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/*-------------------------------------------------------------------------
*
* var.c
* Var node manipulation routines
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.23 1999/08/22 20:14:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include <sys/types.h>
#include "postgres.h"
#include "optimizer/clauses.h"
#include "optimizer/var.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);
/*
* pull_varnos
*
* Create a list of all the distinct varnos present in a parsetree
* (tlist or qual).
*/
List *
pull_varnos(Node *node)
{
List *result = NIL;
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.
*
* Returns true if any varnode found.
*/
bool
contain_var_clause(Node *clause)
{
return contain_var_clause_walker(clause, NULL);
}
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 an expression clause.
*
* Returns list of varnodes found. Note the varnodes themselves are not
* copied, only referenced.
*/
List *
pull_var_clause(Node *clause)
{
List *result = NIL;
pull_var_clause_walker(clause, &result);
return result;
}
static bool
pull_var_clause_walker(Node *node, List **listptr)
{
if (node == NULL)
return false;
if (IsA(node, Var))
{
*listptr = lappend(*listptr, node);
return false;
}
return expression_tree_walker(node, pull_var_clause_walker,
(void *) listptr);
}
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