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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: trackword.c,v 1.2 2001/02/04 19:52:53 mdw Exp $ |
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4 | * |
5 | * Matches trackwords |
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: trackword.c,v $ |
9bdeb40d |
32 | * Revision 1.2 2001/02/04 19:52:53 mdw |
33 | * Remove debugging. |
34 | * |
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35 | * Revision 1.1 2001/02/04 17:14:42 mdw |
36 | * Initial checkin |
37 | * |
38 | */ |
39 | |
40 | /*----- Header files ------------------------------------------------------*/ |
41 | |
42 | #include "anag.h" |
43 | |
44 | /*----- Data structures ---------------------------------------------------*/ |
45 | |
46 | enum { N, NE, E, SE, S, SW, W, NW, NDIR }; |
47 | |
48 | typedef struct tcell { |
49 | struct tcell *hop[NDIR]; |
50 | char ch; |
51 | unsigned char f; |
52 | } tcell; |
53 | |
54 | typedef struct node_track { |
55 | node n; |
56 | unsigned x; |
57 | unsigned y; |
58 | tcell *c; |
59 | } node_track; |
60 | |
61 | /*----- Utility functions -------------------------------------------------*/ |
62 | |
63 | /* --- @isqrt@ --- * |
64 | * |
65 | * Arguments: @long a@ = the target value |
66 | * |
67 | * Returns: %$\lfloor \sqrt{a} \rfloor$% |
68 | * |
69 | * Use: Computes an integer square root. This algorithm is |
70 | * Newton-Raphson with integers. I've stolen this more-or-less |
71 | * wholesale fom the multiprecision integer square-root function |
72 | * in Catacomb. |
73 | */ |
74 | |
75 | long isqrt(long a) |
76 | { |
77 | long i, q; |
78 | |
79 | /* --- Initial guess is half the input length --- */ |
80 | |
81 | for (i = q = a; q; q >>= 2) |
82 | i >>= 1; |
83 | |
84 | /* --- Do the main series iteration --- */ |
85 | |
86 | for (;;) { |
87 | q = i * i - a; |
88 | if (!q || (q < 0 && -q <= 2 * i)) |
89 | return (i); |
90 | q /= 2 * i; |
91 | if (!q) |
92 | i--; |
93 | else |
94 | i -= q; |
95 | } |
96 | } |
97 | |
98 | /*----- Main code ---------------------------------------------------------*/ |
99 | |
100 | /* --- @track@ --- * |
101 | * |
102 | * Arguments: @tcell *c@ = pointer to start cell |
103 | * @const char *p@ = string to match |
104 | * |
105 | * Returns: Nonzero for a match, zero if no match was found. |
106 | * |
107 | * Use: Searches for a match in a trackword. |
108 | */ |
109 | |
110 | static int track(tcell *c, const char *p) |
111 | { |
112 | int i; |
113 | |
114 | if (*p++ != c->ch) |
115 | return (0); |
116 | if (!*p) |
117 | return (1); |
118 | c->f = 1; |
119 | for (i = 0; i < NDIR; i++) { |
120 | if (!c->hop[i] || c->hop[i]->f) |
121 | continue; |
122 | if (track(c->hop[i], p)) { |
123 | c->f = 0; |
124 | return (1); |
125 | } |
126 | } |
127 | c->f = 0; |
128 | return (0); |
129 | } |
130 | |
131 | /* --- Node matcher --- */ |
132 | |
133 | static int n_track(node *nn, const char *p, size_t sz) |
134 | { |
135 | node_track *n = (node_track *)nn; |
136 | tcell *c; |
137 | |
138 | if (!*p) |
139 | return (1); |
140 | for (c = n->c; c->ch; c++) { |
141 | if (track(c, p)) |
142 | return (1); |
143 | } |
144 | return (0); |
145 | } |
146 | |
147 | /* --- Node creation --- */ |
148 | |
149 | node *trackword(const char *const *av) |
150 | { |
151 | node_track *n; |
152 | unsigned x, y; |
153 | unsigned i, j; |
154 | const char *p = av[0], *q, *l; |
155 | size_t sz = strlen(p); |
156 | tcell *c; |
157 | |
158 | /* --- Work out the dimensions --- */ |
159 | |
160 | x = strcspn(p, "/"); |
161 | if (!p[x]) { |
162 | x = isqrt(sz); |
163 | if (x * x != sz) |
164 | die("bad trackword `%s': not square, and no line markers", p); |
165 | y = x; |
166 | } |
167 | |
168 | if (!x) |
169 | die("bad trackword `%s': no columns", p); |
170 | |
171 | y = 0; |
172 | l = p + sz; |
173 | q = p; |
174 | for (;;) { |
175 | if (*q == '/') |
176 | q++; |
177 | if (!*q) |
178 | break; |
179 | if (l - q < x) |
180 | die("bad trackword `%s': inconsistent line lengths", p); |
181 | q += x; |
182 | y++; |
183 | } |
184 | |
185 | if (!y) |
186 | die("bad trackword `%s': no rows", p); |
187 | |
188 | /* --- Build the match node --- */ |
189 | |
190 | n = xmalloc(sizeof(*n)); |
191 | n->n.func = n_track; |
192 | n->x = x; n->y = y; |
193 | n->c = xmalloc((x * y + 1) * sizeof(tcell)); |
194 | |
195 | q = p; |
196 | c = n->c; |
197 | for (j = 0; j < y; j++) { |
198 | if (*q == '/') |
199 | q++; |
200 | for (i = 0; i < x; i++) { |
201 | c->ch = *q++; |
202 | c->f = 0; |
203 | |
204 | #define NOK (j > 0) |
205 | #define SOK (j < y - 1) |
206 | #define WOK (i > 0) |
207 | #define EOK (i < x - 1) |
208 | |
209 | c->hop[N] = NOK ? c - x : 0; |
210 | c->hop[S] = SOK ? c + x : 0; |
211 | c->hop[W] = WOK ? c - 1 : 0; |
212 | c->hop[E] = EOK ? c + 1 : 0; |
213 | |
214 | c->hop[NW] = NOK && WOK ? c - x - 1 : 0; |
215 | c->hop[NE] = NOK && EOK ? c - x + 1 : 0; |
216 | c->hop[SW] = SOK && WOK ? c + x - 1 : 0; |
217 | c->hop[SE] = SOK && EOK ? c + x + 1 : 0; |
218 | |
219 | #undef NOK |
220 | #undef SOK |
221 | #undef WOK |
222 | #undef EOK |
223 | |
224 | c++; |
225 | } |
226 | } |
227 | c->ch = 0; |
228 | |
229 | /* --- Done --- */ |
230 | |
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231 | return (&n->n); |
232 | } |
233 | |
234 | /*----- That's all, folks -------------------------------------------------*/ |