1# Copyright 2016 Google Inc. All rights reserved. 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); 4# you may not use this file except in compliance with the License. 5# You may obtain a copy of the License at 6# 7# http://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, 11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12# See the License for the specific language governing permissions and 13# limitations under the License. 14 15""" A tiny version of `six` to help with backwards compability. Also includes 16 compatibility helpers for numpy. """ 17 18import sys 19 20PY2 = sys.version_info[0] == 2 21PY26 = sys.version_info[0:2] == (2, 6) 22PY27 = sys.version_info[0:2] == (2, 7) 23PY275 = sys.version_info[0:3] >= (2, 7, 5) 24PY3 = sys.version_info[0] == 3 25PY34 = sys.version_info[0:2] >= (3, 4) 26 27if PY3: 28 import importlib.machinery 29 string_types = (str,) 30 binary_types = (bytes,bytearray) 31 range_func = range 32 memoryview_type = memoryview 33 struct_bool_decl = "?" 34else: 35 import imp 36 string_types = (unicode,) 37 if PY26 or PY27: 38 binary_types = (str,bytearray) 39 else: 40 binary_types = (str,) 41 range_func = xrange 42 if PY26 or (PY27 and not PY275): 43 memoryview_type = buffer 44 struct_bool_decl = "<b" 45 else: 46 memoryview_type = memoryview 47 struct_bool_decl = "?" 48 49# Helper functions to facilitate making numpy optional instead of required 50 51def import_numpy(): 52 """ 53 Returns the numpy module if it exists on the system, 54 otherwise returns None. 55 """ 56 if PY3: 57 numpy_exists = ( 58 importlib.machinery.PathFinder.find_spec('numpy') is not None) 59 else: 60 try: 61 imp.find_module('numpy') 62 numpy_exists = True 63 except ImportError: 64 numpy_exists = False 65 66 if numpy_exists: 67 # We do this outside of try/except block in case numpy exists 68 # but is not installed correctly. We do not want to catch an 69 # incorrect installation which would manifest as an 70 # ImportError. 71 import numpy as np 72 else: 73 np = None 74 75 return np 76 77 78class NumpyRequiredForThisFeature(RuntimeError): 79 """ 80 Error raised when user tries to use a feature that 81 requires numpy without having numpy installed. 82 """ 83 pass 84 85 86# NOTE: Future Jython support may require code here (look at `six`). 87