1 /* $NetBSD: operator.c,v 1.5 1997/10/19 11:52:55 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 1.5 1997/10/19 11:52:55 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 /* 57 * yanknode -- 58 * destructively removes the top from the plan 59 */ 60 static PLAN * 61 yanknode(planp) 62 PLAN **planp; /* pointer to top of plan (modified) */ 63 { 64 PLAN *node; /* top node removed from the plan */ 65 66 if ((node = (*planp)) == NULL) 67 return (NULL); 68 (*planp) = (*planp)->next; 69 node->next = NULL; 70 return (node); 71 } 72 73 /* 74 * yankexpr -- 75 * Removes one expression from the plan. This is used mainly by 76 * paren_squish. In comments below, an expression is either a 77 * simple node or a N_EXPR node containing a list of simple nodes. 78 */ 79 static PLAN * 80 yankexpr(planp) 81 PLAN **planp; /* pointer to top of plan (modified) */ 82 { 83 PLAN *next; /* temp node holding subexpression results */ 84 PLAN *node; /* pointer to returned node or expression */ 85 PLAN *tail; /* pointer to tail of subplan */ 86 PLAN *subplan; /* pointer to head of ( ) expression */ 87 88 /* first pull the top node from the plan */ 89 if ((node = yanknode(planp)) == NULL) 90 return (NULL); 91 92 /* 93 * If the node is an '(' then we recursively slurp up expressions 94 * until we find its associated ')'. If it's a closing paren we 95 * just return it and unwind our recursion; all other nodes are 96 * complete expressions, so just return them. 97 */ 98 if (node->type == N_OPENPAREN) 99 for (tail = subplan = NULL;;) { 100 if ((next = yankexpr(planp)) == NULL) 101 err(1, "(: missing closing ')'"); 102 /* 103 * If we find a closing ')' we store the collected 104 * subplan in our '(' node and convert the node to 105 * a N_EXPR. The ')' we found is ignored. Otherwise, 106 * we just continue to add whatever we get to our 107 * subplan. 108 */ 109 if (next->type == N_CLOSEPAREN) { 110 if (subplan == NULL) 111 errx(1, "(): empty inner expression"); 112 node->p_data[0] = subplan; 113 node->type = N_EXPR; 114 node->eval = f_expr; 115 break; 116 } else { 117 if (subplan == NULL) 118 tail = subplan = next; 119 else { 120 tail->next = next; 121 tail = next; 122 } 123 tail->next = NULL; 124 } 125 } 126 return (node); 127 } 128 129 /* 130 * paren_squish -- 131 * replaces "parentheisized" plans in our search plan with "expr" nodes. 132 */ 133 PLAN * 134 paren_squish(plan) 135 PLAN *plan; /* plan with ( ) nodes */ 136 { 137 PLAN *expr; /* pointer to next expression */ 138 PLAN *tail; /* pointer to tail of result plan */ 139 PLAN *result; /* pointer to head of result plan */ 140 141 result = tail = NULL; 142 143 /* 144 * the basic idea is to have yankexpr do all our work and just 145 * collect it's results together. 146 */ 147 while ((expr = yankexpr(&plan)) != NULL) { 148 /* 149 * if we find an unclaimed ')' it means there is a missing 150 * '(' someplace. 151 */ 152 if (expr->type == N_CLOSEPAREN) 153 errx(1, "): no beginning '('"); 154 155 /* add the expression to our result plan */ 156 if (result == NULL) 157 tail = result = expr; 158 else { 159 tail->next = expr; 160 tail = expr; 161 } 162 tail->next = NULL; 163 } 164 return (result); 165 } 166 167 /* 168 * not_squish -- 169 * compresses "!" expressions in our search plan. 170 */ 171 PLAN * 172 not_squish(plan) 173 PLAN *plan; /* plan to process */ 174 { 175 PLAN *next; /* next node being processed */ 176 PLAN *node; /* temporary node used in N_NOT processing */ 177 PLAN *tail; /* pointer to tail of result plan */ 178 PLAN *result; /* pointer to head of result plan */ 179 180 tail = result = next = NULL; 181 182 while ((next = yanknode(&plan)) != NULL) { 183 /* 184 * if we encounter a ( expression ) then look for nots in 185 * the expr subplan. 186 */ 187 if (next->type == N_EXPR) 188 next->p_data[0] = not_squish(next->p_data[0]); 189 190 /* 191 * if we encounter a not, then snag the next node and place 192 * it in the not's subplan. As an optimization we compress 193 * several not's to zero or one not. 194 */ 195 if (next->type == N_NOT) { 196 int notlevel = 1; 197 198 node = yanknode(&plan); 199 while (node->type == N_NOT) { 200 ++notlevel; 201 node = yanknode(&plan); 202 } 203 if (node == NULL) 204 errx(1, "!: no following expression"); 205 if (node->type == N_OR) 206 errx(1, "!: nothing between ! and -o"); 207 if (notlevel % 2 != 1) 208 next = node; 209 else 210 next->p_data[0] = node; 211 } 212 213 /* add the node to our result plan */ 214 if (result == NULL) 215 tail = result = next; 216 else { 217 tail->next = next; 218 tail = next; 219 } 220 tail->next = NULL; 221 } 222 return (result); 223 } 224 225 /* 226 * or_squish -- 227 * compresses -o expressions in our search plan. 228 */ 229 PLAN * 230 or_squish(plan) 231 PLAN *plan; /* plan with ors to be squished */ 232 { 233 PLAN *next; /* next node being processed */ 234 PLAN *tail; /* pointer to tail of result plan */ 235 PLAN *result; /* pointer to head of result plan */ 236 237 tail = result = next = NULL; 238 239 while ((next = yanknode(&plan)) != NULL) { 240 /* 241 * if we encounter a ( expression ) then look for or's in 242 * the expr subplan. 243 */ 244 if (next->type == N_EXPR) 245 next->p_data[0] = or_squish(next->p_data[0]); 246 247 /* if we encounter a not then look for not's in the subplan */ 248 if (next->type == N_NOT) 249 next->p_data[0] = or_squish(next->p_data[0]); 250 251 /* 252 * if we encounter an or, then place our collected plan in the 253 * or's first subplan and then recursively collect the 254 * remaining stuff into the second subplan and return the or. 255 */ 256 if (next->type == N_OR) { 257 if (result == NULL) 258 errx(1, "-o: no expression before -o"); 259 next->p_data[0] = result; 260 next->p_data[1] = or_squish(plan); 261 if (next->p_data[1] == NULL) 262 errx(1, "-o: no expression after -o"); 263 return (next); 264 } 265 266 /* add the node to our result plan */ 267 if (result == NULL) 268 tail = result = next; 269 else { 270 tail->next = next; 271 tail = next; 272 } 273 tail->next = NULL; 274 } 275 return (result); 276 } 277