6e403221 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: trackword.c,v 1.1 2001/02/04 17:14:42 mdw Exp $ |
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 $ |
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 | enum { N, NE, E, SE, S, SW, W, NW, NDIR }; |
44 | |
45 | typedef struct tcell { |
46 | struct tcell *hop[NDIR]; |
47 | char ch; |
48 | unsigned char f; |
49 | } tcell; |
50 | |
51 | typedef struct node_track { |
52 | node n; |
53 | unsigned x; |
54 | unsigned y; |
55 | tcell *c; |
56 | } node_track; |
57 | |
58 | /*----- Utility functions -------------------------------------------------*/ |
59 | |
60 | /* --- @isqrt@ --- * |
61 | * |
62 | * Arguments: @long a@ = the target value |
63 | * |
64 | * Returns: %$\lfloor \sqrt{a} \rfloor$% |
65 | * |
66 | * Use: Computes an integer square root. This algorithm is |
67 | * Newton-Raphson with integers. I've stolen this more-or-less |
68 | * wholesale fom the multiprecision integer square-root function |
69 | * in Catacomb. |
70 | */ |
71 | |
72 | long isqrt(long a) |
73 | { |
74 | long i, q; |
75 | |
76 | /* --- Initial guess is half the input length --- */ |
77 | |
78 | for (i = q = a; q; q >>= 2) |
79 | i >>= 1; |
80 | |
81 | /* --- Do the main series iteration --- */ |
82 | |
83 | for (;;) { |
84 | q = i * i - a; |
85 | if (!q || (q < 0 && -q <= 2 * i)) |
86 | return (i); |
87 | q /= 2 * i; |
88 | if (!q) |
89 | i--; |
90 | else |
91 | i -= q; |
92 | } |
93 | } |
94 | |
95 | /*----- Main code ---------------------------------------------------------*/ |
96 | |
97 | /* --- @track@ --- * |
98 | * |
99 | * Arguments: @tcell *c@ = pointer to start cell |
100 | * @const char *p@ = string to match |
101 | * |
102 | * Returns: Nonzero for a match, zero if no match was found. |
103 | * |
104 | * Use: Searches for a match in a trackword. |
105 | */ |
106 | |
107 | static int track(tcell *c, const char *p) |
108 | { |
109 | int i; |
110 | |
111 | if (*p++ != c->ch) |
112 | return (0); |
113 | if (!*p) |
114 | return (1); |
115 | c->f = 1; |
116 | for (i = 0; i < NDIR; i++) { |
117 | if (!c->hop[i] || c->hop[i]->f) |
118 | continue; |
119 | if (track(c->hop[i], p)) { |
120 | c->f = 0; |
121 | return (1); |
122 | } |
123 | } |
124 | c->f = 0; |
125 | return (0); |
126 | } |
127 | |
128 | /* --- Node matcher --- */ |
129 | |
130 | static int n_track(node *nn, const char *p, size_t sz) |
131 | { |
132 | node_track *n = (node_track *)nn; |
133 | tcell *c; |
134 | |
135 | if (!*p) |
136 | return (1); |
137 | for (c = n->c; c->ch; c++) { |
138 | if (track(c, p)) |
139 | return (1); |
140 | } |
141 | return (0); |
142 | } |
143 | |
144 | /* --- Node creation --- */ |
145 | |
146 | node *trackword(const char *const *av) |
147 | { |
148 | node_track *n; |
149 | unsigned x, y; |
150 | unsigned i, j; |
151 | const char *p = av[0], *q, *l; |
152 | size_t sz = strlen(p); |
153 | tcell *c; |
154 | |
155 | /* --- Work out the dimensions --- */ |
156 | |
157 | x = strcspn(p, "/"); |
158 | if (!p[x]) { |
159 | x = isqrt(sz); |
160 | if (x * x != sz) |
161 | die("bad trackword `%s': not square, and no line markers", p); |
162 | y = x; |
163 | } |
164 | |
165 | if (!x) |
166 | die("bad trackword `%s': no columns", p); |
167 | |
168 | y = 0; |
169 | l = p + sz; |
170 | q = p; |
171 | for (;;) { |
172 | if (*q == '/') |
173 | q++; |
174 | if (!*q) |
175 | break; |
176 | if (l - q < x) |
177 | die("bad trackword `%s': inconsistent line lengths", p); |
178 | q += x; |
179 | y++; |
180 | } |
181 | |
182 | if (!y) |
183 | die("bad trackword `%s': no rows", p); |
184 | |
185 | /* --- Build the match node --- */ |
186 | |
187 | n = xmalloc(sizeof(*n)); |
188 | n->n.func = n_track; |
189 | n->x = x; n->y = y; |
190 | n->c = xmalloc((x * y + 1) * sizeof(tcell)); |
191 | |
192 | q = p; |
193 | c = n->c; |
194 | for (j = 0; j < y; j++) { |
195 | if (*q == '/') |
196 | q++; |
197 | for (i = 0; i < x; i++) { |
198 | c->ch = *q++; |
199 | c->f = 0; |
200 | |
201 | #define NOK (j > 0) |
202 | #define SOK (j < y - 1) |
203 | #define WOK (i > 0) |
204 | #define EOK (i < x - 1) |
205 | |
206 | c->hop[N] = NOK ? c - x : 0; |
207 | c->hop[S] = SOK ? c + x : 0; |
208 | c->hop[W] = WOK ? c - 1 : 0; |
209 | c->hop[E] = EOK ? c + 1 : 0; |
210 | |
211 | c->hop[NW] = NOK && WOK ? c - x - 1 : 0; |
212 | c->hop[NE] = NOK && EOK ? c - x + 1 : 0; |
213 | c->hop[SW] = SOK && WOK ? c + x - 1 : 0; |
214 | c->hop[SE] = SOK && EOK ? c + x + 1 : 0; |
215 | |
216 | #undef NOK |
217 | #undef SOK |
218 | #undef WOK |
219 | #undef EOK |
220 | |
221 | c++; |
222 | } |
223 | } |
224 | c->ch = 0; |
225 | |
226 | /* --- Done --- */ |
227 | |
228 | c = n->c; |
229 | for (j = 0; j < y; j++) { |
230 | for (i = 0; i < x; i++) { |
231 | printf("%c ", c->ch); |
232 | c++; |
233 | } |
234 | fputc('\n', stdout); |
235 | } |
236 | |
237 | return (&n->n); |
238 | } |
239 | |
240 | /*----- That's all, folks -------------------------------------------------*/ |