"Java isn't that complicated, you can build it with PHP" - Sorin

php_pattern_matching.php

<?php

class Magic
{
    public function add()
    {
        $args = func_get_args();
        $count = count($args);

        $methods = [];

        $refl = new ReflectionClass(static::class);
        foreach ($refl->getMethods() as $method) {
            if (0 === strpos($method->getName(), '_' . __FUNCTION__ . '_')
                && $method->getNumberOfParameters() === $count
            ) {
                $methods[] = $method;
            }
        }

        $types = array_map('gettype', $args);
        foreach ($methods as $method) {
            $params = $method->getParameters();

            $paramTypes = [];

            foreach ($params as $param) {
                $paramTypes[$param->getPosition()] = $param->hasType() ? $this->normalize($param->getType()->getName()) : 'mixed';
            }

            if ($types === $paramTypes) {
                return call_user_func_array([$this, $method->getName()], $args);
            }
        }
    }

    private function normalize(string $type)
    {
        switch ($type) {
            case 'int':
                return 'integer';
            default:
                return $type;
        }
    }

    private function _add_1($a)
    {
        return $a;
    }

    private function _add_2_a(string $a, int $b)
    {
        return $a + $b;
    }

    private function _add_2_b(int $a, string $b)
    {
        return $a + $b;
    }

    private function _add_3(...$numbers)
    {
        return array_reduce(
            $numbers,
            'add',
            0
        );
    }
}

function add($a, $b): int
{
    return $a + $b;
}

$a = $b = $c = 2;

$obj = new Magic();
echo $obj->add("4", 56);
echo $obj->add(42, "88");