/*-------------------------------------------------------------------------
 *
 * makefuncs.c
 *	  creator functions for primitive nodes. The functions here are for
 *	  the most frequently created nodes.
 *
 * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/nodes/makefuncs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_class.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "utils/lsyscache.h"


/*
 * makeA_Expr -
 *		makes an A_Expr node
 */
A_Expr *
makeA_Expr(A_Expr_Kind kind, List *name,
		   Node *lexpr, Node *rexpr, int location)
{
	A_Expr	   *a = makeNode(A_Expr);

	a->kind = kind;
	a->name = name;
	a->lexpr = lexpr;
	a->rexpr = rexpr;
	a->location = location;
	return a;
}

/*
 * makeSimpleA_Expr -
 *		As above, given a simple (unqualified) operator name
 */
A_Expr *
makeSimpleA_Expr(A_Expr_Kind kind, char *name,
				 Node *lexpr, Node *rexpr, int location)
{
	A_Expr	   *a = makeNode(A_Expr);

	a->kind = kind;
	a->name = list_make1(makeString((char *) name));
	a->lexpr = lexpr;
	a->rexpr = rexpr;
	a->location = location;
	return a;
}

/*
 * makeVar -
 *	  creates a Var node
 */
Var *
makeVar(Index varno,
		AttrNumber varattno,
		Oid vartype,
		int32 vartypmod,
		Oid varcollid,
		Index varlevelsup)
{
	Var		   *var = makeNode(Var);

	var->varno = varno;
	var->varattno = varattno;
	var->vartype = vartype;
	var->vartypmod = vartypmod;
	var->varcollid = varcollid;
	var->varlevelsup = varlevelsup;

	/*
	 * Since few if any routines ever create Var nodes with varnoold/varoattno
	 * different from varno/varattno, we don't provide separate arguments for
	 * them, but just initialize them to the given varno/varattno. This
	 * reduces code clutter and chance of error for most callers.
	 */
	var->varnoold = varno;
	var->varoattno = varattno;

	/* Likewise, we just set location to "unknown" here */
	var->location = -1;

	return var;
}

/*
 * makeVarFromTargetEntry -
 *		convenience function to create a same-level Var node from a
 *		TargetEntry
 */
Var *
makeVarFromTargetEntry(Index varno,
					   TargetEntry *tle)
{
	return makeVar(varno,
				   tle->resno,
				   exprType((Node *) tle->expr),
				   exprTypmod((Node *) tle->expr),
				   exprCollation((Node *) tle->expr),
				   0);
}

/*
 * makeWholeRowVar -
 *	  creates a Var node representing a whole row of the specified RTE
 *
 * A whole-row reference is a Var with varno set to the correct range
 * table entry, and varattno == 0 to signal that it references the whole
 * tuple.  (Use of zero here is unclean, since it could easily be confused
 * with error cases, but it's not worth changing now.)  The vartype indicates
 * a rowtype; either a named composite type, or RECORD.  This function
 * encapsulates the logic for determining the correct rowtype OID to use.
 *
 * If allowScalar is true, then for the case where the RTE is a function
 * returning a non-composite result type, we produce a normal Var referencing
 * the function's result directly, instead of the single-column composite
 * value that the whole-row notation might otherwise suggest.
 */
Var *
makeWholeRowVar(RangeTblEntry *rte,
				Index varno,
				Index varlevelsup,
				bool allowScalar)
{
	Var		   *result;
	Oid			toid;

	switch (rte->rtekind)
	{
		case RTE_RELATION:
			/* relation: the rowtype is a named composite type */
			toid = get_rel_type_id(rte->relid);
			if (!OidIsValid(toid))
				elog(ERROR, "could not find type OID for relation %u",
					 rte->relid);
			result = makeVar(varno,
							 InvalidAttrNumber,
							 toid,
							 -1,
							 InvalidOid,
							 varlevelsup);
			break;
		case RTE_FUNCTION:
			toid = exprType(rte->funcexpr);
			if (type_is_rowtype(toid))
			{
				/* func returns composite; same as relation case */
				result = makeVar(varno,
								 InvalidAttrNumber,
								 toid,
								 -1,
								 InvalidOid,
								 varlevelsup);
			}
			else if (allowScalar)
			{
				/* func returns scalar; just return its output as-is */
				result = makeVar(varno,
								 1,
								 toid,
								 -1,
								 exprCollation(rte->funcexpr),
								 varlevelsup);
			}
			else
			{
				/* func returns scalar, but we want a composite result */
				result = makeVar(varno,
								 InvalidAttrNumber,
								 RECORDOID,
								 -1,
								 InvalidOid,
								 varlevelsup);
			}
			break;
		default:

			/*
			 * RTE is a join, subselect, or VALUES.  We represent this as a
			 * whole-row Var of RECORD type. (Note that in most cases the Var
			 * will be expanded to a RowExpr during planning, but that is not
			 * our concern here.)
			 */
			result = makeVar(varno,
							 InvalidAttrNumber,
							 RECORDOID,
							 -1,
							 InvalidOid,
							 varlevelsup);
			break;
	}

	return result;
}

/*
 * makeTargetEntry -
 *	  creates a TargetEntry node
 */
TargetEntry *
makeTargetEntry(Expr *expr,
				AttrNumber resno,
				char *resname,
				bool resjunk)
{
	TargetEntry *tle = makeNode(TargetEntry);

	tle->expr = expr;
	tle->resno = resno;
	tle->resname = resname;

	/*
	 * We always set these fields to 0. If the caller wants to change them he
	 * must do so explicitly.  Few callers do that, so omitting these
	 * arguments reduces the chance of error.
	 */
	tle->ressortgroupref = 0;
	tle->resorigtbl = InvalidOid;
	tle->resorigcol = 0;

	tle->resjunk = resjunk;

	return tle;
}

/*
 * flatCopyTargetEntry -
 *	  duplicate a TargetEntry, but don't copy substructure
 *
 * This is commonly used when we just want to modify the resno or substitute
 * a new expression.
 */
TargetEntry *
flatCopyTargetEntry(TargetEntry *src_tle)
{
	TargetEntry *tle = makeNode(TargetEntry);

	Assert(IsA(src_tle, TargetEntry));
	memcpy(tle, src_tle, sizeof(TargetEntry));
	return tle;
}

/*
 * makeFromExpr -
 *	  creates a FromExpr node
 */
FromExpr *
makeFromExpr(List *fromlist, Node *quals)
{
	FromExpr   *f = makeNode(FromExpr);

	f->fromlist = fromlist;
	f->quals = quals;
	return f;
}

/*
 * makeConst -
 *	  creates a Const node
 */
Const *
makeConst(Oid consttype,
		  int32 consttypmod,
		  Oid constcollid,
		  int constlen,
		  Datum constvalue,
		  bool constisnull,
		  bool constbyval)
{
	Const	   *cnst = makeNode(Const);

	cnst->consttype = consttype;
	cnst->consttypmod = consttypmod;
	cnst->constcollid = constcollid;
	cnst->constlen = constlen;
	cnst->constvalue = constvalue;
	cnst->constisnull = constisnull;
	cnst->constbyval = constbyval;
	cnst->location = -1;		/* "unknown" */

	return cnst;
}

/*
 * makeNullConst -
 *	  creates a Const node representing a NULL of the specified type/typmod
 *
 * This is a convenience routine that just saves a lookup of the type's
 * storage properties.
 */
Const *
makeNullConst(Oid consttype, int32 consttypmod, Oid constcollid)
{
	int16		typLen;
	bool		typByVal;

	get_typlenbyval(consttype, &typLen, &typByVal);
	return makeConst(consttype,
					 consttypmod,
					 constcollid,
					 (int) typLen,
					 (Datum) 0,
					 true,
					 typByVal);
}

/*
 * makeBoolConst -
 *	  creates a Const node representing a boolean value (can be NULL too)
 */
Node *
makeBoolConst(bool value, bool isnull)
{
	/* note that pg_type.h hardwires size of bool as 1 ... duplicate it */
	return (Node *) makeConst(BOOLOID, -1, InvalidOid, 1,
							  BoolGetDatum(value), isnull, true);
}

/*
 * makeBoolExpr -
 *	  creates a BoolExpr node
 */
Expr *
makeBoolExpr(BoolExprType boolop, List *args, int location)
{
	BoolExpr   *b = makeNode(BoolExpr);

	b->boolop = boolop;
	b->args = args;
	b->location = location;

	return (Expr *) b;
}

/*
 * makeAlias -
 *	  creates an Alias node
 *
 * NOTE: the given name is copied, but the colnames list (if any) isn't.
 */
Alias *
makeAlias(const char *aliasname, List *colnames)
{
	Alias	   *a = makeNode(Alias);

	a->aliasname = pstrdup(aliasname);
	a->colnames = colnames;

	return a;
}

/*
 * makeRelabelType -
 *	  creates a RelabelType node
 */
RelabelType *
makeRelabelType(Expr *arg, Oid rtype, int32 rtypmod, Oid rcollid,
				CoercionForm rformat)
{
	RelabelType *r = makeNode(RelabelType);

	r->arg = arg;
	r->resulttype = rtype;
	r->resulttypmod = rtypmod;
	r->resultcollid = rcollid;
	r->relabelformat = rformat;
	r->location = -1;

	return r;
}

/*
 * makeRangeVar -
 *	  creates a RangeVar node (rather oversimplified case)
 */
RangeVar *
makeRangeVar(char *schemaname, char *relname, int location)
{
	RangeVar   *r = makeNode(RangeVar);

	r->catalogname = NULL;
	r->schemaname = schemaname;
	r->relname = relname;
	r->inhOpt = INH_DEFAULT;
	r->relpersistence = RELPERSISTENCE_PERMANENT;
	r->alias = NULL;
	r->location = location;

	return r;
}

/*
 * makeTypeName -
 *	build a TypeName node for an unqualified name.
 *
 * typmod is defaulted, but can be changed later by caller.
 */
TypeName *
makeTypeName(char *typnam)
{
	return makeTypeNameFromNameList(list_make1(makeString(typnam)));
}

/*
 * makeTypeNameFromNameList -
 *	build a TypeName node for a String list representing a qualified name.
 *
 * typmod is defaulted, but can be changed later by caller.
 */
TypeName *
makeTypeNameFromNameList(List *names)
{
	TypeName   *n = makeNode(TypeName);

	n->names = names;
	n->typmods = NIL;
	n->typemod = -1;
	n->location = -1;
	return n;
}

/*
 * makeTypeNameFromOid -
 *	build a TypeName node to represent a type already known by OID/typmod.
 */
TypeName *
makeTypeNameFromOid(Oid typeOid, int32 typmod)
{
	TypeName   *n = makeNode(TypeName);

	n->typeOid = typeOid;
	n->typemod = typmod;
	n->location = -1;
	return n;
}

/*
 * makeFuncExpr -
 *	build an expression tree representing a function call.
 *
 * The argument expressions must have been transformed already.
 */
FuncExpr *
makeFuncExpr(Oid funcid, Oid rettype, List *args,
			 Oid funccollid, Oid inputcollid, CoercionForm fformat)
{
	FuncExpr   *funcexpr;

	funcexpr = makeNode(FuncExpr);
	funcexpr->funcid = funcid;
	funcexpr->funcresulttype = rettype;
	funcexpr->funcretset = false;		/* only allowed case here */
	funcexpr->funcformat = fformat;
	funcexpr->funccollid = funccollid;
	funcexpr->inputcollid = inputcollid;
	funcexpr->args = args;
	funcexpr->location = -1;

	return funcexpr;
}

/*
 * makeDefElem -
 *	build a DefElem node
 *
 * This is sufficient for the "typical" case with an unqualified option name
 * and no special action.
 */
DefElem *
makeDefElem(char *name, Node *arg)
{
	DefElem    *res = makeNode(DefElem);

	res->defnamespace = NULL;
	res->defname = name;
	res->arg = arg;
	res->defaction = DEFELEM_UNSPEC;

	return res;
}

/*
 * makeDefElemExtended -
 *	build a DefElem node with all fields available to be specified
 */
DefElem *
makeDefElemExtended(char *nameSpace, char *name, Node *arg,
					DefElemAction defaction)
{
	DefElem    *res = makeNode(DefElem);

	res->defnamespace = nameSpace;
	res->defname = name;
	res->arg = arg;
	res->defaction = defaction;

	return res;
}
