Source Code for Package SCons.compat

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  2  # Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 The SCons Foundation 
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 22  # 
 23   
 24  __doc__ = """ 
 25  SCons compatibility package for old Python versions 
 26   
 27  This subpackage holds modules that provide backwards-compatible 
 28  implementations of various things that we'd like to use in SCons but which 
 29  only show up in later versions of Python than the early, old version(s) 
 30  we still support. 
 31   
 32  This package will be imported by other code: 
 33   
 34      import SCons.compat 
 35   
 36  But other code will not generally reference things in this package through 
 37  the SCons.compat namespace.  The modules included here add things to 
 38  the __builtin__ namespace or the global module list so that the rest 
 39  of our code can use the objects and names imported here regardless of 
 40  Python version. 
 41   
 42  Simply enough, things that go in the __builtin__ name space come from 
 43  our builtins module. 
 44   
 45  The rest of the things here will be in individual compatibility modules 
 46  that are either: 1) suitably modified copies of the future modules that 
 47  we want to use; or 2) backwards compatible re-implementations of the 
 48  specific portions of a future module's API that we want to use. 
 49   
 50  GENERAL WARNINGS:  Implementations of functions in the SCons.compat 
 51  modules are *NOT* guaranteed to be fully compliant with these functions in 
 52  later versions of Python.  We are only concerned with adding functionality 
 53  that we actually use in SCons, so be wary if you lift this code for 
 54  other uses.  (That said, making these more nearly the same as later, 
 55  official versions is still a desirable goal, we just don't need to be 
 56  obsessive about it.) 
 57   
 58  We name the compatibility modules with an initial '_scons_' (for example, 
 59  _scons_subprocess.py is our compatibility module for subprocess) so 
 60  that we can still try to import the real module name and fall back to 
 61  our compatibility module if we get an ImportError.  The import_as() 
 62  function defined below loads the module as the "real" name (without the 
 63  '_scons'), after which all of the "import {module}" statements in the 
 64  rest of our code will find our pre-loaded compatibility module. 
 65  """ 
 66   
 67  __revision__ = "src/engine/SCons/compat/__init__.py 2725 2008/03/31 12:52:02 knight" 
 68   
 69 -def import_as(module, name): 
 70      """ 
 71      Imports the specified module (from our local directory) as the 
 72      specified name. 
 73      """ 
 74      import imp 
 75      import os.path 
 76      dir = os.path.split(__file__)[0] 
 77      file, filename, suffix_mode_type = imp.find_module(module, [dir]) 
 78      imp.load_module(name, file, filename, suffix_mode_type) 
 79   
 80  import builtins 
 81   
 82  try: 
 83      import hashlib 
 84  except ImportError: 
 85      # Pre-2.5 Python has no hashlib module. 
 86      try: 
 87          import_as('_scons_hashlib', 'hashlib') 
 88      except ImportError: 
 89          # If we failed importing our compatibility module, it probably 
 90          # means this version of Python has no md5 module.  Don't do 
 91          # anything and let the higher layer discover this fact, so it 
 92          # can fall back to using timestamp. 
 93          pass 
 94   
 95  try: 
 96      set 
 97  except NameError: 
 98      # Pre-2.4 Python has no native set type 
 99      try: 
100          # Python 2.2 and 2.3 can use the copy of the 2.[45] sets module 
101          # that we grabbed. 
102          import_as('_scons_sets', 'sets') 
103      except (ImportError, SyntaxError): 
104          # Python 1.5 (ImportError, no __future_ module) and 2.1 
105          # (SyntaxError, no generators in __future__) will blow up 
106          # trying to import the 2.[45] sets module, so back off to a 
107          # custom sets module that can be discarded easily when we 
108          # stop supporting those versions. 
109          import_as('_scons_sets15', 'sets') 
110      import __builtin__ 
111      import sets 
112      __builtin__.set = sets.Set 
113   
114  import fnmatch 
115  try: 
116      fnmatch.filter 
117  except AttributeError: 
118      # Pre-2.2 Python has no fnmatch.filter() function. 
119 -    def filter(names, pat): 
120          """Return the subset of the list NAMES that match PAT""" 
121          import os,posixpath 
122          result=[] 
123          pat = os.path.normcase(pat) 
124          if not fnmatch._cache.has_key(pat): 
125              import re 
126              res = fnmatch.translate(pat) 
127              fnmatch._cache[pat] = re.compile(res) 
128          match = fnmatch._cache[pat].match 
129          if os.path is posixpath: 
130              # normcase on posix is NOP. Optimize it away from the loop. 
131              for name in names: 
132                  if match(name): 
133                      result.append(name) 
134          else: 
135              for name in names: 
136                  if match(os.path.normcase(name)): 
137                      result.append(name) 
138          return result 
139      fnmatch.filter = filter 
140      del filter 
141      
142   
143  # If we need the compatibility version of textwrap, it  must be imported 
144  # before optparse, which uses it. 
145  try: 
146      import textwrap 
147  except ImportError: 
148      # Pre-2.3 Python has no textwrap module. 
149      import_as('_scons_textwrap', 'textwrap') 
150   
151  try: 
152      import optparse 
153  except ImportError: 
154      # Pre-2.3 Python has no optparse module. 
155      import_as('_scons_optparse', 'optparse') 
156   
157  import shlex 
158  try: 
159      shlex.split 
160  except AttributeError: 
161      # Pre-2.3 Python has no shlex.split() function. 
162      # 
163      # The full white-space splitting semantics of shlex.split() are 
164      # complicated to reproduce by hand, so just use a compatibility 
165      # version of the shlex module cribbed from Python 2.5 with some 
166      # minor modifications for older Python versions. 
167      del shlex 
168      import_as('_scons_shlex', 'shlex') 
169   
170  try: 
171      import subprocess 
172  except ImportError: 
173      # Pre-2.4 Python has no subprocess module. 
174      import_as('_scons_subprocess', 'subprocess') 
175   
176  import sys 
177  try: 
178      sys.version_info 
179  except AttributeError: 
180      # Pre-1.6 Python has no sys.version_info 
181      import string 
182      version_string = string.split(sys.version)[0] 
183      version_ints = map(int, string.split(version_string, '.')) 
184      sys.version_info = tuple(version_ints + ['final', 0]) 
185   
186  try: 
187      import UserString 
188  except ImportError: 
189      # Pre-1.6 Python has no UserString module. 
190      import_as('_scons_UserString', 'UserString') 
191