exectuples.c

PostgreSQL7.4.6 for Linux

/* --------------------------------
 *		ExecSetSlotDescriptor
 *
 *		This function is used to set the tuple descriptor associated
 *		with the slot's tuple.
 * --------------------------------
 */
void
ExecSetSlotDescriptor(TupleTableSlot *slot,		/* slot to change */
					  TupleDesc tupdesc,		/* new tuple descriptor */
					  bool shouldFree)	/* is desc owned by slot? */
{
	if (slot->ttc_shouldFreeDesc &&
		slot->ttc_tupleDescriptor != NULL)
		FreeTupleDesc(slot->ttc_tupleDescriptor);

	slot->ttc_tupleDescriptor = tupdesc;
	slot->ttc_shouldFreeDesc = shouldFree;
}

/* --------------------------------
 *		ExecSetSlotDescriptorIsNew
 *
 *		This function is used to change the setting of the "isNew" flag
 * --------------------------------
 */
void
ExecSetSlotDescriptorIsNew(TupleTableSlot *slot,		/* slot to change */
						   bool isNew)	/* "isNew" setting */
{
	slot->ttc_descIsNew = isNew;
}

/* ----------------------------------------------------------------
 *				  tuple table slot status predicates
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *				convenience initialization routines
 * ----------------------------------------------------------------
 */
/* --------------------------------
 *		ExecInit{Result,Scan,Extra}TupleSlot
 *
 *		These are convenience routines to initialize the specified slot
 *		in nodes inheriting the appropriate state.	ExecInitExtraTupleSlot
 *		is used for initializing special-purpose slots.
 * --------------------------------
 */
#define INIT_SLOT_DEFS \
	TupleTable	   tupleTable; \
	TupleTableSlot*   slot

#define INIT_SLOT_ALLOC \
	tupleTable = (TupleTable) estate->es_tupleTable; \
	slot =		 ExecAllocTableSlot(tupleTable);

/* ----------------
 *		ExecInitResultTupleSlot
 * ----------------
 */
void
ExecInitResultTupleSlot(EState *estate, PlanState *planstate)
{
	INIT_SLOT_DEFS;
	INIT_SLOT_ALLOC;
	planstate->ps_ResultTupleSlot = slot;
}

/* ----------------
 *		ExecInitScanTupleSlot
 * ----------------
 */
void
ExecInitScanTupleSlot(EState *estate, ScanState *scanstate)
{
	INIT_SLOT_DEFS;
	INIT_SLOT_ALLOC;
	scanstate->ss_ScanTupleSlot = slot;
}

/* ----------------
 *		ExecInitExtraTupleSlot
 * ----------------
 */
TupleTableSlot *
ExecInitExtraTupleSlot(EState *estate)
{
	INIT_SLOT_DEFS;
	INIT_SLOT_ALLOC;
	return slot;
}

/* ----------------
 *		ExecInitNullTupleSlot
 *
 * Build a slot containing an all-nulls tuple of the given type.
 * This is used as a substitute for an input tuple when performing an
 * outer join.
 * ----------------
 */
TupleTableSlot *
ExecInitNullTupleSlot(EState *estate, TupleDesc tupType)
{
	TupleTableSlot *slot = ExecInitExtraTupleSlot(estate);

	/*
	 * Since heap_getattr() will treat attributes beyond a tuple's t_natts
	 * as being NULL, we can make an all-nulls tuple just by making it be
	 * of zero length.	However, the slot descriptor must match the real
	 * tupType.
	 */
	HeapTuple	nullTuple;
	Datum		values[1];
	char		nulls[1];
	static struct tupleDesc NullTupleDesc;		/* we assume this inits to
												 * zeroes */

	ExecSetSlotDescriptor(slot, tupType, false);

	nullTuple = heap_formtuple(&NullTupleDesc, values, nulls);

	return ExecStoreTuple(nullTuple, slot, InvalidBuffer, true);
}

/* ----------------------------------------------------------------
 *		ExecTypeFromTL
 *
 *		Generate a tuple descriptor for the result tuple of a targetlist.
 *		(A parse/plan tlist must be passed, not an ExprState tlist.)
 *		Note that resjunk columns, if any, are included in the result.
 *
 *		Currently there are about 4 different places where we create
 *		TupleDescriptors.  They should all be merged, or perhaps
 *		be rewritten to call BuildDesc().
 * ----------------------------------------------------------------
 */
TupleDesc
ExecTypeFromTL(List *targetList, bool hasoid)
{
	TupleDesc	typeInfo;
	List	   *tlitem;
	int			len;

	/*
	 * allocate a new typeInfo
	 */
	len = ExecTargetListLength(targetList);
	typeInfo = CreateTemplateTupleDesc(len, hasoid);

	/*
	 * scan list, generate type info for each entry
	 */
	foreach(tlitem, targetList)
	{
		TargetEntry *tle = lfirst(tlitem);
		Resdom	   *resdom = tle->resdom;

		TupleDescInitEntry(typeInfo,
						   resdom->resno,
						   resdom->resname,
						   resdom->restype,
						   resdom->restypmod,
						   0,
						   false);
	}

	return typeInfo;
}

/* ----------------------------------------------------------------
 *		ExecCleanTypeFromTL
 *
 *		Same as above, but resjunk columns are omitted from the result.
 * ----------------------------------------------------------------
 */
TupleDesc
ExecCleanTypeFromTL(List *targetList, bool hasoid)
{
	TupleDesc	typeInfo;
	List	   *tlitem;
	int			len;
	int			cleanresno;

	/*
	 * allocate a new typeInfo
	 */
	len = ExecCleanTargetListLength(targetList);
	typeInfo = CreateTemplateTupleDesc(len, hasoid);

	/*
	 * scan list, generate type info for each entry
	 */
	cleanresno = 1;
	foreach(tlitem, targetList)
	{
		TargetEntry *tle = lfirst(tlitem);
		Resdom	   *resdom = tle->resdom;

		if (resdom->resjunk)
			continue;
		TupleDescInitEntry(typeInfo,
						   cleanresno++,
						   resdom->resname,
						   resdom->restype,
						   resdom->restypmod,
						   0,
						   false);
	}

	return typeInfo;
}

/*
 * TupleDescGetSlot - Initialize a slot based on the supplied tupledesc
 */
TupleTableSlot *
TupleDescGetSlot(TupleDesc tupdesc)
{
	TupleTableSlot *slot;

	/* Make a standalone slot */
	slot = MakeTupleTableSlot();

	/* Bind the tuple description to the slot */
	ExecSetSlotDescriptor(slot, tupdesc, true);

	/* Return the slot */
	return slot;
}

/*
 * TupleDescGetAttInMetadata - Build an AttInMetadata structure based on the
 * supplied TupleDesc. AttInMetadata can be used in conjunction with C strings
 * to produce a properly formed tuple.
 */
AttInMetadata *
TupleDescGetAttInMetadata(TupleDesc tupdesc)
{
	int			natts = tupdesc->natts;
	int			i;
	Oid			atttypeid;
	Oid			attinfuncid;
	FmgrInfo   *attinfuncinfo;
	Oid		   *attelems;
	int32	   *atttypmods;
	AttInMetadata *attinmeta;

	attinmeta = (AttInMetadata *) palloc(sizeof(AttInMetadata));

	/*
	 * Gather info needed later to call the "in" function for each
	 * attribute
	 */
	attinfuncinfo = (FmgrInfo *) palloc0(natts * sizeof(FmgrInfo));
	attelems = (Oid *) palloc0(natts * sizeof(Oid));
	atttypmods = (int32 *) palloc0(natts * sizeof(int32));

	for (i = 0; i < natts; i++)
	{
		/* Ignore dropped attributes */
		if (!tupdesc->attrs[i]->attisdropped)
		{
			atttypeid = tupdesc->attrs[i]->atttypid;
			getTypeInputInfo(atttypeid, &attinfuncid, &attelems[i]);
			fmgr_info(attinfuncid, &attinfuncinfo[i]);
			atttypmods[i] = tupdesc->attrs[i]->atttypmod;
		}
	}
	attinmeta->tupdesc = tupdesc;
	attinmeta->attinfuncs = attinfuncinfo;
	attinmeta->attelems = attelems;
	attinmeta->atttypmods = atttypmods;

	return attinmeta;
}

/*
 * BuildTupleFromCStrings - build a HeapTuple given user data in C string form.
 * values is an array of C strings, one for each attribute of the return tuple.
 */
HeapTuple
BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values)
{
	TupleDesc	tupdesc = attinmeta->tupdesc;
	int			natts = tupdesc->natts;
	Datum	   *dvalues;
	char	   *nulls;
	int			i;
	Oid			attelem;
	int32		atttypmod;
	HeapTuple	tuple;

	dvalues = (Datum *) palloc(natts * sizeof(Datum));
	nulls = (char *) palloc(natts * sizeof(char));

	/* Call the "in" function for each non-null, non-dropped attribute */
	for (i = 0; i < natts; i++)
	{
		if (!tupdesc->attrs[i]->attisdropped)
		{
			/* Non-dropped attributes */
			if (values[i] != NULL)
			{
				attelem = attinmeta->attelems[i];
				atttypmod = attinmeta->atttypmods[i];

				dvalues[i] = FunctionCall3(&attinmeta->attinfuncs[i],
										   CStringGetDatum(values[i]),
										   ObjectIdGetDatum(attelem),
										   Int32GetDatum(atttypmod));
				nulls[i] = ' ';
			}
			else
			{
				dvalues[i] = (Datum) 0;
				nulls[i] = 'n';
			}
		}
		else
		{
			/* Handle dropped attributes by setting to NULL */
			dvalues[i] = (Datum) 0;
			nulls[i] = 'n';
		}
	}

	/*
	 * Form a tuple
	 */
	tuple = heap_formtuple(tupdesc, dvalues, nulls);

	/*
	 * Release locally palloc'd space.  XXX would probably be good to
	 * pfree values of pass-by-reference datums, as well.
	 */
	pfree(dvalues);
	pfree(nulls);

	return tuple;
}

/*
 * Functions for sending tuples to the frontend (or other specified destination)
 * as though it is a SELECT result. These are used by utility commands that
 * need to project directly to the destination and don't need or want full
 * Table Function capability. Currently used by EXPLAIN and SHOW ALL
 */
TupOutputState *
begin_tup_output_tupdesc(DestReceiver *dest, TupleDesc tupdesc)
{
	TupOutputState *tstate;

	tstate = (TupOutputState *) palloc(sizeof(TupOutputState));

	tstate->metadata = TupleDescGetAttInMetadata(tupdesc);
	tstate->dest = dest;

	(*tstate->dest->rStartup) (tstate->dest, (int) CMD_SELECT, tupdesc);

	return tstate;
}

/*
 * write a single tuple
 *
 * values is a list of the external C string representations of the values
 * to be projected.
 */
void
do_tup_output(TupOutputState *tstate, char **values)
{
	/* build a tuple from the input strings using the tupdesc */
	HeapTuple	tuple = BuildTupleFromCStrings(tstate->metadata, values);

	/* send the tuple to the receiver */
	(*tstate->dest->receiveTuple) (tuple,
								   tstate->metadata->tupdesc,
								   tstate->dest);
	/* clean up */
	heap_freetuple(tuple);
}

/*
 * write a chunk of text, breaking at newline characters
 *
 * NB: scribbles on its input!
 *
 * Should only be used with a single-TEXT-attribute tupdesc.
 */
void
do_text_output_multiline(TupOutputState *tstate, char *text)
{
	while (*text)
	{
		char	   *eol;

		eol = strchr(text, '\n');
		if (eol)
			*eol++ = '\0';
		else
			eol = text +strlen(text);

		do_tup_output(tstate, &text);
		text = eol;
	}
}

void
end_tup_output(TupOutputState *tstate)
{
	(*tstate->dest->rShutdown) (tstate->dest);
	/* note that destroying the dest is not ours to do */
	/* XXX worth cleaning up the attinmetadata? */
	pfree(tstate);
}