thirdparty/google_appengine/google/appengine/dist/py_imp.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2007 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17
  18 """Stub replacement for Python's imp module."""
  19
  20
  21 import os
  22 import sys
  23
  24
  25 PY_SOURCE, PY_COMPILED, C_EXTENSION = 1, 2, 3
  26 PKG_DIRECTORY, C_BUILTIN, PY_FROZEN = 5, 6, 7
  27
  28
  29 def get_magic():
  30   """Return the magic string used to recognize byte-compiled code files."""
  31   return '\0\0\0\0'
  32
  33
  34 _PY_SOURCE_SUFFIX = ('.py', 'U', PY_SOURCE)
  35 _PKG_DIRECTORY_SUFFIX = ('', '', PKG_DIRECTORY)
  36
  37
  38 def get_suffixes():
  39   """Return a list that describes the files that find_module() looks for."""
  40   return [_PY_SOURCE_SUFFIX]
  41
  42
  43 def find_module(name, path=None):
  44   """Try to find the named module on the given search path or sys.path."""
  45   if path == None:
  46     path = sys.path
  47
  48   for directory in path:
  49     filename = os.path.join(directory, '%s.py' % name)
  50     if os.path.exists(filename):
  51       return open(filename, 'U'), filename, _PY_SOURCE_SUFFIX
  52
  53     dirname = os.path.join(directory, name)
  54     filename = os.path.join(dirname, '__init__.py')
  55     if os.path.exists(filename):
  56       return None, dirname, _PKG_DIRECTORY_SUFFIX
  57
  58   raise ImportError('No module named %s' % name)
  59
  60
  61 def load_module(name, file_, pathname, description):
  62   """Load or reload the specified module.
  63
  64   Please note that this function has only rudimentary supported on App Engine:
  65   Only loading packages is supported.
  66   """
  67   suffix, mode, type_ = description
  68   if type_ == PKG_DIRECTORY:
  69     if name in sys.modules:
  70       mod = sys.modules[name]
  71     else:
  72       mod = new_module(name)
  73       sys.modules[name] = mod
  74     filename = os.path.join(pathname, '__init__.py')
  75     mod.__file__ = filename
  76     execfile(filename, mod.__dict__, mod.__dict__)
  77     return mod
  78   else:
  79     raise NotImplementedError('Only importing packages is supported on '
  80                               'App Engine')
  81
  82
  83 def new_module(name):
  84   """Return a new empty module object."""
  85   return type(sys)(name)
  86
  87
  88 def lock_held():
  89   """Return False since threading is not supported."""
  90   return False
  91
  92
  93 def acquire_lock():
  94   """Acquiring the lock is a no-op since no threading is supported."""
  95   pass
  96
  97
  98 def release_lock():
  99   """There is no lock to release since acquiring is a no-op when there is no
 100   threading."""
 101   pass
 102
 103
 104 def init_builtin(name):
 105   raise NotImplementedError('This function is not supported on App Engine.')
 106
 107
 108 def init_frozen(name):
 109   raise NotImplementedError('This function is not supported on App Engine.')
 110
 111
 112 def is_builtin(name):
 113   return name in sys.builtin_module_names
 114
 115
 116 def is_frozen(name):
 117   return False
 118
 119
 120 def load_compiled(name, pathname, file_=None):
 121   raise NotImplementedError('This function is not supported on App Engine.')
 122
 123
 124 def load_dynamic(name, pathname, file_=None):
 125   raise NotImplementedError('This function is not supported on App Engine.')
 126
 127
 128 def load_source(name, pathname, file_=None):
 129   raise NotImplementedError('This function is not supported on App Engine.')
 130
 131
 132 class NullImporter(object):
 133   """Null importer object"""
 134
 135   def __init__(self, path_string):
 136     if not path_string:
 137       raise ImportError("empty pathname")
 138     elif os.path.isdir(path_string):
 139       raise ImportError("existing directory")
 140
 141   def find_module(self, fullname):
 142     return None