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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: assoc.c,v 1.4 2004/04/08 01:36:11 mdw Exp $ |
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4 | * |
5 | * Assocation tables |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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18 | * |
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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. |
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23 | * |
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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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include "alloc.h" |
33 | #include "assoc.h" |
34 | #include "atom.h" |
35 | #include "hash.h" |
36 | |
37 | /*----- Main code ---------------------------------------------------------*/ |
38 | |
39 | /* --- @assoc_create@ --- * |
40 | * |
41 | * Arguments: @assoc_table *t@ = pointer to an association table |
42 | * |
43 | * Returns: --- |
44 | * |
45 | * Use: Creates a new association table. |
46 | */ |
47 | |
48 | void assoc_create(assoc_table *t) |
49 | { |
50 | hash_create(&t->t, SYM_INITSZ); |
51 | t->load = SYM_LIMIT(SYM_INITSZ); |
52 | } |
53 | |
54 | /* --- @assoc_destroy@ --- * |
55 | * |
56 | * Arguments: @assoc_table *t@ = pointer to an association table |
57 | * |
58 | * Returns: --- |
59 | * |
60 | * Use: Destroys an association table. |
61 | */ |
62 | |
63 | void assoc_destroy(assoc_table *t) |
64 | { |
65 | hash_iter i; |
66 | |
67 | HASH_MKITER(&i, &t->t); |
68 | for (;;) { |
69 | hash_base *p; |
70 | HASH_NEXT(&i, p); |
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71 | if (!p) |
72 | break; |
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73 | x_free(t->t.a, p); |
74 | } |
75 | hash_destroy(&t->t); |
76 | } |
77 | |
78 | /* --- @assoc_find@ --- * |
79 | * |
80 | * Arguments: @assoc_table *t@ = pointer to an association table |
81 | * @atom *a@ = an atom to label the item |
82 | * @size_t sz@ = size of block to allocate |
83 | * @unsigned *f@ = pointer to `found' flag |
84 | * |
85 | * Returns: A pointer to the item located or null. |
86 | * |
87 | * Use: Looks up an atom in an association table. If the atom is |
88 | * found, the association is returned. If not, and @sz@ is |
89 | * zero, a null pointer is returned. Otherwise, a block of size |
90 | * @sz@ is allocated, its @assoc_base@ header is filled in, and |
91 | * the pointer returned. The flag @*f@ is cleared if the item |
92 | * couldn't be found, or set if it was. |
93 | * |
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94 | * All the atoms used in a particular table should |
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95 | */ |
96 | |
97 | void *assoc_find(assoc_table *t, atom *a, size_t sz, unsigned *f) |
98 | { |
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99 | hash_base **bin = HASH_BIN(&t->t, ATOM_HASH(a)), **p; |
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100 | assoc_base *q; |
101 | |
102 | /* --- Try to find the association --- */ |
103 | |
104 | for (p = bin; *p; p = &(*p)->next) { |
105 | q = (assoc_base *)*p; |
106 | if (q->a == a) { |
107 | *p = q->b.next; |
108 | q->b.next = *bin; |
109 | *bin = &q->b; |
110 | if (f) *f = 1; |
111 | return (q); |
112 | } |
113 | } |
114 | |
115 | /* --- Failed to find a match --- */ |
116 | |
117 | if (f) *f = 0; |
118 | if (!sz) return (0); |
119 | |
120 | /* --- Make a new assoication --- */ |
121 | |
122 | q = x_alloc(t->t.a, sz); |
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123 | q->a = a; |
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124 | q->b.next = *bin; |
125 | q->b.hash = ATOM_HASH(a); |
126 | *bin = &q->b; |
127 | |
128 | /* --- Maybe extend the table --- */ |
129 | |
130 | if (t->load) |
131 | t->load--; |
132 | if (!t->load && hash_extend(&t->t)) |
133 | t->load = SYM_LIMIT(t->t.mask + 1); |
134 | return (q); |
135 | } |
136 | |
137 | /* --- @assoc_remove@ --- * |
138 | * |
139 | * Arguments: @assoc_table *t@ = pointer to an association table |
140 | * @void *p@ = pointer to a block to remove |
141 | * |
142 | * Returns: --- |
143 | * |
144 | * Use: Removes an association from a table. |
145 | */ |
146 | |
147 | void assoc_remove(assoc_table *t, void *p) |
148 | { |
149 | assoc_base *q = p; |
150 | hash_remove(&t->t, &q->b); |
151 | x_free(t->t.a, q); |
152 | t->load++; |
153 | } |
154 | |
155 | /* --- @assoc_mkiter@, @assoc_next@ --- * |
156 | * |
157 | * Arguments: @assoc_iter *i@ = pointer to an iterator |
158 | * @assoc_table *t@ = pointer to an association table |
159 | * |
160 | * Returns: Next association, or null, for @assoc_next@; nothing for |
161 | * @assoc_mkiter@. |
162 | * |
163 | * Use: Iterates over the associations in a table. |
164 | */ |
165 | |
166 | void assoc_mkiter(assoc_iter *i, assoc_table *t) { ASSOC_MKITER(i, t); } |
167 | void *assoc_next(assoc_iter *i) { void *p; ASSOC_NEXT(i, p); return (p); } |
168 | |
169 | /*----- That's all, folks -------------------------------------------------*/ |