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# Copyright DataStax, Inc.
#
# 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.
from __future__ import division
from datetime import datetime
from cassandra.cqlengine import UnicodeMixin, ValidationError
import sys
if sys.version_info >= (2, 7):
def get_total_seconds(td):
return td.total_seconds()
else:
def get_total_seconds(td):
# integer division used here to emulate built-in total_seconds
return ((86400 * td.days + td.seconds) * 10 ** 6 + td.microseconds) / 10 ** 6
class QueryValue(UnicodeMixin):
"""
Base class for query filter values. Subclasses of these classes can
be passed into .filter() keyword args
"""
format_string = '%({0})s'
def __init__(self, value):
self.value = value
self.context_id = None
def __unicode__(self):
return self.format_string.format(self.context_id)
def set_context_id(self, ctx_id):
self.context_id = ctx_id
def get_context_size(self):
return 1
def update_context(self, ctx):
ctx[str(self.context_id)] = self.value
class BaseQueryFunction(QueryValue):
"""
Base class for filtering functions. Subclasses of these classes can
be passed into .filter() and will be translated into CQL functions in
the resulting query
"""
pass
class TimeUUIDQueryFunction(BaseQueryFunction):
def __init__(self, value):
"""
:param value: the time to create bounding time uuid from
:type value: datetime
"""
if not isinstance(value, datetime):
raise ValidationError('datetime instance is required')
super(TimeUUIDQueryFunction, self).__init__(value)
def to_database(self, val):
epoch = datetime(1970, 1, 1, tzinfo=val.tzinfo)
offset = get_total_seconds(epoch.tzinfo.utcoffset(epoch)) if epoch.tzinfo else 0
return int((get_total_seconds(val - epoch) - offset) * 1000)
def update_context(self, ctx):
ctx[str(self.context_id)] = self.to_database(self.value)
class MinTimeUUID(TimeUUIDQueryFunction):
"""
return a fake timeuuid corresponding to the smallest possible timeuuid for the given timestamp
http://cassandra.apache.org/doc/cql3/CQL-3.0.html#timeuuidFun
"""
format_string = 'MinTimeUUID(%({0})s)'
class MaxTimeUUID(TimeUUIDQueryFunction):
"""
return a fake timeuuid corresponding to the largest possible timeuuid for the given timestamp
http://cassandra.apache.org/doc/cql3/CQL-3.0.html#timeuuidFun
"""
format_string = 'MaxTimeUUID(%({0})s)'
class Token(BaseQueryFunction):
"""
compute the token for a given partition key
http://cassandra.apache.org/doc/cql3/CQL-3.0.html#tokenFun
"""
def __init__(self, *values):
if len(values) == 1 and isinstance(values[0], (list, tuple)):
values = values[0]
super(Token, self).__init__(values)
self._columns = None
def set_columns(self, columns):
self._columns = columns
def get_context_size(self):
return len(self.value)
def __unicode__(self):
token_args = ', '.join('%({0})s'.format(self.context_id + i) for i in range(self.get_context_size()))
return "token({0})".format(token_args)
def update_context(self, ctx):
for i, (col, val) in enumerate(zip(self._columns, self.value)):
ctx[str(self.context_id + i)] = col.to_database(val)
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