* 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 5.1 (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
* find_squish_paren. In comments below, an expression is either
* a simple node or a T_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
= find_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
== T_OPENPAREN
)
for (tail
= subplan
= NULL
;;) {
if ((next
= find_yankexpr(planp
)) == NULL
)
bad_arg("(", "missing closing ')'");
* If we find a closing ')' we store the collected
* subplan in our '(' node and convert the node to
* a T_EXPR. The ')' we found is ignored. Otherwise,
* we just continue to add whatever we get to our
if (next
->type
== T_CLOSEPAREN
) {
bad_arg("()", "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 find_yankexpr do all our work and just
* collect it's results together.
while ((expr
= find_yankexpr(&plan
)) != NULL
) {
* if we find an unclaimed ')' it means there is a missing
if (expr
->type
== T_CLOSEPAREN
)
bad_arg(")", "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 T_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
= find_yanknode(&plan
)) != NULL
) {
* if we encounter a ( expression ) then look for nots in
if (next
->type
== T_EXPR
)
next
->p_data
[0] = find_squish_not(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
== T_NOT
) {
node
= find_yanknode(&plan
);
while (node
->type
== T_NOT
) {
node
= find_yanknode(&plan
);
bad_arg("!", "no following expression");
bad_arg("!", "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
= find_yanknode(&plan
)) != NULL
) {
* if we encounter a ( expression ) then look for or's in
if (next
->type
== T_EXPR
)
next
->p_data
[0] = find_squish_or(next
->p_data
[0]);
/* if we encounter a not then look for not's in the subplan */
next
->p_data
[0] = find_squish_or(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
== T_OR
) {
bad_arg("-o", "no expression before -o");
next
->p_data
[0] = result
;
next
->p_data
[1] = find_squish_or(plan
);
if (next
->p_data
[1] == NULL
)
bad_arg("-o", "no expression after -o");
/* add the node to our result plan */