# イテレータプロトコル (iterator protocol)

イテレータを扱うための固有の関数は二つあります。

int PyIter_Check(PyObject *o)
  次に属します: Stable ABI (バージョン 3.8 より).

  Return non-zero if the object o can be safely passed to `PyIter_Next()`, and `0` otherwise. This function always succeeds.

int PyAIter_Check(PyObject *o)
  次に属します: Stable ABI (バージョン 3.10 より).

  Return non-zero if the object o provides the `AsyncIterator` protocol, and `0` otherwise. This function always succeeds.

  バージョン 3.10 で追加.

PyObject *PyIter_Next(PyObject *o)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  Return the next value from the iterator o. The object must be an iterator according to `PyIter_Check()` (it is up to the caller to check this). If there are no remaining values, returns `NULL` with no exception set. If an error occurs while retrieving the item, returns `NULL` and passes along the exception.

イテレータの返す要素にわたって反復処理を行うループを書くと、C のコードは以下のようになるはずです:

    PyObject *iterator = PyObject_GetIter(obj);
    PyObject *item;

    if (iterator == NULL) {
        /* propagate error */
    }

    while ((item = PyIter_Next(iterator))) {
        /* do something with item */
        ...
        /* release reference when done */
        Py_DECREF(item);
    }

    Py_DECREF(iterator);

    if (PyErr_Occurred()) {
        /* propagate error */
    }
    else {
        /* continue doing useful work */
    }

type PySendResult

  The enum value used to represent different results of `PyIter_Send()`.

  バージョン 3.10 で追加.

PySendResult PyIter_Send(PyObject *iter, PyObject *arg, PyObject **presult)
  次に属します: Stable ABI (バージョン 3.10 より).

  Sends the arg value into the iterator iter. Returns:

  - `PYGEN_RETURN` if iterator returns. Return value is returned via presult.

  - `PYGEN_NEXT` if iterator yields. Yielded value is returned via presult.

  - `PYGEN_ERROR` if iterator has raised and exception. presult is set to `NULL`.

  バージョン 3.10 で追加.