2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Cimarron D. Taylor of the University of California, Berkeley.
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11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
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36 static char sccsid[] = "@(#)operator.c 8.1 (Berkeley) 6/6/93";
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include <sys/types.h>
51 static PLAN *yanknode(PLAN **);
52 static PLAN *yankexpr(PLAN **);
56 * destructively removes the top from the plan
59 yanknode(PLAN **planp)
61 PLAN *node; /* top node removed from the plan */
63 if ((node = (*planp)) == NULL)
65 (*planp) = (*planp)->next;
72 * Removes one expression from the plan. This is used mainly by
73 * paren_squish. In comments below, an expression is either a
74 * simple node or a f_expr node containing a list of simple nodes.
77 yankexpr(PLAN **planp)
79 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 */
84 /* first pull the top node from the plan */
85 if ((node = yanknode(planp)) == NULL)
89 * If the node is an '(' then we recursively slurp up expressions
90 * until we find its associated ')'. If it's a closing paren we
91 * just return it and unwind our recursion; all other nodes are
92 * complete expressions, so just return them.
94 if (node->execute == f_openparen)
95 for (tail = subplan = NULL;;) {
96 if ((next = yankexpr(planp)) == NULL)
97 errx(1, "(: missing closing ')'");
99 * If we find a closing ')' we store the collected
100 * subplan in our '(' node and convert the node to
101 * a f_expr. The ')' we found is ignored. Otherwise,
102 * we just continue to add whatever we get to our
105 if (next->execute == f_closeparen) {
107 errx(1, "(): empty inner expression");
108 node->p_data[0] = subplan;
109 node->execute = f_expr;
113 tail = subplan = next;
126 * replaces "parenthesized" plans in our search plan with "expr" nodes.
129 paren_squish(PLAN *plan)
131 PLAN *expr; /* pointer to next expression */
132 PLAN *tail; /* pointer to tail of result plan */
133 PLAN *result; /* pointer to head of result plan */
135 result = tail = NULL;
138 * the basic idea is to have yankexpr do all our work and just
139 * collect its results together.
141 while ((expr = yankexpr(&plan)) != NULL) {
143 * if we find an unclaimed ')' it means there is a missing
146 if (expr->execute == f_closeparen)
147 errx(1, "): no beginning '('");
149 /* add the expression to our result plan */
151 tail = result = expr;
163 * compresses "!" expressions in our search plan.
166 not_squish(PLAN *plan)
168 PLAN *next; /* next node being processed */
169 PLAN *node; /* temporary node used in f_not processing */
170 PLAN *tail; /* pointer to tail of result plan */
171 PLAN *result; /* pointer to head of result plan */
173 tail = result = NULL;
175 while ((next = yanknode(&plan))) {
177 * if we encounter a ( expression ) then look for nots in
180 if (next->execute == f_expr)
181 next->p_data[0] = not_squish(next->p_data[0]);
184 * if we encounter a not, then snag the next node and place
185 * it in the not's subplan. As an optimization we compress
186 * several not's to zero or one not.
188 if (next->execute == f_not) {
191 node = yanknode(&plan);
192 while (node != NULL && node->execute == f_not) {
194 node = yanknode(&plan);
197 errx(1, "!: no following expression");
198 if (node->execute == f_or)
199 errx(1, "!: nothing between ! and -o");
201 * If we encounter ! ( expr ) then look for nots in
204 if (node->execute == f_expr)
205 node->p_data[0] = not_squish(node->p_data[0]);
206 if (notlevel % 2 != 1)
209 next->p_data[0] = node;
212 /* add the node to our result plan */
214 tail = result = next;
226 * compresses -o expressions in our search plan.
229 or_squish(PLAN *plan)
231 PLAN *next; /* next node being processed */
232 PLAN *tail; /* pointer to tail of result plan */
233 PLAN *result; /* pointer to head of result plan */
235 tail = result = next = NULL;
237 while ((next = yanknode(&plan)) != NULL) {
239 * if we encounter a ( expression ) then look for or's in
242 if (next->execute == f_expr)
243 next->p_data[0] = or_squish(next->p_data[0]);
245 /* if we encounter a not then look for or's in the subplan */
246 if (next->execute == f_not)
247 next->p_data[0] = or_squish(next->p_data[0]);
250 * if we encounter an or, then place our collected plan in the
251 * or's first subplan and then recursively collect the
252 * remaining stuff into the second subplan and return the or.
254 if (next->execute == f_or) {
256 errx(1, "-o: no expression before -o");
257 next->p_data[0] = result;
258 next->p_data[1] = or_squish(plan);
259 if (next->p_data[1] == NULL)
260 errx(1, "-o: no expression after -o");
264 /* add the node to our result plan */
266 tail = result = next;