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6 * Cimarron D. Taylor of the University of California, Berkeley.
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32 * $FreeBSD: src/usr.bin/find/operator.c,v 1.17 2010/12/11 08:32:16 joel Exp $
34 * @(#)operator.c 8.1 (Berkeley) 6/6/93
37 #include <sys/types.h>
45 static PLAN *yanknode(PLAN **);
46 static PLAN *yankexpr(PLAN **);
50 * destructively removes the top from the plan
53 yanknode(PLAN **planp)
55 PLAN *node; /* top node removed from the plan */
57 if ((node = (*planp)) == NULL)
59 (*planp) = (*planp)->next;
66 * Removes one expression from the plan. This is used mainly by
67 * paren_squish. In comments below, an expression is either a
68 * simple node or a f_expr node containing a list of simple nodes.
71 yankexpr(PLAN **planp)
73 PLAN *next; /* temp node holding subexpression results */
74 PLAN *node; /* pointer to returned node or expression */
75 PLAN *tail; /* pointer to tail of subplan */
76 PLAN *subplan; /* pointer to head of ( ) expression */
78 /* first pull the top node from the plan */
79 if ((node = yanknode(planp)) == NULL)
83 * If the node is an '(' then we recursively slurp up expressions
84 * until we find its associated ')'. If it's a closing paren we
85 * just return it and unwind our recursion; all other nodes are
86 * complete expressions, so just return them.
88 if (node->execute == f_openparen)
89 for (tail = subplan = NULL;;) {
90 if ((next = yankexpr(planp)) == NULL)
91 errx(1, "(: missing closing ')'");
93 * If we find a closing ')' we store the collected
94 * subplan in our '(' node and convert the node to
95 * a f_expr. The ')' we found is ignored. Otherwise,
96 * we just continue to add whatever we get to our
99 if (next->execute == f_closeparen) {
101 errx(1, "(): empty inner expression");
102 node->p_data[0] = subplan;
103 node->execute = f_expr;
107 tail = subplan = next;
120 * replaces "parenthesized" plans in our search plan with "expr" nodes.
123 paren_squish(PLAN *plan)
125 PLAN *expr; /* pointer to next expression */
126 PLAN *tail; /* pointer to tail of result plan */
127 PLAN *result; /* pointer to head of result plan */
129 result = tail = NULL;
132 * the basic idea is to have yankexpr do all our work and just
133 * collect its results together.
135 while ((expr = yankexpr(&plan)) != NULL) {
137 * if we find an unclaimed ')' it means there is a missing
140 if (expr->execute == f_closeparen)
141 errx(1, "): no beginning '('");
143 /* add the expression to our result plan */
145 tail = result = expr;
157 * compresses "!" expressions in our search plan.
160 not_squish(PLAN *plan)
162 PLAN *next; /* next node being processed */
163 PLAN *node; /* temporary node used in f_not processing */
164 PLAN *tail; /* pointer to tail of result plan */
165 PLAN *result; /* pointer to head of result plan */
167 tail = result = NULL;
169 while ((next = yanknode(&plan))) {
171 * if we encounter a ( expression ) then look for nots in
174 if (next->execute == f_expr)
175 next->p_data[0] = not_squish(next->p_data[0]);
178 * if we encounter a not, then snag the next node and place
179 * it in the not's subplan. As an optimization we compress
180 * several not's to zero or one not.
182 if (next->execute == f_not) {
185 node = yanknode(&plan);
186 while (node != NULL && node->execute == f_not) {
188 node = yanknode(&plan);
191 errx(1, "!: no following expression");
192 if (node->execute == f_or)
193 errx(1, "!: nothing between ! and -o");
195 * If we encounter ! ( expr ) then look for nots in
198 if (node->execute == f_expr)
199 node->p_data[0] = not_squish(node->p_data[0]);
200 if (notlevel % 2 != 1)
203 next->p_data[0] = node;
206 /* add the node to our result plan */
208 tail = result = next;
220 * compresses -o expressions in our search plan.
223 or_squish(PLAN *plan)
225 PLAN *next; /* next node being processed */
226 PLAN *tail; /* pointer to tail of result plan */
227 PLAN *result; /* pointer to head of result plan */
229 tail = result = next = NULL;
231 while ((next = yanknode(&plan)) != NULL) {
233 * if we encounter a ( expression ) then look for or's in
236 if (next->execute == f_expr)
237 next->p_data[0] = or_squish(next->p_data[0]);
239 /* if we encounter a not then look for or's in the subplan */
240 if (next->execute == f_not)
241 next->p_data[0] = or_squish(next->p_data[0]);
244 * if we encounter an or, then place our collected plan in the
245 * or's first subplan and then recursively collect the
246 * remaining stuff into the second subplan and return the or.
248 if (next->execute == f_or) {
250 errx(1, "-o: no expression before -o");
251 next->p_data[0] = result;
252 next->p_data[1] = or_squish(plan);
253 if (next->p_data[1] == NULL)
254 errx(1, "-o: no expression after -o");
258 /* add the node to our result plan */
260 tail = result = next;