1 /* $NetBSD: operator.c,v 1.8 2003/08/07 11:13:43 agc 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93"; 39 #else 40 __RCSID("$NetBSD: operator.c,v 1.8 2003/08/07 11:13:43 agc Exp $"); 41 #endif 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 46 #include <err.h> 47 #include <fts.h> 48 #include <stdio.h> 49 50 #include "find.h" 51 52 static PLAN *yanknode __P((PLAN **)); 53 static PLAN *yankexpr __P((PLAN **)); 54 55 /* 56 * yanknode -- 57 * destructively removes the top from the plan 58 */ 59 static PLAN * 60 yanknode(planp) 61 PLAN **planp; /* pointer to top of plan (modified) */ 62 { 63 PLAN *node; /* top node removed from the plan */ 64 65 if ((node = (*planp)) == NULL) 66 return (NULL); 67 (*planp) = (*planp)->next; 68 node->next = NULL; 69 return (node); 70 } 71 72 /* 73 * yankexpr -- 74 * Removes one expression from the plan. This is used mainly by 75 * paren_squish. In comments below, an expression is either a 76 * simple node or a N_EXPR node containing a list of simple nodes. 77 */ 78 static PLAN * 79 yankexpr(planp) 80 PLAN **planp; /* pointer to top of plan (modified) */ 81 { 82 PLAN *next; /* temp node holding subexpression results */ 83 PLAN *node; /* pointer to returned node or expression */ 84 PLAN *tail; /* pointer to tail of subplan */ 85 PLAN *subplan; /* pointer to head of ( ) expression */ 86 87 /* first pull the top node from the plan */ 88 if ((node = yanknode(planp)) == NULL) 89 return (NULL); 90 91 /* 92 * If the node is an '(' then we recursively slurp up expressions 93 * until we find its associated ')'. If it's a closing paren we 94 * just return it and unwind our recursion; all other nodes are 95 * complete expressions, so just return them. 96 */ 97 if (node->type == N_OPENPAREN) 98 for (tail = subplan = NULL;;) { 99 if ((next = yankexpr(planp)) == NULL) 100 err(1, "(: missing closing ')'"); 101 /* 102 * If we find a closing ')' we store the collected 103 * subplan in our '(' node and convert the node to 104 * a N_EXPR. The ')' we found is ignored. Otherwise, 105 * we just continue to add whatever we get to our 106 * subplan. 107 */ 108 if (next->type == N_CLOSEPAREN) { 109 if (subplan == NULL) 110 errx(1, "(): empty inner expression"); 111 node->p_data[0] = subplan; 112 node->type = N_EXPR; 113 node->eval = f_expr; 114 break; 115 } else { 116 if (subplan == NULL) 117 tail = subplan = next; 118 else { 119 tail->next = next; 120 tail = next; 121 } 122 tail->next = NULL; 123 } 124 } 125 return (node); 126 } 127 128 /* 129 * paren_squish -- 130 * replaces "parentheisized" plans in our search plan with "expr" nodes. 131 */ 132 PLAN * 133 paren_squish(plan) 134 PLAN *plan; /* plan with ( ) nodes */ 135 { 136 PLAN *expr; /* pointer to next expression */ 137 PLAN *tail; /* pointer to tail of result plan */ 138 PLAN *result; /* pointer to head of result plan */ 139 140 result = tail = NULL; 141 142 /* 143 * the basic idea is to have yankexpr do all our work and just 144 * collect it's results together. 145 */ 146 while ((expr = yankexpr(&plan)) != NULL) { 147 /* 148 * if we find an unclaimed ')' it means there is a missing 149 * '(' someplace. 150 */ 151 if (expr->type == N_CLOSEPAREN) 152 errx(1, "): no beginning '('"); 153 154 /* add the expression to our result plan */ 155 if (result == NULL) 156 tail = result = expr; 157 else { 158 tail->next = expr; 159 tail = expr; 160 } 161 tail->next = NULL; 162 } 163 return (result); 164 } 165 166 /* 167 * not_squish -- 168 * compresses "!" expressions in our search plan. 169 */ 170 PLAN * 171 not_squish(plan) 172 PLAN *plan; /* plan to process */ 173 { 174 PLAN *next; /* next node being processed */ 175 PLAN *node; /* temporary node used in N_NOT processing */ 176 PLAN *tail; /* pointer to tail of result plan */ 177 PLAN *result; /* pointer to head of result plan */ 178 179 tail = result = next = NULL; 180 181 while ((next = yanknode(&plan)) != NULL) { 182 /* 183 * if we encounter a ( expression ) then look for nots in 184 * the expr subplan. 185 */ 186 if (next->type == N_EXPR) 187 next->p_data[0] = not_squish(next->p_data[0]); 188 189 /* 190 * if we encounter a not, then snag the next node and place 191 * it in the not's subplan. As an optimization we compress 192 * several not's to zero or one not. 193 */ 194 if (next->type == N_NOT) { 195 int notlevel = 1; 196 197 node = yanknode(&plan); 198 while (node != NULL && node->type == N_NOT) { 199 ++notlevel; 200 node = yanknode(&plan); 201 } 202 if (node == NULL) 203 errx(1, "!: no following expression"); 204 if (node->type == N_OR) 205 errx(1, "!: nothing between ! and -o"); 206 if (node->type == N_EXPR) 207 node = not_squish(node); 208 if (notlevel % 2 != 1) 209 next = node; 210 else 211 next->p_data[0] = node; 212 } 213 214 /* add the node to our result plan */ 215 if (result == NULL) 216 tail = result = next; 217 else { 218 tail->next = next; 219 tail = next; 220 } 221 tail->next = NULL; 222 } 223 return (result); 224 } 225 226 /* 227 * or_squish -- 228 * compresses -o expressions in our search plan. 229 */ 230 PLAN * 231 or_squish(plan) 232 PLAN *plan; /* plan with ors to be squished */ 233 { 234 PLAN *next; /* next node being processed */ 235 PLAN *tail; /* pointer to tail of result plan */ 236 PLAN *result; /* pointer to head of result plan */ 237 238 tail = result = next = NULL; 239 240 while ((next = yanknode(&plan)) != NULL) { 241 /* 242 * if we encounter a ( expression ) then look for or's in 243 * the expr subplan. 244 */ 245 if (next->type == N_EXPR) 246 next->p_data[0] = or_squish(next->p_data[0]); 247 248 /* if we encounter a not then look for not's in the subplan */ 249 if (next->type == N_NOT) 250 next->p_data[0] = or_squish(next->p_data[0]); 251 252 /* 253 * if we encounter an or, then place our collected plan in the 254 * or's first subplan and then recursively collect the 255 * remaining stuff into the second subplan and return the or. 256 */ 257 if (next->type == N_OR) { 258 if (result == NULL) 259 errx(1, "-o: no expression before -o"); 260 next->p_data[0] = result; 261 next->p_data[1] = or_squish(plan); 262 if (next->p_data[1] == NULL) 263 errx(1, "-o: no expression after -o"); 264 return (next); 265 } 266 267 /* add the node to our result plan */ 268 if (result == NULL) 269 tail = result = next; 270 else { 271 tail->next = next; 272 tail = next; 273 } 274 tail->next = NULL; 275 } 276 return (result); 277 } 278