265 lines
7.3 KiB
C
265 lines
7.3 KiB
C
/* $NetBSD: operator.c,v 1.9 2006/10/11 19:51:10 apb Exp $ */
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Cimarron D. Taylor of the University of California, Berkeley.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <sys/types.h>
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#include <err.h>
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#include <fts.h>
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#include <stdio.h>
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#include "find.h"
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static PLAN *yanknode(PLAN **);
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static PLAN *yankexpr(PLAN **);
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/*
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* yanknode --
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* destructively removes the top from the plan
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*/
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static PLAN *
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yanknode(PLAN **planp) /* pointer to top of plan (modified) */
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{
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PLAN *node; /* top node removed from the plan */
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if ((node = (*planp)) == NULL)
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return (NULL);
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(*planp) = (*planp)->next;
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node->next = NULL;
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return (node);
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}
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/*
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* yankexpr --
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* Removes one expression from the plan. This is used mainly by
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* paren_squish. In comments below, an expression is either a
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* simple node or a N_EXPR node containing a list of simple nodes.
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*/
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static PLAN *
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yankexpr(PLAN **planp) /* pointer to top of plan (modified) */
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{
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PLAN *next; /* temp node holding subexpression results */
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PLAN *node; /* pointer to returned node or expression */
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PLAN *tail; /* pointer to tail of subplan */
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PLAN *subplan; /* pointer to head of ( ) expression */
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/* first pull the top node from the plan */
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if ((node = yanknode(planp)) == NULL)
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return (NULL);
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/*
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* If the node is an '(' then we recursively slurp up expressions
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* until we find its associated ')'. If it's a closing paren we
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* just return it and unwind our recursion; all other nodes are
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* complete expressions, so just return them.
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*/
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if (node->type == N_OPENPAREN)
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for (tail = subplan = NULL;;) {
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if ((next = yankexpr(planp)) == NULL)
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err(1, "(: missing closing ')'");
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/*
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* If we find a closing ')' we store the collected
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* subplan in our '(' node and convert the node to
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* a N_EXPR. The ')' we found is ignored. Otherwise,
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* we just continue to add whatever we get to our
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* subplan.
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*/
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if (next->type == N_CLOSEPAREN) {
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if (subplan == NULL)
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errx(1, "(): empty inner expression");
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node->p_data[0] = subplan;
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node->type = N_EXPR;
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node->eval = f_expr;
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break;
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} else {
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if (subplan == NULL)
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tail = subplan = next;
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else {
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tail->next = next;
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tail = next;
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}
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tail->next = NULL;
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}
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}
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return (node);
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}
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/*
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* paren_squish --
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* replaces "parentheisized" plans in our search plan with "expr" nodes.
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*/
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PLAN *
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paren_squish(PLAN *plan) /* plan with ( ) nodes */
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{
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PLAN *expr; /* pointer to next expression */
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PLAN *tail; /* pointer to tail of result plan */
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PLAN *result; /* pointer to head of result plan */
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result = tail = NULL;
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/*
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* the basic idea is to have yankexpr do all our work and just
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* collect it's results together.
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*/
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while ((expr = yankexpr(&plan)) != NULL) {
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/*
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* if we find an unclaimed ')' it means there is a missing
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* '(' someplace.
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*/
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if (expr->type == N_CLOSEPAREN)
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errx(1, "): no beginning '('");
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/* add the expression to our result plan */
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if (result == NULL)
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tail = result = expr;
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else {
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tail->next = expr;
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tail = expr;
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}
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tail->next = NULL;
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}
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return (result);
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}
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/*
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* not_squish --
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* compresses "!" expressions in our search plan.
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*/
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PLAN *
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not_squish(PLAN *plan) /* plan to process */
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{
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PLAN *next; /* next node being processed */
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PLAN *node; /* temporary node used in N_NOT processing */
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PLAN *tail; /* pointer to tail of result plan */
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PLAN *result; /* pointer to head of result plan */
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tail = result = next = NULL;
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while ((next = yanknode(&plan)) != NULL) {
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/*
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* if we encounter a ( expression ) then look for nots in
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* the expr subplan.
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*/
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if (next->type == N_EXPR)
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next->p_data[0] = not_squish(next->p_data[0]);
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/*
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* if we encounter a not, then snag the next node and place
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* it in the not's subplan. As an optimization we compress
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* several not's to zero or one not.
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*/
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if (next->type == N_NOT) {
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int notlevel = 1;
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node = yanknode(&plan);
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while (node != NULL && node->type == N_NOT) {
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++notlevel;
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node = yanknode(&plan);
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}
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if (node == NULL)
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errx(1, "!: no following expression");
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if (node->type == N_OR)
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errx(1, "!: nothing between ! and -o");
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if (node->type == N_EXPR)
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node = not_squish(node);
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if (notlevel % 2 != 1)
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next = node;
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else
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next->p_data[0] = node;
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}
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/* add the node to our result plan */
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if (result == NULL)
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tail = result = next;
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else {
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tail->next = next;
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tail = next;
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}
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tail->next = NULL;
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}
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return (result);
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}
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/*
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* or_squish --
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* compresses -o expressions in our search plan.
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*/
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PLAN *
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or_squish(PLAN *plan) /* plan with ors to be squished */
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{
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PLAN *next; /* next node being processed */
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PLAN *tail; /* pointer to tail of result plan */
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PLAN *result; /* pointer to head of result plan */
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tail = result = next = NULL;
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while ((next = yanknode(&plan)) != NULL) {
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/*
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* if we encounter a ( expression ) then look for or's in
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* the expr subplan.
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*/
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if (next->type == N_EXPR)
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next->p_data[0] = or_squish(next->p_data[0]);
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/* if we encounter a not then look for not's in the subplan */
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if (next->type == N_NOT)
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next->p_data[0] = or_squish(next->p_data[0]);
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/*
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* if we encounter an or, then place our collected plan in the
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* or's first subplan and then recursively collect the
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* remaining stuff into the second subplan and return the or.
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*/
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if (next->type == N_OR) {
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if (result == NULL)
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errx(1, "-o: no expression before -o");
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next->p_data[0] = result;
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next->p_data[1] = or_squish(plan);
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if (next->p_data[1] == NULL)
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errx(1, "-o: no expression after -o");
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return (next);
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}
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/* add the node to our result plan */
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if (result == NULL)
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tail = result = next;
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else {
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tail->next = next;
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tail = next;
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}
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tail->next = NULL;
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}
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return (result);
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}
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