Function make_tuple_from_row

src/pl/plpgsql/src/pl_exec.c:7264–7303

---------- * make_tuple_from_row Make a tuple from the values of a row object * * A NULL return indicates rowtype mismatch; caller must raise suitable error * * The result tuple is freshly palloc'd in caller's context. Some junk * may be left behind in eval_mcontext, too. * ---------- */

 * ----------
 */
static HeapTuple
make_tuple_from_row(PLpgSQL_execstate *estate,
					PLpgSQL_row *row,
					TupleDesc tupdesc)
{
	int			natts = tupdesc->natts;
	HeapTuple	tuple;
	Datum	   *dvalues;
	bool	   *nulls;
	int			i;

	if (natts != row->nfields)
		return NULL;

	dvalues = (Datum *) eval_mcontext_alloc0(estate, natts * sizeof(Datum));
	nulls = (bool *) eval_mcontext_alloc(estate, natts * sizeof(bool));

	for (i = 0; i < natts; i++)
	{
		Oid			fieldtypeid;
		int32		fieldtypmod;

		if (TupleDescAttr(tupdesc, i)->attisdropped)
		{
			nulls[i] = true;	/* leave the column as null */
			continue;
		}

		exec_eval_datum(estate, estate->datums[row->varnos[i]],
						&fieldtypeid, &fieldtypmod,
						&dvalues[i], &nulls[i]);
		if (fieldtypeid != TupleDescAttr(tupdesc, i)->atttypid)
			return NULL;
		/* XXX should we insist on typmod match, too? */
	}

	tuple = heap_form_tuple(tupdesc, dvalues, nulls);

	return tuple;
}

/*
 * deconstruct_composite_datum		extract tuple+tupdesc from composite Datum