parse_func.c

关系型数据库 Postgresql 6.5.2

 *		is returned to the caller, reflecting the structure of the
 *		inheritance tree above the supplied arguments.
 *
 *		The order of this vector is as follows:  all superclasses of the
 *		rightmost complex class are explored first.  The exploration
 *		continues from right to left.  This policy means that we favor
 *		keeping the leftmost argument type as low in the inheritance tree
 *		as possible.  This is intentional; it is exactly what we need to
 *		do for method dispatch.  The last type array we return is all
 *		zeroes.  This will match any functions for which return types are
 *		not defined.  There are lots of these (mostly builtins) in the
 *		catalogs.
 */
static Oid **
argtype_inherit(int nargs, Oid *oid_array)
{
	Oid			relid;
	int			i;
	InhPaths	arginh[MAXFARGS];

	for (i = 0; i < MAXFARGS; i++)
	{
		if (i < nargs)
		{
			arginh[i].self = oid_array[i];
			if ((relid = typeidTypeRelid(oid_array[i])) != InvalidOid)
				arginh[i].nsupers = find_inheritors(relid, &(arginh[i].supervec));
			else
			{
				arginh[i].nsupers = 0;
				arginh[i].supervec = (Oid *) NULL;
			}
		}
		else
		{
			arginh[i].self = InvalidOid;
			arginh[i].nsupers = 0;
			arginh[i].supervec = (Oid *) NULL;
		}
	}

	/* return an ordered cross-product of the classes involved */
	return gen_cross_product(arginh, nargs);
}

static int
find_inheritors(Oid relid, Oid **supervec)
{
	Oid		   *relidvec;
	Relation	inhrel;
	HeapScanDesc inhscan;
	ScanKeyData skey;
	HeapTuple	inhtup;
	TupleDesc	inhtupdesc;
	int			nvisited;
	SuperQE    *qentry,
			   *vnode;
	Dllist	   *visited,
			   *queue;
	Dlelem	   *qe,
			   *elt;

	Relation	rd;
	Datum		d;
	bool		newrelid;
	char		isNull;

	nvisited = 0;
	queue = DLNewList();
	visited = DLNewList();


	inhrel = heap_openr(InheritsRelationName);
	inhtupdesc = RelationGetDescr(inhrel);

	/*
	 * Use queue to do a breadth-first traversal of the inheritance graph
	 * from the relid supplied up to the root.
	 */
	do
	{
		ScanKeyEntryInitialize(&skey, 0x0, Anum_pg_inherits_inhrel,
							   F_OIDEQ,
							   ObjectIdGetDatum(relid));

		inhscan = heap_beginscan(inhrel, 0, SnapshotNow, 1, &skey);

		while (HeapTupleIsValid(inhtup = heap_getnext(inhscan, 0)))
		{
			qentry = (SuperQE *) palloc(sizeof(SuperQE));

			d = fastgetattr(inhtup, Anum_pg_inherits_inhparent,
							inhtupdesc, &isNull);
			qentry->sqe_relid = DatumGetObjectId(d);

			/* put this one on the queue */
			DLAddTail(queue, DLNewElem(qentry));
		}

		heap_endscan(inhscan);

		/* pull next unvisited relid off the queue */
		do
		{
			qe = DLRemHead(queue);
			qentry = qe ? (SuperQE *) DLE_VAL(qe) : NULL;

			if (qentry == (SuperQE *) NULL)
				break;

			relid = qentry->sqe_relid;
			newrelid = true;

			for (elt = DLGetHead(visited); elt; elt = DLGetSucc(elt))
			{
				vnode = (SuperQE *) DLE_VAL(elt);
				if (vnode && (qentry->sqe_relid == vnode->sqe_relid))
				{
					newrelid = false;
					break;
				}
			}
		} while (!newrelid);

		if (qentry != (SuperQE *) NULL)
		{

			/* save the type id, rather than the relation id */
			if ((rd = heap_open(qentry->sqe_relid)) == (Relation) NULL)
				elog(ERROR, "Relid %u does not exist", qentry->sqe_relid);
			qentry->sqe_relid = typeTypeId(typenameType(RelationGetRelationName(rd)->data));
			heap_close(rd);

			DLAddTail(visited, qe);

			nvisited++;
		}
	} while (qentry != (SuperQE *) NULL);

	heap_close(inhrel);

	if (nvisited > 0)
	{
		relidvec = (Oid *) palloc(nvisited * sizeof(Oid));
		*supervec = relidvec;

		for (elt = DLGetHead(visited); elt; elt = DLGetSucc(elt))
		{
			vnode = (SuperQE *) DLE_VAL(elt);
			*relidvec++ = vnode->sqe_relid;
		}

	}
	else
		*supervec = (Oid *) NULL;

	return nvisited;
}

static Oid **
gen_cross_product(InhPaths *arginh, int nargs)
{
	int			nanswers;
	Oid		  **result,
			  **iter;
	Oid		   *oneres;
	int			i,
				j;
	int			cur[MAXFARGS];

	nanswers = 1;
	for (i = 0; i < nargs; i++)
	{
		nanswers *= (arginh[i].nsupers + 2);
		cur[i] = 0;
	}

	iter = result = (Oid **) palloc(sizeof(Oid *) * nanswers);

	/* compute the cross product from right to left */
	for (;;)
	{
		oneres = (Oid *) palloc(MAXFARGS * sizeof(Oid));
		MemSet(oneres, 0, MAXFARGS * sizeof(Oid));

		for (i = nargs - 1; i >= 0 && cur[i] > arginh[i].nsupers; i--)
			continue;

		/* if we're done, terminate with NULL pointer */
		if (i < 0)
		{
			*iter = NULL;
			return result;
		}

		/* no, increment this column and zero the ones after it */
		cur[i] = cur[i] + 1;
		for (j = nargs - 1; j > i; j--)
			cur[j] = 0;

		for (i = 0; i < nargs; i++)
		{
			if (cur[i] == 0)
				oneres[i] = arginh[i].self;
			else if (cur[i] > arginh[i].nsupers)
				oneres[i] = 0;	/* wild card */
			else
				oneres[i] = arginh[i].supervec[cur[i] - 1];
		}

		*iter++ = oneres;
	}
}


/* make_arguments()
 * Given the number and types of arguments to a function, and the
 *	actual arguments and argument types, do the necessary typecasting.
 *
 * There are two ways an input typeid can differ from a function typeid:
 *	1) the input type inherits the function type, so no typecasting required
 *	2) the input type can be typecast into the function type
 * Right now, we only typecast unknowns, and that is all we check for.
 *
 * func_get_detail() now can find coersions for function arguments which
 *	will make this function executable. So, we need to recover these
 *	results here too.
 * - thomas 1998-03-25
 */
static void
make_arguments(ParseState *pstate,
			   int nargs,
			   List *fargs,
			   Oid *input_typeids,
			   Oid *function_typeids)
{
	List	   *current_fargs;
	int			i;

	for (i = 0, current_fargs = fargs;
		 i < nargs;
		 i++, current_fargs = lnext(current_fargs))
	{

		/*
		 * unspecified type for string constant? then use heuristics for
		 * conversion...
		 */
		if (input_typeids[i] == UNKNOWNOID && function_typeids[i] != InvalidOid)
		{
			lfirst(current_fargs) = parser_typecast2(lfirst(current_fargs),
													 input_typeids[i],
										 typeidType(function_typeids[i]),
													 -1);
		}

		/* types don't match? then force coersion using a function call... */
		else if (input_typeids[i] != function_typeids[i])
		{
			lfirst(current_fargs) = coerce_type(pstate,
												lfirst(current_fargs),
												input_typeids[i],
												function_typeids[i], -1);
		}
	}
}

/*
 ** setup_tlist
 **		Build a tlist that says which attribute to project to.
 **		This routine is called by ParseFuncOrColumn() to set up a target list
 **		on a tuple parameter or return value.  Due to a bug in 4.0,
 **		it's not possible to refer to system attributes in this case.
 */
static List *
setup_tlist(char *attname, Oid relid)
{
	TargetEntry *tle;
	Resdom	   *resnode;
	Var		   *varnode;
	Oid			typeid;
	int32		type_mod;
	int			attno;

	attno = get_attnum(relid, attname);
	if (attno < 0)
		elog(ERROR, "Cannot reference attribute '%s'"
			 " of tuple params/return values for functions", attname);

	typeid = get_atttype(relid, attno);
	type_mod = get_atttypmod(relid, attno);

	resnode = makeResdom(1,
						 typeid,
						 type_mod,
						 get_attname(relid, attno),
						 0,
						 InvalidOid,
						 false);
	varnode = makeVar(-1, attno, typeid, type_mod, 0, -1, attno);

	tle = makeTargetEntry(resnode, (Node *) varnode);
	return lcons(tle, NIL);
}

/*
 ** setup_base_tlist
 **		Build a tlist that extracts a base type from the tuple
 **		returned by the executor.
 */
static List *
setup_base_tlist(Oid typeid)
{
	TargetEntry *tle;
	Resdom	   *resnode;
	Var		   *varnode;

	resnode = makeResdom(1,
						 typeid,
						 -1,
						 "<noname>",
						 0,
						 InvalidOid,
						 false);
	varnode = makeVar(-1, 1, typeid, -1, 0, -1, 1);
	tle = makeTargetEntry(resnode, (Node *) varnode);

	return lcons(tle, NIL);
}

/*
 * ParseComplexProjection -
 *	  handles function calls with a single argument that is of complex type.
 *	  This routine returns NULL if it can't handle the projection (eg. sets).
 */
static Node *
ParseComplexProjection(ParseState *pstate,
					   char *funcname,
					   Node *first_arg,
					   bool *attisset)
{
	Oid			argtype;
	Oid			argrelid;
	Relation	rd;
	Oid			relid;
	int			attnum;

	switch (nodeTag(first_arg))
	{
		case T_Iter:
			{
				Func	   *func;
				Iter	   *iter;

				iter = (Iter *) first_arg;
				func = (Func *) ((Expr *) iter->iterexpr)->oper;
				argtype = funcid_get_rettype(func->funcid);
				argrelid = typeidTypeRelid(argtype);
				if (argrelid &&
					((attnum = get_attnum(argrelid, funcname))
					 != InvalidAttrNumber))
				{

					/*
					 * the argument is a function returning a tuple, so
					 * funcname may be a projection
					 */

					/* add a tlist to the func node and return the Iter */
					rd = heap_openr(typeidTypeName(argtype));
					if (RelationIsValid(rd))
					{
						relid = RelationGetRelid(rd);
						heap_close(rd);
					}
					if (RelationIsValid(rd))
					{
						func->func_tlist = setup_tlist(funcname, argrelid);
						iter->itertype = attnumTypeId(rd, attnum);
						return (Node *) iter;
					}
					else
					{
						elog(ERROR, "Function '%s' has bad return type %d",
							 funcname, argtype);
					}
				}
				else
				{
					/* drop through */
					;
				}
				break;
			}
		case T_Var:
			{

				/*
				 * The argument is a set, so this is either a projection
				 * or a function call on this set.
				 */
				*attisset = true;
				break;
			}
		case T_Expr:
			{
				Expr	   *expr = (Expr *) first_arg;
				Func	   *funcnode;

				if (expr->opType != FUNC_EXPR)
					break;

				funcnode = (Func *) expr->oper;
				argtype = funcid_get_rettype(funcnode->funcid);
				argrelid = typeidTypeRelid(argtype);

				/*
				 * the argument is a function returning a tuple, so
				 * funcname may be a projection
				 */
				if (argrelid &&
					(attnum = get_attnum(argrelid, funcname))
					!= InvalidAttrNumber)
				{

					/* add a tlist to the func node */
					rd = heap_openr(typeidTypeName(argtype));
					if (RelationIsValid(rd))
					{
						relid = RelationGetRelid(rd);
						heap_close(rd);
					}
					if (RelationIsValid(rd))
					{
						Expr	   *newexpr;

						funcnode->func_tlist = setup_tlist(funcname, argrelid);
						funcnode->functype = attnumTypeId(rd, attnum);

						newexpr = makeNode(Expr);
						newexpr->typeOid = funcnode->functype;
						newexpr->opType = FUNC_EXPR;
						newexpr->oper = (Node *) funcnode;
						newexpr->args = expr->args;

						return (Node *) newexpr;
					}

				}

				break;
			}
		case T_Param:
			{
				Param	   *param = (Param *) first_arg;

				/*
				 * If the Param is a complex type, this could be a
				 * projection
				 */
				rd = heap_openr(typeidTypeName(param->paramtype));
				if (RelationIsValid(rd))
				{
					relid = RelationGetRelid(rd);
					heap_close(rd);
					if ((attnum = get_attnum(relid, funcname))
						!= InvalidAttrNumber)
					{
						param->paramtype = attnumTypeId(rd, attnum);
						param->param_tlist = setup_tlist(funcname, relid);
						return (Node *) param;
					}
				}
				break;
			}
		default:
			break;
	}

	return NULL;
}

/*
 * Error message when function lookup fails that gives details of the
 * argument types
 */
void
func_error(char *caller, char *funcname, int nargs, Oid *argtypes, char *msg)
{
	char		p[(NAMEDATALEN + 2) * MAXFMGRARGS],
			   *ptr;
	int			i;

	ptr = p;
	*ptr = '\0';
	for (i = 0; i < nargs; i++)
	{
		if (i)
		{
			*ptr++ = ',';
			*ptr++ = ' ';
		}
		if (argtypes[i] != 0)
		{
			strcpy(ptr, typeidTypeName(argtypes[i]));
			*(ptr + NAMEDATALEN) = '\0';
		}
		else
			strcpy(ptr, "opaque");
		ptr += strlen(ptr);
	}

	if (caller == NULL)
	{
		elog(ERROR, "Function '%s(%s)' does not exist%s%s",
			 funcname, p, ((msg != NULL) ? "\n\t" : ""), ((msg != NULL) ? msg : ""));
	}
	else
	{
		elog(ERROR, "%s: function '%s(%s)' does not exist%s%s",
			 caller, funcname, p, ((msg != NULL) ? "\n\t" : ""), ((msg != NULL) ? msg : ""));
	}
}