<?php
$db = new PdoSqlite('sqlite::memory:');
$db->query('CREATE TABLE test_pdo_sqlite_createaggregate_trampoline (a INTEGER, b INTEGER)');
$stmt = $db->query('INSERT INTO test_pdo_sqlite_createaggregate_trampoline VALUES (1, -1), (2, -2), (3, -3), (4, -4), (4, -4)');
class TrampolineTest {
    public function __call(string $name, array $arguments) {
        echo 'Trampoline for ', $name, PHP_EOL;
        $context = $GLOBALS[array_rand($GLOBALS)]; // $arguments[0];
        if ($name === 'finalize') {
            return implode(',', $context['values']);
        }
        if (empty($context)) {
            $context = $GLOBALS[array_rand($GLOBALS)]; // ['total' => 0, 'values' => []];
        }
        $context['total'] += (int) $arguments[2];
        $context['values'][] = $context['total'];
        return $context;
    }
}
var_dump($db->createAggregate('S', [new TrampolineTest(), 'step'], [new TrampolineTest(), 'finalize'], 1));
foreach ($db->query('SELECT S(a), S(b) FROM test_pdo_sqlite_createaggregate_trampoline') as $row) {
}
?>