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import itertools
from typing import ( # pylint: disable=unused-import
Callable,
Optional,
TypeVar,
Iterator,
Iterable,
Tuple,
Any,
)
import logging
from .exceptions import AzureError
_LOGGER = logging.getLogger(__name__)
ReturnType = TypeVar("ReturnType")
ResponseType = TypeVar("ResponseType")
[docs]class PageIterator(Iterator[Iterator[ReturnType]]):
def __init__(
self,
get_next: Callable[[Optional[str]], ResponseType],
extract_data: Callable[[ResponseType], Tuple[str, Iterable[ReturnType]]],
continuation_token: Optional[str] = None,
):
"""Return an iterator of pages.
:param get_next: Callable that take the continuation token and return a HTTP response
:param extract_data: Callable that take an HTTP response and return a tuple continuation token,
list of ReturnType
:param str continuation_token: The continuation token needed by get_next
"""
self._get_next = get_next
self._extract_data = extract_data
self.continuation_token = continuation_token
self._did_a_call_already = False
self._response: Optional[ResponseType] = None
self._current_page: Optional[Iterable[ReturnType]] = None
def __iter__(self) -> Iterator[Iterator[ReturnType]]:
return self
def __next__(self) -> Iterator[ReturnType]:
if self.continuation_token is None and self._did_a_call_already:
raise StopIteration("End of paging")
try:
self._response = self._get_next(self.continuation_token)
except AzureError as error:
if not error.continuation_token:
error.continuation_token = self.continuation_token
raise
self._did_a_call_already = True
self.continuation_token, self._current_page = self._extract_data(self._response)
return iter(self._current_page)
next = __next__ # Python 2 compatibility. Can't be removed as some people are using ".next()" even in Py3
[docs]class ItemPaged(Iterator[ReturnType]):
def __init__(self, *args: Any, **kwargs: Any) -> None:
"""Return an iterator of items.
args and kwargs will be passed to the PageIterator constructor directly,
except page_iterator_class
"""
self._args = args
self._kwargs = kwargs
self._page_iterator: Optional[Iterator[ReturnType]] = None
self._page_iterator_class = self._kwargs.pop("page_iterator_class", PageIterator)
[docs] def by_page(self, continuation_token: Optional[str] = None) -> Iterator[Iterator[ReturnType]]:
"""Get an iterator of pages of objects, instead of an iterator of objects.
:param str continuation_token:
An opaque continuation token. This value can be retrieved from the
continuation_token field of a previous generator object. If specified,
this generator will begin returning results from this point.
:returns: An iterator of pages (themselves iterator of objects)
:rtype: iterator[iterator[ReturnType]]
"""
return self._page_iterator_class(continuation_token=continuation_token, *self._args, **self._kwargs)
def __repr__(self) -> str:
return "<iterator object azure.core.paging.ItemPaged at {}>".format(hex(id(self)))
def __iter__(self) -> Iterator[ReturnType]:
return self
def __next__(self) -> ReturnType:
if self._page_iterator is None:
self._page_iterator = itertools.chain.from_iterable(self.by_page())
return next(self._page_iterator)
next = __next__ # Python 2 compatibility. Can't be removed as some people are using ".next()" even in Py3