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# Copyright 2013 OpenStack Foundation
# Copyright 2013 IBM Corp.
#
# 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.
class Hints(object):
"""Encapsulate driver hints for listing entities.
Hints are modifiers that affect the return of entities from a
list_<entities> operation. They are typically passed to a driver to give
direction as to what filtering, pagination or list limiting actions are
being requested.
It is optional for a driver to action some or all of the list hints,
but any filters that it does satisfy must be marked as such by calling
removing the filter from the list.
A Hint object contains filters, which is a list of dicts that can be
accessed publicly. Also it contains a dict called limit, which will
indicate the amount of data we want to limit our listing to.
If the filter is discovered to never match, then `cannot_match` can be set
to indicate that there will not be any matches and the backend work can be
short-circuited.
Each filter term consists of:
* ``name``: the name of the attribute being matched
* ``value``: the value against which it is being matched
* ``comparator``: the operation, which can be one of ``equals``,
``startswith`` or ``endswith``
* ``case_sensitive``: whether any comparison should take account of
case
* ``type``: will always be 'filter'
"""
def __init__(self):
self.limit = None
self.filters = list()
self.cannot_match = False
def add_filter(self, name, value, comparator='equals',
case_sensitive=False):
"""Adds a filter to the filters list, which is publicly accessible."""
self.filters.append({'name': name, 'value': value,
'comparator': comparator,
'case_sensitive': case_sensitive,
'type': 'filter'})
def get_exact_filter_by_name(self, name):
"""Return a filter key and value if exact filter exists for name."""
for entry in self.filters:
if (entry['type'] == 'filter' and entry['name'] == name and
entry['comparator'] == 'equals'):
return entry
def set_limit(self, limit, truncated=False):
"""Set a limit to indicate the list should be truncated."""
self.limit = {'limit': limit, 'type': 'limit', 'truncated': truncated}
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