| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: trackword.c,v 1.2 2001/02/04 19:52:53 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 1.2 2001/02/04 19:52:53 mdw |
| 33 | * Remove debugging. |
| 34 | * |
| 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 | |
| 231 | return (&n->n); |
| 232 | } |
| 233 | |
| 234 | /*----- That's all, folks -------------------------------------------------*/ |