dcda5944 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: assoc.c,v 1.1 2001/01/20 11:50:58 mdw Exp $ |
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 $ |
33 | * Revision 1.1 2001/01/20 11:50:58 mdw |
34 | * Hash tables indexed by atoms, to avoid expense of hashing keys on each |
35 | * lookup, and to reduce storage used by key texts. |
36 | * |
37 | */ |
38 | |
39 | /*----- Header files ------------------------------------------------------*/ |
40 | |
41 | #include "alloc.h" |
42 | #include "assoc.h" |
43 | #include "atom.h" |
44 | #include "hash.h" |
45 | |
46 | /*----- Main code ---------------------------------------------------------*/ |
47 | |
48 | /* --- @assoc_create@ --- * |
49 | * |
50 | * Arguments: @assoc_table *t@ = pointer to an association table |
51 | * |
52 | * Returns: --- |
53 | * |
54 | * Use: Creates a new association table. |
55 | */ |
56 | |
57 | void assoc_create(assoc_table *t) |
58 | { |
59 | hash_create(&t->t, SYM_INITSZ); |
60 | t->load = SYM_LIMIT(SYM_INITSZ); |
61 | } |
62 | |
63 | /* --- @assoc_destroy@ --- * |
64 | * |
65 | * Arguments: @assoc_table *t@ = pointer to an association table |
66 | * |
67 | * Returns: --- |
68 | * |
69 | * Use: Destroys an association table. |
70 | */ |
71 | |
72 | void assoc_destroy(assoc_table *t) |
73 | { |
74 | hash_iter i; |
75 | |
76 | HASH_MKITER(&i, &t->t); |
77 | for (;;) { |
78 | hash_base *p; |
79 | HASH_NEXT(&i, p); |
80 | x_free(t->t.a, p); |
81 | } |
82 | hash_destroy(&t->t); |
83 | } |
84 | |
85 | /* --- @assoc_find@ --- * |
86 | * |
87 | * Arguments: @assoc_table *t@ = pointer to an association table |
88 | * @atom *a@ = an atom to label the item |
89 | * @size_t sz@ = size of block to allocate |
90 | * @unsigned *f@ = pointer to `found' flag |
91 | * |
92 | * Returns: A pointer to the item located or null. |
93 | * |
94 | * Use: Looks up an atom in an association table. If the atom is |
95 | * found, the association is returned. If not, and @sz@ is |
96 | * zero, a null pointer is returned. Otherwise, a block of size |
97 | * @sz@ is allocated, its @assoc_base@ header is filled in, and |
98 | * the pointer returned. The flag @*f@ is cleared if the item |
99 | * couldn't be found, or set if it was. |
100 | * |
101 | * All the atoms used in a particular table should |
102 | */ |
103 | |
104 | void *assoc_find(assoc_table *t, atom *a, size_t sz, unsigned *f) |
105 | { |
106 | hash_base **bin = HASH_BIN(&t->t, a->b.b.hash), **p; |
107 | assoc_base *q; |
108 | |
109 | /* --- Try to find the association --- */ |
110 | |
111 | for (p = bin; *p; p = &(*p)->next) { |
112 | q = (assoc_base *)*p; |
113 | if (q->a == a) { |
114 | *p = q->b.next; |
115 | q->b.next = *bin; |
116 | *bin = &q->b; |
117 | if (f) *f = 1; |
118 | return (q); |
119 | } |
120 | } |
121 | |
122 | /* --- Failed to find a match --- */ |
123 | |
124 | if (f) *f = 0; |
125 | if (!sz) return (0); |
126 | |
127 | /* --- Make a new assoication --- */ |
128 | |
129 | q = x_alloc(t->t.a, sz); |
130 | q->b.next = *bin; |
131 | q->b.hash = ATOM_HASH(a); |
132 | *bin = &q->b; |
133 | |
134 | /* --- Maybe extend the table --- */ |
135 | |
136 | if (t->load) |
137 | t->load--; |
138 | if (!t->load && hash_extend(&t->t)) |
139 | t->load = SYM_LIMIT(t->t.mask + 1); |
140 | return (q); |
141 | } |
142 | |
143 | /* --- @assoc_remove@ --- * |
144 | * |
145 | * Arguments: @assoc_table *t@ = pointer to an association table |
146 | * @void *p@ = pointer to a block to remove |
147 | * |
148 | * Returns: --- |
149 | * |
150 | * Use: Removes an association from a table. |
151 | */ |
152 | |
153 | void assoc_remove(assoc_table *t, void *p) |
154 | { |
155 | assoc_base *q = p; |
156 | hash_remove(&t->t, &q->b); |
157 | x_free(t->t.a, q); |
158 | t->load++; |
159 | } |
160 | |
161 | /* --- @assoc_mkiter@, @assoc_next@ --- * |
162 | * |
163 | * Arguments: @assoc_iter *i@ = pointer to an iterator |
164 | * @assoc_table *t@ = pointer to an association table |
165 | * |
166 | * Returns: Next association, or null, for @assoc_next@; nothing for |
167 | * @assoc_mkiter@. |
168 | * |
169 | * Use: Iterates over the associations in a table. |
170 | */ |
171 | |
172 | void assoc_mkiter(assoc_iter *i, assoc_table *t) { ASSOC_MKITER(i, t); } |
173 | void *assoc_next(assoc_iter *i) { void *p; ASSOC_NEXT(i, p); return (p); } |
174 | |
175 | /*----- That's all, folks -------------------------------------------------*/ |