1 /* $NetBSD: operator.c,v 1.4 1997/01/09 20:19:15 tls 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 #ifndef lint 40 /*static char sccsid[] = "from: @(#)operator.c 8.1 (Berkeley) 6/6/93";*/ 41 static char rcsid[] = "$NetBSD: operator.c,v 1.4 1997/01/09 20:19:15 tls Exp $"; 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 /* 53 * yanknode -- 54 * destructively removes the top from the plan 55 */ 56 static PLAN * 57 yanknode(planp) 58 PLAN **planp; /* pointer to top of plan (modified) */ 59 { 60 PLAN *node; /* top node removed from the plan */ 61 62 if ((node = (*planp)) == NULL) 63 return (NULL); 64 (*planp) = (*planp)->next; 65 node->next = NULL; 66 return (node); 67 } 68 69 /* 70 * yankexpr -- 71 * Removes one expression from the plan. This is used mainly by 72 * paren_squish. In comments below, an expression is either a 73 * simple node or a N_EXPR node containing a list of simple nodes. 74 */ 75 static PLAN * 76 yankexpr(planp) 77 PLAN **planp; /* pointer to top of plan (modified) */ 78 { 79 register PLAN *next; /* temp node holding subexpression results */ 80 PLAN *node; /* pointer to returned node or expression */ 81 PLAN *tail; /* pointer to tail of subplan */ 82 PLAN *subplan; /* pointer to head of ( ) expression */ 83 int f_expr(); 84 85 /* first pull the top node from the plan */ 86 if ((node = yanknode(planp)) == NULL) 87 return (NULL); 88 89 /* 90 * If the node is an '(' then we recursively slurp up expressions 91 * until we find its associated ')'. If it's a closing paren we 92 * just return it and unwind our recursion; all other nodes are 93 * complete expressions, so just return them. 94 */ 95 if (node->type == N_OPENPAREN) 96 for (tail = subplan = NULL;;) { 97 if ((next = yankexpr(planp)) == NULL) 98 err(1, "(: missing closing ')'"); 99 /* 100 * If we find a closing ')' we store the collected 101 * subplan in our '(' node and convert the node to 102 * a N_EXPR. The ')' we found is ignored. Otherwise, 103 * we just continue to add whatever we get to our 104 * subplan. 105 */ 106 if (next->type == N_CLOSEPAREN) { 107 if (subplan == NULL) 108 errx(1, "(): empty inner expression"); 109 node->p_data[0] = subplan; 110 node->type = N_EXPR; 111 node->eval = f_expr; 112 break; 113 } else { 114 if (subplan == NULL) 115 tail = subplan = next; 116 else { 117 tail->next = next; 118 tail = next; 119 } 120 tail->next = NULL; 121 } 122 } 123 return (node); 124 } 125 126 /* 127 * paren_squish -- 128 * replaces "parentheisized" plans in our search plan with "expr" nodes. 129 */ 130 PLAN * 131 paren_squish(plan) 132 PLAN *plan; /* plan with ( ) nodes */ 133 { 134 register PLAN *expr; /* pointer to next expression */ 135 register PLAN *tail; /* pointer to tail of result plan */ 136 PLAN *result; /* pointer to head of result plan */ 137 138 result = tail = NULL; 139 140 /* 141 * the basic idea is to have yankexpr do all our work and just 142 * collect it's results together. 143 */ 144 while ((expr = yankexpr(&plan)) != NULL) { 145 /* 146 * if we find an unclaimed ')' it means there is a missing 147 * '(' someplace. 148 */ 149 if (expr->type == N_CLOSEPAREN) 150 errx(1, "): no beginning '('"); 151 152 /* add the expression to our result plan */ 153 if (result == NULL) 154 tail = result = expr; 155 else { 156 tail->next = expr; 157 tail = expr; 158 } 159 tail->next = NULL; 160 } 161 return (result); 162 } 163 164 /* 165 * not_squish -- 166 * compresses "!" expressions in our search plan. 167 */ 168 PLAN * 169 not_squish(plan) 170 PLAN *plan; /* plan to process */ 171 { 172 register PLAN *next; /* next node being processed */ 173 register PLAN *node; /* temporary node used in N_NOT processing */ 174 register PLAN *tail; /* pointer to tail of result plan */ 175 PLAN *result; /* pointer to head of result plan */ 176 177 tail = result = next = NULL; 178 179 while ((next = yanknode(&plan)) != NULL) { 180 /* 181 * if we encounter a ( expression ) then look for nots in 182 * the expr subplan. 183 */ 184 if (next->type == N_EXPR) 185 next->p_data[0] = not_squish(next->p_data[0]); 186 187 /* 188 * if we encounter a not, then snag the next node and place 189 * it in the not's subplan. As an optimization we compress 190 * several not's to zero or one not. 191 */ 192 if (next->type == N_NOT) { 193 int notlevel = 1; 194 195 node = yanknode(&plan); 196 while (node->type == N_NOT) { 197 ++notlevel; 198 node = yanknode(&plan); 199 } 200 if (node == NULL) 201 errx(1, "!: no following expression"); 202 if (node->type == N_OR) 203 errx(1, "!: nothing between ! and -o"); 204 if (notlevel % 2 != 1) 205 next = node; 206 else 207 next->p_data[0] = node; 208 } 209 210 /* add the node to our result plan */ 211 if (result == NULL) 212 tail = result = next; 213 else { 214 tail->next = next; 215 tail = next; 216 } 217 tail->next = NULL; 218 } 219 return (result); 220 } 221 222 /* 223 * or_squish -- 224 * compresses -o expressions in our search plan. 225 */ 226 PLAN * 227 or_squish(plan) 228 PLAN *plan; /* plan with ors to be squished */ 229 { 230 register PLAN *next; /* next node being processed */ 231 register PLAN *tail; /* pointer to tail of result plan */ 232 PLAN *result; /* pointer to head of result plan */ 233 234 tail = result = next = NULL; 235 236 while ((next = yanknode(&plan)) != NULL) { 237 /* 238 * if we encounter a ( expression ) then look for or's in 239 * the expr subplan. 240 */ 241 if (next->type == N_EXPR) 242 next->p_data[0] = or_squish(next->p_data[0]); 243 244 /* if we encounter a not then look for not's in the subplan */ 245 if (next->type == N_NOT) 246 next->p_data[0] = or_squish(next->p_data[0]); 247 248 /* 249 * if we encounter an or, then place our collected plan in the 250 * or's first subplan and then recursively collect the 251 * remaining stuff into the second subplan and return the or. 252 */ 253 if (next->type == N_OR) { 254 if (result == NULL) 255 errx(1, "-o: no expression before -o"); 256 next->p_data[0] = result; 257 next->p_data[1] = or_squish(plan); 258 if (next->p_data[1] == NULL) 259 errx(1, "-o: no expression after -o"); 260 return (next); 261 } 262 263 /* add the node to our result plan */ 264 if (result == NULL) 265 tail = result = next; 266 else { 267 tail->next = next; 268 tail = next; 269 } 270 tail->next = NULL; 271 } 272 return (result); 273 } 274