1 /* $NetBSD: operator.c,v 1.7 1999/01/02 02:34:15 lukem Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Cimarron D. Taylor of the University of California, Berkeley. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93"; 43 #else 44 __RCSID("$NetBSD: operator.c,v 1.7 1999/01/02 02:34:15 lukem Exp $"); 45 #endif 46 #endif /* not lint */ 47 48 #include <sys/types.h> 49 50 #include <err.h> 51 #include <fts.h> 52 #include <stdio.h> 53 54 #include "find.h" 55 56 static PLAN *yanknode __P((PLAN **)); 57 static PLAN *yankexpr __P((PLAN **)); 58 59 /* 60 * yanknode -- 61 * destructively removes the top from the plan 62 */ 63 static PLAN * 64 yanknode(planp) 65 PLAN **planp; /* pointer to top of plan (modified) */ 66 { 67 PLAN *node; /* top node removed from the plan */ 68 69 if ((node = (*planp)) == NULL) 70 return (NULL); 71 (*planp) = (*planp)->next; 72 node->next = NULL; 73 return (node); 74 } 75 76 /* 77 * yankexpr -- 78 * Removes one expression from the plan. This is used mainly by 79 * paren_squish. In comments below, an expression is either a 80 * simple node or a N_EXPR node containing a list of simple nodes. 81 */ 82 static PLAN * 83 yankexpr(planp) 84 PLAN **planp; /* pointer to top of plan (modified) */ 85 { 86 PLAN *next; /* temp node holding subexpression results */ 87 PLAN *node; /* pointer to returned node or expression */ 88 PLAN *tail; /* pointer to tail of subplan */ 89 PLAN *subplan; /* pointer to head of ( ) expression */ 90 91 /* first pull the top node from the plan */ 92 if ((node = yanknode(planp)) == NULL) 93 return (NULL); 94 95 /* 96 * If the node is an '(' then we recursively slurp up expressions 97 * until we find its associated ')'. If it's a closing paren we 98 * just return it and unwind our recursion; all other nodes are 99 * complete expressions, so just return them. 100 */ 101 if (node->type == N_OPENPAREN) 102 for (tail = subplan = NULL;;) { 103 if ((next = yankexpr(planp)) == NULL) 104 err(1, "(: missing closing ')'"); 105 /* 106 * If we find a closing ')' we store the collected 107 * subplan in our '(' node and convert the node to 108 * a N_EXPR. The ')' we found is ignored. Otherwise, 109 * we just continue to add whatever we get to our 110 * subplan. 111 */ 112 if (next->type == N_CLOSEPAREN) { 113 if (subplan == NULL) 114 errx(1, "(): empty inner expression"); 115 node->p_data[0] = subplan; 116 node->type = N_EXPR; 117 node->eval = f_expr; 118 break; 119 } else { 120 if (subplan == NULL) 121 tail = subplan = next; 122 else { 123 tail->next = next; 124 tail = next; 125 } 126 tail->next = NULL; 127 } 128 } 129 return (node); 130 } 131 132 /* 133 * paren_squish -- 134 * replaces "parentheisized" plans in our search plan with "expr" nodes. 135 */ 136 PLAN * 137 paren_squish(plan) 138 PLAN *plan; /* plan with ( ) nodes */ 139 { 140 PLAN *expr; /* pointer to next expression */ 141 PLAN *tail; /* pointer to tail of result plan */ 142 PLAN *result; /* pointer to head of result plan */ 143 144 result = tail = NULL; 145 146 /* 147 * the basic idea is to have yankexpr do all our work and just 148 * collect it's results together. 149 */ 150 while ((expr = yankexpr(&plan)) != NULL) { 151 /* 152 * if we find an unclaimed ')' it means there is a missing 153 * '(' someplace. 154 */ 155 if (expr->type == N_CLOSEPAREN) 156 errx(1, "): no beginning '('"); 157 158 /* add the expression to our result plan */ 159 if (result == NULL) 160 tail = result = expr; 161 else { 162 tail->next = expr; 163 tail = expr; 164 } 165 tail->next = NULL; 166 } 167 return (result); 168 } 169 170 /* 171 * not_squish -- 172 * compresses "!" expressions in our search plan. 173 */ 174 PLAN * 175 not_squish(plan) 176 PLAN *plan; /* plan to process */ 177 { 178 PLAN *next; /* next node being processed */ 179 PLAN *node; /* temporary node used in N_NOT processing */ 180 PLAN *tail; /* pointer to tail of result plan */ 181 PLAN *result; /* pointer to head of result plan */ 182 183 tail = result = next = NULL; 184 185 while ((next = yanknode(&plan)) != NULL) { 186 /* 187 * if we encounter a ( expression ) then look for nots in 188 * the expr subplan. 189 */ 190 if (next->type == N_EXPR) 191 next->p_data[0] = not_squish(next->p_data[0]); 192 193 /* 194 * if we encounter a not, then snag the next node and place 195 * it in the not's subplan. As an optimization we compress 196 * several not's to zero or one not. 197 */ 198 if (next->type == N_NOT) { 199 int notlevel = 1; 200 201 node = yanknode(&plan); 202 while (node != NULL && node->type == N_NOT) { 203 ++notlevel; 204 node = yanknode(&plan); 205 } 206 if (node == NULL) 207 errx(1, "!: no following expression"); 208 if (node->type == N_OR) 209 errx(1, "!: nothing between ! and -o"); 210 if (node->type == N_EXPR) 211 node = not_squish(node); 212 if (notlevel % 2 != 1) 213 next = node; 214 else 215 next->p_data[0] = node; 216 } 217 218 /* add the node to our result plan */ 219 if (result == NULL) 220 tail = result = next; 221 else { 222 tail->next = next; 223 tail = next; 224 } 225 tail->next = NULL; 226 } 227 return (result); 228 } 229 230 /* 231 * or_squish -- 232 * compresses -o expressions in our search plan. 233 */ 234 PLAN * 235 or_squish(plan) 236 PLAN *plan; /* plan with ors to be squished */ 237 { 238 PLAN *next; /* next node being processed */ 239 PLAN *tail; /* pointer to tail of result plan */ 240 PLAN *result; /* pointer to head of result plan */ 241 242 tail = result = next = NULL; 243 244 while ((next = yanknode(&plan)) != NULL) { 245 /* 246 * if we encounter a ( expression ) then look for or's in 247 * the expr subplan. 248 */ 249 if (next->type == N_EXPR) 250 next->p_data[0] = or_squish(next->p_data[0]); 251 252 /* if we encounter a not then look for not's in the subplan */ 253 if (next->type == N_NOT) 254 next->p_data[0] = or_squish(next->p_data[0]); 255 256 /* 257 * if we encounter an or, then place our collected plan in the 258 * or's first subplan and then recursively collect the 259 * remaining stuff into the second subplan and return the or. 260 */ 261 if (next->type == N_OR) { 262 if (result == NULL) 263 errx(1, "-o: no expression before -o"); 264 next->p_data[0] = result; 265 next->p_data[1] = or_squish(plan); 266 if (next->p_data[1] == NULL) 267 errx(1, "-o: no expression after -o"); 268 return (next); 269 } 270 271 /* add the node to our result plan */ 272 if (result == NULL) 273 tail = result = next; 274 else { 275 tail->next = next; 276 tail = next; 277 } 278 tail->next = NULL; 279 } 280 return (result); 281 } 282