* Copyright (c) 1990 The Regents of the University of California.
* This code is derived from software contributed to Berkeley by
* Cimarron D. Taylor of the University of California, Berkeley.
* %sccs.include.redist.c%
static char sccsid
[] = "@(#)operator.c 5.5 (Berkeley) %G%";
* destructively removes the top from the plan
PLAN
**planp
; /* pointer to top of plan (modified) */
PLAN
*node
; /* top node removed from the plan */
if ((node
= (*planp
)) == NULL
)
(*planp
) = (*planp
)->next
;
* Removes one expression from the plan. This is used mainly by
* paren_squish. In comments below, an expression is either a
* simple node or a N_EXPR node containing a list of simple nodes.
PLAN
**planp
; /* pointer to top of plan (modified) */
register PLAN
*next
; /* temp node holding subexpression results */
PLAN
*node
; /* pointer to returned node or expression */
PLAN
*tail
; /* pointer to tail of subplan */
PLAN
*subplan
; /* pointer to head of ( ) expression */
/* first pull the top node from the plan */
if ((node
= yanknode(planp
)) == NULL
)
* If the node is an '(' then we recursively slurp up expressions
* until we find its associated ')'. If it's a closing paren we
* just return it and unwind our recursion; all other nodes are
* complete expressions, so just return them.
if (node
->type
== N_OPENPAREN
)
for (tail
= subplan
= NULL
;;) {
if ((next
= yankexpr(planp
)) == NULL
)
err(1, "(: missing closing ')'");
* If we find a closing ')' we store the collected
* subplan in our '(' node and convert the node to
* a N_EXPR. The ')' we found is ignored. Otherwise,
* we just continue to add whatever we get to our
if (next
->type
== N_CLOSEPAREN
) {
errx(1, "(): empty inner expression");
node
->p_data
[0] = subplan
;
* replaces "parentheisized" plans in our search plan with "expr" nodes.
PLAN
*plan
; /* plan with ( ) nodes */
register PLAN
*expr
; /* pointer to next expression */
register PLAN
*tail
; /* pointer to tail of result plan */
PLAN
*result
; /* pointer to head of result plan */
* the basic idea is to have yankexpr do all our work and just
* collect it's results together.
while ((expr
= yankexpr(&plan
)) != NULL
) {
* if we find an unclaimed ')' it means there is a missing
if (expr
->type
== N_CLOSEPAREN
)
errx(1, "): no beginning '('");
/* add the expression to our result plan */
* compresses "!" expressions in our search plan.
PLAN
*plan
; /* plan to process */
register PLAN
*next
; /* next node being processed */
register PLAN
*node
; /* temporary node used in N_NOT processing */
register PLAN
*tail
; /* pointer to tail of result plan */
PLAN
*result
; /* pointer to head of result plan */
tail
= result
= next
= NULL
;
while ((next
= yanknode(&plan
)) != NULL
) {
* if we encounter a ( expression ) then look for nots in
if (next
->type
== N_EXPR
)
next
->p_data
[0] = not_squish(next
->p_data
[0]);
* if we encounter a not, then snag the next node and place
* it in the not's subplan. As an optimization we compress
* several not's to zero or one not.
if (next
->type
== N_NOT
) {
while (node
->type
== N_NOT
) {
errx(1, "!: no following expression");
errx(1, "!: nothing between ! and -o");
/* add the node to our result plan */
* compresses -o expressions in our search plan.
PLAN
*plan
; /* plan with ors to be squished */
register PLAN
*next
; /* next node being processed */
register PLAN
*tail
; /* pointer to tail of result plan */
PLAN
*result
; /* pointer to head of result plan */
tail
= result
= next
= NULL
;
while ((next
= yanknode(&plan
)) != NULL
) {
* if we encounter a ( expression ) then look for or's in
if (next
->type
== N_EXPR
)
next
->p_data
[0] = or_squish(next
->p_data
[0]);
/* if we encounter a not then look for not's in the subplan */
next
->p_data
[0] = or_squish(next
->p_data
[0]);
* if we encounter an or, then place our collected plan in the
* or's first subplan and then recursively collect the
* remaining stuff into the second subplan and return the or.
if (next
->type
== N_OR
) {
errx(1, "-o: no expression before -o");
next
->p_data
[0] = result
;
next
->p_data
[1] = or_squish(plan
);
if (next
->p_data
[1] == NULL
)
errx(1, "-o: no expression after -o");
/* add the node to our result plan */