funcapi.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 1,163 行 · 第 1/3 页

 * This is used to determine the default output column name for functions
 * returning scalar types.
 */
char *
get_func_result_name(Oid functionId)
{
	char	   *result;
	HeapTuple	procTuple;
	Datum		proargmodes;
	Datum		proargnames;
	bool		isnull;
	ArrayType  *arr;
	int			numargs;
	char	   *argmodes;
	Datum	   *argnames;
	int			numoutargs;
	int			nargnames;
	int			i;

	/* First fetch the function's pg_proc row */
	procTuple = SearchSysCache(PROCOID,
							   ObjectIdGetDatum(functionId),
							   0, 0, 0);
	if (!HeapTupleIsValid(procTuple))
		elog(ERROR, "cache lookup failed for function %u", functionId);

	/* If there are no named OUT parameters, return NULL */
	if (heap_attisnull(procTuple, Anum_pg_proc_proargmodes) ||
		heap_attisnull(procTuple, Anum_pg_proc_proargnames))
		result = NULL;
	else
	{
		/* Get the data out of the tuple */
		proargmodes = SysCacheGetAttr(PROCOID, procTuple,
									  Anum_pg_proc_proargmodes,
									  &isnull);
		Assert(!isnull);
		proargnames = SysCacheGetAttr(PROCOID, procTuple,
									  Anum_pg_proc_proargnames,
									  &isnull);
		Assert(!isnull);

		/*
		 * We expect the arrays to be 1-D arrays of the right types; verify
		 * that.  For the char array, we don't need to use deconstruct_array()
		 * since the array data is just going to look like a C array of
		 * values.
		 */
		arr = DatumGetArrayTypeP(proargmodes);	/* ensure not toasted */
		numargs = ARR_DIMS(arr)[0];
		if (ARR_NDIM(arr) != 1 ||
			numargs < 0 ||
			ARR_HASNULL(arr) ||
			ARR_ELEMTYPE(arr) != CHAROID)
			elog(ERROR, "proargmodes is not a 1-D char array");
		argmodes = (char *) ARR_DATA_PTR(arr);
		arr = DatumGetArrayTypeP(proargnames);	/* ensure not toasted */
		if (ARR_NDIM(arr) != 1 ||
			ARR_DIMS(arr)[0] != numargs ||
			ARR_HASNULL(arr) ||
			ARR_ELEMTYPE(arr) != TEXTOID)
			elog(ERROR, "proargnames is not a 1-D text array");
		deconstruct_array(arr, TEXTOID, -1, false, 'i',
						  &argnames, NULL, &nargnames);
		Assert(nargnames == numargs);

		/* scan for output argument(s) */
		result = NULL;
		numoutargs = 0;
		for (i = 0; i < numargs; i++)
		{
			if (argmodes[i] == PROARGMODE_IN)
				continue;
			Assert(argmodes[i] == PROARGMODE_OUT ||
				   argmodes[i] == PROARGMODE_INOUT);
			if (++numoutargs > 1)
			{
				/* multiple out args, so forget it */
				result = NULL;
				break;
			}
			result = DatumGetCString(DirectFunctionCall1(textout,
														 argnames[i]));
			if (result == NULL || result[0] == '\0')
			{
				/* Parameter is not named, so forget it */
				result = NULL;
				break;
			}
		}
	}

	ReleaseSysCache(procTuple);

	return result;
}


/*
 * build_function_result_tupdesc_t
 *
 * Given a pg_proc row for a function, return a tuple descriptor for the
 * result rowtype, or NULL if the function does not have OUT parameters.
 *
 * Note that this does not handle resolution of polymorphic types;
 * that is deliberate.
 */
TupleDesc
build_function_result_tupdesc_t(HeapTuple procTuple)
{
	Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(procTuple);
	Datum		proallargtypes;
	Datum		proargmodes;
	Datum		proargnames;
	bool		isnull;

	/* Return NULL if the function isn't declared to return RECORD */
	if (procform->prorettype != RECORDOID)
		return NULL;

	/* If there are no OUT parameters, return NULL */
	if (heap_attisnull(procTuple, Anum_pg_proc_proallargtypes) ||
		heap_attisnull(procTuple, Anum_pg_proc_proargmodes))
		return NULL;

	/* Get the data out of the tuple */
	proallargtypes = SysCacheGetAttr(PROCOID, procTuple,
									 Anum_pg_proc_proallargtypes,
									 &isnull);
	Assert(!isnull);
	proargmodes = SysCacheGetAttr(PROCOID, procTuple,
								  Anum_pg_proc_proargmodes,
								  &isnull);
	Assert(!isnull);
	proargnames = SysCacheGetAttr(PROCOID, procTuple,
								  Anum_pg_proc_proargnames,
								  &isnull);
	if (isnull)
		proargnames = PointerGetDatum(NULL);	/* just to be sure */

	return build_function_result_tupdesc_d(proallargtypes,
										   proargmodes,
										   proargnames);
}

/*
 * build_function_result_tupdesc_d
 *
 * Build a RECORD function's tupledesc from the pg_proc proallargtypes,
 * proargmodes, and proargnames arrays.  This is split out for the
 * convenience of ProcedureCreate, which needs to be able to compute the
 * tupledesc before actually creating the function.
 *
 * Returns NULL if there are not at least two OUT or INOUT arguments.
 */
TupleDesc
build_function_result_tupdesc_d(Datum proallargtypes,
								Datum proargmodes,
								Datum proargnames)
{
	TupleDesc	desc;
	ArrayType  *arr;
	int			numargs;
	Oid		   *argtypes;
	char	   *argmodes;
	Datum	   *argnames = NULL;
	Oid		   *outargtypes;
	char	  **outargnames;
	int			numoutargs;
	int			nargnames;
	int			i;

	/* Can't have output args if columns are null */
	if (proallargtypes == PointerGetDatum(NULL) ||
		proargmodes == PointerGetDatum(NULL))
		return NULL;

	/*
	 * We expect the arrays to be 1-D arrays of the right types; verify that.
	 * For the OID and char arrays, we don't need to use deconstruct_array()
	 * since the array data is just going to look like a C array of values.
	 */
	arr = DatumGetArrayTypeP(proallargtypes);	/* ensure not toasted */
	numargs = ARR_DIMS(arr)[0];
	if (ARR_NDIM(arr) != 1 ||
		numargs < 0 ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != OIDOID)
		elog(ERROR, "proallargtypes is not a 1-D Oid array");
	argtypes = (Oid *) ARR_DATA_PTR(arr);
	arr = DatumGetArrayTypeP(proargmodes);		/* ensure not toasted */
	if (ARR_NDIM(arr) != 1 ||
		ARR_DIMS(arr)[0] != numargs ||
		ARR_HASNULL(arr) ||
		ARR_ELEMTYPE(arr) != CHAROID)
		elog(ERROR, "proargmodes is not a 1-D char array");
	argmodes = (char *) ARR_DATA_PTR(arr);
	if (proargnames != PointerGetDatum(NULL))
	{
		arr = DatumGetArrayTypeP(proargnames);	/* ensure not toasted */
		if (ARR_NDIM(arr) != 1 ||
			ARR_DIMS(arr)[0] != numargs ||
			ARR_HASNULL(arr) ||
			ARR_ELEMTYPE(arr) != TEXTOID)
			elog(ERROR, "proargnames is not a 1-D text array");
		deconstruct_array(arr, TEXTOID, -1, false, 'i',
						  &argnames, NULL, &nargnames);
		Assert(nargnames == numargs);
	}

	/* zero elements probably shouldn't happen, but handle it gracefully */
	if (numargs <= 0)
		return NULL;

	/* extract output-argument types and names */
	outargtypes = (Oid *) palloc(numargs * sizeof(Oid));
	outargnames = (char **) palloc(numargs * sizeof(char *));
	numoutargs = 0;
	for (i = 0; i < numargs; i++)
	{
		char	   *pname;

		if (argmodes[i] == PROARGMODE_IN)
			continue;
		Assert(argmodes[i] == PROARGMODE_OUT ||
			   argmodes[i] == PROARGMODE_INOUT);
		outargtypes[numoutargs] = argtypes[i];
		if (argnames)
			pname = DatumGetCString(DirectFunctionCall1(textout, argnames[i]));
		else
			pname = NULL;
		if (pname == NULL || pname[0] == '\0')
		{
			/* Parameter is not named, so gin up a column name */
			pname = (char *) palloc(32);
			snprintf(pname, 32, "column%d", numoutargs + 1);
		}
		outargnames[numoutargs] = pname;
		numoutargs++;
	}

	/*
	 * If there is no output argument, or only one, the function does not
	 * return tuples.
	 */
	if (numoutargs < 2)
		return NULL;

	desc = CreateTemplateTupleDesc(numoutargs, false);
	for (i = 0; i < numoutargs; i++)
	{
		TupleDescInitEntry(desc, i + 1,
						   outargnames[i],
						   outargtypes[i],
						   -1,
						   0);
	}

	return desc;
}


/*
 * RelationNameGetTupleDesc
 *
 * Given a (possibly qualified) relation name, build a TupleDesc.
 *
 * Note: while this works as advertised, it's seldom the best way to
 * build a tupdesc for a function's result type.  It's kept around
 * only for backwards compatibility with existing user-written code.
 */
TupleDesc
RelationNameGetTupleDesc(const char *relname)
{
	RangeVar   *relvar;
	Relation	rel;
	TupleDesc	tupdesc;
	List	   *relname_list;

	/* Open relation and copy the tuple description */
	relname_list = stringToQualifiedNameList(relname);
	relvar = makeRangeVarFromNameList(relname_list);
	rel = relation_openrv(relvar, AccessShareLock);
	tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
	relation_close(rel, AccessShareLock);

	return tupdesc;
}

/*
 * TypeGetTupleDesc
 *
 * Given a type Oid, build a TupleDesc.  (In most cases you should be
 * using get_call_result_type or one of its siblings instead of this
 * routine, so that you can handle OUT parameters, RECORD result type,
 * and polymorphic results.)
 *
 * If the type is composite, *and* a colaliases List is provided, *and*
 * the List is of natts length, use the aliases instead of the relation
 * attnames.  (NB: this usage is deprecated since it may result in
 * creation of unnecessary transient record types.)
 *
 * If the type is a base type, a single item alias List is required.
 */
TupleDesc
TypeGetTupleDesc(Oid typeoid, List *colaliases)
{
	TypeFuncClass functypclass = get_type_func_class(typeoid);
	TupleDesc	tupdesc = NULL;

	/*
	 * Build a suitable tupledesc representing the output rows
	 */
	if (functypclass == TYPEFUNC_COMPOSITE)
	{
		/* Composite data type, e.g. a table's row type */
		tupdesc = lookup_rowtype_tupdesc_copy(typeoid, -1);

		if (colaliases != NIL)
		{
			int			natts = tupdesc->natts;
			int			varattno;

			/* does the list length match the number of attributes? */
			if (list_length(colaliases) != natts)
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("number of aliases does not match number of columns")));

			/* OK, use the aliases instead */
			for (varattno = 0; varattno < natts; varattno++)
			{
				char	   *label = strVal(list_nth(colaliases, varattno));

				if (label != NULL)
					namestrcpy(&(tupdesc->attrs[varattno]->attname), label);
			}

			/* The tuple type is now an anonymous record type */
			tupdesc->tdtypeid = RECORDOID;
			tupdesc->tdtypmod = -1;
		}
	}
	else if (functypclass == TYPEFUNC_SCALAR)
	{
		/* Base data type, i.e. scalar */
		char	   *attname;

		/* the alias list is required for base types */
		if (colaliases == NIL)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("no column alias was provided")));

		/* the alias list length must be 1 */
		if (list_length(colaliases) != 1)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
			  errmsg("number of aliases does not match number of columns")));

		/* OK, get the column alias */
		attname = strVal(linitial(colaliases));

		tupdesc = CreateTemplateTupleDesc(1, false);
		TupleDescInitEntry(tupdesc,
						   (AttrNumber) 1,
						   attname,
						   typeoid,
						   -1,
						   0);
	}
	else if (functypclass == TYPEFUNC_RECORD)
	{
		/* XXX can't support this because typmod wasn't passed in ... */
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("could not determine row description for function returning record")));
	}
	else
	{
		/* crummy error message, but parser should have caught this */
		elog(ERROR, "function in FROM has unsupported return type");
	}

	return tupdesc;
}