nodeFuncs.c 65.5 KB
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/*-------------------------------------------------------------------------
 *
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 * nodeFuncs.c
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 *		Various general-purpose manipulations of Node trees
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 *
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 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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 * Portions Copyright (c) 1994, Regents of the University of California
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 *
 *
 * IDENTIFICATION
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 *	  $PostgreSQL: pgsql/src/backend/nodes/nodeFuncs.c,v 1.35 2008/10/21 20:42:52 tgl Exp $
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 *
 *-------------------------------------------------------------------------
 */
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#include "postgres.h"
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#include "catalog/pg_type.h"
#include "miscadmin.h"
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#include "nodes/nodeFuncs.h"
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#include "nodes/relation.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
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static bool expression_returns_set_walker(Node *node, void *context);
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static int	leftmostLoc(int loc1, int loc2);
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/*
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 *	exprType -
 *	  returns the Oid of the type of the expression. (Used for typechecking.)
 */
Oid
exprType(Node *expr)
{
	Oid			type;

	if (!expr)
		return InvalidOid;

	switch (nodeTag(expr))
	{
		case T_Var:
			type = ((Var *) expr)->vartype;
			break;
		case T_Const:
			type = ((Const *) expr)->consttype;
			break;
		case T_Param:
			type = ((Param *) expr)->paramtype;
			break;
		case T_Aggref:
			type = ((Aggref *) expr)->aggtype;
			break;
		case T_ArrayRef:
			{
				ArrayRef   *arrayref = (ArrayRef *) expr;

				/* slice and/or store operations yield the array type */
				if (arrayref->reflowerindexpr || arrayref->refassgnexpr)
					type = arrayref->refarraytype;
				else
					type = arrayref->refelemtype;
			}
			break;
		case T_FuncExpr:
			type = ((FuncExpr *) expr)->funcresulttype;
			break;
		case T_OpExpr:
			type = ((OpExpr *) expr)->opresulttype;
			break;
		case T_DistinctExpr:
			type = ((DistinctExpr *) expr)->opresulttype;
			break;
		case T_ScalarArrayOpExpr:
			type = BOOLOID;
			break;
		case T_BoolExpr:
			type = BOOLOID;
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) expr;

				if (sublink->subLinkType == EXPR_SUBLINK ||
					sublink->subLinkType == ARRAY_SUBLINK)
				{
					/* get the type of the subselect's first target column */
					Query	   *qtree = (Query *) sublink->subselect;
					TargetEntry *tent;

					if (!qtree || !IsA(qtree, Query))
						elog(ERROR, "cannot get type for untransformed sublink");
					tent = (TargetEntry *) linitial(qtree->targetList);
					Assert(IsA(tent, TargetEntry));
					Assert(!tent->resjunk);
					type = exprType((Node *) tent->expr);
					if (sublink->subLinkType == ARRAY_SUBLINK)
					{
						type = get_array_type(type);
						if (!OidIsValid(type))
							ereport(ERROR,
									(errcode(ERRCODE_UNDEFINED_OBJECT),
									 errmsg("could not find array type for data type %s",
							format_type_be(exprType((Node *) tent->expr)))));
					}
				}
				else
				{
					/* for all other sublink types, result is boolean */
					type = BOOLOID;
				}
			}
			break;
		case T_SubPlan:
			{
				/*
				 * Although the parser does not ever deal with already-planned
				 * expression trees, we support SubPlan nodes in this routine
				 * for the convenience of ruleutils.c.
				 */
				SubPlan    *subplan = (SubPlan *) expr;

				if (subplan->subLinkType == EXPR_SUBLINK ||
					subplan->subLinkType == ARRAY_SUBLINK)
				{
					/* get the type of the subselect's first target column */
					type = subplan->firstColType;
					if (subplan->subLinkType == ARRAY_SUBLINK)
					{
						type = get_array_type(type);
						if (!OidIsValid(type))
							ereport(ERROR,
									(errcode(ERRCODE_UNDEFINED_OBJECT),
									 errmsg("could not find array type for data type %s",
									format_type_be(subplan->firstColType))));
					}
				}
				else
				{
					/* for all other subplan types, result is boolean */
					type = BOOLOID;
				}
			}
			break;
		case T_AlternativeSubPlan:
			{
				/* As above, supported for the convenience of ruleutils.c */
				AlternativeSubPlan *asplan = (AlternativeSubPlan *) expr;

				/* subplans should all return the same thing */
				type = exprType((Node *) linitial(asplan->subplans));
			}
			break;
		case T_FieldSelect:
			type = ((FieldSelect *) expr)->resulttype;
			break;
		case T_FieldStore:
			type = ((FieldStore *) expr)->resulttype;
			break;
		case T_RelabelType:
			type = ((RelabelType *) expr)->resulttype;
			break;
		case T_CoerceViaIO:
			type = ((CoerceViaIO *) expr)->resulttype;
			break;
		case T_ArrayCoerceExpr:
			type = ((ArrayCoerceExpr *) expr)->resulttype;
			break;
		case T_ConvertRowtypeExpr:
			type = ((ConvertRowtypeExpr *) expr)->resulttype;
			break;
		case T_CaseExpr:
			type = ((CaseExpr *) expr)->casetype;
			break;
		case T_CaseTestExpr:
			type = ((CaseTestExpr *) expr)->typeId;
			break;
		case T_ArrayExpr:
			type = ((ArrayExpr *) expr)->array_typeid;
			break;
		case T_RowExpr:
			type = ((RowExpr *) expr)->row_typeid;
			break;
		case T_RowCompareExpr:
			type = BOOLOID;
			break;
		case T_CoalesceExpr:
			type = ((CoalesceExpr *) expr)->coalescetype;
			break;
		case T_MinMaxExpr:
			type = ((MinMaxExpr *) expr)->minmaxtype;
			break;
		case T_XmlExpr:
			if (((XmlExpr *) expr)->op == IS_DOCUMENT)
				type = BOOLOID;
			else if (((XmlExpr *) expr)->op == IS_XMLSERIALIZE)
				type = TEXTOID;
			else
				type = XMLOID;
			break;
		case T_NullIfExpr:
			type = exprType((Node *) linitial(((NullIfExpr *) expr)->args));
			break;
		case T_NullTest:
			type = BOOLOID;
			break;
		case T_BooleanTest:
			type = BOOLOID;
			break;
		case T_CoerceToDomain:
			type = ((CoerceToDomain *) expr)->resulttype;
			break;
		case T_CoerceToDomainValue:
			type = ((CoerceToDomainValue *) expr)->typeId;
			break;
		case T_SetToDefault:
			type = ((SetToDefault *) expr)->typeId;
			break;
		case T_CurrentOfExpr:
			type = BOOLOID;
			break;
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		case T_PlaceHolderVar:
			type = exprType((Node *) ((PlaceHolderVar *) expr)->phexpr);
			break;
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		default:
			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
			type = InvalidOid;	/* keep compiler quiet */
			break;
	}
	return type;
}

/*
 *	exprTypmod -
 *	  returns the type-specific attrmod of the expression, if it can be
 *	  determined.  In most cases, it can't and we return -1.
 */
int32
exprTypmod(Node *expr)
{
	if (!expr)
		return -1;

	switch (nodeTag(expr))
	{
		case T_Var:
			return ((Var *) expr)->vartypmod;
		case T_Const:
			return ((Const *) expr)->consttypmod;
		case T_Param:
			return ((Param *) expr)->paramtypmod;
		case T_ArrayRef:
			/* typmod is the same for array or element */
			return ((ArrayRef *) expr)->reftypmod;
		case T_FuncExpr:
			{
				int32		coercedTypmod;

				/* Be smart about length-coercion functions... */
				if (exprIsLengthCoercion(expr, &coercedTypmod))
					return coercedTypmod;
			}
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) expr;

				if (sublink->subLinkType == EXPR_SUBLINK ||
					sublink->subLinkType == ARRAY_SUBLINK)
				{
					/* get the typmod of the subselect's first target column */
					Query	   *qtree = (Query *) sublink->subselect;
					TargetEntry *tent;

					if (!qtree || !IsA(qtree, Query))
						elog(ERROR, "cannot get type for untransformed sublink");
					tent = (TargetEntry *) linitial(qtree->targetList);
					Assert(IsA(tent, TargetEntry));
					Assert(!tent->resjunk);
					return exprTypmod((Node *) tent->expr);
					/* note we don't need to care if it's an array */
				}
			}
			break;
		case T_FieldSelect:
			return ((FieldSelect *) expr)->resulttypmod;
		case T_RelabelType:
			return ((RelabelType *) expr)->resulttypmod;
		case T_ArrayCoerceExpr:
			return ((ArrayCoerceExpr *) expr)->resulttypmod;
		case T_CaseExpr:
			{
				/*
				 * If all the alternatives agree on type/typmod, return that
				 * typmod, else use -1
				 */
				CaseExpr   *cexpr = (CaseExpr *) expr;
				Oid			casetype = cexpr->casetype;
				int32		typmod;
				ListCell   *arg;

				if (!cexpr->defresult)
					return -1;
				if (exprType((Node *) cexpr->defresult) != casetype)
					return -1;
				typmod = exprTypmod((Node *) cexpr->defresult);
				if (typmod < 0)
					return -1;	/* no point in trying harder */
				foreach(arg, cexpr->args)
				{
					CaseWhen   *w = (CaseWhen *) lfirst(arg);

					Assert(IsA(w, CaseWhen));
					if (exprType((Node *) w->result) != casetype)
						return -1;
					if (exprTypmod((Node *) w->result) != typmod)
						return -1;
				}
				return typmod;
			}
			break;
		case T_CaseTestExpr:
			return ((CaseTestExpr *) expr)->typeMod;
		case T_ArrayExpr:
			{
				/*
				 * If all the elements agree on type/typmod, return that
				 * typmod, else use -1
				 */
				ArrayExpr  *arrayexpr = (ArrayExpr *) expr;
				Oid			commontype;
				int32		typmod;
				ListCell   *elem;

				if (arrayexpr->elements == NIL)
					return -1;
				typmod = exprTypmod((Node *) linitial(arrayexpr->elements));
				if (typmod < 0)
					return -1;	/* no point in trying harder */
				if (arrayexpr->multidims)
					commontype = arrayexpr->array_typeid;
				else
					commontype = arrayexpr->element_typeid;
				foreach(elem, arrayexpr->elements)
				{
					Node	   *e = (Node *) lfirst(elem);

					if (exprType(e) != commontype)
						return -1;
					if (exprTypmod(e) != typmod)
						return -1;
				}
				return typmod;
			}
			break;
		case T_CoalesceExpr:
			{
				/*
				 * If all the alternatives agree on type/typmod, return that
				 * typmod, else use -1
				 */
				CoalesceExpr *cexpr = (CoalesceExpr *) expr;
				Oid			coalescetype = cexpr->coalescetype;
				int32		typmod;
				ListCell   *arg;

				if (exprType((Node *) linitial(cexpr->args)) != coalescetype)
					return -1;
				typmod = exprTypmod((Node *) linitial(cexpr->args));
				if (typmod < 0)
					return -1;	/* no point in trying harder */
				for_each_cell(arg, lnext(list_head(cexpr->args)))
				{
					Node	   *e = (Node *) lfirst(arg);

					if (exprType(e) != coalescetype)
						return -1;
					if (exprTypmod(e) != typmod)
						return -1;
				}
				return typmod;
			}
			break;
		case T_MinMaxExpr:
			{
				/*
				 * If all the alternatives agree on type/typmod, return that
				 * typmod, else use -1
				 */
				MinMaxExpr *mexpr = (MinMaxExpr *) expr;
				Oid			minmaxtype = mexpr->minmaxtype;
				int32		typmod;
				ListCell   *arg;

				if (exprType((Node *) linitial(mexpr->args)) != minmaxtype)
					return -1;
				typmod = exprTypmod((Node *) linitial(mexpr->args));
				if (typmod < 0)
					return -1;	/* no point in trying harder */
				for_each_cell(arg, lnext(list_head(mexpr->args)))
				{
					Node	   *e = (Node *) lfirst(arg);

					if (exprType(e) != minmaxtype)
						return -1;
					if (exprTypmod(e) != typmod)
						return -1;
				}
				return typmod;
			}
			break;
		case T_NullIfExpr:
			{
				NullIfExpr *nexpr = (NullIfExpr *) expr;

				return exprTypmod((Node *) linitial(nexpr->args));
			}
			break;
		case T_CoerceToDomain:
			return ((CoerceToDomain *) expr)->resulttypmod;
		case T_CoerceToDomainValue:
			return ((CoerceToDomainValue *) expr)->typeMod;
		case T_SetToDefault:
			return ((SetToDefault *) expr)->typeMod;
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		case T_PlaceHolderVar:
			return exprTypmod((Node *) ((PlaceHolderVar *) expr)->phexpr);
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		default:
			break;
	}
	return -1;
}

/*
 * exprIsLengthCoercion
 *		Detect whether an expression tree is an application of a datatype's
 *		typmod-coercion function.  Optionally extract the result's typmod.
 *
 * If coercedTypmod is not NULL, the typmod is stored there if the expression
 * is a length-coercion function, else -1 is stored there.
 *
 * Note that a combined type-and-length coercion will be treated as a
 * length coercion by this routine.
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 */
bool
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exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
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{
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	if (coercedTypmod != NULL)
		*coercedTypmod = -1;	/* default result on failure */

	/*
	 * Scalar-type length coercions are FuncExprs, array-type length coercions
	 * are ArrayCoerceExprs
	 */
	if (expr && IsA(expr, FuncExpr))
	{
		FuncExpr   *func = (FuncExpr *) expr;
		int			nargs;
		Const	   *second_arg;

		/*
		 * If it didn't come from a coercion context, reject.
		 */
		if (func->funcformat != COERCE_EXPLICIT_CAST &&
			func->funcformat != COERCE_IMPLICIT_CAST)
			return false;

		/*
		 * If it's not a two-argument or three-argument function with the
		 * second argument being an int4 constant, it can't have been created
		 * from a length coercion (it must be a type coercion, instead).
		 */
		nargs = list_length(func->args);
		if (nargs < 2 || nargs > 3)
			return false;

		second_arg = (Const *) lsecond(func->args);
		if (!IsA(second_arg, Const) ||
			second_arg->consttype != INT4OID ||
			second_arg->constisnull)
			return false;

		/*
		 * OK, it is indeed a length-coercion function.
		 */
		if (coercedTypmod != NULL)
			*coercedTypmod = DatumGetInt32(second_arg->constvalue);

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		return true;
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	}

	if (expr && IsA(expr, ArrayCoerceExpr))
	{
		ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) expr;

		/* It's not a length coercion unless there's a nondefault typmod */
		if (acoerce->resulttypmod < 0)
			return false;

		/*
		 * OK, it is indeed a length-coercion expression.
		 */
		if (coercedTypmod != NULL)
			*coercedTypmod = acoerce->resulttypmod;

		return true;
	}

	return false;
}

/*
 * expression_returns_set
 *	  Test whether an expression returns a set result.
 *
 * Because we use expression_tree_walker(), this can also be applied to
 * whole targetlists; it'll produce TRUE if any one of the tlist items
 * returns a set.
 */
bool
expression_returns_set(Node *clause)
{
	return expression_returns_set_walker(clause, NULL);
}

static bool
expression_returns_set_walker(Node *node, void *context)
{
	if (node == NULL)
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		return false;
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	if (IsA(node, FuncExpr))
	{
		FuncExpr   *expr = (FuncExpr *) node;

		if (expr->funcretset)
			return true;
		/* else fall through to check args */
	}
	if (IsA(node, OpExpr))
	{
		OpExpr	   *expr = (OpExpr *) node;

		if (expr->opretset)
			return true;
		/* else fall through to check args */
	}

	/* Avoid recursion for some cases that can't return a set */
	if (IsA(node, Aggref))
		return false;
	if (IsA(node, DistinctExpr))
		return false;
	if (IsA(node, ScalarArrayOpExpr))
		return false;
	if (IsA(node, BoolExpr))
		return false;
	if (IsA(node, SubLink))
		return false;
	if (IsA(node, SubPlan))
		return false;
	if (IsA(node, AlternativeSubPlan))
		return false;
	if (IsA(node, ArrayExpr))
		return false;
	if (IsA(node, RowExpr))
		return false;
	if (IsA(node, RowCompareExpr))
		return false;
	if (IsA(node, CoalesceExpr))
		return false;
	if (IsA(node, MinMaxExpr))
		return false;
	if (IsA(node, XmlExpr))
		return false;
	if (IsA(node, NullIfExpr))
		return false;

	return expression_tree_walker(node, expression_returns_set_walker,
								  context);
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}


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/*
 *	exprLocation -
 *	  returns the parse location of an expression tree, for error reports
 *
 * -1 is returned if the location can't be determined.
 *
 * For expressions larger than a single token, the intent here is to
 * return the location of the expression's leftmost token, not necessarily
 * the topmost Node's location field.  For example, an OpExpr's location
 * field will point at the operator name, but if it is not a prefix operator
 * then we should return the location of the left-hand operand instead.
 * The reason is that we want to reference the entire expression not just
 * that operator, and pointing to its start seems to be the most natural way.
 *
 * The location is not perfect --- for example, since the grammar doesn't
 * explicitly represent parentheses in the parsetree, given something that
 * had been written "(a + b) * c" we are going to point at "a" not "(".
 * But it should be plenty good enough for error reporting purposes.
 *
 * You might think that this code is overly general, for instance why check
 * the operands of a FuncExpr node, when the function name can be expected
 * to be to the left of them?  There are a couple of reasons.  The grammar
 * sometimes builds expressions that aren't quite what the user wrote;
 * for instance x IS NOT BETWEEN ... becomes a NOT-expression whose keyword
 * pointer is to the right of its leftmost argument.  Also, nodes that were
 * inserted implicitly by parse analysis (such as FuncExprs for implicit
 * coercions) will have location -1, and so we can have odd combinations of
 * known and unknown locations in a tree.
 */
int
exprLocation(Node *expr)
{
	int			loc;

	if (expr == NULL)
		return -1;
	switch (nodeTag(expr))
	{
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		case T_RangeVar:
			loc = ((RangeVar *) expr)->location;
			break;
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		case T_Var:
			loc = ((Var *) expr)->location;
			break;
		case T_Const:
			loc = ((Const *) expr)->location;
			break;
		case T_Param:
			loc = ((Param *) expr)->location;
			break;
		case T_Aggref:
			/* function name should always be the first thing */
			loc = ((Aggref *) expr)->location;
			break;
		case T_ArrayRef:
			/* just use array argument's location */
			loc = exprLocation((Node *) ((ArrayRef *) expr)->refexpr);
			break;
		case T_FuncExpr:
			{
				FuncExpr   *fexpr = (FuncExpr *) expr;

				/* consider both function name and leftmost arg */
				loc = leftmostLoc(fexpr->location,
								  exprLocation((Node *) fexpr->args));
			}
			break;
		case T_OpExpr:
		case T_DistinctExpr:	/* struct-equivalent to OpExpr */
		case T_NullIfExpr:		/* struct-equivalent to OpExpr */
			{
				OpExpr   *opexpr = (OpExpr *) expr;

				/* consider both operator name and leftmost arg */
				loc = leftmostLoc(opexpr->location,
								  exprLocation((Node *) opexpr->args));
			}
			break;
		case T_ScalarArrayOpExpr:
			{
				ScalarArrayOpExpr *saopexpr = (ScalarArrayOpExpr *) expr;

				/* consider both operator name and leftmost arg */
				loc = leftmostLoc(saopexpr->location,
								  exprLocation((Node *) saopexpr->args));
			}
			break;
		case T_BoolExpr:
			{
				BoolExpr   *bexpr = (BoolExpr *) expr;

				/*
				 * Same as above, to handle either NOT or AND/OR.  We can't
				 * special-case NOT because of the way that it's used for
				 * things like IS NOT BETWEEN.
				 */
				loc = leftmostLoc(bexpr->location,
								  exprLocation((Node *) bexpr->args));
			}
			break;
		case T_SubLink:
			{
				SubLink *sublink = (SubLink *) expr;

				/* check the testexpr, if any, and the operator/keyword */
				loc = leftmostLoc(exprLocation(sublink->testexpr),
								  sublink->location);
			}
			break;
		case T_FieldSelect:
			/* just use argument's location */
			loc = exprLocation((Node *) ((FieldSelect *) expr)->arg);
			break;
		case T_FieldStore:
			/* just use argument's location */
			loc = exprLocation((Node *) ((FieldStore *) expr)->arg);
			break;
		case T_RelabelType:
			{
				RelabelType *rexpr = (RelabelType *) expr;

				/* Much as above */
				loc = leftmostLoc(rexpr->location,
								  exprLocation((Node *) rexpr->arg));
			}
			break;
		case T_CoerceViaIO:
			{
				CoerceViaIO *cexpr = (CoerceViaIO *) expr;

				/* Much as above */
				loc = leftmostLoc(cexpr->location,
								  exprLocation((Node *) cexpr->arg));
			}
			break;
		case T_ArrayCoerceExpr:
			{
				ArrayCoerceExpr *cexpr = (ArrayCoerceExpr *) expr;

				/* Much as above */
				loc = leftmostLoc(cexpr->location,
								  exprLocation((Node *) cexpr->arg));
			}
			break;
		case T_ConvertRowtypeExpr:
			{
				ConvertRowtypeExpr *cexpr = (ConvertRowtypeExpr *) expr;

				/* Much as above */
				loc = leftmostLoc(cexpr->location,
								  exprLocation((Node *) cexpr->arg));
			}
			break;
		case T_CaseExpr:
			/* CASE keyword should always be the first thing */
			loc = ((CaseExpr *) expr)->location;
			break;
		case T_CaseWhen:
			/* WHEN keyword should always be the first thing */
			loc = ((CaseWhen *) expr)->location;
			break;
		case T_ArrayExpr:
			/* the location points at ARRAY or [, which must be leftmost */
			loc = ((ArrayExpr *) expr)->location;
			break;
		case T_RowExpr:
			/* the location points at ROW or (, which must be leftmost */
			loc = ((RowExpr *) expr)->location;
			break;
		case T_RowCompareExpr:
			/* just use leftmost argument's location */
			loc = exprLocation((Node *) ((RowCompareExpr *) expr)->largs);
			break;
		case T_CoalesceExpr:
			/* COALESCE keyword should always be the first thing */
			loc = ((CoalesceExpr *) expr)->location;
			break;
		case T_MinMaxExpr:
			/* GREATEST/LEAST keyword should always be the first thing */
			loc = ((MinMaxExpr *) expr)->location;
			break;
		case T_XmlExpr:
			{
				XmlExpr   *xexpr = (XmlExpr *) expr;

				/* consider both function name and leftmost arg */
				loc = leftmostLoc(xexpr->location,
								  exprLocation((Node *) xexpr->args));
			}
			break;
		case T_NullTest:
			/* just use argument's location */
			loc = exprLocation((Node *) ((NullTest *) expr)->arg);
			break;
		case T_BooleanTest:
			/* just use argument's location */
			loc = exprLocation((Node *) ((BooleanTest *) expr)->arg);
			break;
		case T_CoerceToDomain:
			{
				CoerceToDomain *cexpr = (CoerceToDomain *) expr;

				/* Much as above */
				loc = leftmostLoc(cexpr->location,
								  exprLocation((Node *) cexpr->arg));
			}
			break;
		case T_CoerceToDomainValue:
			loc = ((CoerceToDomainValue *) expr)->location;
			break;
		case T_SetToDefault:
			loc = ((SetToDefault *) expr)->location;
			break;
		case T_TargetEntry:
			/* just use argument's location */
			loc = exprLocation((Node *) ((TargetEntry *) expr)->expr);
			break;
800 801 802 803
		case T_IntoClause:
			/* use the contained RangeVar's location --- close enough */
			loc = exprLocation((Node *) ((IntoClause *) expr)->rel);
			break;
804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866
		case T_List:
			{
				/* report location of first list member that has a location */
				ListCell   *lc;

				loc = -1;		/* just to suppress compiler warning */
				foreach(lc, (List *) expr)
				{
					loc = exprLocation((Node *) lfirst(lc));
					if (loc >= 0)
						break;
				}
			}
			break;
		case T_A_Expr:
			{
				A_Expr *aexpr = (A_Expr *) expr;

				/* use leftmost of operator or left operand (if any) */
				/* we assume right operand can't be to left of operator */
				loc = leftmostLoc(aexpr->location,
								  exprLocation(aexpr->lexpr));
			}
			break;
		case T_ColumnRef:
			loc = ((ColumnRef *) expr)->location;
			break;
		case T_ParamRef:
			loc = ((ParamRef *) expr)->location;
			break;
		case T_A_Const:
			loc = ((A_Const *) expr)->location;
			break;
		case T_FuncCall:
			{
				FuncCall *fc = (FuncCall *) expr;

				/* consider both function name and leftmost arg */
				loc = leftmostLoc(fc->location,
								  exprLocation((Node *) fc->args));
			}
			break;
		case T_A_ArrayExpr:
			/* the location points at ARRAY or [, which must be leftmost */
			loc = ((A_ArrayExpr *) expr)->location;
			break;
		case T_ResTarget:
			/* we need not examine the contained expression (if any) */
			loc = ((ResTarget *) expr)->location;
			break;
		case T_TypeCast:
			{
				TypeCast *tc = (TypeCast *) expr;

				/*
				 * This could represent CAST(), ::, or TypeName 'literal',
				 * so any of the components might be leftmost.
				 */
				loc = exprLocation(tc->arg);
				loc = leftmostLoc(loc, tc->typename->location);
				loc = leftmostLoc(loc, tc->location);
			}
			break;
867 868 869 870
		case T_SortBy:
			/* just use argument's location (ignore operator, if any) */
			loc = exprLocation(((SortBy *) expr)->node);
			break;
871 872 873 874 875 876 877
		case T_TypeName:
			loc = ((TypeName *) expr)->location;
			break;
		case T_XmlSerialize:
			/* XMLSERIALIZE keyword should always be the first thing */
			loc = ((XmlSerialize *) expr)->location;
			break;
878 879 880 881 882 883
		case T_WithClause:
			loc = ((WithClause *) expr)->location;
			break;
		case T_CommonTableExpr:
			loc = ((CommonTableExpr *) expr)->location;
			break;
884 885 886 887
		case T_PlaceHolderVar:
			/* just use argument's location */
			loc = exprLocation((Node *) ((PlaceHolderVar *) expr)->phexpr);
			break;
888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
		default:
			/* for any other node type it's just unknown... */
			loc = -1;
			break;
	}
	return loc;
}

/*
 * leftmostLoc - support for exprLocation
 *
 * Take the minimum of two parse location values, but ignore unknowns
 */
static int
leftmostLoc(int loc1, int loc2)
{
	if (loc1 < 0)
		return loc2;
	else if (loc2 < 0)
		return loc1;
	else
		return Min(loc1, loc2);
}


913
/*
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 * Standard expression-tree walking support
 *
 * We used to have near-duplicate code in many different routines that
 * understood how to recurse through an expression node tree.  That was
 * a pain to maintain, and we frequently had bugs due to some particular
 * routine neglecting to support a particular node type.  In most cases,
 * these routines only actually care about certain node types, and don't
 * care about other types except insofar as they have to recurse through
 * non-primitive node types.  Therefore, we now provide generic tree-walking
 * logic to consolidate the redundant "boilerplate" code.  There are
 * two versions: expression_tree_walker() and expression_tree_mutator().
 */

/*
 * expression_tree_walker() is designed to support routines that traverse
 * a tree in a read-only fashion (although it will also work for routines
 * that modify nodes in-place but never add/delete/replace nodes).
 * A walker routine should look like this:
 *
 * bool my_walker (Node *node, my_struct *context)
 * {
 *		if (node == NULL)
 *			return false;
 *		// check for nodes that special work is required for, eg:
 *		if (IsA(node, Var))
 *		{
 *			... do special actions for Var nodes
 *		}
 *		else if (IsA(node, ...))
 *		{
 *			... do special actions for other node types
 *		}
 *		// for any node type not specially processed, do:
 *		return expression_tree_walker(node, my_walker, (void *) context);
 * }
 *
 * The "context" argument points to a struct that holds whatever context
 * information the walker routine needs --- it can be used to return data
 * gathered by the walker, too.  This argument is not touched by
 * expression_tree_walker, but it is passed down to recursive sub-invocations
 * of my_walker.  The tree walk is started from a setup routine that
 * fills in the appropriate context struct, calls my_walker with the top-level
 * node of the tree, and then examines the results.
 *
 * The walker routine should return "false" to continue the tree walk, or
 * "true" to abort the walk and immediately return "true" to the top-level
 * caller.	This can be used to short-circuit the traversal if the walker
 * has found what it came for.	"false" is returned to the top-level caller
 * iff no invocation of the walker returned "true".
 *
 * The node types handled by expression_tree_walker include all those
 * normally found in target lists and qualifier clauses during the planning
 * stage.  In particular, it handles List nodes since a cnf-ified qual clause
 * will have List structure at the top level, and it handles TargetEntry nodes
 * so that a scan of a target list can be handled without additional code.
 * Also, RangeTblRef, FromExpr, JoinExpr, and SetOperationStmt nodes are
 * handled, so that query jointrees and setOperation trees can be processed
 * without additional code.
 *
 * expression_tree_walker will handle SubLink nodes by recursing normally
 * into the "testexpr" subtree (which is an expression belonging to the outer
 * plan).  It will also call the walker on the sub-Query node; however, when
 * expression_tree_walker itself is called on a Query node, it does nothing
 * and returns "false".  The net effect is that unless the walker does
 * something special at a Query node, sub-selects will not be visited during
 * an expression tree walk. This is exactly the behavior wanted in many cases
 * --- and for those walkers that do want to recurse into sub-selects, special
 * behavior is typically needed anyway at the entry to a sub-select (such as
 * incrementing a depth counter). A walker that wants to examine sub-selects
 * should include code along the lines of:
 *
 *		if (IsA(node, Query))
 *		{
 *			adjust context for subquery;
 *			result = query_tree_walker((Query *) node, my_walker, context,
 *									   0); // adjust flags as needed
 *			restore context if needed;
 *			return result;
 *		}
 *
 * query_tree_walker is a convenience routine (see below) that calls the
 * walker on all the expression subtrees of the given Query node.
 *
 * expression_tree_walker will handle SubPlan nodes by recursing normally
 * into the "testexpr" and the "args" list (which are expressions belonging to
 * the outer plan).  It will not touch the completed subplan, however.	Since
 * there is no link to the original Query, it is not possible to recurse into
 * subselects of an already-planned expression tree.  This is OK for current
 * uses, but may need to be revisited in future.
 */

bool
expression_tree_walker(Node *node,
					   bool (*walker) (),
					   void *context)
{
	ListCell   *temp;

	/*
	 * The walker has already visited the current node, and so we need only
	 * recurse into any sub-nodes it has.
	 *
	 * We assume that the walker is not interested in List nodes per se, so
	 * when we expect a List we just recurse directly to self without
	 * bothering to call the walker.
	 */
	if (node == NULL)
		return false;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	switch (nodeTag(node))
	{
		case T_Var:
		case T_Const:
		case T_Param:
		case T_CoerceToDomainValue:
		case T_CaseTestExpr:
		case T_SetToDefault:
		case T_CurrentOfExpr:
		case T_RangeTblRef:
			/* primitive node types with no expression subnodes */
			break;
		case T_Aggref:
			{
				Aggref	   *expr = (Aggref *) node;

				/* recurse directly on List */
				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_ArrayRef:
			{
				ArrayRef   *aref = (ArrayRef *) node;

				/* recurse directly for upper/lower array index lists */
				if (expression_tree_walker((Node *) aref->refupperindexpr,
										   walker, context))
					return true;
				if (expression_tree_walker((Node *) aref->reflowerindexpr,
										   walker, context))
					return true;
				/* walker must see the refexpr and refassgnexpr, however */
				if (walker(aref->refexpr, context))
					return true;
				if (walker(aref->refassgnexpr, context))
					return true;
			}
			break;
		case T_FuncExpr:
			{
				FuncExpr   *expr = (FuncExpr *) node;

				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_OpExpr:
			{
				OpExpr	   *expr = (OpExpr *) node;

				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_DistinctExpr:
			{
				DistinctExpr *expr = (DistinctExpr *) node;

				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_ScalarArrayOpExpr:
			{
				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;

				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_BoolExpr:
			{
				BoolExpr   *expr = (BoolExpr *) node;

				if (expression_tree_walker((Node *) expr->args,
										   walker, context))
					return true;
			}
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) node;

				if (walker(sublink->testexpr, context))
					return true;

				/*
				 * Also invoke the walker on the sublink's Query node, so it
				 * can recurse into the sub-query if it wants to.
				 */
				return walker(sublink->subselect, context);
			}
			break;
		case T_SubPlan:
			{
				SubPlan    *subplan = (SubPlan *) node;

				/* recurse into the testexpr, but not into the Plan */
				if (walker(subplan->testexpr, context))
					return true;
				/* also examine args list */
				if (expression_tree_walker((Node *) subplan->args,
										   walker, context))
					return true;
			}
			break;
		case T_AlternativeSubPlan:
			return walker(((AlternativeSubPlan *) node)->subplans, context);
		case T_FieldSelect:
			return walker(((FieldSelect *) node)->arg, context);
		case T_FieldStore:
			{
				FieldStore *fstore = (FieldStore *) node;

				if (walker(fstore->arg, context))
					return true;
				if (walker(fstore->newvals, context))
					return true;
			}
			break;
		case T_RelabelType:
			return walker(((RelabelType *) node)->arg, context);
		case T_CoerceViaIO:
			return walker(((CoerceViaIO *) node)->arg, context);
		case T_ArrayCoerceExpr:
			return walker(((ArrayCoerceExpr *) node)->arg, context);
		case T_ConvertRowtypeExpr:
			return walker(((ConvertRowtypeExpr *) node)->arg, context);
		case T_CaseExpr:
			{
				CaseExpr   *caseexpr = (CaseExpr *) node;

				if (walker(caseexpr->arg, context))
					return true;
				/* we assume walker doesn't care about CaseWhens, either */
				foreach(temp, caseexpr->args)
				{
					CaseWhen   *when = (CaseWhen *) lfirst(temp);

					Assert(IsA(when, CaseWhen));
					if (walker(when->expr, context))
						return true;
					if (walker(when->result, context))
						return true;
				}
				if (walker(caseexpr->defresult, context))
					return true;
			}
			break;
		case T_ArrayExpr:
			return walker(((ArrayExpr *) node)->elements, context);
		case T_RowExpr:
1184
			/* Assume colnames isn't interesting */
1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223
			return walker(((RowExpr *) node)->args, context);
		case T_RowCompareExpr:
			{
				RowCompareExpr *rcexpr = (RowCompareExpr *) node;

				if (walker(rcexpr->largs, context))
					return true;
				if (walker(rcexpr->rargs, context))
					return true;
			}
			break;
		case T_CoalesceExpr:
			return walker(((CoalesceExpr *) node)->args, context);
		case T_MinMaxExpr:
			return walker(((MinMaxExpr *) node)->args, context);
		case T_XmlExpr:
			{
				XmlExpr    *xexpr = (XmlExpr *) node;

				if (walker(xexpr->named_args, context))
					return true;
				/* we assume walker doesn't care about arg_names */
				if (walker(xexpr->args, context))
					return true;
			}
			break;
		case T_NullIfExpr:
			return walker(((NullIfExpr *) node)->args, context);
		case T_NullTest:
			return walker(((NullTest *) node)->arg, context);
		case T_BooleanTest:
			return walker(((BooleanTest *) node)->arg, context);
		case T_CoerceToDomain:
			return walker(((CoerceToDomain *) node)->arg, context);
		case T_TargetEntry:
			return walker(((TargetEntry *) node)->expr, context);
		case T_Query:
			/* Do nothing with a sub-Query, per discussion above */
			break;
1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234
		case T_CommonTableExpr:
			{
				CommonTableExpr *cte = (CommonTableExpr *) node;

				/*
				 * Invoke the walker on the CTE's Query node, so it
				 * can recurse into the sub-query if it wants to.
				 */
				return walker(cte->ctequery, context);
			}
			break;
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		case T_List:
			foreach(temp, (List *) node)
			{
				if (walker((Node *) lfirst(temp), context))
					return true;
			}
			break;
		case T_FromExpr:
			{
				FromExpr   *from = (FromExpr *) node;

				if (walker(from->fromlist, context))
					return true;
				if (walker(from->quals, context))
					return true;
			}
			break;
		case T_JoinExpr:
			{
				JoinExpr   *join = (JoinExpr *) node;

				if (walker(join->larg, context))
					return true;
				if (walker(join->rarg, context))
					return true;
				if (walker(join->quals, context))
					return true;

				/*
				 * alias clause, using list are deemed uninteresting.
				 */
			}
			break;
		case T_SetOperationStmt:
			{
				SetOperationStmt *setop = (SetOperationStmt *) node;

				if (walker(setop->larg, context))
					return true;
				if (walker(setop->rarg, context))
					return true;

				/* groupClauses are deemed uninteresting */
			}
			break;
		case T_FlattenedSubLink:
			{
				FlattenedSubLink *fslink = (FlattenedSubLink *) node;

1284
				if (walker(fslink->quals, context))
1285 1286 1287
					return true;
			}
			break;
1288 1289
		case T_PlaceHolderVar:
			return walker(((PlaceHolderVar *) node)->phexpr, context);
1290 1291 1292 1293 1294 1295 1296 1297 1298
		case T_AppendRelInfo:
			{
				AppendRelInfo *appinfo = (AppendRelInfo *) node;

				if (expression_tree_walker((Node *) appinfo->translated_vars,
										   walker, context))
					return true;
			}
			break;
1299 1300
		case T_PlaceHolderInfo:
			return walker(((PlaceHolderInfo *) node)->ph_var, context);
1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316
		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(node));
			break;
	}
	return false;
}

/*
 * query_tree_walker --- initiate a walk of a Query's expressions
 *
 * This routine exists just to reduce the number of places that need to know
 * where all the expression subtrees of a Query are.  Note it can be used
 * for starting a walk at top level of a Query regardless of whether the
 * walker intends to descend into subqueries.  It is also useful for
 * descending into subqueries within a walker.
1317
 *
1318 1319 1320 1321 1322
 * Some callers want to suppress visitation of certain items in the sub-Query,
 * typically because they need to process them specially, or don't actually
 * want to recurse into subqueries.  This is supported by the flags argument,
 * which is the bitwise OR of flag values to suppress visitation of
 * indicated items.  (More flag bits may be added as needed.)
1323 1324
 */
bool
1325 1326 1327 1328
query_tree_walker(Query *query,
				  bool (*walker) (),
				  void *context,
				  int flags)
1329
{
1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345
	Assert(query != NULL && IsA(query, Query));

	if (walker((Node *) query->targetList, context))
		return true;
	if (walker((Node *) query->returningList, context))
		return true;
	if (walker((Node *) query->jointree, context))
		return true;
	if (walker(query->setOperations, context))
		return true;
	if (walker(query->havingQual, context))
		return true;
	if (walker(query->limitOffset, context))
		return true;
	if (walker(query->limitCount, context))
		return true;
1346 1347 1348 1349 1350
	if (!(flags & QTW_IGNORE_CTE_SUBQUERIES))
	{
		if (walker((Node *) query->cteList, context))
			return true;
	}
1351 1352 1353
	if (range_table_walker(query->rtable, walker, context, flags))
		return true;
	return false;
1354 1355
}

1356 1357 1358 1359 1360 1361 1362 1363 1364 1365
/*
 * range_table_walker is just the part of query_tree_walker that scans
 * a query's rangetable.  This is split out since it can be useful on
 * its own.
 */
bool
range_table_walker(List *rtable,
				   bool (*walker) (),
				   void *context,
				   int flags)
1366
{
1367 1368 1369 1370 1371 1372
	ListCell   *rt;

	foreach(rt, rtable)
	{
		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);

1373 1374 1375 1376 1377
		/* For historical reasons, visiting RTEs is not the default */
		if (flags & QTW_EXAMINE_RTES)
			if (walker(rte, context))
				return true;

1378 1379 1380 1381
		switch (rte->rtekind)
		{
			case RTE_RELATION:
			case RTE_SPECIAL:
1382
 			case RTE_CTE:
1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405
				/* nothing to do */
				break;
			case RTE_SUBQUERY:
				if (!(flags & QTW_IGNORE_RT_SUBQUERIES))
					if (walker(rte->subquery, context))
						return true;
				break;
			case RTE_JOIN:
				if (!(flags & QTW_IGNORE_JOINALIASES))
					if (walker(rte->joinaliasvars, context))
						return true;
				break;
			case RTE_FUNCTION:
				if (walker(rte->funcexpr, context))
					return true;
				break;
			case RTE_VALUES:
				if (walker(rte->values_lists, context))
					return true;
				break;
		}
	}
	return false;
1406 1407
}

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/*
 * expression_tree_mutator() is designed to support routines that make a
 * modified copy of an expression tree, with some nodes being added,
 * removed, or replaced by new subtrees.  The original tree is (normally)
 * not changed.  Each recursion level is responsible for returning a copy of
 * (or appropriately modified substitute for) the subtree it is handed.
 * A mutator routine should look like this:
 *
 * Node * my_mutator (Node *node, my_struct *context)
 * {
 *		if (node == NULL)
 *			return NULL;
 *		// check for nodes that special work is required for, eg:
 *		if (IsA(node, Var))
 *		{
 *			... create and return modified copy of Var node
 *		}
 *		else if (IsA(node, ...))
 *		{
 *			... do special transformations of other node types
 *		}
 *		// for any node type not specially processed, do:
 *		return expression_tree_mutator(node, my_mutator, (void *) context);
 * }
 *
 * The "context" argument points to a struct that holds whatever context
 * information the mutator routine needs --- it can be used to return extra
 * data gathered by the mutator, too.  This argument is not touched by
 * expression_tree_mutator, but it is passed down to recursive sub-invocations
 * of my_mutator.  The tree walk is started from a setup routine that
 * fills in the appropriate context struct, calls my_mutator with the
 * top-level node of the tree, and does any required post-processing.
 *
 * Each level of recursion must return an appropriately modified Node.
 * If expression_tree_mutator() is called, it will make an exact copy
 * of the given Node, but invoke my_mutator() to copy the sub-node(s)
 * of that Node.  In this way, my_mutator() has full control over the
 * copying process but need not directly deal with expression trees
 * that it has no interest in.
 *
 * Just as for expression_tree_walker, the node types handled by
 * expression_tree_mutator include all those normally found in target lists
 * and qualifier clauses during the planning stage.
 *
 * expression_tree_mutator will handle SubLink nodes by recursing normally
 * into the "testexpr" subtree (which is an expression belonging to the outer
 * plan).  It will also call the mutator on the sub-Query node; however, when
 * expression_tree_mutator itself is called on a Query node, it does nothing
 * and returns the unmodified Query node.  The net effect is that unless the
 * mutator does something special at a Query node, sub-selects will not be
 * visited or modified; the original sub-select will be linked to by the new
 * SubLink node.  Mutators that want to descend into sub-selects will usually
 * do so by recognizing Query nodes and calling query_tree_mutator (below).
 *
 * expression_tree_mutator will handle a SubPlan node by recursing into the
 * "testexpr" and the "args" list (which belong to the outer plan), but it
 * will simply copy the link to the inner plan, since that's typically what
 * expression tree mutators want.  A mutator that wants to modify the subplan
 * can force appropriate behavior by recognizing SubPlan expression nodes
 * and doing the right thing.
 */

Node *
expression_tree_mutator(Node *node,
						Node *(*mutator) (),
						void *context)
{
	/*
	 * The mutator has already decided not to modify the current node, but we
	 * must call the mutator for any sub-nodes.
	 */

#define FLATCOPY(newnode, node, nodetype)  \
	( (newnode) = (nodetype *) palloc(sizeof(nodetype)), \
	  memcpy((newnode), (node), sizeof(nodetype)) )

#define CHECKFLATCOPY(newnode, node, nodetype)	\
	( AssertMacro(IsA((node), nodetype)), \
	  (newnode) = (nodetype *) palloc(sizeof(nodetype)), \
	  memcpy((newnode), (node), sizeof(nodetype)) )

#define MUTATE(newfield, oldfield, fieldtype)  \
		( (newfield) = (fieldtype) mutator((Node *) (oldfield), context) )

	if (node == NULL)
		return NULL;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	switch (nodeTag(node))
	{
			/*
			 * Primitive node types with no expression subnodes.  Var and
			 * Const are frequent enough to deserve special cases, the others
			 * we just use copyObject for.
			 */
		case T_Var:
			{
				Var		   *var = (Var *) node;
				Var		   *newnode;

				FLATCOPY(newnode, var, Var);
				return (Node *) newnode;
			}
			break;
		case T_Const:
			{
				Const	   *oldnode = (Const *) node;
				Const	   *newnode;

				FLATCOPY(newnode, oldnode, Const);
				/* XXX we don't bother with datumCopy; should we? */
				return (Node *) newnode;
			}
			break;
		case T_Param:
		case T_CoerceToDomainValue:
		case T_CaseTestExpr:
		case T_SetToDefault:
		case T_CurrentOfExpr:
		case T_RangeTblRef:
			return (Node *) copyObject(node);
		case T_Aggref:
			{
				Aggref	   *aggref = (Aggref *) node;
				Aggref	   *newnode;

				FLATCOPY(newnode, aggref, Aggref);
				MUTATE(newnode->args, aggref->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_ArrayRef:
			{
				ArrayRef   *arrayref = (ArrayRef *) node;
				ArrayRef   *newnode;

				FLATCOPY(newnode, arrayref, ArrayRef);
				MUTATE(newnode->refupperindexpr, arrayref->refupperindexpr,
					   List *);
				MUTATE(newnode->reflowerindexpr, arrayref->reflowerindexpr,
					   List *);
				MUTATE(newnode->refexpr, arrayref->refexpr,
					   Expr *);
				MUTATE(newnode->refassgnexpr, arrayref->refassgnexpr,
					   Expr *);
				return (Node *) newnode;
			}
			break;
		case T_FuncExpr:
			{
				FuncExpr   *expr = (FuncExpr *) node;
				FuncExpr   *newnode;

				FLATCOPY(newnode, expr, FuncExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_OpExpr:
			{
				OpExpr	   *expr = (OpExpr *) node;
				OpExpr	   *newnode;

				FLATCOPY(newnode, expr, OpExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_DistinctExpr:
			{
				DistinctExpr *expr = (DistinctExpr *) node;
				DistinctExpr *newnode;

				FLATCOPY(newnode, expr, DistinctExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_ScalarArrayOpExpr:
			{
				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
				ScalarArrayOpExpr *newnode;

				FLATCOPY(newnode, expr, ScalarArrayOpExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_BoolExpr:
			{
				BoolExpr   *expr = (BoolExpr *) node;
				BoolExpr   *newnode;

				FLATCOPY(newnode, expr, BoolExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) node;
				SubLink    *newnode;

				FLATCOPY(newnode, sublink, SubLink);
				MUTATE(newnode->testexpr, sublink->testexpr, Node *);

				/*
				 * Also invoke the mutator on the sublink's Query node, so it
				 * can recurse into the sub-query if it wants to.
				 */
				MUTATE(newnode->subselect, sublink->subselect, Node *);
				return (Node *) newnode;
			}
			break;
		case T_SubPlan:
			{
				SubPlan    *subplan = (SubPlan *) node;
				SubPlan    *newnode;

				FLATCOPY(newnode, subplan, SubPlan);
				/* transform testexpr */
				MUTATE(newnode->testexpr, subplan->testexpr, Node *);
				/* transform args list (params to be passed to subplan) */
				MUTATE(newnode->args, subplan->args, List *);
				/* but not the sub-Plan itself, which is referenced as-is */
				return (Node *) newnode;
			}
			break;
		case T_AlternativeSubPlan:
			{
				AlternativeSubPlan *asplan = (AlternativeSubPlan *) node;
				AlternativeSubPlan *newnode;

				FLATCOPY(newnode, asplan, AlternativeSubPlan);
				MUTATE(newnode->subplans, asplan->subplans, List *);
				return (Node *) newnode;
			}
			break;
		case T_FieldSelect:
			{
				FieldSelect *fselect = (FieldSelect *) node;
				FieldSelect *newnode;

				FLATCOPY(newnode, fselect, FieldSelect);
				MUTATE(newnode->arg, fselect->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_FieldStore:
			{
				FieldStore *fstore = (FieldStore *) node;
				FieldStore *newnode;

				FLATCOPY(newnode, fstore, FieldStore);
				MUTATE(newnode->arg, fstore->arg, Expr *);
				MUTATE(newnode->newvals, fstore->newvals, List *);
				newnode->fieldnums = list_copy(fstore->fieldnums);
				return (Node *) newnode;
			}
			break;
		case T_RelabelType:
			{
				RelabelType *relabel = (RelabelType *) node;
				RelabelType *newnode;

				FLATCOPY(newnode, relabel, RelabelType);
				MUTATE(newnode->arg, relabel->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_CoerceViaIO:
			{
				CoerceViaIO *iocoerce = (CoerceViaIO *) node;
				CoerceViaIO *newnode;

				FLATCOPY(newnode, iocoerce, CoerceViaIO);
				MUTATE(newnode->arg, iocoerce->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_ArrayCoerceExpr:
			{
				ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node;
				ArrayCoerceExpr *newnode;

				FLATCOPY(newnode, acoerce, ArrayCoerceExpr);
				MUTATE(newnode->arg, acoerce->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_ConvertRowtypeExpr:
			{
				ConvertRowtypeExpr *convexpr = (ConvertRowtypeExpr *) node;
				ConvertRowtypeExpr *newnode;

				FLATCOPY(newnode, convexpr, ConvertRowtypeExpr);
				MUTATE(newnode->arg, convexpr->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_CaseExpr:
			{
				CaseExpr   *caseexpr = (CaseExpr *) node;
				CaseExpr   *newnode;

				FLATCOPY(newnode, caseexpr, CaseExpr);
				MUTATE(newnode->arg, caseexpr->arg, Expr *);
				MUTATE(newnode->args, caseexpr->args, List *);
				MUTATE(newnode->defresult, caseexpr->defresult, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_CaseWhen:
			{
				CaseWhen   *casewhen = (CaseWhen *) node;
				CaseWhen   *newnode;

				FLATCOPY(newnode, casewhen, CaseWhen);
				MUTATE(newnode->expr, casewhen->expr, Expr *);
				MUTATE(newnode->result, casewhen->result, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_ArrayExpr:
			{
				ArrayExpr  *arrayexpr = (ArrayExpr *) node;
				ArrayExpr  *newnode;

				FLATCOPY(newnode, arrayexpr, ArrayExpr);
				MUTATE(newnode->elements, arrayexpr->elements, List *);
				return (Node *) newnode;
			}
			break;
		case T_RowExpr:
			{
				RowExpr    *rowexpr = (RowExpr *) node;
				RowExpr    *newnode;

				FLATCOPY(newnode, rowexpr, RowExpr);
				MUTATE(newnode->args, rowexpr->args, List *);
1751
				/* Assume colnames needn't be duplicated */
1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850
				return (Node *) newnode;
			}
			break;
		case T_RowCompareExpr:
			{
				RowCompareExpr *rcexpr = (RowCompareExpr *) node;
				RowCompareExpr *newnode;

				FLATCOPY(newnode, rcexpr, RowCompareExpr);
				MUTATE(newnode->largs, rcexpr->largs, List *);
				MUTATE(newnode->rargs, rcexpr->rargs, List *);
				return (Node *) newnode;
			}
			break;
		case T_CoalesceExpr:
			{
				CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
				CoalesceExpr *newnode;

				FLATCOPY(newnode, coalesceexpr, CoalesceExpr);
				MUTATE(newnode->args, coalesceexpr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_MinMaxExpr:
			{
				MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
				MinMaxExpr *newnode;

				FLATCOPY(newnode, minmaxexpr, MinMaxExpr);
				MUTATE(newnode->args, minmaxexpr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_XmlExpr:
			{
				XmlExpr    *xexpr = (XmlExpr *) node;
				XmlExpr    *newnode;

				FLATCOPY(newnode, xexpr, XmlExpr);
				MUTATE(newnode->named_args, xexpr->named_args, List *);
				/* assume mutator does not care about arg_names */
				MUTATE(newnode->args, xexpr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_NullIfExpr:
			{
				NullIfExpr *expr = (NullIfExpr *) node;
				NullIfExpr *newnode;

				FLATCOPY(newnode, expr, NullIfExpr);
				MUTATE(newnode->args, expr->args, List *);
				return (Node *) newnode;
			}
			break;
		case T_NullTest:
			{
				NullTest   *ntest = (NullTest *) node;
				NullTest   *newnode;

				FLATCOPY(newnode, ntest, NullTest);
				MUTATE(newnode->arg, ntest->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_BooleanTest:
			{
				BooleanTest *btest = (BooleanTest *) node;
				BooleanTest *newnode;

				FLATCOPY(newnode, btest, BooleanTest);
				MUTATE(newnode->arg, btest->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_CoerceToDomain:
			{
				CoerceToDomain *ctest = (CoerceToDomain *) node;
				CoerceToDomain *newnode;

				FLATCOPY(newnode, ctest, CoerceToDomain);
				MUTATE(newnode->arg, ctest->arg, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_TargetEntry:
			{
				TargetEntry *targetentry = (TargetEntry *) node;
				TargetEntry *newnode;

				FLATCOPY(newnode, targetentry, TargetEntry);
				MUTATE(newnode->expr, targetentry->expr, Expr *);
				return (Node *) newnode;
			}
			break;
		case T_Query:
			/* Do nothing with a sub-Query, per discussion above */
			return node;
1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865
		case T_CommonTableExpr:
			{
				CommonTableExpr *cte = (CommonTableExpr *) node;
				CommonTableExpr *newnode;

				FLATCOPY(newnode, cte, CommonTableExpr);

				/*
				 * Also invoke the mutator on the CTE's Query node, so it
				 * can recurse into the sub-query if it wants to.
				 */
				MUTATE(newnode->ctequery, cte->ctequery, Node *);
				return (Node *) newnode;
			}
			break;
1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932
		case T_List:
			{
				/*
				 * We assume the mutator isn't interested in the list nodes
				 * per se, so just invoke it on each list element. NOTE: this
				 * would fail badly on a list with integer elements!
				 */
				List	   *resultlist;
				ListCell   *temp;

				resultlist = NIL;
				foreach(temp, (List *) node)
				{
					resultlist = lappend(resultlist,
										 mutator((Node *) lfirst(temp),
												 context));
				}
				return (Node *) resultlist;
			}
			break;
		case T_FromExpr:
			{
				FromExpr   *from = (FromExpr *) node;
				FromExpr   *newnode;

				FLATCOPY(newnode, from, FromExpr);
				MUTATE(newnode->fromlist, from->fromlist, List *);
				MUTATE(newnode->quals, from->quals, Node *);
				return (Node *) newnode;
			}
			break;
		case T_JoinExpr:
			{
				JoinExpr   *join = (JoinExpr *) node;
				JoinExpr   *newnode;

				FLATCOPY(newnode, join, JoinExpr);
				MUTATE(newnode->larg, join->larg, Node *);
				MUTATE(newnode->rarg, join->rarg, Node *);
				MUTATE(newnode->quals, join->quals, Node *);
				/* We do not mutate alias or using by default */
				return (Node *) newnode;
			}
			break;
		case T_SetOperationStmt:
			{
				SetOperationStmt *setop = (SetOperationStmt *) node;
				SetOperationStmt *newnode;

				FLATCOPY(newnode, setop, SetOperationStmt);
				MUTATE(newnode->larg, setop->larg, Node *);
				MUTATE(newnode->rarg, setop->rarg, Node *);
				/* We do not mutate groupClauses by default */
				return (Node *) newnode;
			}
			break;
		case T_FlattenedSubLink:
			{
				FlattenedSubLink *fslink = (FlattenedSubLink *) node;
				FlattenedSubLink *newnode;

				FLATCOPY(newnode, fslink, FlattenedSubLink);
				/* Assume we need not copy the relids bitmapsets */
				MUTATE(newnode->quals, fslink->quals, Expr *);
				return (Node *) newnode;
			}
			break;
1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943
		case T_PlaceHolderVar:
			{
				PlaceHolderVar *phv = (PlaceHolderVar *) node;
				PlaceHolderVar *newnode;

				FLATCOPY(newnode, phv, PlaceHolderVar);
				MUTATE(newnode->phexpr, phv->phexpr, Expr *);
				/* Assume we need not copy the relids bitmapset */
				return (Node *) newnode;
			}
			break;
1944 1945 1946 1947 1948 1949 1950 1951 1952 1953
		case T_AppendRelInfo:
			{
				AppendRelInfo *appinfo = (AppendRelInfo *) node;
				AppendRelInfo *newnode;

				FLATCOPY(newnode, appinfo, AppendRelInfo);
				MUTATE(newnode->translated_vars, appinfo->translated_vars, List *);
				return (Node *) newnode;
			}
			break;
1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964
		case T_PlaceHolderInfo:
			{
				PlaceHolderInfo *phinfo = (PlaceHolderInfo *) node;
				PlaceHolderInfo *newnode;

				FLATCOPY(newnode, phinfo, PlaceHolderInfo);
				MUTATE(newnode->ph_var, phinfo->ph_var, PlaceHolderVar *);
				/* Assume we need not copy the relids bitmapsets */
				return (Node *) newnode;
			}
			break;
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		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(node));
			break;
	}
	/* can't get here, but keep compiler happy */
	return NULL;
}


/*
 * query_tree_mutator --- initiate modification of a Query's expressions
 *
 * This routine exists just to reduce the number of places that need to know
 * where all the expression subtrees of a Query are.  Note it can be used
 * for starting a walk at top level of a Query regardless of whether the
 * mutator intends to descend into subqueries.	It is also useful for
 * descending into subqueries within a mutator.
 *
 * Some callers want to suppress mutating of certain items in the Query,
 * typically because they need to process them specially, or don't actually
 * want to recurse into subqueries.  This is supported by the flags argument,
 * which is the bitwise OR of flag values to suppress mutating of
 * indicated items.  (More flag bits may be added as needed.)
 *
 * Normally the Query node itself is copied, but some callers want it to be
 * modified in-place; they must pass QTW_DONT_COPY_QUERY in flags.	All
 * modified substructure is safely copied in any case.
 */
Query *
query_tree_mutator(Query *query,
				   Node *(*mutator) (),
				   void *context,
				   int flags)
{
	Assert(query != NULL && IsA(query, Query));

	if (!(flags & QTW_DONT_COPY_QUERY))
	{
		Query	   *newquery;

		FLATCOPY(newquery, query, Query);
		query = newquery;
	}

	MUTATE(query->targetList, query->targetList, List *);
	MUTATE(query->returningList, query->returningList, List *);
	MUTATE(query->jointree, query->jointree, FromExpr *);
	MUTATE(query->setOperations, query->setOperations, Node *);
	MUTATE(query->havingQual, query->havingQual, Node *);
	MUTATE(query->limitOffset, query->limitOffset, Node *);
	MUTATE(query->limitCount, query->limitCount, Node *);
2017 2018 2019 2020
	if (!(flags & QTW_IGNORE_CTE_SUBQUERIES))
		MUTATE(query->cteList, query->cteList, List *);
	else						/* else copy CTE list as-is */
		query->cteList = copyObject(query->cteList);
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	query->rtable = range_table_mutator(query->rtable,
										mutator, context, flags);
	return query;
}

/*
 * range_table_mutator is just the part of query_tree_mutator that processes
 * a query's rangetable.  This is split out since it can be useful on
 * its own.
 */
List *
range_table_mutator(List *rtable,
					Node *(*mutator) (),
					void *context,
					int flags)
{
	List	   *newrt = NIL;
	ListCell   *rt;

	foreach(rt, rtable)
	{
		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
		RangeTblEntry *newrte;

		FLATCOPY(newrte, rte, RangeTblEntry);
		switch (rte->rtekind)
		{
			case RTE_RELATION:
			case RTE_SPECIAL:
2050
			case RTE_CTE:
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				/* we don't bother to copy eref, aliases, etc; OK? */
				break;
			case RTE_SUBQUERY:
				if (!(flags & QTW_IGNORE_RT_SUBQUERIES))
				{
					CHECKFLATCOPY(newrte->subquery, rte->subquery, Query);
					MUTATE(newrte->subquery, newrte->subquery, Query *);
				}
				else
				{
					/* else, copy RT subqueries as-is */
					newrte->subquery = copyObject(rte->subquery);
				}
				break;
			case RTE_JOIN:
				if (!(flags & QTW_IGNORE_JOINALIASES))
					MUTATE(newrte->joinaliasvars, rte->joinaliasvars, List *);
				else
				{
					/* else, copy join aliases as-is */
					newrte->joinaliasvars = copyObject(rte->joinaliasvars);
				}
				break;
			case RTE_FUNCTION:
				MUTATE(newrte->funcexpr, rte->funcexpr, Node *);
				break;
			case RTE_VALUES:
				MUTATE(newrte->values_lists, rte->values_lists, List *);
				break;
		}
		newrt = lappend(newrt, newrte);
	}
	return newrt;
}

/*
 * query_or_expression_tree_walker --- hybrid form
 *
 * This routine will invoke query_tree_walker if called on a Query node,
 * else will invoke the walker directly.  This is a useful way of starting
 * the recursion when the walker's normal change of state is not appropriate
 * for the outermost Query node.
 */
2094
bool
2095 2096 2097 2098
query_or_expression_tree_walker(Node *node,
								bool (*walker) (),
								void *context,
								int flags)
2099
{
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	if (node && IsA(node, Query))
		return query_tree_walker((Query *) node,
								 walker,
								 context,
								 flags);
	else
		return walker(node, context);
}

/*
 * query_or_expression_tree_mutator --- hybrid form
 *
 * This routine will invoke query_tree_mutator if called on a Query node,
 * else will invoke the mutator directly.  This is a useful way of starting
 * the recursion when the mutator's normal change of state is not appropriate
 * for the outermost Query node.
 */
Node *
query_or_expression_tree_mutator(Node *node,
								 Node *(*mutator) (),
								 void *context,
								 int flags)
{
	if (node && IsA(node, Query))
		return (Node *) query_tree_mutator((Query *) node,
										   mutator,
										   context,
										   flags);
	else
		return mutator(node, context);
2130
}
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/*
 * raw_expression_tree_walker --- walk raw parse trees
 *
 * This has exactly the same API as expression_tree_walker, but instead of
 * walking post-analysis parse trees, it knows how to walk the node types
 * found in raw grammar output.  (There is not currently any need for a
 * combined walker, so we keep them separate in the name of efficiency.)
 * Unlike expression_tree_walker, there is no special rule about query
 * boundaries: we descend to everything that's possibly interesting.
 *
 * Currently, the node type coverage extends to SelectStmt and everything
 * that could appear under it, but not other statement types.
 */
bool
raw_expression_tree_walker(Node *node, bool (*walker) (), void *context)
{
	ListCell   *temp;

	/*
	 * The walker has already visited the current node, and so we need only
	 * recurse into any sub-nodes it has.
	 */
	if (node == NULL)
		return false;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	switch (nodeTag(node))
	{
		case T_SetToDefault:
		case T_CurrentOfExpr:
		case T_Integer:
		case T_Float:
		case T_String:
		case T_BitString:
		case T_Null:
		case T_ParamRef:
		case T_A_Const:
		case T_A_Star:
			/* primitive node types with no subnodes */
			break;
		case T_Alias:
			/* we assume the colnames list isn't interesting */
			break;
		case T_RangeVar:
			return walker(((RangeVar *) node)->alias, context);
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) node;

				if (walker(sublink->testexpr, context))
					return true;
				/* we assume the operName is not interesting */
				if (walker(sublink->subselect, context))
					return true;
			}
			break;
		case T_CaseExpr:
			{
				CaseExpr   *caseexpr = (CaseExpr *) node;

				if (walker(caseexpr->arg, context))
					return true;
				/* we assume walker doesn't care about CaseWhens, either */
				foreach(temp, caseexpr->args)
				{
					CaseWhen   *when = (CaseWhen *) lfirst(temp);

					Assert(IsA(when, CaseWhen));
					if (walker(when->expr, context))
						return true;
					if (walker(when->result, context))
						return true;
				}
				if (walker(caseexpr->defresult, context))
					return true;
			}
			break;
		case T_RowExpr:
2213
			/* Assume colnames isn't interesting */
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			return walker(((RowExpr *) node)->args, context);
		case T_CoalesceExpr:
			return walker(((CoalesceExpr *) node)->args, context);
		case T_MinMaxExpr:
			return walker(((MinMaxExpr *) node)->args, context);
		case T_XmlExpr:
			{
				XmlExpr    *xexpr = (XmlExpr *) node;

				if (walker(xexpr->named_args, context))
					return true;
				/* we assume walker doesn't care about arg_names */
				if (walker(xexpr->args, context))
					return true;
			}
			break;
		case T_NullTest:
			return walker(((NullTest *) node)->arg, context);
		case T_BooleanTest:
			return walker(((BooleanTest *) node)->arg, context);
		case T_JoinExpr:
			{
				JoinExpr   *join = (JoinExpr *) node;

				if (walker(join->larg, context))
					return true;
				if (walker(join->rarg, context))
					return true;
				if (walker(join->quals, context))
					return true;
				if (walker(join->alias, context))
					return true;
				/* using list is deemed uninteresting */
			}
			break;
		case T_IntoClause:
			{
				IntoClause *into = (IntoClause *) node;

				if (walker(into->rel, context))
					return true;
				/* colNames, options are deemed uninteresting */
			}
			break;
		case T_List:
			foreach(temp, (List *) node)
			{
				if (walker((Node *) lfirst(temp), context))
					return true;
			}
			break;
		case T_SelectStmt:
			{
				SelectStmt *stmt = (SelectStmt *) node;

				if (walker(stmt->distinctClause, context))
					return true;
				if (walker(stmt->intoClause, context))
					return true;
				if (walker(stmt->targetList, context))
					return true;
				if (walker(stmt->fromClause, context))
					return true;
				if (walker(stmt->whereClause, context))
					return true;
				if (walker(stmt->groupClause, context))
					return true;
				if (walker(stmt->havingClause, context))
					return true;
				if (walker(stmt->withClause, context))
					return true;
				if (walker(stmt->valuesLists, context))
					return true;
				if (walker(stmt->sortClause, context))
					return true;
				if (walker(stmt->limitOffset, context))
					return true;
				if (walker(stmt->limitCount, context))
					return true;
				if (walker(stmt->lockingClause, context))
					return true;
				if (walker(stmt->larg, context))
					return true;
				if (walker(stmt->rarg, context))
					return true;
			}
			break;
		case T_A_Expr:
			{
				A_Expr *expr = (A_Expr *) node;

				if (walker(expr->lexpr, context))
					return true;
				if (walker(expr->rexpr, context))
					return true;
				/* operator name is deemed uninteresting */
			}
			break;
		case T_ColumnRef:
			/* we assume the fields contain nothing interesting */
			break;
		case T_FuncCall:
			{
				FuncCall *fcall = (FuncCall *) node;

				if (walker(fcall->args, context))
					return true;
				/* function name is deemed uninteresting */
			}
			break;
		case T_A_Indices:
			{
				A_Indices *indices = (A_Indices *) node;

				if (walker(indices->lidx, context))
					return true;
				if (walker(indices->uidx, context))
					return true;
			}
			break;
		case T_A_Indirection:
			{
				A_Indirection *indir = (A_Indirection *) node;

				if (walker(indir->arg, context))
					return true;
				if (walker(indir->indirection, context))
					return true;
			}
			break;
		case T_A_ArrayExpr:
			return walker(((A_ArrayExpr *) node)->elements, context);
		case T_ResTarget:
			{
				ResTarget *rt = (ResTarget *) node;

				if (walker(rt->indirection, context))
					return true;
				if (walker(rt->val, context))
					return true;
			}
			break;
		case T_TypeCast:
			{
				TypeCast *tc = (TypeCast *) node;

				if (walker(tc->arg, context))
					return true;
				if (walker(tc->typename, context))
					return true;
			}
			break;
		case T_SortBy:
			return walker(((SortBy *) node)->node, context);
		case T_RangeSubselect:
			{
				RangeSubselect *rs = (RangeSubselect *) node;

				if (walker(rs->subquery, context))
					return true;
				if (walker(rs->alias, context))
					return true;
			}
			break;
		case T_RangeFunction:
			{
				RangeFunction *rf = (RangeFunction *) node;

				if (walker(rf->funccallnode, context))
					return true;
				if (walker(rf->alias, context))
					return true;
			}
			break;
		case T_TypeName:
			{
				TypeName *tn = (TypeName *) node;

				if (walker(tn->typmods, context))
					return true;
				if (walker(tn->arrayBounds, context))
					return true;
				/* type name itself is deemed uninteresting */
			}
			break;
		case T_ColumnDef:
			{
				ColumnDef *coldef = (ColumnDef *) node;

				if (walker(coldef->typename, context))
					return true;
				if (walker(coldef->raw_default, context))
					return true;
				/* for now, constraints are ignored */
			}
			break;
		case T_LockingClause:
			return walker(((LockingClause *) node)->lockedRels, context);
		case T_XmlSerialize:
			{
				XmlSerialize *xs = (XmlSerialize *) node;

				if (walker(xs->expr, context))
					return true;
				if (walker(xs->typename, context))
					return true;
			}
			break;
		case T_WithClause:
			return walker(((WithClause *) node)->ctes, context);
		case T_CommonTableExpr:
			return walker(((CommonTableExpr *) node)->ctequery, context);
		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(node));
			break;
	}
	return false;
}