2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Cimarron D. Taylor of the University of California, Berkeley.
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9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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15 * documentation and/or other materials provided with the distribution.
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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.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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39 static char sccsid[] = "@(#)operator.c 8.1 (Berkeley) 6/6/93";
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
46 #include <sys/types.h>
54 static PLAN *yanknode(PLAN **);
55 static PLAN *yankexpr(PLAN **);
59 * destructively removes the top from the plan
62 yanknode(PLAN **planp)
64 PLAN *node; /* top node removed from the plan */
66 if ((node = (*planp)) == NULL)
68 (*planp) = (*planp)->next;
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 f_expr node containing a list of simple nodes.
80 yankexpr(PLAN **planp)
82 PLAN *next; /* temp node holding subexpression results */
83 PLAN *node; /* pointer to returned node or expression */
84 PLAN *tail; /* pointer to tail of subplan */
85 PLAN *subplan; /* pointer to head of ( ) expression */
87 /* first pull the top node from the plan */
88 if ((node = yanknode(planp)) == NULL)
92 * If the node is an '(' then we recursively slurp up expressions
93 * until we find its associated ')'. If it's a closing paren we
94 * just return it and unwind our recursion; all other nodes are
95 * complete expressions, so just return them.
97 if (node->execute == f_openparen)
98 for (tail = subplan = NULL;;) {
99 if ((next = yankexpr(planp)) == NULL)
100 errx(1, "(: missing closing ')'");
102 * If we find a closing ')' we store the collected
103 * subplan in our '(' node and convert the node to
104 * a f_expr. The ')' we found is ignored. Otherwise,
105 * we just continue to add whatever we get to our
108 if (next->execute == f_closeparen) {
110 errx(1, "(): empty inner expression");
111 node->p_data[0] = subplan;
112 node->execute = f_expr;
116 tail = subplan = next;
129 * replaces "parenthesized" plans in our search plan with "expr" nodes.
132 paren_squish(PLAN *plan)
134 PLAN *expr; /* pointer to next expression */
135 PLAN *tail; /* pointer to tail of result plan */
136 PLAN *result; /* pointer to head of result plan */
138 result = tail = NULL;
141 * the basic idea is to have yankexpr do all our work and just
142 * collect its results together.
144 while ((expr = yankexpr(&plan)) != NULL) {
146 * if we find an unclaimed ')' it means there is a missing
149 if (expr->execute == f_closeparen)
150 errx(1, "): no beginning '('");
152 /* add the expression to our result plan */
154 tail = result = expr;
166 * compresses "!" expressions in our search plan.
169 not_squish(PLAN *plan)
171 PLAN *next; /* next node being processed */
172 PLAN *node; /* temporary node used in f_not processing */
173 PLAN *tail; /* pointer to tail of result plan */
174 PLAN *result; /* pointer to head of result plan */
176 tail = result = NULL;
178 while ((next = yanknode(&plan))) {
180 * if we encounter a ( expression ) then look for nots in
183 if (next->execute == f_expr)
184 next->p_data[0] = not_squish(next->p_data[0]);
187 * if we encounter a not, then snag the next node and place
188 * it in the not's subplan. As an optimization we compress
189 * several not's to zero or one not.
191 if (next->execute == f_not) {
194 node = yanknode(&plan);
195 while (node != NULL && node->execute == f_not) {
197 node = yanknode(&plan);
200 errx(1, "!: no following expression");
201 if (node->execute == f_or)
202 errx(1, "!: nothing between ! and -o");
204 * If we encounter ! ( expr ) then look for nots in
207 if (node->execute == f_expr)
208 node->p_data[0] = not_squish(node->p_data[0]);
209 if (notlevel % 2 != 1)
212 next->p_data[0] = node;
215 /* add the node to our result plan */
217 tail = result = next;
229 * compresses -o expressions in our search plan.
232 or_squish(PLAN *plan)
234 PLAN *next; /* next node being processed */
235 PLAN *tail; /* pointer to tail of result plan */
236 PLAN *result; /* pointer to head of result plan */
238 tail = result = next = NULL;
240 while ((next = yanknode(&plan)) != NULL) {
242 * if we encounter a ( expression ) then look for or's in
245 if (next->execute == f_expr)
246 next->p_data[0] = or_squish(next->p_data[0]);
248 /* if we encounter a not then look for or's in the subplan */
249 if (next->execute == f_not)
250 next->p_data[0] = or_squish(next->p_data[0]);
253 * if we encounter an or, then place our collected plan in the
254 * or's first subplan and then recursively collect the
255 * remaining stuff into the second subplan and return the or.
257 if (next->execute == f_or) {
259 errx(1, "-o: no expression before -o");
260 next->p_data[0] = result;
261 next->p_data[1] = or_squish(plan);
262 if (next->p_data[1] == NULL)
263 errx(1, "-o: no expression after -o");
267 /* add the node to our result plan */
269 tail = result = next;