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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37 static char sccsid[] = "@(#)operator.c 8.1 (Berkeley) 6/6/93";
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
44 #include <sys/types.h>
53 static PLAN *yanknode(PLAN **);
54 static PLAN *yankexpr(PLAN **);
58 * destructively removes the top from the plan
61 yanknode(PLAN **planp)
63 PLAN *node; /* top node removed from the plan */
65 if ((node = (*planp)) == NULL)
67 (*planp) = (*planp)->next;
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 f_expr node containing a list of simple nodes.
79 yankexpr(PLAN **planp)
81 PLAN *next; /* temp node holding subexpression results */
82 PLAN *node; /* pointer to returned node or expression */
83 PLAN *tail; /* pointer to tail of subplan */
84 PLAN *subplan; /* pointer to head of ( ) expression */
86 /* first pull the top node from the plan */
87 if ((node = yanknode(planp)) == NULL)
91 * If the node is an '(' then we recursively slurp up expressions
92 * until we find its associated ')'. If it's a closing paren we
93 * just return it and unwind our recursion; all other nodes are
94 * complete expressions, so just return them.
96 if (node->execute == f_openparen)
97 for (tail = subplan = NULL;;) {
98 if ((next = yankexpr(planp)) == NULL)
99 errx(1, "(: missing closing ')'");
101 * If we find a closing ')' we store the collected
102 * subplan in our '(' node and convert the node to
103 * a f_expr. The ')' we found is ignored. Otherwise,
104 * we just continue to add whatever we get to our
107 if (next->execute == f_closeparen) {
109 errx(1, "(): empty inner expression");
110 node->p_data[0] = subplan;
111 node->execute = f_expr;
115 tail = subplan = next;
128 * replaces "parenthesized" plans in our search plan with "expr" nodes.
131 paren_squish(PLAN *plan)
133 PLAN *expr; /* pointer to next expression */
134 PLAN *tail; /* pointer to tail of result plan */
135 PLAN *result; /* pointer to head of result plan */
137 result = tail = NULL;
140 * the basic idea is to have yankexpr do all our work and just
141 * collect its results together.
143 while ((expr = yankexpr(&plan)) != NULL) {
145 * if we find an unclaimed ')' it means there is a missing
148 if (expr->execute == f_closeparen)
149 errx(1, "): no beginning '('");
151 /* add the expression to our result plan */
153 tail = result = expr;
165 * compresses "!" expressions in our search plan.
168 not_squish(PLAN *plan)
170 PLAN *next; /* next node being processed */
171 PLAN *node; /* temporary node used in f_not processing */
172 PLAN *tail; /* pointer to tail of result plan */
173 PLAN *result; /* pointer to head of result plan */
175 tail = result = NULL;
177 while ((next = yanknode(&plan))) {
179 * if we encounter a ( expression ) then look for nots in
182 if (next->execute == f_expr)
183 next->p_data[0] = not_squish(next->p_data[0]);
186 * if we encounter a not, then snag the next node and place
187 * it in the not's subplan. As an optimization we compress
188 * several not's to zero or one not.
190 if (next->execute == f_not) {
193 node = yanknode(&plan);
194 while (node != NULL && node->execute == f_not) {
196 node = yanknode(&plan);
199 errx(1, "!: no following expression");
200 if (node->execute == f_or)
201 errx(1, "!: nothing between ! and -o");
203 * If we encounter ! ( expr ) then look for nots in
206 if (node->execute == f_expr)
207 node->p_data[0] = not_squish(node->p_data[0]);
208 if (notlevel % 2 != 1)
211 next->p_data[0] = node;
214 /* add the node to our result plan */
216 tail = result = next;
228 * compresses -o expressions in our search plan.
231 or_squish(PLAN *plan)
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 */
237 tail = result = next = NULL;
239 while ((next = yanknode(&plan)) != NULL) {
241 * if we encounter a ( expression ) then look for or's in
244 if (next->execute == f_expr)
245 next->p_data[0] = or_squish(next->p_data[0]);
247 /* if we encounter a not then look for or's in the subplan */
248 if (next->execute == f_not)
249 next->p_data[0] = or_squish(next->p_data[0]);
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.
256 if (next->execute == f_or) {
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");
266 /* add the node to our result plan */
268 tail = result = next;