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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) | |