6e403221 |
1 | /* -*-c-*- |
6e403221 |
2 | * |
3 | * Matches trackwords |
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 | |
c088671a |
33 | #define NDIR 9 |
6e403221 |
34 | |
35 | typedef struct tcell { |
36 | struct tcell *hop[NDIR]; |
37 | char ch; |
38 | unsigned char f; |
39 | } tcell; |
40 | |
41 | typedef struct node_track { |
42 | node n; |
43 | unsigned x; |
44 | unsigned y; |
45 | tcell *c; |
46 | } node_track; |
47 | |
48 | /*----- Utility functions -------------------------------------------------*/ |
49 | |
50 | /* --- @isqrt@ --- * |
51 | * |
52 | * Arguments: @long a@ = the target value |
53 | * |
54 | * Returns: %$\lfloor \sqrt{a} \rfloor$% |
55 | * |
56 | * Use: Computes an integer square root. This algorithm is |
57 | * Newton-Raphson with integers. I've stolen this more-or-less |
58 | * wholesale fom the multiprecision integer square-root function |
59 | * in Catacomb. |
60 | */ |
61 | |
62 | long isqrt(long a) |
63 | { |
64 | long i, q; |
65 | |
66 | /* --- Initial guess is half the input length --- */ |
67 | |
68 | for (i = q = a; q; q >>= 2) |
69 | i >>= 1; |
70 | |
71 | /* --- Do the main series iteration --- */ |
72 | |
73 | for (;;) { |
74 | q = i * i - a; |
75 | if (!q || (q < 0 && -q <= 2 * i)) |
76 | return (i); |
77 | q /= 2 * i; |
78 | if (!q) |
79 | i--; |
80 | else |
81 | i -= q; |
82 | } |
83 | } |
84 | |
85 | /*----- Main code ---------------------------------------------------------*/ |
86 | |
87 | /* --- @track@ --- * |
88 | * |
89 | * Arguments: @tcell *c@ = pointer to start cell |
90 | * @const char *p@ = string to match |
91 | * |
92 | * Returns: Nonzero for a match, zero if no match was found. |
93 | * |
94 | * Use: Searches for a match in a trackword. |
95 | */ |
96 | |
97 | static int track(tcell *c, const char *p) |
98 | { |
c088671a |
99 | tcell **cc; |
6e403221 |
100 | |
101 | if (*p++ != c->ch) |
102 | return (0); |
103 | if (!*p) |
104 | return (1); |
105 | c->f = 1; |
c088671a |
106 | |
107 | for (cc = c->hop; *cc; cc++) { |
108 | if ((*cc)->f) |
6e403221 |
109 | continue; |
c088671a |
110 | if (track(*cc, p)) { |
6e403221 |
111 | c->f = 0; |
112 | return (1); |
113 | } |
114 | } |
115 | c->f = 0; |
116 | return (0); |
117 | } |
118 | |
119 | /* --- Node matcher --- */ |
120 | |
121 | static int n_track(node *nn, const char *p, size_t sz) |
122 | { |
123 | node_track *n = (node_track *)nn; |
124 | tcell *c; |
125 | |
126 | if (!*p) |
127 | return (1); |
128 | for (c = n->c; c->ch; c++) { |
129 | if (track(c, p)) |
130 | return (1); |
131 | } |
132 | return (0); |
133 | } |
134 | |
135 | /* --- Node creation --- */ |
136 | |
137 | node *trackword(const char *const *av) |
138 | { |
139 | node_track *n; |
140 | unsigned x, y; |
141 | unsigned i, j; |
142 | const char *p = av[0], *q, *l; |
143 | size_t sz = strlen(p); |
c088671a |
144 | tcell *c, **cc, **ccc; |
6e403221 |
145 | |
146 | /* --- Work out the dimensions --- */ |
147 | |
148 | x = strcspn(p, "/"); |
149 | if (!p[x]) { |
150 | x = isqrt(sz); |
151 | if (x * x != sz) |
152 | die("bad trackword `%s': not square, and no line markers", p); |
153 | y = x; |
154 | } |
155 | |
156 | if (!x) |
157 | die("bad trackword `%s': no columns", p); |
158 | |
159 | y = 0; |
160 | l = p + sz; |
161 | q = p; |
162 | for (;;) { |
163 | if (*q == '/') |
164 | q++; |
165 | if (!*q) |
166 | break; |
167 | if (l - q < x) |
168 | die("bad trackword `%s': inconsistent line lengths", p); |
169 | q += x; |
170 | y++; |
171 | } |
172 | |
173 | if (!y) |
174 | die("bad trackword `%s': no rows", p); |
175 | |
176 | /* --- Build the match node --- */ |
177 | |
178 | n = xmalloc(sizeof(*n)); |
179 | n->n.func = n_track; |
180 | n->x = x; n->y = y; |
181 | n->c = xmalloc((x * y + 1) * sizeof(tcell)); |
182 | |
183 | q = p; |
184 | c = n->c; |
185 | for (j = 0; j < y; j++) { |
186 | if (*q == '/') |
187 | q++; |
188 | for (i = 0; i < x; i++) { |
189 | c->ch = *q++; |
190 | c->f = 0; |
c088671a |
191 | cc = c->hop; |
6e403221 |
192 | |
193 | #define NOK (j > 0) |
194 | #define SOK (j < y - 1) |
195 | #define WOK (i > 0) |
196 | #define EOK (i < x - 1) |
197 | |
c088671a |
198 | if (NOK) *cc++ = c - x; |
199 | if (SOK) *cc++ = c + x; |
200 | if (WOK) *cc++ = c - 1; |
201 | if (EOK) *cc++ = c + 1; |
6e403221 |
202 | |
c088671a |
203 | if (NOK && WOK) *cc++ = c - x - 1; |
204 | if (NOK && EOK) *cc++ = c - x + 1; |
205 | if (SOK && WOK) *cc++ = c + x - 1; |
206 | if (SOK && EOK) *cc++ = c + x + 1; |
6e403221 |
207 | |
208 | #undef NOK |
209 | #undef SOK |
210 | #undef WOK |
211 | #undef EOK |
212 | |
c088671a |
213 | *cc++ = 0; |
6e403221 |
214 | c++; |
215 | } |
216 | } |
217 | c->ch = 0; |
218 | |
c088671a |
219 | /* --- Now prune out bogus links --- */ |
220 | |
221 | for (c = n->c; c->ch; c++) { |
222 | ccc = c->hop; |
223 | for (cc = c->hop; *cc; cc++) { |
224 | if (isalpha((unsigned char)(*cc)->ch)) { |
225 | *ccc++ = *cc; |
226 | } |
227 | } |
228 | *ccc++ = 0; |
229 | } |
230 | |
6e403221 |
231 | /* --- Done --- */ |
232 | |
6e403221 |
233 | return (&n->n); |
234 | } |
235 | |
236 | /*----- That's all, folks -------------------------------------------------*/ |