parse_target.c

关系型数据库 Postgresql 6.5.2

			while (ilist != NIL)
			{
				A_Indices  *ind = lfirst(ilist);

				ind->lidx = transformExpr(pstate, ind->lidx, EXPR_COLUMN_FIRST);
				ind->uidx = transformExpr(pstate, ind->uidx, EXPR_COLUMN_FIRST);
				ilist = lnext(ilist);
			}
		}
		res->name = colname;
		return MakeTargetEntryExpr(pstate, res->name, expr,
								   res->indirection, false);
	}
}

/*
 *	MakeTargetEntryAttr()
 *	Make a TargetEntry from a complex node.
 */
static TargetEntry *
MakeTargetEntryAttr(ParseState *pstate,
					ResTarget *res)
{
	Oid			type_id;
	int32		type_mod;
	Attr	   *att = (Attr *) res->val;
	Node	   *result;
	char	   *attrname;
	char	   *resname;
	Resdom	   *resnode;
	int			resdomno;
	List	   *attrs = att->attrs;
	TargetEntry *tent;

	attrname = strVal(lfirst(att->attrs));

	/*
	 * Target item is fully specified: ie. relation.attribute
	 */
	result = ParseNestedFuncOrColumn(pstate, att, &pstate->p_last_resno, EXPR_COLUMN_FIRST);
	handleTargetColname(pstate, &res->name, att->relname, attrname);
	if (att->indirection != NIL)
	{
		List	   *ilist = att->indirection;

		while (ilist != NIL)
		{
			A_Indices  *ind = lfirst(ilist);

			ind->lidx = transformExpr(pstate, ind->lidx, EXPR_COLUMN_FIRST);
			ind->uidx = transformExpr(pstate, ind->uidx, EXPR_COLUMN_FIRST);
			ilist = lnext(ilist);
		}
		result = (Node *) make_array_ref(result, att->indirection);
	}
	type_id = exprType(result);
	if (nodeTag(result) == T_Var)
		type_mod = ((Var *) result)->vartypmod;
	else
		type_mod = -1;
	/* move to last entry */
	while (lnext(attrs) != NIL)
		attrs = lnext(attrs);
	resname = (res->name) ? res->name : strVal(lfirst(attrs));
	if (pstate->p_is_insert || pstate->p_is_update)
	{
		Relation	rd;

		/*
		 * insert or update query -- insert, update work only on one
		 * relation, so multiple occurence of same resdomno is bogus
		 */
		rd = pstate->p_target_relation;
		Assert(rd != NULL);
		resdomno = attnameAttNum(rd, res->name);
	}
	else
		resdomno = pstate->p_last_resno++;
	resnode = makeResdom((AttrNumber) resdomno,
						 (Oid) type_id,
						 type_mod,
						 resname,
						 (Index) 0,
						 (Oid) 0,
						 false);
	tent = makeNode(TargetEntry);
	tent->resdom = resnode;
	tent->expr = result;
	return tent;
}


/* transformTargetList()
 * Turns a list of ResTarget's into a list of TargetEntry's.
 */
List *
transformTargetList(ParseState *pstate, List *targetlist)
{
	List	   *p_target = NIL;
	List	   *tail_p_target = NIL;

	while (targetlist != NIL)
	{
		ResTarget  *res = (ResTarget *) lfirst(targetlist);
		TargetEntry *tent = NULL;

		switch (nodeTag(res->val))
		{
			case T_Ident:
				{
					char	   *identname;

					identname = ((Ident *) res->val)->name;
					tent = MakeTargetEntryIdent(pstate,
												(Node *) res->val, &res->name, NULL, identname, false);
					break;
				}
			case T_ParamNo:
			case T_FuncCall:
			case T_A_Const:
			case T_A_Expr:
				{
					tent = MakeTargetEntryComplex(pstate, res);
					break;
				}
			case T_CaseExpr:
				{
					tent = MakeTargetEntryCase(pstate, res);
					break;
				}
			case T_Attr:
				{
					bool		expand_star = false;
					char	   *attrname;
					Attr	   *att = (Attr *) res->val;

					/*
					 * Target item is a single '*', expand all tables (eg.
					 * SELECT * FROM emp)
					 */
					if (att->relname != NULL && !strcmp(att->relname, "*"))
					{
						if (tail_p_target == NIL)
							p_target = tail_p_target = ExpandAllTables(pstate);
						else
							lnext(tail_p_target) = ExpandAllTables(pstate);
						expand_star = true;
					}
					else
					{

						/*
						 * Target item is relation.*, expand the table
						 * (eg. SELECT emp.*, dname FROM emp, dept)
						 */
						attrname = strVal(lfirst(att->attrs));
						if (att->attrs != NIL && !strcmp(attrname, "*"))
						{

							/*
							 * tail_p_target is the target list we're
							 * building in the while loop. Make sure we
							 * fix it after appending more nodes.
							 */
							if (tail_p_target == NIL)
								p_target = tail_p_target = expandAll(pstate, att->relname,
									att->relname, &pstate->p_last_resno);
							else
								lnext(tail_p_target) = expandAll(pstate, att->relname, att->relname,
												  &pstate->p_last_resno);
							expand_star = true;
						}
					}
					if (expand_star)
					{
						while (lnext(tail_p_target) != NIL)
							/* make sure we point to the last target entry */
							tail_p_target = lnext(tail_p_target);

						/*
						 * skip rest of while loop
						 */
						targetlist = lnext(targetlist);
						continue;
					}
					else
					{
						tent = MakeTargetEntryAttr(pstate, res);
						break;
					}
				}
			default:
				/* internal error */
				elog(ERROR, "Unable to transform targetlist (internal error)");
				break;
		}

		if (p_target == NIL)
			p_target = tail_p_target = lcons(tent, NIL);
		else
		{
			lnext(tail_p_target) = lcons(tent, NIL);
			tail_p_target = lnext(tail_p_target);
		}
		targetlist = lnext(targetlist);
	}

	return p_target;
}	/* transformTargetList() */


Node *
CoerceTargetExpr(ParseState *pstate,
				 Node *expr,
				 Oid type_id,
				 Oid attrtype)
{
	if (can_coerce_type(1, &type_id, &attrtype))
		expr = coerce_type(pstate, expr, type_id, attrtype, -1);

#ifndef DISABLE_STRING_HACKS

	/*
	 * string hacks to get transparent conversions w/o explicit
	 * conversions
	 */
	else if ((attrtype == BPCHAROID) || (attrtype == VARCHAROID))
	{
		Oid			text_id = TEXTOID;

		if (type_id == TEXTOID)
		{
		}
		else if (can_coerce_type(1, &type_id, &text_id))
			expr = coerce_type(pstate, expr, type_id, text_id, -1);
		else
			expr = NULL;
	}
#endif

	else
		expr = NULL;

	return expr;
}	/* CoerceTargetExpr() */


/* SizeTargetExpr()
 * Apparently going to a fixed-length string?
 * Then explicitly size for storage...
 */
static Node *
SizeTargetExpr(ParseState *pstate,
			   Node *expr,
			   Oid attrtype,
			   int32 attrtypmod)
{
	int			i;
	HeapTuple	ftup;
	char	   *funcname;
	Oid			oid_array[MAXFARGS];

	FuncCall   *func;
	A_Const    *cons;

	funcname = typeidTypeName(attrtype);
	oid_array[0] = attrtype;
	oid_array[1] = INT4OID;
	for (i = 2; i < MAXFARGS; i++)
		oid_array[i] = InvalidOid;

	/* attempt to find with arguments exactly as specified... */
	ftup = SearchSysCacheTuple(PRONAME,
							   PointerGetDatum(funcname),
							   Int32GetDatum(2),
							   PointerGetDatum(oid_array),
							   0);

	if (HeapTupleIsValid(ftup))
	{
		func = makeNode(FuncCall);
		func->funcname = funcname;

		cons = makeNode(A_Const);
		cons->val.type = T_Integer;
		cons->val.val.ival = attrtypmod;
		func->args = lappend(lcons(expr, NIL), cons);

		expr = transformExpr(pstate, (Node *) func, EXPR_COLUMN_FIRST);
	}

	return expr;
}	/* SizeTargetExpr() */


/*
 * makeTargetNames -
 *	  generate a list of column names if not supplied or
 *	  test supplied column names to make sure they are in target table
 *	  (used exclusively for inserts)
 */
List *
makeTargetNames(ParseState *pstate, List *cols)
{
	List	   *tl = NULL;

	/* Generate ResTarget if not supplied */

	if (cols == NIL)
	{
		int			numcol;
		int			i;
		Form_pg_attribute *attr = pstate->p_target_relation->rd_att->attrs;

		numcol = pstate->p_target_relation->rd_rel->relnatts;
		for (i = 0; i < numcol; i++)
		{
			Ident	   *id = makeNode(Ident);

			id->name = palloc(NAMEDATALEN);
			StrNCpy(id->name, attr[i]->attname.data, NAMEDATALEN);
			id->indirection = NIL;
			id->isRel = false;
			if (tl == NIL)
				cols = tl = lcons(id, NIL);
			else
			{
				lnext(tl) = lcons(id, NIL);
				tl = lnext(tl);
			}
		}
	}
	else
	{
		foreach(tl, cols)
		{
			List	   *nxt;
			char	   *name = ((Ident *) lfirst(tl))->name;

			/* elog on failure */
			attnameAttNum(pstate->p_target_relation, name);
			foreach(nxt, lnext(tl))
				if (!strcmp(name, ((Ident *) lfirst(nxt))->name))
				elog(ERROR, "Attribute '%s' should be specified only once", name);
		}
	}

	return cols;
}

/*
 * ExpandAllTables -
 *	  turns '*' (in the target list) into a list of attributes
 *	   (of all relations in the range table)
 */
static List *
ExpandAllTables(ParseState *pstate)
{
	List	   *target = NIL;
	List	   *legit_rtable = NIL;
	List	   *rt,
			   *rtable;

	rtable = pstate->p_rtable;
	if (pstate->p_is_rule)
	{

		/*
		 * skip first two entries, "*new*" and "*current*"
		 */
		rtable = lnext(lnext(pstate->p_rtable));
	}

	/* SELECT *; */
	if (rtable == NULL)
		elog(ERROR, "Wildcard with no tables specified.");

	/*
	 * go through the range table and make a list of range table entries
	 * which we will expand.
	 */
	foreach(rt, rtable)
	{
		RangeTblEntry *rte = lfirst(rt);

		/*
		 * we only expand those specify in the from clause. (This will
		 * also prevent us from using the wrong table in inserts: eg.
		 * tenk2 in "insert into tenk2 select * from tenk1;")
		 */
		if (!rte->inFromCl)
			continue;
		legit_rtable = lappend(legit_rtable, rte);
	}

	foreach(rt, legit_rtable)
	{
		RangeTblEntry *rte = lfirst(rt);
		List	   *temp = target;

		if (temp == NIL)
			target = expandAll(pstate, rte->relname, rte->refname,
							   &pstate->p_last_resno);
		else
		{
			while (temp != NIL && lnext(temp) != NIL)
				temp = lnext(temp);
			lnext(temp) = expandAll(pstate, rte->relname, rte->refname,
									&pstate->p_last_resno);
		}
	}
	return target;
}

/*
 * FigureColname -
 *	  if the name of the resulting column is not specified in the target
 *	  list, we have to guess.
 *
 */
static char *
FigureColname(Node *expr, Node *resval)
{
	switch (nodeTag(expr))
	{
			case T_Aggref:
			return (char *) ((Aggref *) expr)->aggname;
		case T_Expr:
			if (((Expr *) expr)->opType == FUNC_EXPR)
			{
				if (nodeTag(resval) == T_FuncCall)
					return ((FuncCall *) resval)->funcname;
			}
			break;
		case T_CaseExpr:
			{
				char	   *name;

				name = FigureColname(((CaseExpr *) expr)->defresult, resval);
				if (!strcmp(name, "?column?"))
					name = "case";
				return name;
			}
			break;
		default:
			break;
	}

	return "?column?";
}