84 lines
2.5 KiB
Python
84 lines
2.5 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2019 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Functions for working with dictionaries representing yaml files."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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def GetOrCreate(obj, path, constructor=dict):
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"""Get or create the object by following the field names in the path.
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not exist, create the appropriate value.
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Args:
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obj: A dictionary representing a yaml dictionary
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path: A list of strings representing fields to follow.
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constructor: If the object at the end of the path does not exist, create an
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object using the constructor given.
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Returns:
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An object at found by following the path.
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"""
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first, rest = path[0], path[1:]
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if rest:
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if first not in obj:
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obj[first] = dict()
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return GetOrCreate(obj[first], rest, constructor)
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else:
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if first not in obj:
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obj[first] = constructor()
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return obj[first]
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def GetAll(obj, path):
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"""Given a yaml object, yield all objects found by following a path.
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Given a yaml object, read each field in the path and return the object
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found at the end. If a field has a list value, follow the path for each
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object in the list.
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E.g.
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>>> X = {'A': {'B': [{'C': {'D': 1}}, {'C': {'D': 2}}]}}
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>>> sorted(list(GetAll(X, path=('A', 'B', 'C', 'D'))))
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[1, 2]
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Args:
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obj: A dictionary representing a yaml dictionary
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path: A list of strings representing fields to follow.
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Yields:
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Values that are found by following the given path.
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"""
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if not path:
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yield obj
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return
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first, rest = path[0], path[1:]
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if first in obj:
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if isinstance(obj[first], dict):
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for extracted_obj in GetAll(obj[first], rest):
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yield extracted_obj
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elif isinstance(obj[first], list):
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for x in obj[first]:
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for extracted_obj in GetAll(x, rest):
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yield extracted_obj
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else:
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if rest:
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raise ValueError(first + ' is not a dictionary or a list')
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else:
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yield obj[first]
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