision 1.8 1999/08/02 14:45:48 mdw
55 * Break low-level hashtable code out from sym.
57 * Revision 1.7 1999/06/01 09:49:08 mdw
58 * Allow things to be looked up by just their caller-supplied hashes. This
59 * actually needs to be thought through better.
61 * Revision 1.6 1999/05/26 21:08:31 mdw
62 * Rename symbols in line with newer conventions.
64 * Revision 1.5 1999/05/13 22:48:37 mdw
65 * Twiddle the extension threshold. Change `-ise' to `-ize' throughout.
67 * Revision 1.4 1999/05/06 19:51:35 mdw
68 * Reformatted the LGPL notice a little bit.
70 * Revision 1.3 1999/05/05 18:50:31 mdw
71 * Change licensing conditions to LGPL.
73 * Revision 1.2 1998/11/26 19:27:33 mdw
74 * Move SYM_NAME into the header file. Fix bugs.
76 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
77 * Initial version of mLib
81 /*----- Header files ------------------------------------------------------*/
83 /* --- ANSI headers --- */
89 /* --- Local headers --- */
100 /*----- Main code ---------------------------------------------------------*/
102 /* --- @sym_create@ --- *
104 * Arguments: @sym_table *t@ = symbol table to initialize
108 * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if
109 * there isn't enough memory.
112 void sym_create(sym_table *t)
114 hash_create(&t->t, SYM_INITSZ);
116 t->load = SYM_LIMIT(SYM_INITSZ);
119 /* --- @sym_destroy@ --- *
121 * Arguments: @sym_table *t@ = pointer to symbol table in question
125 * Use: Destroys a symbol table, freeing all the memory it used to
129 void sym_destroy(sym_table *t)
144 /* --- @sym_find@ --- *
146 * Arguments: @sym_table *t@ = pointer to symbol table in question
147 * @const char *n@ = pointer to symbol name to look up
148 * @long l@ = length of the name string or negative to measure
149 * @size_t sz@ = size of desired symbol object, or zero
150 * @unsigned *f@ = pointer to a flag, or null.
152 * Returns: The address of a @sym_base@ structure, or null if not found
155 * Use: Looks up a symbol in a given symbol table. The name is
156 * passed by the address of its first character. The length
157 * may be given, in which case the name may contain arbitrary
158 * binary data, or it may be given as a negative number, in
159 * which case the length of the name is calculated as
162 * The return value is the address of a pointer to a @sym_base@
163 * block (which may have other things on the end, as above). If
164 * the symbol could be found, the return value points to the
165 * symbol block. If the symbol wasn't there, then if @sz@ is
166 * nonzero, a new symbol is created and its address is returned;
167 * otherwise a null pointer is returned. The exception
168 * @EXC_NOMEM@ is raised if the block can't be allocated.
170 * The value of @*f@ indicates whether a new symbol entry was
171 * created: a nonzero value indicates that an old value was
175 void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
179 hash_base **bin, **p;
182 /* --- Find the correct bin --- */
184 len = l < 0 ? strlen(n) : l;
185 hash = UNIHASH(&unihash_global, n, len);
186 bin = HASH_BIN(&t->t, hash);
188 /* --- Search the bin list --- */
190 for (p = bin; *p; p = &(*p)->next) {
192 if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) {
194 /* --- Found a match --- *
196 * As a minor, and probably pointless, tweak, move the item to the
197 * front of its bin list.
204 /* --- Return the block --- */
211 /* --- Couldn't find the item there --- */
216 /* --- Create a new symbol block and initialize it --- *
218 * The name is attached to the end of the symbol block.
221 q = x_alloc(t->t.a, sz + len + 1);
224 q->name = (char *)q + sz;
225 memcpy(q->name, n, len);
230 /* --- Consider growing the array --- */
234 if (!t->load && hash_extend(&t->t))
235 t->load = SYM_LIMIT(t->t.mask + 1);
237 /* --- Finished that, so return the new symbol block --- */
242 /* --- @sym_remove@ --- *
244 * Arguments: @sym_table *t@ = pointer to a symbol table object
245 * @void *p@ = pointer to symbol table entry
249 * Use: Removes the object from the symbol table. The space occupied
250 * by the object and its name is freed; anything else attached
251 * to the entry should already be gone by this point.
254 void sym_remove(sym_table *t, void *p)
257 hash_remove(&t->t, &q->b);
262 /* --- @sym_mkiter@ --- *
264 * Arguments: @sym_iter *i@ = pointer to an iterator object
265 * @sym_table *t@ = pointer to a symbol table object
269 * Use: Creates a new symbol table iterator which may be used to
270 * iterate through a symbol table.
273 void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); }
275 /* --- @sym_next@ --- *
277 * Arguments: @sym_iter *i@ = pointer to iterator object
279 * Returns: Pointer to the next symbol found, or null when finished.
281 * Use: Returns the next symbol from the table. Symbols are not
282 * returned in any particular order.
285 void *sym_next(sym_iter *i)
292 /*----- That's all, folks -------------------------------------------------*/