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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: assoc.c,v 1.2 2001/01/21 19:04:59 mdw Exp $ |
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4 | * |
5 | * Assocation tables |
6 | * |
7 | * (c) 2000 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: assoc.c,v $ |
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33 | * Revision 1.2 2001/01/21 19:04:59 mdw |
34 | * Fix bugs. |
35 | * |
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36 | * Revision 1.1 2001/01/20 11:50:58 mdw |
37 | * Hash tables indexed by atoms, to avoid expense of hashing keys on each |
38 | * lookup, and to reduce storage used by key texts. |
39 | * |
40 | */ |
41 | |
42 | /*----- Header files ------------------------------------------------------*/ |
43 | |
44 | #include "alloc.h" |
45 | #include "assoc.h" |
46 | #include "atom.h" |
47 | #include "hash.h" |
48 | |
49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
51 | /* --- @assoc_create@ --- * |
52 | * |
53 | * Arguments: @assoc_table *t@ = pointer to an association table |
54 | * |
55 | * Returns: --- |
56 | * |
57 | * Use: Creates a new association table. |
58 | */ |
59 | |
60 | void assoc_create(assoc_table *t) |
61 | { |
62 | hash_create(&t->t, SYM_INITSZ); |
63 | t->load = SYM_LIMIT(SYM_INITSZ); |
64 | } |
65 | |
66 | /* --- @assoc_destroy@ --- * |
67 | * |
68 | * Arguments: @assoc_table *t@ = pointer to an association table |
69 | * |
70 | * Returns: --- |
71 | * |
72 | * Use: Destroys an association table. |
73 | */ |
74 | |
75 | void assoc_destroy(assoc_table *t) |
76 | { |
77 | hash_iter i; |
78 | |
79 | HASH_MKITER(&i, &t->t); |
80 | for (;;) { |
81 | hash_base *p; |
82 | HASH_NEXT(&i, p); |
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83 | if (!p) |
84 | break; |
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85 | x_free(t->t.a, p); |
86 | } |
87 | hash_destroy(&t->t); |
88 | } |
89 | |
90 | /* --- @assoc_find@ --- * |
91 | * |
92 | * Arguments: @assoc_table *t@ = pointer to an association table |
93 | * @atom *a@ = an atom to label the item |
94 | * @size_t sz@ = size of block to allocate |
95 | * @unsigned *f@ = pointer to `found' flag |
96 | * |
97 | * Returns: A pointer to the item located or null. |
98 | * |
99 | * Use: Looks up an atom in an association table. If the atom is |
100 | * found, the association is returned. If not, and @sz@ is |
101 | * zero, a null pointer is returned. Otherwise, a block of size |
102 | * @sz@ is allocated, its @assoc_base@ header is filled in, and |
103 | * the pointer returned. The flag @*f@ is cleared if the item |
104 | * couldn't be found, or set if it was. |
105 | * |
106 | * All the atoms used in a particular table should |
107 | */ |
108 | |
109 | void *assoc_find(assoc_table *t, atom *a, size_t sz, unsigned *f) |
110 | { |
111 | hash_base **bin = HASH_BIN(&t->t, a->b.b.hash), **p; |
112 | assoc_base *q; |
113 | |
114 | /* --- Try to find the association --- */ |
115 | |
116 | for (p = bin; *p; p = &(*p)->next) { |
117 | q = (assoc_base *)*p; |
118 | if (q->a == a) { |
119 | *p = q->b.next; |
120 | q->b.next = *bin; |
121 | *bin = &q->b; |
122 | if (f) *f = 1; |
123 | return (q); |
124 | } |
125 | } |
126 | |
127 | /* --- Failed to find a match --- */ |
128 | |
129 | if (f) *f = 0; |
130 | if (!sz) return (0); |
131 | |
132 | /* --- Make a new assoication --- */ |
133 | |
134 | q = x_alloc(t->t.a, sz); |
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135 | q->a = a; |
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136 | q->b.next = *bin; |
137 | q->b.hash = ATOM_HASH(a); |
138 | *bin = &q->b; |
139 | |
140 | /* --- Maybe extend the table --- */ |
141 | |
142 | if (t->load) |
143 | t->load--; |
144 | if (!t->load && hash_extend(&t->t)) |
145 | t->load = SYM_LIMIT(t->t.mask + 1); |
146 | return (q); |
147 | } |
148 | |
149 | /* --- @assoc_remove@ --- * |
150 | * |
151 | * Arguments: @assoc_table *t@ = pointer to an association table |
152 | * @void *p@ = pointer to a block to remove |
153 | * |
154 | * Returns: --- |
155 | * |
156 | * Use: Removes an association from a table. |
157 | */ |
158 | |
159 | void assoc_remove(assoc_table *t, void *p) |
160 | { |
161 | assoc_base *q = p; |
162 | hash_remove(&t->t, &q->b); |
163 | x_free(t->t.a, q); |
164 | t->load++; |
165 | } |
166 | |
167 | /* --- @assoc_mkiter@, @assoc_next@ --- * |
168 | * |
169 | * Arguments: @assoc_iter *i@ = pointer to an iterator |
170 | * @assoc_table *t@ = pointer to an association table |
171 | * |
172 | * Returns: Next association, or null, for @assoc_next@; nothing for |
173 | * @assoc_mkiter@. |
174 | * |
175 | * Use: Iterates over the associations in a table. |
176 | */ |
177 | |
178 | void assoc_mkiter(assoc_iter *i, assoc_table *t) { ASSOC_MKITER(i, t); } |
179 | void *assoc_next(assoc_iter *i) { void *p; ASSOC_NEXT(i, p); return (p); } |
180 | |
181 | /*----- That's all, folks -------------------------------------------------*/ |