3 * $Id: trackword.c,v 1.3 2001/02/07 09:08:44 mdw Exp $
7 * (c) 2001 Mark Wooding
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Anag: a simple wordgame helper.
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.
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.
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.
29 /*----- Revision history --------------------------------------------------*
31 * $Log: trackword.c,v $
32 * Revision 1.3 2001/02/07 09:08:44 mdw
33 * Optimize the graph by removing edges to non-matching cells. Make all of
34 * the graph links be contiguous so the main loop can give up earlier.
36 * Revision 1.2 2001/02/04 19:52:53 mdw
39 * Revision 1.1 2001/02/04 17:14:42 mdw
44 /*----- Header files ------------------------------------------------------*/
48 /*----- Data structures ---------------------------------------------------*/
52 typedef struct tcell {
53 struct tcell *hop[NDIR];
58 typedef struct node_track {
65 /*----- Utility functions -------------------------------------------------*/
69 * Arguments: @long a@ = the target value
71 * Returns: %$\lfloor \sqrt{a} \rfloor$%
73 * Use: Computes an integer square root. This algorithm is
74 * Newton-Raphson with integers. I've stolen this more-or-less
75 * wholesale fom the multiprecision integer square-root function
83 /* --- Initial guess is half the input length --- */
85 for (i = q = a; q; q >>= 2)
88 /* --- Do the main series iteration --- */
92 if (!q || (q < 0 && -q <= 2 * i))
102 /*----- Main code ---------------------------------------------------------*/
106 * Arguments: @tcell *c@ = pointer to start cell
107 * @const char *p@ = string to match
109 * Returns: Nonzero for a match, zero if no match was found.
111 * Use: Searches for a match in a trackword.
114 static int track(tcell *c, const char *p)
124 for (cc = c->hop; *cc; cc++) {
136 /* --- Node matcher --- */
138 static int n_track(node *nn, const char *p, size_t sz)
140 node_track *n = (node_track *)nn;
145 for (c = n->c; c->ch; c++) {
152 /* --- Node creation --- */
154 node *trackword(const char *const *av)
159 const char *p = av[0], *q, *l;
160 size_t sz = strlen(p);
161 tcell *c, **cc, **ccc;
163 /* --- Work out the dimensions --- */
169 die("bad trackword `%s': not square, and no line markers", p);
174 die("bad trackword `%s': no columns", p);
185 die("bad trackword `%s': inconsistent line lengths", p);
191 die("bad trackword `%s': no rows", p);
193 /* --- Build the match node --- */
195 n = xmalloc(sizeof(*n));
198 n->c = xmalloc((x * y + 1) * sizeof(tcell));
202 for (j = 0; j < y; j++) {
205 for (i = 0; i < x; i++) {
211 #define SOK (j < y - 1)
213 #define EOK (i < x - 1)
215 if (NOK) *cc++ = c - x;
216 if (SOK) *cc++ = c + x;
217 if (WOK) *cc++ = c - 1;
218 if (EOK) *cc++ = c + 1;
220 if (NOK && WOK) *cc++ = c - x - 1;
221 if (NOK && EOK) *cc++ = c - x + 1;
222 if (SOK && WOK) *cc++ = c + x - 1;
223 if (SOK && EOK) *cc++ = c + x + 1;
236 /* --- Now prune out bogus links --- */
238 for (c = n->c; c->ch; c++) {
240 for (cc = c->hop; *cc; cc++) {
241 if (isalpha((unsigned char)(*cc)->ch)) {
253 /*----- That's all, folks -------------------------------------------------*/