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# Copyright 2011 OpenStack Foundation
# All Rights Reserved.
#
# 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.
import bisect
import collections
import urllib.parse as urllib_parse
def url_quote(s):
if s is None:
return s
return urllib_parse.quote(str(s))
def paginate_list(li, limit=None, marker=None, include_marker=False,
key=lambda x: x):
"""Sort the given list and return a sublist containing a page of items.
:param list li: The list to be paginated.
:param int limit: Maximum number of items to be returned.
:param marker: Key of the first item to appear on the sublist.
:param bool include_marker: Include the marker value itself in the sublist.
:param lambda key: Sorting expression.
:return:
"""
sli = sorted(li, key=key)
index = [key(item) for item in sli]
if marker is None:
marker = ''
if include_marker:
pos = bisect.bisect_left(index, marker)
else:
pos = bisect.bisect(index, marker)
if limit and pos + limit < len(sli):
page = sli[pos:pos + limit]
return page, key(page[-1])
else:
return sli[pos:], None
def paginate_object_list(li, attr_name, limit=None, marker=None,
include_marker=False):
"""Wrapper for paginate_list to handle lists of generic objects paginated
based on an attribute.
"""
return paginate_list(li, limit=limit, marker=marker,
include_marker=include_marker,
key=lambda x: getattr(x, attr_name))
def paginate_dict_list(li, key, limit=None, marker=None, include_marker=False):
"""Wrapper for paginate_list to handle lists of dicts paginated
based on a key.
"""
return paginate_list(li, limit=limit, marker=marker,
include_marker=include_marker,
key=lambda x: x[key])
class PaginatedDataView(object):
def __init__(self, collection_type, collection, current_page_url,
next_page_marker=None):
self.collection_type = collection_type
self.collection = collection
self.current_page_url = current_page_url
self.next_page_marker = url_quote(next_page_marker)
def data(self):
return {self.collection_type: self.collection,
'links': self._links,
}
def _links(self):
if not self.next_page_marker:
return []
app_url = AppUrl(self.current_page_url)
next_url = app_url.change_query_params(marker=self.next_page_marker)
next_link = {
'rel': 'next',
'href': str(next_url),
}
return [next_link]
class SimplePaginatedDataView(object):
# In some cases, we can't create a PaginatedDataView because
# we don't have a collection query object to create a view on.
# In that case, we have to supply the URL and collection manually.
def __init__(self, url, name, view, marker):
self.url = url
self.name = name
self.view = view
self.marker = url_quote(marker)
def data(self):
if not self.marker:
return self.view.data()
app_url = AppUrl(self.url)
next_url = str(app_url.change_query_params(marker=self.marker))
next_link = {'rel': 'next',
'href': next_url}
view_data = {self.name: self.view.data()[self.name],
'links': [next_link]}
return view_data
class AppUrl(object):
def __init__(self, url):
self.url = url
def __str__(self):
return self.url
def change_query_params(self, **kwargs):
# Seeks out the query params in a URL and changes/appends to them
# from the kwargs given. So change_query_params(foo='bar')
# would remove from the URL any old instance of foo=something and
# then add &foo=bar to the URL.
parsed_url = urllib_parse.urlparse(self.url)
# Build a dictionary out of the query parameters in the URL
# with an OrderedDict to preserve the order of the URL.
query_params = collections.OrderedDict(
urllib_parse.parse_qsl(parsed_url.query))
# Use kwargs to change or update any values in the query dict.
query_params.update(kwargs)
# Build a new query based on the updated query dict.
new_query_params = urllib_parse.urlencode(query_params)
return self.__class__(
# Force HTTPS.
urllib_parse.ParseResult('https',
parsed_url.netloc, parsed_url.path,
parsed_url.params, new_query_params,
parsed_url.fragment).geturl())
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