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# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Helpers for server-side streaming in REST."""
from typing import Union
import proto
import requests
import google.protobuf.message
from google.api_core._rest_streaming_base import BaseResponseIterator
class ResponseIterator(BaseResponseIterator):
"""Iterator over REST API responses.
Args:
response (requests.Response): An API response object.
response_message_cls (Union[proto.Message, google.protobuf.message.Message]): A response
class expected to be returned from an API.
Raises:
ValueError:
- If `response_message_cls` is not a subclass of `proto.Message` or `google.protobuf.message.Message`.
"""
def __init__(
self,
response: requests.Response,
response_message_cls: Union[proto.Message, google.protobuf.message.Message],
):
self._response = response
# Inner iterator over HTTP response's content.
self._response_itr = self._response.iter_content(decode_unicode=True)
super(ResponseIterator, self).__init__(
response_message_cls=response_message_cls
)
def cancel(self):
"""Cancel existing streaming operation."""
self._response.close()
def __next__(self):
while not self._ready_objs:
try:
chunk = next(self._response_itr)
self._process_chunk(chunk)
except StopIteration as e:
if self._level > 0:
raise ValueError("Unfinished stream: %s" % self._obj)
raise e
return self._grab()
def __iter__(self):
return self
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