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