parse_func.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

{
	bool		result = false;
	Oid			relid;
	Relation	inhrel;
	List	   *visited,
			   *queue;
	ListCell   *queue_item;

	if (!ISCOMPLEX(subclassTypeId) || !ISCOMPLEX(superclassTypeId))
		return false;
	relid = typeidTypeRelid(subclassTypeId);
	if (relid == InvalidOid)
		return false;

	/*
	 * Begin the search at the relation itself, so add relid to the queue.
	 */
	queue = list_make1_oid(relid);
	visited = NIL;

	inhrel = heap_open(InheritsRelationId, AccessShareLock);

	/*
	 * Use queue to do a breadth-first traversal of the inheritance graph from
	 * the relid supplied up to the root.  Notice that we append to the queue
	 * inside the loop --- this is okay because the foreach() macro doesn't
	 * advance queue_item until the next loop iteration begins.
	 */
	foreach(queue_item, queue)
	{
		Oid			this_relid = lfirst_oid(queue_item);
		ScanKeyData skey;
		HeapScanDesc inhscan;
		HeapTuple	inhtup;

		/* If we've seen this relid already, skip it */
		if (list_member_oid(visited, this_relid))
			continue;

		/*
		 * Okay, this is a not-yet-seen relid. Add it to the list of
		 * already-visited OIDs, then find all the types this relid inherits
		 * from and add them to the queue. The one exception is we don't add
		 * the original relation to 'visited'.
		 */
		if (queue_item != list_head(queue))
			visited = lappend_oid(visited, this_relid);

		ScanKeyInit(&skey,
					Anum_pg_inherits_inhrelid,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(this_relid));

		inhscan = heap_beginscan(inhrel, SnapshotNow, 1, &skey);

		while ((inhtup = heap_getnext(inhscan, ForwardScanDirection)) != NULL)
		{
			Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inhtup);
			Oid			inhparent = inh->inhparent;

			/* If this is the target superclass, we're done */
			if (get_rel_type_id(inhparent) == superclassTypeId)
			{
				result = true;
				break;
			}

			/* Else add to queue */
			queue = lappend_oid(queue, inhparent);
		}

		heap_endscan(inhscan);

		if (result)
			break;
	}

	heap_close(inhrel, AccessShareLock);

	list_free(visited);
	list_free(queue);

	return result;
}


/*
 * make_fn_arguments()
 *
 * Given the actual argument expressions for a function, and the desired
 * input types for the function, add any necessary typecasting to the
 * expression tree.  Caller should already have verified that casting is
 * allowed.
 *
 * Caution: given argument list is modified in-place.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
void
make_fn_arguments(ParseState *pstate,
				  List *fargs,
				  Oid *actual_arg_types,
				  Oid *declared_arg_types)
{
	ListCell   *current_fargs;
	int			i = 0;

	foreach(current_fargs, fargs)
	{
		/* types don't match? then force coercion using a function call... */
		if (actual_arg_types[i] != declared_arg_types[i])
		{
			lfirst(current_fargs) = coerce_type(pstate,
												lfirst(current_fargs),
												actual_arg_types[i],
												declared_arg_types[i], -1,
												COERCION_IMPLICIT,
												COERCE_IMPLICIT_CAST);
		}
		i++;
	}
}

/*
 * ParseComplexProjection -
 *	  handles function calls with a single argument that is of complex type.
 *	  If the function call is actually a column projection, return a suitably
 *	  transformed expression tree.	If not, return NULL.
 */
static Node *
ParseComplexProjection(ParseState *pstate, char *funcname, Node *first_arg)
{
	TupleDesc	tupdesc;
	int			i;

	/*
	 * Special case for whole-row Vars so that we can resolve (foo.*).bar even
	 * when foo is a reference to a subselect, join, or RECORD function. A
	 * bonus is that we avoid generating an unnecessary FieldSelect; our
	 * result can omit the whole-row Var and just be a Var for the selected
	 * field.
	 *
	 * This case could be handled by expandRecordVariable, but it's more
	 * efficient to do it this way when possible.
	 */
	if (IsA(first_arg, Var) &&
		((Var *) first_arg)->varattno == InvalidAttrNumber)
	{
		RangeTblEntry *rte;

		rte = GetRTEByRangeTablePosn(pstate,
									 ((Var *) first_arg)->varno,
									 ((Var *) first_arg)->varlevelsup);
		/* Return a Var if funcname matches a column, else NULL */
		return scanRTEForColumn(pstate, rte, funcname);
	}

	/*
	 * Else do it the hard way with get_expr_result_type().
	 *
	 * If it's a Var of type RECORD, we have to work even harder: we have to
	 * find what the Var refers to, and pass that to get_expr_result_type.
	 * That task is handled by expandRecordVariable().
	 */
	if (IsA(first_arg, Var) &&
		((Var *) first_arg)->vartype == RECORDOID)
		tupdesc = expandRecordVariable(pstate, (Var *) first_arg, 0);
	else if (get_expr_result_type(first_arg, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
		return NULL;			/* unresolvable RECORD type */
	Assert(tupdesc);

	for (i = 0; i < tupdesc->natts; i++)
	{
		Form_pg_attribute att = tupdesc->attrs[i];

		if (strcmp(funcname, NameStr(att->attname)) == 0 &&
			!att->attisdropped)
		{
			/* Success, so generate a FieldSelect expression */
			FieldSelect *fselect = makeNode(FieldSelect);

			fselect->arg = (Expr *) first_arg;
			fselect->fieldnum = i + 1;
			fselect->resulttype = att->atttypid;
			fselect->resulttypmod = att->atttypmod;
			return (Node *) fselect;
		}
	}

	return NULL;				/* funcname does not match any column */
}

/*
 * helper routine for delivering "column does not exist" error message
 */
static void
unknown_attribute(ParseState *pstate, Node *relref, char *attname)
{
	RangeTblEntry *rte;

	if (IsA(relref, Var) &&
		((Var *) relref)->varattno == InvalidAttrNumber)
	{
		/* Reference the RTE by alias not by actual table name */
		rte = GetRTEByRangeTablePosn(pstate,
									 ((Var *) relref)->varno,
									 ((Var *) relref)->varlevelsup);
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_COLUMN),
				 errmsg("column %s.%s does not exist",
						rte->eref->aliasname, attname)));
	}
	else
	{
		/* Have to do it by reference to the type of the expression */
		Oid			relTypeId = exprType(relref);

		if (ISCOMPLEX(relTypeId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_COLUMN),
					 errmsg("column \"%s\" not found in data type %s",
							attname, format_type_be(relTypeId))));
		else if (relTypeId == RECORDOID)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_COLUMN),
			   errmsg("could not identify column \"%s\" in record data type",
					  attname)));
		else
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
					 errmsg("column notation .%s applied to type %s, "
							"which is not a composite type",
							attname, format_type_be(relTypeId))));
	}
}

/*
 * funcname_signature_string
 *		Build a string representing a function name, including arg types.
 *		The result is something like "foo(integer)".
 *
 * This is typically used in the construction of function-not-found error
 * messages.
 */
const char *
funcname_signature_string(const char *funcname,
						  int nargs, const Oid *argtypes)
{
	StringInfoData argbuf;
	int			i;

	initStringInfo(&argbuf);

	appendStringInfo(&argbuf, "%s(", funcname);

	for (i = 0; i < nargs; i++)
	{
		if (i)
			appendStringInfoString(&argbuf, ", ");
		appendStringInfoString(&argbuf, format_type_be(argtypes[i]));
	}

	appendStringInfoChar(&argbuf, ')');

	return argbuf.data;			/* return palloc'd string buffer */
}

/*
 * func_signature_string
 *		As above, but function name is passed as a qualified name list.
 */
const char *
func_signature_string(List *funcname, int nargs, const Oid *argtypes)
{
	return funcname_signature_string(NameListToString(funcname),
									 nargs, argtypes);
}

/*
 * find_aggregate_func
 *		Convenience routine to check that a function exists and is an
 *		aggregate.
 *
 * Note: basetype is ANYOID if we are looking for an aggregate on
 * all types.
 */
Oid
find_aggregate_func(List *aggname, Oid basetype, bool noError)
{
	Oid			oid;
	HeapTuple	ftup;
	Form_pg_proc pform;

	oid = LookupFuncName(aggname, 1, &basetype, true);

	if (!OidIsValid(oid))
	{
		if (noError)
			return InvalidOid;
		if (basetype == ANYOID)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_FUNCTION),
					 errmsg("aggregate %s(*) does not exist",
							NameListToString(aggname))));
		else
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_FUNCTION),
					 errmsg("aggregate %s(%s) does not exist",
							NameListToString(aggname),
							format_type_be(basetype))));
	}

	/* Make sure it's an aggregate */
	ftup = SearchSysCache(PROCOID,
						  ObjectIdGetDatum(oid),
						  0, 0, 0);
	if (!HeapTupleIsValid(ftup))	/* should not happen */
		elog(ERROR, "cache lookup failed for function %u", oid);
	pform = (Form_pg_proc) GETSTRUCT(ftup);

	if (!pform->proisagg)
	{
		ReleaseSysCache(ftup);
		if (noError)
			return InvalidOid;
		/* we do not use the (*) notation for functions... */
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("function %s(%s) is not an aggregate",
					  NameListToString(aggname), format_type_be(basetype))));
	}

	ReleaseSysCache(ftup);

	return oid;
}

/*
 * LookupFuncName
 *		Given a possibly-qualified function name and a set of argument types,
 *		look up the function.
 *
 * If the function name is not schema-qualified, it is sought in the current
 * namespace search path.
 *
 * If the function is not found, we return InvalidOid if noError is true,
 * else raise an error.
 */
Oid
LookupFuncName(List *funcname, int nargs, const Oid *argtypes, bool noError)
{
	FuncCandidateList clist;

	clist = FuncnameGetCandidates(funcname, nargs);

	while (clist)
	{
		if (memcmp(argtypes, clist->args, nargs * sizeof(Oid)) == 0)
			return clist->oid;
		clist = clist->next;
	}

	if (!noError)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("function %s does not exist",
						func_signature_string(funcname, nargs, argtypes))));

	return InvalidOid;
}

/*
 * LookupFuncNameTypeNames
 *		Like LookupFuncName, but the argument types are specified by a
 *		list of TypeName nodes.
 */
Oid
LookupFuncNameTypeNames(List *funcname, List *argtypes, bool noError)
{
	Oid			argoids[FUNC_MAX_ARGS];
	int			argcount;
	int			i;
	ListCell   *args_item;

	argcount = list_length(argtypes);
	if (argcount > FUNC_MAX_ARGS)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
				 errmsg("functions cannot have more than %d arguments",
						FUNC_MAX_ARGS)));

	args_item = list_head(argtypes);
	for (i = 0; i < argcount; i++)
	{
		TypeName   *t = (TypeName *) lfirst(args_item);

		argoids[i] = LookupTypeName(t);

		if (!OidIsValid(argoids[i]))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("type \"%s\" does not exist",
							TypeNameToString(t))));

		args_item = lnext(args_item);
	}

	return LookupFuncName(funcname, argcount, argoids, noError);
}