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1 | /* -*-c-*- |
2 | * |
3 | * $Id: anagram.c,v 1.1 2001/02/04 17:14:42 mdw Exp $ |
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 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: anagram.c,v $ |
32 | * Revision 1.1 2001/02/04 17:14:42 mdw |
33 | * Initial checkin |
34 | * |
35 | */ |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include "anag.h" |
40 | |
41 | /*----- Data structures ---------------------------------------------------*/ |
42 | |
43 | typedef struct node_gram { |
44 | node n; |
45 | size_t sz; |
46 | unsigned f[UCHAR_MAX + 1]; |
47 | } node_gram; |
48 | |
49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
51 | /* --- @compile@ --- * |
52 | * |
53 | * Arguments: @node_gram *n@ = pointer to node to fill in |
54 | * @const char *p@ = pointer to string to compile from |
55 | * |
56 | * Returns: The length of the string. |
57 | * |
58 | * Use: Fills in an anagram node with letter frequencies. |
59 | */ |
60 | |
61 | static size_t compile(node_gram *n, const char *p) |
62 | { |
63 | size_t len = 0; |
64 | unsigned i; |
65 | memset(n->f, 0, sizeof(n->f)); |
66 | while (*p) { |
67 | i = (unsigned char)*p++; |
68 | n->f[i]++; |
69 | len++; |
70 | } |
71 | return (len); |
72 | } |
73 | |
74 | /* --- Node matcher --- */ |
75 | |
76 | static int n_gram(node *nn, const char *p, size_t sz) |
77 | { |
78 | node_gram *n = (node_gram *)nn; |
79 | unsigned f[UCHAR_MAX]; |
80 | const char *q; |
81 | unsigned i; |
82 | |
83 | if (n->sz && sz != n->sz) |
84 | return (0); |
85 | memcpy(f, n->f, sizeof(f)); |
86 | q = p + sz; |
87 | while (p < q) { |
88 | i = (unsigned char)*p++; |
89 | if (!f[i]) |
90 | return (0); |
91 | f[i]--; |
92 | } |
93 | return (1); |
94 | } |
95 | |
96 | /* --- Node creation --- */ |
97 | |
98 | node *anagram(const char *const *av) |
99 | { |
100 | node_gram *n = xmalloc(sizeof(*n)); |
101 | n->n.func = n_gram; |
102 | n->sz = compile(n, av[0]); |
103 | return (&n->n); |
104 | } |
105 | |
106 | node *subgram(const char *const *av) |
107 | { |
108 | node_gram *n = xmalloc(sizeof(*n)); |
109 | n->n.func = n_gram; |
110 | n->sz = 0; |
111 | compile(n, av[0]); |
112 | return (&n->n); |
113 | } |
114 | |
115 | /*----- That's all, folks -------------------------------------------------*/ |