diff options
author | Johan Lundberg <lundberg@nordu.net> | 2015-04-02 10:43:33 +0200 |
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committer | Johan Lundberg <lundberg@nordu.net> | 2015-04-02 10:43:33 +0200 |
commit | bd611ac59f7c4db885a2f8631ef0bcdcd1901ca0 (patch) | |
tree | e60f5333a7699cd021b33c7f5292af55b774001b /definate/filter_factory.py |
Diffstat (limited to 'definate/filter_factory.py')
-rwxr-xr-x | definate/filter_factory.py | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/definate/filter_factory.py b/definate/filter_factory.py new file mode 100755 index 0000000..1ad1d3f --- /dev/null +++ b/definate/filter_factory.py @@ -0,0 +1,104 @@ +#!/usr/bin/python +# +# Copyright 2012 Google Inc. 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. + +"""Functionality to allow easily retrieving certain filter objects.""" + +__author__ = 'msu@google.com (Martin Suess)' + + +import definition_filter +import file_filter + +DEFINITION_FILTER = 1 +FILE_FILTER = 2 +GLOBAL_FILTER = 3 + +PRE_FILTERS = 'PreFilters' +POST_FILTERS = 'PostFilters' + + +class Error(Exception): + """Base error class.""" + + +class FilterIdentificationError(Error): + """Exception to use when FilterFactory fails to identify the Filter.""" + + +class FilterFactory(object): + """Functionality to get a filter object easily based on its name. + + This class can be initialized and the GetFilter() method allows retrieving a + specific filter based on the name of the filter and the scope (global, file + and definition). + """ + + def __init__(self): + """Initializer.""" + self._filters = { + DEFINITION_FILTER: { + 'PostFilters': { + 'SortFilter': definition_filter.SortFilter, + 'AlignFilter': definition_filter.AlignFilter, + }, + }, + FILE_FILTER: { + 'PostFilters': { + 'PrintFilter': file_filter.PrintFilter, + 'WriteFileFilter': file_filter.WriteFileFilter, + }, + }, + GLOBAL_FILTER: { + 'PreFilters': { + }, + 'PostFilters': { + }, + }, + } + + def GetFilter(self, scope, identifier, sequence): + """Returns a specific filter instance based on the identifier. + + Args: + scope: Type of filter to be returned. Valid types are listed as globals + in the beginning of this module. + identifier: String identifier for the filter to get. + sequence: String identifier for the sequence information to determine + when the filter should be applied. Valid values: + - 'PreFilters': Filters that are applied before processing the data + (e.g. before the definition is created). + - 'PostFilters': Filters that are applied after processing the data + (e.g. after the definition has been created). + + Raises: + FilterIdentificationError: If the filter cannot be identified. + + Returns: + Filter instance based on the identifier passed in. + """ + if scope not in self._filters: + raise FilterIdentificationError( + 'Filter scope \'%d\' could not be found in filters.' % scope) + if sequence not in self._filters[scope]: + raise FilterIdentificationError( + 'Filter sequence \'%s\' is not applicable to scope \'%d\'.' % ( + sequence, scope)) + filters = self._filters[scope][sequence] + if identifier not in filters: + raise FilterIdentificationError( + 'Filter \'%s\' could not be identified. Wrong scope (%d) or sequence' + ' (%s)?' % (identifier, scope, sequence)) + return filters[identifier]() |