C++ DirectFunctionCall1函数代码示例

Datum
oid_text(PG_FUNCTION_ARGS)
{
	Oid			oid = PG_GETARG_OID(0);
	text	   *result;
	int			len;
	char	   *str;

	str = DatumGetCString(DirectFunctionCall1(oidout,
											  ObjectIdGetDatum(oid)));
	len = strlen(str) + VARHDRSZ;

	result = (text *) palloc(len);

	VARATT_SIZEP(result) = len;
	memcpy(VARDATA(result), str, (len - VARHDRSZ));
	pfree(str);

	PG_RETURN_TEXT_P(result);
}

static Datum
uuid_generate_internal(int mode, const uuid_t *ns, const char *name)
{
	uuid_t	   *uuid;
	char	   *str;
	uuid_rc_t	rc;

	rc = uuid_create(&uuid);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);
	rc = uuid_make(uuid, mode, ns, name);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);
	str = uuid_to_string(uuid);
	rc = uuid_destroy(uuid);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);

	return DirectFunctionCall1(uuid_in, CStringGetDatum(str));
}

static Datum
special_uuid_value(const char *name)
{
	uuid_t	   *uuid;
	char	   *str;
	uuid_rc_t	rc;

	rc = uuid_create(&uuid);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);
	rc = uuid_load(uuid, name);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);
	str = uuid_to_string(uuid);
	rc = uuid_destroy(uuid);
	if (rc != UUID_RC_OK)
		pguuid_complain(rc);

	return DirectFunctionCall1(uuid_in, CStringGetDatum(str));
}

/*
 * Convert string using encoding_name. The destination
 * encoding is the DB encoding.
 *
 * TEXT convert_from(BYTEA string, NAME encoding_name) */
Datum
pg_convert_from(PG_FUNCTION_ARGS)
{
	Datum		string = PG_GETARG_DATUM(0);
	Datum		src_encoding_name = PG_GETARG_DATUM(1);
	Datum		dest_encoding_name = DirectFunctionCall1(namein,
									CStringGetDatum(DatabaseEncoding->name));
	Datum		result;

	result = DirectFunctionCall3(pg_convert, string,
								 src_encoding_name, dest_encoding_name);

	/*
	 * pg_convert returns a bytea, which we in turn return as text, relying on
	 * the fact that they are both in fact varlena types, and thus
	 * structurally identical. Although not all bytea values are valid text,
	 * in this case it will be because we've told pg_convert to return one
	 * that is valid as text in the current database encoding.
	 */
	PG_RETURN_DATUM(result);
}

PATH *
poly2path(POLYGON *poly)
{
	int			i;
	char	   *output = (char *) palloc(2 * (P_MAXDIG + 1) * poly->npts + 64);
	char		buf[2 * (P_MAXDIG) + 20];

	sprintf(output, "(1, %*d", P_MAXDIG, poly->npts);

	for (i = 0; i < poly->npts; i++)
	{
		snprintf(buf, sizeof(buf), ",%*g,%*g",
				 P_MAXDIG, poly->p[i].x, P_MAXDIG, poly->p[i].y);
		strcat(output, buf);
	}

	snprintf(buf, sizeof(buf), "%c", RDELIM);
	strcat(output, buf);
	return DatumGetPathP(DirectFunctionCall1(path_in,
											 CStringGetDatum(output)));
}

Datum
text_macaddr(PG_FUNCTION_ARGS)
{
	text	   *addr = PG_GETARG_TEXT_P(0);
	Datum		result;
	char		str[100];
	int			len;

	len = (VARSIZE(addr) - VARHDRSZ);
	if (len >= sizeof(str))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
				 errmsg("text too long to convert to MAC address")));

	memcpy(str, VARDATA(addr), len);
	*(str + len) = '\0';

	result = DirectFunctionCall1(macaddr_in, CStringGetDatum(str));

	return (result);
}

Datum
macaddr_text(PG_FUNCTION_ARGS)
{
	/* Input is a macaddr, but may as well leave it in Datum form */
	Datum		addr = PG_GETARG_DATUM(0);
	text	   *result;
	char	   *str;
	int			len;

	str = DatumGetCString(DirectFunctionCall1(macaddr_out, addr));

	len = (strlen(str) + VARHDRSZ);

	result = palloc(len);

	SET_VARSIZE(result, len);
	memcpy(VARDATA(result), str, (len - VARHDRSZ));

	pfree(str);

	PG_RETURN_TEXT_P(result);
}

/*
 *		float4_text		- converts a float4 number to a text string
 */
Datum
float4_text(PG_FUNCTION_ARGS)
{
	float4		num = PG_GETARG_FLOAT4(0);
	text	   *result;
	int			len;
	char	   *str;

	str = DatumGetCString(DirectFunctionCall1(float4out,
											  Float4GetDatum(num)));

	len = strlen(str) + VARHDRSZ;

	result = (text *) palloc(len);

	VARATT_SIZEP(result) = len;
	memcpy(VARDATA(result), str, (len - VARHDRSZ));

	pfree(str);

	PG_RETURN_TEXT_P(result);
}

Datum pcpoint_get_value(PG_FUNCTION_ARGS)
{
	SERIALIZED_POINT *serpt = PG_GETARG_SERPOINT_P(0);
	text *dim_name = PG_GETARG_TEXT_P(1);
	char *dim_str;
	float8 double_result;

    PCSCHEMA *schema = pc_schema_from_pcid(serpt->pcid, fcinfo);
	PCPOINT *pt = pc_point_deserialize(serpt, schema);
	if ( ! pt )
		PG_RETURN_NULL();	

	dim_str = text_to_cstring(dim_name);		
	if ( ! pc_point_get_double_by_name(pt, dim_str, &double_result) )
	{
		pc_point_free(pt);
		elog(ERROR, "dimension \"%s\" does not exist in schema", dim_str);		
	}
	pfree(dim_str);
	pc_point_free(pt);
	PG_RETURN_DATUM(DirectFunctionCall1(float8_numeric, Float8GetDatum(double_result)));
}

Datum LWGEOM_asText(PG_FUNCTION_ARGS)
{
	LWGEOM_UNPARSER_RESULT lwg_unparser_result;
	PG_LWGEOM *lwgeom;
	PG_LWGEOM *ogclwgeom;
	int len, result;
	char *lwgeom_result,*loc_wkt;
	char *semicolonLoc;

	POSTGIS_DEBUG(2, "LWGEOM_asText called.");

	lwgeom = (PG_LWGEOM *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));

	/* Force to 2d */
	ogclwgeom = (PG_LWGEOM *)DatumGetPointer(DirectFunctionCall1(
	                LWGEOM_force_2d, PointerGetDatum(lwgeom)));

	result =  serialized_lwgeom_to_ewkt(&lwg_unparser_result, SERIALIZED_FORM(ogclwgeom), PARSER_CHECK_NONE);
	if (result)
		PG_UNPARSER_ERROR(lwg_unparser_result);

	semicolonLoc = strchr(lwg_unparser_result.wkoutput,';');

	/* loc points to start of wkt */
	if (semicolonLoc == NULL) loc_wkt = lwg_unparser_result.wkoutput;
	else loc_wkt = semicolonLoc +1;

	len = strlen(loc_wkt)+VARHDRSZ;
	lwgeom_result = palloc(len);
	SET_VARSIZE(lwgeom_result, len);

	memcpy(VARDATA(lwgeom_result), loc_wkt, len-VARHDRSZ);

	pfree(lwg_unparser_result.wkoutput);
	PG_FREE_IF_COPY(lwgeom, 0);
	if ( ogclwgeom != lwgeom ) pfree(ogclwgeom);

	PG_RETURN_POINTER(lwgeom_result);
}

Datum
current_schemas(PG_FUNCTION_ARGS)
{
    List	   *search_path = fetch_search_path(PG_GETARG_BOOL(0));
    ListCell   *l;
    Datum	   *names;
    int			i;
    ArrayType  *array;

    names = (Datum *) palloc(list_length(search_path) * sizeof(Datum));
    i = 0;
    foreach(l, search_path)
    {
        char	   *nspname;

        nspname = get_namespace_name(lfirst_oid(l));
        if (nspname)			/* watch out for deleted namespace */
        {
            names[i] = DirectFunctionCall1(namein, CStringGetDatum(nspname));
            i++;
        }
    }

/*
 * This creates a large object, and sets its OID to the value in the
 * supplied string.
 *
 * If the string is empty, then a new LargeObject is created, and its oid
 * is placed in the resulting lo.
 */
Blob *
lo_in(char *str)
{
	Blob	   *result;
	Oid			oid;
	int			count;

	if (strlen(str) > 0)
	{
		count = sscanf(str, "%u", &oid);

		if (count < 1)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("error in parsing \"%s\"", str)));

		if (oid == InvalidOid)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("illegal oid: \"%s\"", str)));
	}
	else
	{
		/*
		 * There is no Oid passed, so create a new one
		 */
		oid = DatumGetObjectId(DirectFunctionCall1(lo_creat,
								   Int32GetDatum(INV_READ | INV_WRITE)));
		if (oid == InvalidOid)
			/* internal error */
			elog(ERROR, "InvalidOid returned from lo_creat");
	}

	result = (Blob *) palloc(sizeof(Blob));

	*result = oid;

	return (result);
}

Datum
spherepoly_out(PG_FUNCTION_ARGS)
{
	SPOLY	   *poly = PG_GETARG_SPOLY(0);
	int32		i;
	char	   *out = (char *) palloc(128 * poly->npts);
	char	   *tmp;

	strcpy(out, "{");
	for (i = 0; i < poly->npts; i++)
	{
		if (i > 0)
		{
			strcat(out, ",");
		}
		tmp = DatumGetPointer(DirectFunctionCall1(spherepoint_out,
												  PointerGetDatum(&poly->p[i])));
		strcat(out, tmp);
		pfree(tmp);
	}
	strcat(out, "}");
	PG_RETURN_CSTRING(out);
}

Datum
months_between(PG_FUNCTION_ARGS)
{
	DateADT date1 = PG_GETARG_DATEADT(0);
	DateADT date2 = PG_GETARG_DATEADT(1);

	int y1, m1, d1;
	int y2, m2, d2;

	float8 result;

	j2date(date1 + POSTGRES_EPOCH_JDATE, &y1, &m1, &d1);
	j2date(date2 + POSTGRES_EPOCH_JDATE, &y2, &m2, &d2);

	/* Ignore day components for last days, or based on a 31-day month. */
	if (d1 == days_of_month(y1, m1) && d2 == days_of_month(y2, m2))
		result = (y1 - y2) * 12 + (m1 - m2);
	else
		result = (y1 - y2) * 12 + (m1 - m2) + (d1 - d2) / 31.0;

	PG_RETURN_NUMERIC(
		DirectFunctionCall1(float8_numeric, Float8GetDatumFast(result)));
}

/*
 * GenereatePartitioningInformation returns the partitioning type and partition column
 * for the given parent table in the form of "PARTITION TYPE (partitioning column(s)/expression(s))".
 */
char *
GeneratePartitioningInformation(Oid parentTableId)
{
	char *partitionBoundCString = "";

#if (PG_VERSION_NUM >= 100000)
	Datum partitionBoundDatum = 0;

	if (!PartitionedTable(parentTableId))
	{
		char *relationName = get_rel_name(parentTableId);

		ereport(ERROR, (errmsg("\"%s\" is not a parent table", relationName)));
	}

	partitionBoundDatum = DirectFunctionCall1(pg_get_partkeydef,
											  ObjectIdGetDatum(parentTableId));

	partitionBoundCString = TextDatumGetCString(partitionBoundDatum);
#endif

	return partitionBoundCString;
}