operator.c revision 1591
1/*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Cimarron D. Taylor of the University of California, Berkeley. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#ifndef lint 38static char sccsid[] = "@(#)operator.c 8.1 (Berkeley) 6/6/93"; 39#endif /* not lint */ 40 41#include <sys/types.h> 42 43#include <err.h> 44#include <fts.h> 45#include <stdio.h> 46 47#include "find.h" 48 49/* 50 * yanknode -- 51 * destructively removes the top from the plan 52 */ 53static PLAN * 54yanknode(planp) 55 PLAN **planp; /* pointer to top of plan (modified) */ 56{ 57 PLAN *node; /* top node removed from the plan */ 58 59 if ((node = (*planp)) == NULL) 60 return (NULL); 61 (*planp) = (*planp)->next; 62 node->next = NULL; 63 return (node); 64} 65 66/* 67 * yankexpr -- 68 * Removes one expression from the plan. This is used mainly by 69 * paren_squish. In comments below, an expression is either a 70 * simple node or a N_EXPR node containing a list of simple nodes. 71 */ 72static PLAN * 73yankexpr(planp) 74 PLAN **planp; /* pointer to top of plan (modified) */ 75{ 76 register PLAN *next; /* temp node holding subexpression results */ 77 PLAN *node; /* pointer to returned node or expression */ 78 PLAN *tail; /* pointer to tail of subplan */ 79 PLAN *subplan; /* pointer to head of ( ) expression */ 80 int f_expr(); 81 82 /* first pull the top node from the plan */ 83 if ((node = yanknode(planp)) == NULL) 84 return (NULL); 85 86 /* 87 * If the node is an '(' then we recursively slurp up expressions 88 * until we find its associated ')'. If it's a closing paren we 89 * just return it and unwind our recursion; all other nodes are 90 * complete expressions, so just return them. 91 */ 92 if (node->type == N_OPENPAREN) 93 for (tail = subplan = NULL;;) { 94 if ((next = yankexpr(planp)) == NULL) 95 err(1, "(: missing closing ')'"); 96 /* 97 * If we find a closing ')' we store the collected 98 * subplan in our '(' node and convert the node to 99 * a N_EXPR. The ')' we found is ignored. Otherwise, 100 * we just continue to add whatever we get to our 101 * subplan. 102 */ 103 if (next->type == N_CLOSEPAREN) { 104 if (subplan == NULL) 105 errx(1, "(): empty inner expression"); 106 node->p_data[0] = subplan; 107 node->type = N_EXPR; 108 node->eval = f_expr; 109 break; 110 } else { 111 if (subplan == NULL) 112 tail = subplan = next; 113 else { 114 tail->next = next; 115 tail = next; 116 } 117 tail->next = NULL; 118 } 119 } 120 return (node); 121} 122 123/* 124 * paren_squish -- 125 * replaces "parentheisized" plans in our search plan with "expr" nodes. 126 */ 127PLAN * 128paren_squish(plan) 129 PLAN *plan; /* plan with ( ) nodes */ 130{ 131 register PLAN *expr; /* pointer to next expression */ 132 register PLAN *tail; /* pointer to tail of result plan */ 133 PLAN *result; /* pointer to head of result plan */ 134 135 result = tail = NULL; 136 137 /* 138 * the basic idea is to have yankexpr do all our work and just 139 * collect it's results together. 140 */ 141 while ((expr = yankexpr(&plan)) != NULL) { 142 /* 143 * if we find an unclaimed ')' it means there is a missing 144 * '(' someplace. 145 */ 146 if (expr->type == N_CLOSEPAREN) 147 errx(1, "): no beginning '('"); 148 149 /* add the expression to our result plan */ 150 if (result == NULL) 151 tail = result = expr; 152 else { 153 tail->next = expr; 154 tail = expr; 155 } 156 tail->next = NULL; 157 } 158 return (result); 159} 160 161/* 162 * not_squish -- 163 * compresses "!" expressions in our search plan. 164 */ 165PLAN * 166not_squish(plan) 167 PLAN *plan; /* plan to process */ 168{ 169 register PLAN *next; /* next node being processed */ 170 register PLAN *node; /* temporary node used in N_NOT processing */ 171 register PLAN *tail; /* pointer to tail of result plan */ 172 PLAN *result; /* pointer to head of result plan */ 173 174 tail = result = next = NULL; 175 176 while ((next = yanknode(&plan)) != NULL) { 177 /* 178 * if we encounter a ( expression ) then look for nots in 179 * the expr subplan. 180 */ 181 if (next->type == N_EXPR) 182 next->p_data[0] = not_squish(next->p_data[0]); 183 184 /* 185 * if we encounter a not, then snag the next node and place 186 * it in the not's subplan. As an optimization we compress 187 * several not's to zero or one not. 188 */ 189 if (next->type == N_NOT) { 190 int notlevel = 1; 191 192 node = yanknode(&plan); 193 while (node->type == N_NOT) { 194 ++notlevel; 195 node = yanknode(&plan); 196 } 197 if (node == NULL) 198 errx(1, "!: no following expression"); 199 if (node->type == N_OR) 200 errx(1, "!: nothing between ! and -o"); 201 if (notlevel % 2 != 1) 202 next = node; 203 else 204 next->p_data[0] = node; 205 } 206 207 /* add the node to our result plan */ 208 if (result == NULL) 209 tail = result = next; 210 else { 211 tail->next = next; 212 tail = next; 213 } 214 tail->next = NULL; 215 } 216 return (result); 217} 218 219/* 220 * or_squish -- 221 * compresses -o expressions in our search plan. 222 */ 223PLAN * 224or_squish(plan) 225 PLAN *plan; /* plan with ors to be squished */ 226{ 227 register PLAN *next; /* next node being processed */ 228 register PLAN *tail; /* pointer to tail of result plan */ 229 PLAN *result; /* pointer to head of result plan */ 230 231 tail = result = next = NULL; 232 233 while ((next = yanknode(&plan)) != NULL) { 234 /* 235 * if we encounter a ( expression ) then look for or's in 236 * the expr subplan. 237 */ 238 if (next->type == N_EXPR) 239 next->p_data[0] = or_squish(next->p_data[0]); 240 241 /* if we encounter a not then look for not's in the subplan */ 242 if (next->type == N_NOT) 243 next->p_data[0] = or_squish(next->p_data[0]); 244 245 /* 246 * if we encounter an or, then place our collected plan in the 247 * or's first subplan and then recursively collect the 248 * remaining stuff into the second subplan and return the or. 249 */ 250 if (next->type == N_OR) { 251 if (result == NULL) 252 errx(1, "-o: no expression before -o"); 253 next->p_data[0] = result; 254 next->p_data[1] = or_squish(plan); 255 if (next->p_data[1] == NULL) 256 errx(1, "-o: no expression after -o"); 257 return (next); 258 } 259 260 /* add the node to our result plan */ 261 if (result == NULL) 262 tail = result = next; 263 else { 264 tail->next = next; 265 tail = next; 266 } 267 tail->next = NULL; 268 } 269 return (result); 270} 271