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bazel-skylib/lib/collections.bzl
2017-10-10 07:59:31 -07:00

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Python

# Copyright 2017 The Bazel Authors. 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.
"""Skylib module containing functions that operate on collections."""
def _after_each(separator, iterable):
"""Inserts `separator` after each item in `iterable`.
Args:
separator: The value to insert after each item in `iterable`.
iterable: The list into which to intersperse the separator.
Returns:
A new list with `separator` after each item in `iterable`.
"""
result = []
for x in iterable:
result.append(x)
result.append(separator)
return result
def _before_each(separator, iterable):
"""Inserts `separator` before each item in `iterable`.
Args:
separator: The value to insert before each item in `iterable`.
iterable: The list into which to intersperse the separator.
Returns:
A new list with `separator` before each item in `iterable`.
"""
result = []
for x in iterable:
result.append(separator)
result.append(x)
return result
def _uniq(iterable):
"""Returns a list of unique elements in `iterable`.
Requires all the elements to be hashable.
Args:
iterable: An iterable to filter.
Returns:
A new list with all unique elements from `iterable`.
"""
unique_elements = {element: None for element in iterable}
return unique_elements.keys()
collections = struct(
after_each=_after_each,
before_each=_before_each,
uniq=_uniq,
)