Function exec_assign_expr

src/pl/plpgsql/src/pl_exec.c:4938–4970

---------- * exec_assign_expr Put an expression's result into a variable. * ---------- */

 * ----------
 */
static void
exec_assign_expr(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
				 PLpgSQL_expr *expr)
{
	Datum		value;
	bool		isnull;
	Oid			valtype;
	int32		valtypmod;

	/*
	 * If first time through, create a plan for this expression.
	 */
	if (expr->plan == NULL)
	{
		/*
		 * Mark the expression as being an assignment source, if target is a
		 * simple variable.  (This is a bit messy, but it seems cleaner than
		 * modifying the API of exec_prepare_plan for the purpose.  We need to
		 * stash the target dno into the expr anyway, so that it will be
		 * available if we have to replan.)
		 */
		if (target->dtype == PLPGSQL_DTYPE_VAR)
			expr->target_param = target->dno;
		else
			expr->target_param = -1;	/* should be that already */

		exec_prepare_plan(estate, expr, 0);
	}

	value = exec_eval_expr(estate, expr, &isnull, &valtype, &valtypmod);
	exec_assign_value(estate, target, value, isnull, valtype, valtypmod);
	exec_eval_cleanup(estate);
}


/* ----------