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# Copyright 2016 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.
""" A tiny version of `six` to help with backwards compability. Also includes
compatibility helpers for numpy. """
import sys
PY2 = sys.version_info[0] == 2
PY26 = sys.version_info[0:2] == (2, 6)
PY27 = sys.version_info[0:2] == (2, 7)
PY275 = sys.version_info[0:3] >= (2, 7, 5)
PY3 = sys.version_info[0] == 3
PY34 = sys.version_info[0:2] >= (3, 4)
if PY3:
import importlib.machinery
string_types = (str,)
binary_types = (bytes,bytearray)
range_func = range
memoryview_type = memoryview
struct_bool_decl = "?"
else:
import imp
string_types = (unicode,)
if PY26 or PY27:
binary_types = (str,bytearray)
else:
binary_types = (str,)
range_func = xrange
if PY26 or (PY27 and not PY275):
memoryview_type = buffer
struct_bool_decl = "<b"
else:
memoryview_type = memoryview
struct_bool_decl = "?"
# Helper functions to facilitate making numpy optional instead of required
def import_numpy():
"""
Returns the numpy module if it exists on the system,
otherwise returns None.
"""
if PY3:
numpy_exists = (
importlib.machinery.PathFinder.find_spec('numpy') is not None)
else:
try:
imp.find_module('numpy')
numpy_exists = True
except ImportError:
numpy_exists = False
if numpy_exists:
# We do this outside of try/except block in case numpy exists
# but is not installed correctly. We do not want to catch an
# incorrect installation which would manifest as an
# ImportError.
import numpy as np
else:
np = None
return np
class NumpyRequiredForThisFeature(RuntimeError):
"""
Error raised when user tries to use a feature that
requires numpy without having numpy installed.
"""
pass
# NOTE: Future Jython support may require code here (look at `six`).
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