Commit | Line | Data |
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6e403221 | 1 | /* -*-c-*- |
2 | * | |
6e403221 | 3 | * Matches anagrams and subgrams |
4 | * | |
5 | * (c) 2001 Mark Wooding | |
6 | */ | |
7 | ||
0279756e | 8 | /*----- Licensing notice --------------------------------------------------* |
6e403221 | 9 | * |
10 | * This file is part of Anag: a simple wordgame helper. | |
11 | * | |
12 | * Anag is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
0279756e | 16 | * |
6e403221 | 17 | * Anag is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
0279756e | 21 | * |
6e403221 | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with Anag; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
6e403221 | 27 | /*----- Header files ------------------------------------------------------*/ |
28 | ||
29 | #include "anag.h" | |
30 | ||
31 | /*----- Data structures ---------------------------------------------------*/ | |
32 | ||
904ac13a MW |
33 | typedef unsigned countmap[UCHAR_MAX + 1]; |
34 | ||
6e403221 | 35 | typedef struct node_gram { |
36 | node n; | |
37 | size_t sz; | |
904ac13a | 38 | countmap count; |
6e403221 | 39 | } node_gram; |
40 | ||
41 | /*----- Main code ---------------------------------------------------------*/ | |
42 | ||
43 | /* --- @compile@ --- * | |
44 | * | |
45 | * Arguments: @node_gram *n@ = pointer to node to fill in | |
46 | * @const char *p@ = pointer to string to compile from | |
47 | * | |
904ac13a | 48 | * Returns: --- |
6e403221 | 49 | * |
50 | * Use: Fills in an anagram node with letter frequencies. | |
51 | */ | |
52 | ||
904ac13a | 53 | static void compile(const char *p, countmap count) |
6e403221 | 54 | { |
904ac13a MW |
55 | memset(count, 0, sizeof(countmap)); |
56 | while (*p) count[(unsigned char)*p++]++; | |
6e403221 | 57 | } |
58 | ||
59 | /* --- Node matcher --- */ | |
60 | ||
61 | static int n_gram(node *nn, const char *p, size_t sz) | |
62 | { | |
904ac13a MW |
63 | /* A string X is a subgram of Y unless, for some character CH, X has more |
64 | * characters of value CH than Y. | |
65 | * | |
66 | * Special feature: count `.' in the pattern as meaning `don't care'. | |
67 | */ | |
68 | ||
6e403221 | 69 | node_gram *n = (node_gram *)nn; |
904ac13a | 70 | countmap count; |
6e403221 | 71 | const char *q; |
72 | unsigned i; | |
73 | ||
904ac13a MW |
74 | if (n->sz && sz != n->sz) return (0); |
75 | memcpy(count, n->count, sizeof(count)); | |
6e403221 | 76 | q = p + sz; |
77 | while (p < q) { | |
78 | i = (unsigned char)*p++; | |
904ac13a MW |
79 | if (count[i]) count[i]--; |
80 | else if (count['.']) count['.']--; | |
81 | else return (0); | |
6e403221 | 82 | } |
83 | return (1); | |
84 | } | |
85 | ||
86 | /* --- Node creation --- */ | |
87 | ||
88 | node *anagram(const char *const *av) | |
89 | { | |
90 | node_gram *n = xmalloc(sizeof(*n)); | |
91 | n->n.func = n_gram; | |
904ac13a MW |
92 | compile(av[0], n->count); |
93 | n->sz = strlen(av[0]); | |
6e403221 | 94 | return (&n->n); |
95 | } | |
96 | ||
97 | node *subgram(const char *const *av) | |
98 | { | |
99 | node_gram *n = xmalloc(sizeof(*n)); | |
100 | n->n.func = n_gram; | |
904ac13a | 101 | compile(av[0], n->count); |
6e403221 | 102 | n->sz = 0; |
6e403221 | 103 | return (&n->n); |
104 | } | |
105 | ||
106 | /*----- That's all, folks -------------------------------------------------*/ |