2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
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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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35 #include <sys/types.h>
44 static PLAN *yanknode(PLAN **);
45 static PLAN *yankexpr(PLAN **);
49 * destructively removes the top from the plan
52 yanknode(PLAN **planp)
54 PLAN *node; /* top node removed from the plan */
56 if ((node = (*planp)) == NULL)
58 (*planp) = (*planp)->next;
65 * Removes one expression from the plan. This is used mainly by
66 * paren_squish. In comments below, an expression is either a
67 * simple node or a f_expr node containing a list of simple nodes.
70 yankexpr(PLAN **planp)
72 PLAN *next; /* temp node holding subexpression results */
73 PLAN *node; /* pointer to returned node or expression */
74 PLAN *tail; /* pointer to tail of subplan */
75 PLAN *subplan; /* pointer to head of ( ) expression */
77 /* first pull the top node from the plan */
78 if ((node = yanknode(planp)) == NULL)
82 * If the node is an '(' then we recursively slurp up expressions
83 * until we find its associated ')'. If it's a closing paren we
84 * just return it and unwind our recursion; all other nodes are
85 * complete expressions, so just return them.
87 if (node->execute == f_openparen)
88 for (tail = subplan = NULL;;) {
89 if ((next = yankexpr(planp)) == NULL)
90 errx(1, "(: missing closing ')'");
92 * If we find a closing ')' we store the collected
93 * subplan in our '(' node and convert the node to
94 * a f_expr. The ')' we found is ignored. Otherwise,
95 * we just continue to add whatever we get to our
98 if (next->execute == f_closeparen) {
100 errx(1, "(): empty inner expression");
101 node->p_data[0] = subplan;
102 node->execute = f_expr;
106 tail = subplan = next;
119 * replaces "parenthesized" plans in our search plan with "expr" nodes.
122 paren_squish(PLAN *plan)
124 PLAN *expr; /* pointer to next expression */
125 PLAN *tail; /* pointer to tail of result plan */
126 PLAN *result; /* pointer to head of result plan */
128 result = tail = NULL;
131 * the basic idea is to have yankexpr do all our work and just
132 * collect its results together.
134 while ((expr = yankexpr(&plan)) != NULL) {
136 * if we find an unclaimed ')' it means there is a missing
139 if (expr->execute == f_closeparen)
140 errx(1, "): no beginning '('");
142 /* add the expression to our result plan */
144 tail = result = expr;
156 * compresses "!" expressions in our search plan.
159 not_squish(PLAN *plan)
161 PLAN *next; /* next node being processed */
162 PLAN *node; /* temporary node used in f_not processing */
163 PLAN *tail; /* pointer to tail of result plan */
164 PLAN *result; /* pointer to head of result plan */
166 tail = result = NULL;
168 while ((next = yanknode(&plan))) {
170 * if we encounter a ( expression ) then look for nots in
173 if (next->execute == f_expr)
174 next->p_data[0] = not_squish(next->p_data[0]);
177 * if we encounter a not, then snag the next node and place
178 * it in the not's subplan. As an optimization we compress
179 * several not's to zero or one not.
181 if (next->execute == f_not) {
184 node = yanknode(&plan);
185 while (node != NULL && node->execute == f_not) {
187 node = yanknode(&plan);
190 errx(1, "!: no following expression");
191 if (node->execute == f_or)
192 errx(1, "!: nothing between ! and -o");
194 * If we encounter ! ( expr ) then look for nots in
197 if (node->execute == f_expr)
198 node->p_data[0] = not_squish(node->p_data[0]);
199 if (notlevel % 2 != 1)
202 next->p_data[0] = node;
205 /* add the node to our result plan */
207 tail = result = next;
219 * compresses -o expressions in our search plan.
222 or_squish(PLAN *plan)
224 PLAN *next; /* next node being processed */
225 PLAN *tail; /* pointer to tail of result plan */
226 PLAN *result; /* pointer to head of result plan */
228 tail = result = next = NULL;
230 while ((next = yanknode(&plan)) != NULL) {
232 * if we encounter a ( expression ) then look for or's in
235 if (next->execute == f_expr)
236 next->p_data[0] = or_squish(next->p_data[0]);
238 /* if we encounter a not then look for or's in the subplan */
239 if (next->execute == f_not)
240 next->p_data[0] = or_squish(next->p_data[0]);
243 * if we encounter an or, then place our collected plan in the
244 * or's first subplan and then recursively collect the
245 * remaining stuff into the second subplan and return the or.
247 if (next->execute == f_or) {
249 errx(1, "-o: no expression before -o");
250 next->p_data[0] = result;
251 next->p_data[1] = or_squish(plan);
252 if (next->p_data[1] == NULL)
253 errx(1, "-o: no expression after -o");
257 /* add the node to our result plan */
259 tail = result = next;