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1 | /* -*-c-*- |
2 | * |
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3 | * $Id$ |
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4 | * |
5 | * Matches anagrams and subgrams |
6 | * |
7 | * (c) 2001 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Anag: a simple wordgame helper. |
13 | * |
14 | * Anag is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * Anag 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 General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with Anag; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include "anag.h" |
32 | |
33 | /*----- Data structures ---------------------------------------------------*/ |
34 | |
35 | typedef struct node_gram { |
36 | node n; |
37 | size_t sz; |
38 | unsigned f[UCHAR_MAX + 1]; |
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 | * |
48 | * Returns: The length of the string. |
49 | * |
50 | * Use: Fills in an anagram node with letter frequencies. |
51 | */ |
52 | |
53 | static size_t compile(node_gram *n, const char *p) |
54 | { |
55 | size_t len = 0; |
56 | unsigned i; |
57 | memset(n->f, 0, sizeof(n->f)); |
58 | while (*p) { |
59 | i = (unsigned char)*p++; |
60 | n->f[i]++; |
61 | len++; |
62 | } |
63 | return (len); |
64 | } |
65 | |
66 | /* --- Node matcher --- */ |
67 | |
68 | static int n_gram(node *nn, const char *p, size_t sz) |
69 | { |
70 | node_gram *n = (node_gram *)nn; |
71 | unsigned f[UCHAR_MAX]; |
72 | const char *q; |
73 | unsigned i; |
74 | |
75 | if (n->sz && sz != n->sz) |
76 | return (0); |
77 | memcpy(f, n->f, sizeof(f)); |
78 | q = p + sz; |
79 | while (p < q) { |
80 | i = (unsigned char)*p++; |
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81 | if (f[i]) |
82 | f[i]--; |
83 | else if (f['.']) |
84 | f['.']--; |
85 | else |
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86 | return (0); |
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87 | } |
88 | return (1); |
89 | } |
90 | |
91 | /* --- Node creation --- */ |
92 | |
93 | node *anagram(const char *const *av) |
94 | { |
95 | node_gram *n = xmalloc(sizeof(*n)); |
96 | n->n.func = n_gram; |
97 | n->sz = compile(n, av[0]); |
98 | return (&n->n); |
99 | } |
100 | |
101 | node *subgram(const char *const *av) |
102 | { |
103 | node_gram *n = xmalloc(sizeof(*n)); |
104 | n->n.func = n_gram; |
105 | n->sz = 0; |
106 | compile(n, av[0]); |
107 | return (&n->n); |
108 | } |
109 | |
110 | /*----- That's all, folks -------------------------------------------------*/ |