mirror of
https://github.com/bazelbuild/bazel-skylib
synced 2024-11-28 08:43:51 +00:00
146 lines
3.6 KiB
Python
146 lines
3.6 KiB
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 common set algorithms.
|
|
|
|
CAUTION: Operating on sets, particularly sets contained in providers, may
|
|
asymptotically slow down the analysis phase. While constructing large sets with
|
|
addition/union is fast (there is no linear-time copy involved), the
|
|
`difference` function and various comparison predicates involve linear-time
|
|
traversals.
|
|
|
|
For convenience, the functions in this module can take either sets or lists as
|
|
inputs; operations that take lists treat them as if they were sets (i.e.,
|
|
duplicate elements are ignored). Functions that return new sets always return
|
|
them as the `set` type, regardless of the types of the inputs.
|
|
"""
|
|
|
|
|
|
def _precondition_only_sets_or_lists(*args):
|
|
"""Verifies that all arguments are either sets or lists.
|
|
|
|
The build will fail if any of the arguments is neither a set nor a list.
|
|
|
|
Args:
|
|
*args: A list of values that must be sets or lists.
|
|
"""
|
|
for a in args:
|
|
t = type(a)
|
|
if t not in("depset", "list"):
|
|
fail("Expected arguments to be depset or list, but found type %s: %r" %
|
|
(t, a))
|
|
|
|
|
|
def _is_equal(a, b):
|
|
"""Returns whether two sets are equal.
|
|
|
|
Args:
|
|
a: A depset or a list.
|
|
b: A depset or a list.
|
|
Returns:
|
|
True if `a` is equal to `b`, False otherwise.
|
|
"""
|
|
_precondition_only_sets_or_lists(a, b)
|
|
return sorted(depset(a)) == sorted(depset(b))
|
|
|
|
|
|
def _is_subset(a, b):
|
|
"""Returns whether `a` is a subset of `b`.
|
|
|
|
Args:
|
|
a: A depset or a list.
|
|
b: A depset or a list.
|
|
|
|
Returns:
|
|
True if `a` is a subset of `b`, False otherwise.
|
|
"""
|
|
_precondition_only_sets_or_lists(a, b)
|
|
for e in a:
|
|
if e not in b:
|
|
return False
|
|
return True
|
|
|
|
|
|
def _disjoint(a, b):
|
|
"""Returns whether two sets are disjoint.
|
|
|
|
Two sets are disjoint if they have no elements in common.
|
|
|
|
Args:
|
|
a: A set or list.
|
|
b: A set or list.
|
|
|
|
Returns:
|
|
True if `a` and `b` are disjoint, False otherwise.
|
|
"""
|
|
_precondition_only_sets_or_lists(a, b)
|
|
for e in a:
|
|
if e in b:
|
|
return False
|
|
return True
|
|
|
|
|
|
def _intersection(a, b):
|
|
"""Returns the intersection of two sets.
|
|
|
|
Args:
|
|
a: A set or list.
|
|
b: A set or list.
|
|
|
|
Returns:
|
|
A set containing the elements that are in both `a` and `b`.
|
|
"""
|
|
_precondition_only_sets_or_lists(a, b)
|
|
return depset([e for e in a if e in b])
|
|
|
|
|
|
def _union(*args):
|
|
"""Returns the union of several sets.
|
|
|
|
Args:
|
|
*args: An arbitrary number of sets or lists.
|
|
|
|
Returns:
|
|
The set union of all sets or lists in `*args`.
|
|
"""
|
|
_precondition_only_sets_or_lists(*args)
|
|
r = depset()
|
|
for a in args:
|
|
r += a
|
|
return r
|
|
|
|
|
|
def _difference(a, b):
|
|
"""Returns the elements in `a` that are not in `b`.
|
|
|
|
Args:
|
|
a: A set or list.
|
|
b: A set or list.
|
|
|
|
Returns:
|
|
A set containing the elements that are in `a` but not in `b`.
|
|
"""
|
|
_precondition_only_sets_or_lists(a, b)
|
|
return depset([e for e in a if e not in b])
|
|
|
|
|
|
sets = struct(
|
|
difference = _difference,
|
|
disjoint = _disjoint,
|
|
intersection = _intersection,
|
|
is_equal = _is_equal,
|
|
is_subset = _is_subset,
|
|
union = _union,
|
|
)
|