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Create a generic expression-tree-walker subroutine, which

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will gradually replace all of the boilerplate tree-walk-recursion code that
currently exists in O(N) slightly different forms in N subroutines.
I've had it with adding missing cases to these subroutines...
This commit is contained in:
Tom Lane
1999-06-19 03:41:45 +00:00
parent d30c4b0562
commit 86f36719db
3 changed files with 272 additions and 252 deletions
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226
src/backend/optimizer/util/var.c
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@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.19 1999/05/25 16:10:05 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.20 1999/06/19 03:41:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -15,8 +15,7 @@
#include "postgres.h"
#include <nodes/relation.h>
#include "nodes/relation.h"
#include "nodes/primnodes.h"
#include "nodes/plannodes.h"
#include "nodes/nodeFuncs.h"
@@ -27,45 +26,42 @@
#include "parser/parsetree.h"
static bool pull_varnos_walker(Node *node, List **listptr);
static bool contain_var_clause_walker(Node *node, void *context);
static bool pull_var_clause_walker(Node *node, List **listptr);
/*
* find_varnos
* pull_varnos
*
* Descends down part of a parsetree (qual or tlist),
*
* XXX assumes varno's are always integers, which shouldn't be true...
* (though it currently is, see primnodes.h)
* Create a list of all the distinct varnos present in a parsetree
* (tlist or qual).
*/
List *
pull_varnos(Node *me)
pull_varnos(Node *node)
{
List *i,
*result = NIL;
List *result = NIL;
if (me == NULL)
return NIL;
switch (nodeTag(me))
{
case T_List:
foreach(i, (List *) me)
result = nconc(result, pull_varnos(lfirst(i)));
break;
case T_ArrayRef:
foreach(i, ((ArrayRef *) me)->refupperindexpr)
result = nconc(result, pull_varnos(lfirst(i)));
foreach(i, ((ArrayRef *) me)->reflowerindexpr)
result = nconc(result, pull_varnos(lfirst(i)));
result = nconc(result, pull_varnos(((ArrayRef *) me)->refassgnexpr));
break;
case T_Var:
result = lconsi(((Var *) me)->varno, NIL);
break;
default:
break;
}
pull_varnos_walker(node, &result);
return result;
}
static bool
pull_varnos_walker(Node *node, List **listptr)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (!intMember(var->varno, *listptr))
*listptr = lconsi(var->varno, *listptr);
return false;
}
return expression_tree_walker(node, pull_varnos_walker, (void *) listptr);
}
/*
* contain_var_clause
* Recursively scan a clause to discover whether it contains any Var nodes.
@@ -75,92 +71,22 @@ pull_varnos(Node *me)
bool
contain_var_clause(Node *clause)
{
List *temp;
return contain_var_clause_walker(clause, NULL);
}
if (clause == NULL)
return FALSE;
else if (IsA(clause, Var))
return TRUE;
else if (single_node(clause))
return FALSE;
else if (IsA(clause, Iter))
return contain_var_clause(((Iter *) clause)->iterexpr);
else if (is_subplan(clause))
{
foreach(temp, ((Expr *) clause)->args)
{
if (contain_var_clause(lfirst(temp)))
return TRUE;
}
/* Also check left sides of Oper-s */
foreach(temp, ((SubPlan *) ((Expr *) clause)->oper)->sublink->oper)
{
if (contain_var_clause(lfirst(((Expr *) lfirst(temp))->args)))
return TRUE;
}
return FALSE;
}
else if (IsA(clause, Expr))
{
/*
* Recursively scan the arguments of an expression. NOTE: this
* must come after is_subplan() case since subplan is a kind of
* Expr node.
*/
foreach(temp, ((Expr *) clause)->args)
{
if (contain_var_clause(lfirst(temp)))
return TRUE;
}
return FALSE;
}
else if (IsA(clause, Aggref))
return contain_var_clause(((Aggref *) clause)->target);
else if (IsA(clause, ArrayRef))
{
foreach(temp, ((ArrayRef *) clause)->refupperindexpr)
{
if (contain_var_clause(lfirst(temp)))
return TRUE;
}
foreach(temp, ((ArrayRef *) clause)->reflowerindexpr)
{
if (contain_var_clause(lfirst(temp)))
return TRUE;
}
if (contain_var_clause(((ArrayRef *) clause)->refexpr))
return TRUE;
if (contain_var_clause(((ArrayRef *) clause)->refassgnexpr))
return TRUE;
return FALSE;
}
else if (case_clause(clause))
{
foreach(temp, ((CaseExpr *) clause)->args)
{
CaseWhen *when = (CaseWhen *) lfirst(temp);
if (contain_var_clause(when->expr))
return TRUE;
if (contain_var_clause(when->result))
return TRUE;
}
return (contain_var_clause(((CaseExpr *) clause)->defresult));
}
else
{
elog(ERROR, "contain_var_clause: Cannot handle node type %d",
nodeTag(clause));
}
return FALSE;
static bool
contain_var_clause_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, Var))
return true; /* abort the tree traversal and return true */
return expression_tree_walker(node, contain_var_clause_walker, context);
}
/*
* pull_var_clause
* Recursively pulls all var nodes from a clause by pulling vars from the
* left and right operands of the clause.
* Recursively pulls all var nodes from an expression clause.
*
* Returns list of varnodes found. Note the varnodes themselves are not
* copied, only referenced.
@@ -168,68 +94,24 @@ contain_var_clause(Node *clause)
List *
pull_var_clause(Node *clause)
{
List *retval = NIL;
List *temp;
List *result = NIL;
if (clause == NULL)
return NIL;
else if (IsA(clause, Var))
retval = lcons(clause, NIL);
else if (single_node(clause))
retval = NIL;
else if (IsA(clause, Iter))
retval = pull_var_clause(((Iter *) clause)->iterexpr);
else if (is_subplan(clause))
{
foreach(temp, ((Expr *) clause)->args)
retval = nconc(retval, pull_var_clause(lfirst(temp)));
/* Also get Var-s from left sides of Oper-s */
foreach(temp, ((SubPlan *) ((Expr *) clause)->oper)->sublink->oper)
retval = nconc(retval,
pull_var_clause(lfirst(((Expr *) lfirst(temp))->args)));
}
else if (IsA(clause, Expr))
{
pull_var_clause_walker(clause, &result);
return result;
}
/*
* Recursively scan the arguments of an expression. NOTE: this
* must come after is_subplan() case since subplan is a kind of
* Expr node.
*/
foreach(temp, ((Expr *) clause)->args)
retval = nconc(retval, pull_var_clause(lfirst(temp)));
}
else if (IsA(clause, Aggref))
retval = pull_var_clause(((Aggref *) clause)->target);
else if (IsA(clause, ArrayRef))
static bool
pull_var_clause_walker(Node *node, List **listptr)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
foreach(temp, ((ArrayRef *) clause)->refupperindexpr)
retval = nconc(retval, pull_var_clause(lfirst(temp)));
foreach(temp, ((ArrayRef *) clause)->reflowerindexpr)
retval = nconc(retval, pull_var_clause(lfirst(temp)));
retval = nconc(retval,
pull_var_clause(((ArrayRef *) clause)->refexpr));
retval = nconc(retval,
pull_var_clause(((ArrayRef *) clause)->refassgnexpr));
*listptr = lappend(*listptr, node);
return false;
}
else if (case_clause(clause))
{
foreach(temp, ((CaseExpr *) clause)->args)
{
CaseWhen *when = (CaseWhen *) lfirst(temp);
retval = nconc(retval, pull_var_clause(when->expr));
retval = nconc(retval, pull_var_clause(when->result));
}
retval = nconc(retval, pull_var_clause(((CaseExpr *) clause)->defresult));
}
else
{
elog(ERROR, "pull_var_clause: Cannot handle node type %d",
nodeTag(clause));
}
return retval;
return expression_tree_walker(node, pull_var_clause_walker,
(void *) listptr);
}
/*