Function exec_eval_datum

src/pl/plpgsql/src/pl_exec.c:5237–5380

* exec_eval_datum Get current value of a PLpgSQL_datum * * The type oid, typmod, value in Datum format, and null flag are returned. * * At present this doesn't handle PLpgSQL_expr datums; that's not needed * because we never pass references to such datums to SPI. * * NOTE: the returned Datum points right at the stored value in the case of * pass-by-reference datatypes. Generally caller

 * it into the estate's eval_mcontext.
 */
static void
exec_eval_datum(PLpgSQL_execstate *estate,
				PLpgSQL_datum *datum,
				Oid *typeid,
				int32 *typetypmod,
				Datum *value,
				bool *isnull)
{
	MemoryContext oldcontext;

	switch (datum->dtype)
	{
		case PLPGSQL_DTYPE_PROMISE:
			/* fulfill promise if needed, then handle like regular var */
			plpgsql_fulfill_promise(estate, (PLpgSQL_var *) datum);

			/* FALL THRU */

		case PLPGSQL_DTYPE_VAR:
			{
				PLpgSQL_var *var = (PLpgSQL_var *) datum;

				*typeid = var->datatype->typoid;
				*typetypmod = var->datatype->atttypmod;
				*value = var->value;
				*isnull = var->isnull;
				break;
			}

		case PLPGSQL_DTYPE_ROW:
			{
				PLpgSQL_row *row = (PLpgSQL_row *) datum;
				HeapTuple	tup;

				/* We get here if there are multiple OUT parameters */
				if (!row->rowtupdesc)	/* should not happen */
					elog(ERROR, "row variable has no tupdesc");
				/* Make sure we have a valid type/typmod setting */
				BlessTupleDesc(row->rowtupdesc);
				oldcontext = MemoryContextSwitchTo(get_eval_mcontext(estate));
				tup = make_tuple_from_row(estate, row, row->rowtupdesc);
				if (tup == NULL)	/* should not happen */
					elog(ERROR, "row not compatible with its own tupdesc");
				*typeid = row->rowtupdesc->tdtypeid;
				*typetypmod = row->rowtupdesc->tdtypmod;
				*value = HeapTupleGetDatum(tup);
				*isnull = false;
				MemoryContextSwitchTo(oldcontext);
				break;
			}

		case PLPGSQL_DTYPE_REC:
			{
				PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;

				if (rec->erh == NULL)
				{
					/* Treat uninstantiated record as a simple NULL */