text: #
  # Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 The SCons Foundation
  #
  # Permission is hereby granted, free of charge, to any person obtaining
  # a copy of this software and associated documentation files (the
  # "Software"), to deal in the Software without restriction, including
  # without limitation the rights to use, copy, modify, merge, publish,
  # distribute, sublicense, and/or sell copies of the Software, and to
  # permit persons to whom the Software is furnished to do so, subject to
  # the following conditions:
  #
  # The above copyright notice and this permission notice shall be included
  # in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  # KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  # WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  #
  
  __doc__ = """
  SCons compatibility package for old Python versions
  
  This subpackage holds modules that provide backwards-compatible
  implementations of various things that we'd like to use in SCons but which
  only show up in later versions of Python than the early, old version(s)
  we still support.
  
  Other code will not generally reference things in this package through
  the SCons.compat namespace.  The modules included here add things to
  the __builtin__ namespace or the global module list so that the rest
  of our code can use the objects and names imported here regardless of
  Python version.
  
  Simply enough, things that go in the __builtin__ name space come from
  our builtins module.
  
  The rest of the things here will be in individual compatibility modules
  that are either: 1) suitably modified copies of the future modules that
  we want to use; or 2) backwards compatible re-implementations of the
  specific portions of a future module's API that we want to use.
  
  GENERAL WARNINGS:  Implementations of functions in the SCons.compat
  modules are *NOT* guaranteed to be fully compliant with these functions in
  later versions of Python.  We are only concerned with adding functionality
  that we actually use in SCons, so be wary if you lift this code for
  other uses.  (That said, making these more nearly the same as later,
  official versions is still a desirable goal, we just don't need to be
  obsessive about it.)
  
  We name the compatibility modules with an initial '_scons_' (for example,
  _scons_subprocess.py is our compatibility module for subprocess) so
  that we can still try to import the real module name and fall back to
  our compatibility module if we get an ImportError.  The import_as()
  function defined below loads the module as the "real" name (without the
  '_scons'), after which all of the "import {module}" statements in the
  rest of our code will find our pre-loaded compatibility module.
  """
  
  __revision__ = "src/engine/SCons/compat/__init__.py 4369 2009/09/19 15:58:29 scons"
  
  def import_as(module, name):
      """
      Imports the specified module (from our local directory) as the
      specified name.
      """
      import imp
      import os.path
      dir = os.path.split(__file__)[0]
      file, filename, suffix_mode_type = imp.find_module(module, [dir])
      imp.load_module(name, file, filename, suffix_mode_type)
  
  import builtins
  
  try:
      import hashlib
  except ImportError:
      # Pre-2.5 Python has no hashlib module.
      try:
          import_as('_scons_hashlib', 'hashlib')
      except ImportError:
          # If we failed importing our compatibility module, it probably
          # means this version of Python has no md5 module.  Don't do
          # anything and let the higher layer discover this fact, so it
          # can fall back to using timestamp.
          pass
  
  try:
      set
  except NameError:
      # Pre-2.4 Python has no native set type
      try:
          # Python 2.2 and 2.3 can use the copy of the 2.[45] sets module
          # that we grabbed.
          import_as('_scons_sets', 'sets')
      except (ImportError, SyntaxError):
          # Python 1.5 (ImportError, no __future_ module) and 2.1
          # (SyntaxError, no generators in __future__) will blow up
          # trying to import the 2.[45] sets module, so back off to a
          # custom sets module that can be discarded easily when we
          # stop supporting those versions.
          import_as('_scons_sets15', 'sets')
      import __builtin__
      import sets
      __builtin__.set = sets.Set
  
  import fnmatch
  try:
      fnmatch.filter
  except AttributeError:
      # Pre-2.2 Python has no fnmatch.filter() function.
      def filter(names, pat):
          """Return the subset of the list NAMES that match PAT"""
          import os,posixpath
          result=[]
          pat = os.path.normcase(pat)
          if pat not in fnmatch._cache:
              import re
              res = fnmatch.translate(pat)
              fnmatch._cache[pat] = re.compile(res)
          match = fnmatch._cache[pat].match
          if os.path is posixpath:
              # normcase on posix is NOP. Optimize it away from the loop.
              for name in names:
                  if match(name):
                      result.append(name)
          else:
              for name in names:
                  if match(os.path.normcase(name)):
                      result.append(name)
          return result
      fnmatch.filter = filter
      del filter
  
  try:
      import itertools
  except ImportError:
      # Pre-2.3 Python has no itertools module.
      import_as('_scons_itertools', 'itertools')
  
  # If we need the compatibility version of textwrap, it  must be imported
  # before optparse, which uses it.
  try:
      import textwrap
  except ImportError:
      # Pre-2.3 Python has no textwrap module.
      import_as('_scons_textwrap', 'textwrap')
  
  try:
      import optparse
  except ImportError:
      # Pre-2.3 Python has no optparse module.
      import_as('_scons_optparse', 'optparse')
  
  import os
  try:
      os.devnull
  except AttributeError:
      # Pre-2.4 Python has no os.devnull attribute
      import sys
      _names = sys.builtin_module_names
      if 'posix' in _names:
          os.devnull = '/dev/null'
      elif 'nt' in _names:
          os.devnull = 'nul'
      os.path.devnull = os.devnull
  try:
      os.path.lexists
  except AttributeError:
      # Pre-2.4 Python has no os.path.lexists function
      def lexists(path):
          return os.path.exists(path) or os.path.islink(path)
      os.path.lexists = lexists
  
  import shlex
  try:
      shlex.split
  except AttributeError:
      # Pre-2.3 Python has no shlex.split() function.
      #
      # The full white-space splitting semantics of shlex.split() are
      # complicated to reproduce by hand, so just use a compatibility
      # version of the shlex module cribbed from Python 2.5 with some
      # minor modifications for older Python versions.
      del shlex
      import_as('_scons_shlex', 'shlex')
  
  
  import shutil
  try:
      shutil.move
  except AttributeError:
      # Pre-2.3 Python has no shutil.move() function.
      #
      # Cribbed from Python 2.5.
      import os
  
      def move(src, dst):
          """Recursively move a file or directory to another location.
  
          If the destination is on our current filesystem, then simply use
          rename.  Otherwise, copy src to the dst and then remove src.
          A lot more could be done here...  A look at a mv.c shows a lot of
          the issues this implementation glosses over.
  
          """
          try:
              os.rename(src, dst)
          except OSError:
              if os.path.isdir(src):
                  if shutil.destinsrc(src, dst):
                      raise Error("Cannot move a directory '%s' into itself '%s'." % (src, dst))
                  shutil.copytree(src, dst, symlinks=True)
                  shutil.rmtree(src)
              else:
                  shutil.copy2(src,dst)
                  os.unlink(src)
      shutil.move = move
      del move
  
      def destinsrc(src, dst):
          src = os.path.abspath(src)
          return os.path.abspath(dst)[:len(src)] == src
      shutil.destinsrc = destinsrc
      del destinsrc
  
  
  try:
      import subprocess
  except ImportError:
      # Pre-2.4 Python has no subprocess module.
      import_as('_scons_subprocess', 'subprocess')
  
  import sys
  try:
      sys.version_info
  except AttributeError:
      # Pre-1.6 Python has no sys.version_info
      import string
      version_string = string.split(sys.version)[0]
      version_ints = map(int, string.split(version_string, '.'))
      sys.version_info = tuple(version_ints + ['final', 0])
  
  try:
      import UserString
  except ImportError:
      # Pre-1.6 Python has no UserString module.
      import_as('_scons_UserString', 'UserString')
  
  # Local Variables:
  # tab-width:4
  # indent-tabs-mode:nil
  # End:
  # vim: set expandtab tabstop=4 shiftwidth=4:
  