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cnf'ify cleanup
This commit is contained in:
Bruce Momjian
parent
2d69fd90b9
commit
3f8bc47d6a
@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.10 1998/09/01 03:23:43 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.11 1998/10/04 03:30:56 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -32,7 +32,7 @@ static Expr *push_nots(Expr *qual);
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static Expr *normalize(Expr *qual);
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static List *or_normalize(List *orlist);
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static List *distribute_args(List *item, List *args);
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static List *qualcleanup(Expr *qual);
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static List *qual_cleanup(Expr *qual);
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static List *remove_ands(Expr *qual);
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static List *remove_duplicates(List *list);
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@ -52,7 +52,7 @@ static List *remove_duplicates(List *list);
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/*
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* cnfify--
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* cnfify
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* Convert a qualification to conjunctive normal form by applying
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* successive normalizations.
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*
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@ -73,7 +73,7 @@ cnfify(Expr *qual, bool removeAndFlag)
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{
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newqual = find_nots(pull_args(qual));
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newqual = normalize(pull_args(newqual));
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newqual = (Expr *) qualcleanup(pull_args(newqual));
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newqual = (Expr *) qual_cleanup(pull_args(newqual));
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newqual = pull_args(newqual);;
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if (removeAndFlag)
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@ -84,106 +84,12 @@ cnfify(Expr *qual, bool removeAndFlag)
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newqual = (Expr *) remove_ands(make_andclause(lcons(newqual, NIL)));
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}
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}
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else if (qual != NULL)
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newqual = (Expr *) lcons(qual, NIL);
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return (List *) (newqual);
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}
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/*
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* pull-args--
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* Given a qualification, eliminate nested 'and' and 'or' clauses.
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*
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* Returns the modified qualification.
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*
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*/
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static Expr *
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pull_args(Expr *qual)
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{
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if (qual == NULL)
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return NULL;
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if (is_opclause((Node *) qual))
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{
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return (make_clause(qual->opType, qual->oper,
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lcons(pull_args((Expr *) get_leftop(qual)),
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lcons(pull_args((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, pull_args(lfirst(temp)));
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return make_andclause(pull_ands(t_list));
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}
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else if (or_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, pull_args(lfirst(temp)));
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return make_orclause(pull_ors(t_list));
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}
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else if (not_clause((Node *) qual))
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return make_notclause(pull_args(get_notclausearg(qual)));
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else
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return qual;
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}
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/*
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* pull-ors--
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* Pull the arguments of an 'or' clause nested within another 'or'
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* clause up into the argument list of the parent.
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*
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* Returns the modified list.
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*/
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static List *
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pull_ors(List *orlist)
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{
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if (orlist == NIL)
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return NIL;
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if (or_clause(lfirst(orlist)))
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{
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List *args = ((Expr *) lfirst(orlist))->args;
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return (pull_ors(nconc(copyObject((Node *) args),
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copyObject((Node *) lnext(orlist)))));
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}
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else
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return lcons(lfirst(orlist), pull_ors(lnext(orlist)));
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}
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/*
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* pull-ands--
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* Pull the arguments of an 'and' clause nested within another 'and'
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* clause up into the argument list of the parent.
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*
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* Returns the modified list.
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*/
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static List *
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pull_ands(List *andlist)
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{
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if (andlist == NIL)
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return NIL;
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if (and_clause(lfirst(andlist)))
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{
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List *args = ((Expr *) lfirst(andlist))->args;
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return (pull_ands(nconc(copyObject((Node *) args),
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copyObject((Node *) lnext(andlist)))));
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}
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else
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return lcons(lfirst(andlist), pull_ands(lnext(andlist)));
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}
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/*
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* find-nots--
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* find_nots
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* Traverse the qualification, looking for 'not's to take care of.
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* For 'not' clauses, remove the 'not' and push it down to the clauses'
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* descendants.
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@ -231,7 +137,224 @@ find_nots(Expr *qual)
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}
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/*
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* push-nots--
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* normalize
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* Given a qualification tree with the 'not's pushed down, convert it
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* to a tree in CNF by repeatedly applying the rule:
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* ("OR" A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
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* bottom-up.
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* Note that 'or' clauses will always be turned into 'and' clauses.
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*
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* Returns the modified qualification.
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*
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*/
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static Expr *
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normalize(Expr *qual)
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{
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if (qual == NULL)
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return NULL;
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if (is_opclause((Node *) qual))
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{
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Expr *expr = (Expr *) qual;
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return (make_clause(expr->opType, expr->oper,
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lcons(normalize((Expr *) get_leftop(qual)),
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lcons(normalize((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, normalize(lfirst(temp)));
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return make_andclause(t_list);
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}
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else if (or_clause((Node *) qual))
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{
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/* XXX - let form, maybe incorrect */
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List *orlist = NIL;
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List *temp = NIL;
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bool has_andclause = FALSE;
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foreach(temp, qual->args)
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orlist = lappend(orlist, normalize(lfirst(temp)));
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foreach(temp, orlist)
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{
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if (and_clause(lfirst(temp)))
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{
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has_andclause = TRUE;
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break;
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}
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}
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if (has_andclause == TRUE)
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return make_andclause(or_normalize(orlist));
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else
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return make_orclause(orlist);
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}
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else if (not_clause((Node *) qual))
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return make_notclause(normalize(get_notclausearg(qual)));
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else
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return qual;
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}
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/*
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* qual_cleanup
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* Fix up a qualification by removing duplicate entries (left over from
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* normalization), and by removing 'and' and 'or' clauses which have only
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* one valid expr (e.g., ("AND" A) => A).
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*
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* Returns the modified qualfication.
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*
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*/
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static List *
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qual_cleanup(Expr *qual)
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{
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if (qual == NULL)
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return NIL;
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if (is_opclause((Node *) qual))
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{
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return ((List *) make_clause(qual->opType, qual->oper,
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lcons(qual_cleanup((Expr *) get_leftop(qual)),
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lcons(qual_cleanup((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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List *new_and_args = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, qual_cleanup(lfirst(temp)));
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new_and_args = remove_duplicates(t_list);
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if (length(new_and_args) > 1)
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return (List *) make_andclause(new_and_args);
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else
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return lfirst(new_and_args);
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}
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else if (or_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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List *new_or_args = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, qual_cleanup(lfirst(temp)));
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new_or_args = remove_duplicates(t_list);
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if (length(new_or_args) > 1)
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return (List *) make_orclause(new_or_args);
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else
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return lfirst(new_or_args);
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}
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else if (not_clause((Node *) qual))
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return (List *) make_notclause((Expr *) qual_cleanup((Expr *) get_notclausearg(qual)));
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else
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return (List *) qual;
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}
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/*
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* pull_args
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* Given a qualification, eliminate nested 'and' and 'or' clauses.
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*
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* Returns the modified qualification.
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*
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*/
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static Expr *
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pull_args(Expr *qual)
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{
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if (qual == NULL)
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return NULL;
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if (is_opclause((Node *) qual))
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{
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return (make_clause(qual->opType, qual->oper,
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lcons(pull_args((Expr *) get_leftop(qual)),
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lcons(pull_args((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, pull_args(lfirst(temp)));
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return make_andclause(pull_ands(t_list));
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}
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else if (or_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, pull_args(lfirst(temp)));
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return make_orclause(pull_ors(t_list));
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}
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else if (not_clause((Node *) qual))
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return make_notclause(pull_args(get_notclausearg(qual)));
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else
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return qual;
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}
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/*
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* pull_ors
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* Pull the arguments of an 'or' clause nested within another 'or'
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* clause up into the argument list of the parent.
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*
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* Returns the modified list.
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*/
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static List *
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pull_ors(List *orlist)
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{
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if (orlist == NIL)
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return NIL;
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if (or_clause(lfirst(orlist)))
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{
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List *args = ((Expr *) lfirst(orlist))->args;
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return (pull_ors(nconc(copyObject((Node *) args),
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copyObject((Node *) lnext(orlist)))));
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}
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else
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return lcons(lfirst(orlist), pull_ors(lnext(orlist)));
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}
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/*
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* pull_ands
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* Pull the arguments of an 'and' clause nested within another 'and'
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* clause up into the argument list of the parent.
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*
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* Returns the modified list.
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*/
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static List *
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pull_ands(List *andlist)
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{
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if (andlist == NIL)
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return NIL;
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if (and_clause(lfirst(andlist)))
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{
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List *args = ((Expr *) lfirst(andlist))->args;
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return (pull_ands(nconc(copyObject((Node *) args),
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copyObject((Node *) lnext(andlist)))));
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}
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else
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return lcons(lfirst(andlist), pull_ands(lnext(andlist)));
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}
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/*
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* push_nots
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* Negate the descendants of a 'not' clause.
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*
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* Returns the modified qualification.
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@ -308,71 +431,7 @@ push_nots(Expr *qual)
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}
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/*
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* normalize--
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* Given a qualification tree with the 'not's pushed down, convert it
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* to a tree in CNF by repeatedly applying the rule:
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* ("OR" A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
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* bottom-up.
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* Note that 'or' clauses will always be turned into 'and' clauses.
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*
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* Returns the modified qualification.
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*
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*/
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static Expr *
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normalize(Expr *qual)
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{
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if (qual == NULL)
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return NULL;
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if (is_opclause((Node *) qual))
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{
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Expr *expr = (Expr *) qual;
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return (make_clause(expr->opType, expr->oper,
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lcons(normalize((Expr *) get_leftop(qual)),
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lcons(normalize((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
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{
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List *temp = NIL;
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List *t_list = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, normalize(lfirst(temp)));
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return make_andclause(t_list);
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}
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else if (or_clause((Node *) qual))
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{
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/* XXX - let form, maybe incorrect */
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List *orlist = NIL;
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List *temp = NIL;
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bool has_andclause = FALSE;
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foreach(temp, qual->args)
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orlist = lappend(orlist, normalize(lfirst(temp)));
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foreach(temp, orlist)
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{
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if (and_clause(lfirst(temp)))
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{
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has_andclause = TRUE;
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break;
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}
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}
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if (has_andclause == TRUE)
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return make_andclause(or_normalize(orlist));
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else
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return make_orclause(orlist);
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}
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else if (not_clause((Node *) qual))
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return make_notclause(normalize(get_notclausearg(qual)));
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else
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return qual;
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}
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/*
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* or-normalize--
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* or_normalize
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* Given a list of exprs which are 'or'ed together, distribute any
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* 'and' clauses.
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*
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@ -409,7 +468,7 @@ or_normalize(List *orlist)
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}
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/*
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* distribute-args--
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* distribute_args
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* Create new 'or' clauses by or'ing 'item' with each element of 'args'.
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* E.g.: (distribute-args A ("AND" B C)) => ("AND" ("OR" A B) ("OR" A C))
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*
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@ -438,69 +497,7 @@ distribute_args(List *item, List *args)
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}
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/*
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* qualcleanup--
|
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* Fix up a qualification by removing duplicate entries (left over from
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* normalization), and by removing 'and' and 'or' clauses which have only
|
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* one valid expr (e.g., ("AND" A) => A).
|
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*
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* Returns the modified qualfication.
|
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*
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*/
|
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static List *
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qualcleanup(Expr *qual)
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{
|
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if (qual == NULL)
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return NIL;
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|
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if (is_opclause((Node *) qual))
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{
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return ((List *) make_clause(qual->opType, qual->oper,
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lcons(qualcleanup((Expr *) get_leftop(qual)),
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lcons(qualcleanup((Expr *) get_rightop(qual)),
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NIL))));
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}
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else if (and_clause((Node *) qual))
|
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{
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List *temp = NIL;
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List *t_list = NIL;
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List *new_and_args = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, qualcleanup(lfirst(temp)));
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new_and_args = remove_duplicates(t_list);
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if (length(new_and_args) > 1)
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return (List *) make_andclause(new_and_args);
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else
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return lfirst(new_and_args);
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}
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else if (or_clause((Node *) qual))
|
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{
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List *temp = NIL;
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List *t_list = NIL;
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List *new_or_args = NIL;
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foreach(temp, qual->args)
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t_list = lappend(t_list, qualcleanup(lfirst(temp)));
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new_or_args = remove_duplicates(t_list);
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if (length(new_or_args) > 1)
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return (List *) make_orclause(new_or_args);
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else
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return lfirst(new_or_args);
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}
|
||||
else if (not_clause((Node *) qual))
|
||||
return (List *) make_notclause((Expr *) qualcleanup((Expr *) get_notclausearg(qual)));
|
||||
|
||||
else
|
||||
return (List *) qual;
|
||||
}
|
||||
|
||||
/*
|
||||
* remove-ands--
|
||||
* remove_ands
|
||||
* Remove the explicit "AND"s from the qualification:
|
||||
* ("AND" A B) => (A B)
|
||||
*
|
||||
@ -543,12 +540,9 @@ remove_ands(Expr *qual)
|
||||
return (List *) qual;
|
||||
}
|
||||
|
||||
/*****************************************************************************
|
||||
*
|
||||
*
|
||||
*
|
||||
*****************************************************************************/
|
||||
|
||||
/*
|
||||
* remove_duplicates
|
||||
*/
|
||||
static List *
|
||||
remove_duplicates(List *list)
|
||||
{
|
||||
|
||||
Loading…
Reference in New Issue
Block a user