[ Feature ] Support for PHP generators

[TheCelavi]

Is it possible to add support for PHP generators to be passed to Python?

Per example, pandas dataframe object could work with generators for large datasets...

[chaz6chez]

You can implement a Python iterator class on the PHP side like this:

declare(strict_types=1);

namespace YourNamespace;

use Closure;
use Exception;
use Generator;

#[\PyInherit('Iterator', 'typing')]
class Iterator extends \PyClass
{
    protected Generator $generator;

    /**
     * @param Generator|Closure $generator
     * @throws Exception
     */
    public function __construct(
        Generator|Closure $generator
    )
    {
        parent::__construct();
        if ($generator instanceof Closure) {
            $generator = $generator();
            if (!$generator instanceof Generator) {
                throw new \InvalidArgumentException('Closure must return a Generator. ');
            }
        }
        $this->generator = $generator;
    }

    public function __iter__()
    {
        return $this->self();
    }

    public function __next__()
    {
        if (!$this->generator->valid()) {
            return null;
        }
        $value = $this->generator->current();
        $this->generator->next();
        return $value;
    }

    public function __invoke(): ?\PyIter
    {
        $res = $this->self();
        return $res instanceof \PyIter ? $res : null;
    }
}
\PyClass::setProxyPath(__DIR__);

Then, make a slight tweak to the proxy generated by phpy—specifically, in the implementation of next, add logic to throw a StopIteration:

import typing

class workbunny_phporc_iterator(typing.Iterator):
  def __init__(self, _this):
    self.__this = _this
    _this.set('_super', super())
    _this.set('_self', self)
    _this.call('__init')

  def __iter__(self, ):
    return self.__this.call('__iter__', )

  def __next__(self, ):
    res = self.__this.call('__next__', )
    if res == None:
      raise StopIteration
    return res

  def __init(self, ):
    return self.__this.call('__init', )

I've implemented this approach in the php-orc project, so feel free to check it out.