3 * $Id: trackword.c,v 1.2 2001/02/04 19:52:53 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 1.2 2001/02/04 19:52:53 mdw
35 * Revision 1.1 2001/02/04 17:14:42 mdw
40 /*----- Header files ------------------------------------------------------*/
44 /*----- Data structures ---------------------------------------------------*/
46 enum { N
, NE
, E
, SE
, S
, SW
, W
, NW
, NDIR
};
48 typedef struct tcell
{
49 struct tcell
*hop
[NDIR
];
54 typedef struct node_track
{
61 /*----- Utility functions -------------------------------------------------*/
65 * Arguments: @long a@ = the target value
67 * Returns: %$\lfloor \sqrt{a} \rfloor$%
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
79 /* --- Initial guess is half the input length --- */
81 for (i
= q
= a
; q
; q
>>= 2)
84 /* --- Do the main series iteration --- */
88 if (!q
|| (q
< 0 && -q
<= 2 * i
))
98 /*----- Main code ---------------------------------------------------------*/
102 * Arguments: @tcell *c@ = pointer to start cell
103 * @const char *p@ = string to match
105 * Returns: Nonzero for a match, zero if no match was found.
107 * Use: Searches for a match in a trackword.
110 static int track(tcell
*c
, const char *p
)
119 for (i
= 0; i
< NDIR
; i
++) {
120 if (!c
->hop
[i
] || c
->hop
[i
]->f
)
122 if (track(c
->hop
[i
], p
)) {
131 /* --- Node matcher --- */
133 static int n_track(node
*nn
, const char *p
, size_t sz
)
135 node_track
*n
= (node_track
*)nn
;
140 for (c
= n
->c
; c
->ch
; c
++) {
147 /* --- Node creation --- */
149 node
*trackword(const char *const *av
)
154 const char *p
= av
[0], *q
, *l
;
155 size_t sz
= strlen(p
);
158 /* --- Work out the dimensions --- */
164 die("bad trackword `%s': not square, and no line markers", p
);
169 die("bad trackword `%s': no columns", p
);
180 die("bad trackword `%s': inconsistent line lengths", p
);
186 die("bad trackword `%s': no rows", p
);
188 /* --- Build the match node --- */
190 n
= xmalloc(sizeof(*n
));
193 n
->c
= xmalloc((x
* y
+ 1) * sizeof(tcell
));
197 for (j
= 0; j
< y
; j
++) {
200 for (i
= 0; i
< x
; i
++) {
205 #define SOK (j < y - 1)
207 #define EOK (i < x - 1)
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;
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;
234 /*----- That's all, folks -------------------------------------------------*/