text: """Utilities to support packages."""
  
  # NOTE: This module must remain compatible with Python 2.3, as it is shared
  # by setuptools for distribution with Python 2.3 and up.
  
  import os
  import sys
  import imp
  import os.path
  from types import ModuleType
  
  __all__ = [
      'get_importer', 'iter_importers', 'get_loader', 'find_loader',
      'walk_packages', 'iter_modules', 'get_data',
      'ImpImporter', 'ImpLoader', 'read_code', 'extend_path',
  ]
  
  def read_code(stream):
      # This helper is needed in order for the PEP 302 emulation to
      # correctly handle compiled files
      import marshal
  
      magic = stream.read(4)
      if magic != imp.get_magic():
          return None
  
      stream.read(4) # Skip timestamp
      return marshal.load(stream)
  
  
  def simplegeneric(func):
      """Make a trivial single-dispatch generic function"""
      registry = {}
      def wrapper(*args, **kw):
          ob = args[0]
          try:
              cls = ob.__class__
          except AttributeError:
              cls = type(ob)
          try:
              mro = cls.__mro__
          except AttributeError:
              try:
                  class cls(cls, object):
                      pass
                  mro = cls.__mro__[1:]
              except TypeError:
                  mro = object,   # must be an ExtensionClass or some such  :(
          for t in mro:
              if t in registry:
                  return registry[t](*args, **kw)
          else:
              return func(*args, **kw)
      try:
          wrapper.__name__ = func.__name__
      except (TypeError, AttributeError):
          pass    # Python 2.3 doesn't allow functions to be renamed
  
      def register(typ, func=None):
          if func is None:
              return lambda f: register(typ, f)
          registry[typ] = func
          return func
  
      wrapper.__dict__ = func.__dict__
      wrapper.__doc__ = func.__doc__
      wrapper.register = register
      return wrapper
  
  
  def walk_packages(path=None, prefix='', onerror=None):
      """Yields (module_loader, name, ispkg) for all modules recursively
      on path, or, if path is None, all accessible modules.
  
      'path' should be either None or a list of paths to look for
      modules in.
  
      'prefix' is a string to output on the front of every module name
      on output.
  
      Note that this function must import all *packages* (NOT all
      modules!) on the given path, in order to access the __path__
      attribute to find submodules.
  
      'onerror' is a function which gets called with one argument (the
      name of the package which was being imported) if any exception
      occurs while trying to import a package.  If no onerror function is
      supplied, ImportErrors are caught and ignored, while all other
      exceptions are propagated, terminating the search.
  
      Examples:
  
      # list all modules python can access
      walk_packages()
  
      # list all submodules of ctypes
      walk_packages(ctypes.__path__, ctypes.__name__+'.')
      """
  
      def seen(p, m={}):
          if p in m:
              return True
          m[p] = True
  
      for importer, name, ispkg in iter_modules(path, prefix):
          yield importer, name, ispkg
  
          if ispkg:
              try:
                  __import__(name)
              except ImportError:
                  if onerror is not None:
                      onerror(name)
              except Exception:
                  if onerror is not None:
                      onerror(name)
                  else:
                      raise
              else:
                  path = getattr(sys.modules[name], '__path__', None) or []
  
                  # don't traverse path items we've seen before
                  path = [p for p in path if not seen(p)]
  
                  for item in walk_packages(path, name+'.', onerror):
                      yield item
  
  
  def iter_modules(path=None, prefix=''):
      """Yields (module_loader, name, ispkg) for all submodules on path,
      or, if path is None, all top-level modules on sys.path.
  
      'path' should be either None or a list of paths to look for
      modules in.
  
      'prefix' is a string to output on the front of every module name
      on output.
      """
  
      if path is None:
          importers = iter_importers()
      else:
          importers = map(get_importer, path)
  
      yielded = {}
      for i in importers:
          for name, ispkg in iter_importer_modules(i, prefix):
              if name not in yielded:
                  yielded[name] = 1
                  yield i, name, ispkg
  
  
  #@simplegeneric
  def iter_importer_modules(importer, prefix=''):
      if not hasattr(importer, 'iter_modules'):
          return []
      return importer.iter_modules(prefix)
  
  iter_importer_modules = simplegeneric(iter_importer_modules)
  
  
  class ImpImporter:
      """PEP 302 Importer that wraps Python's "classic" import algorithm
  
      ImpImporter(dirname) produces a PEP 302 importer that searches that
      directory.  ImpImporter(None) produces a PEP 302 importer that searches
      the current sys.path, plus any modules that are frozen or built-in.
  
      Note that ImpImporter does not currently support being used by placement
      on sys.meta_path.
      """
  
      def __init__(self, path=None):
          self.path = path
  
      def find_module(self, fullname, path=None):
          # Note: we ignore 'path' argument since it is only used via meta_path
          subname = fullname.split(".")[-1]
          if subname != fullname and self.path is None:
              return None
          if self.path is None:
              path = None
          else:
              path = [os.path.realpath(self.path)]
          try:
              file, filename, etc = imp.find_module(subname, path)
          except ImportError:
              return None
          return ImpLoader(fullname, file, filename, etc)
  
      def iter_modules(self, prefix=''):
          if self.path is None or not os.path.isdir(self.path):
              return
  
          yielded = {}
          import inspect
          try:
              filenames = os.listdir(self.path)
          except OSError:
              # ignore unreadable directories like import does
              filenames = []
          filenames.sort()  # handle packages before same-named modules
  
          for fn in filenames:
              modname = inspect.getmodulename(fn)
              if modname=='__init__' or modname in yielded:
                  continue
  
              path = os.path.join(self.path, fn)
              ispkg = False
  
              if not modname and os.path.isdir(path) and '.' not in fn:
                  modname = fn
                  try:
                      dircontents = os.listdir(path)
                  except OSError:
                      # ignore unreadable directories like import does
                      dircontents = []
                  for fn in dircontents:
                      subname = inspect.getmodulename(fn)
                      if subname=='__init__':
                          ispkg = True
                          break
                  else:
                      continue    # not a package
  
              if modname and '.' not in modname:
                  yielded[modname] = 1
                  yield prefix + modname, ispkg
  
  
  class ImpLoader:
      """PEP 302 Loader that wraps Python's "classic" import algorithm
      """
      code = source = None
  
      def __init__(self, fullname, file, filename, etc):
          self.file = file
          self.filename = filename
          self.fullname = fullname
          self.etc = etc
  
      def load_module(self, fullname):
          self._reopen()
          try:
              mod = imp.load_module(fullname, self.file, self.filename, self.etc)
          finally:
              if self.file:
                  self.file.close()
          # Note: we don't set __loader__ because we want the module to look
          # normal; i.e. this is just a wrapper for standard import machinery
          return mod
  
      def get_data(self, pathname):
          return open(pathname, "rb").read()
  
      def _reopen(self):
          if self.file and self.file.closed:
              mod_type = self.etc[2]
              if mod_type==imp.PY_SOURCE:
                  self.file = open(self.filename, 'rU')
              elif mod_type in (imp.PY_COMPILED, imp.C_EXTENSION):
                  self.file = open(self.filename, 'rb')
  
      def _fix_name(self, fullname):
          if fullname is None:
              fullname = self.fullname
          elif fullname != self.fullname:
              raise ImportError("Loader for module %s cannot handle "
                                "module %s" % (self.fullname, fullname))
          return fullname
  
      def is_package(self, fullname):
          fullname = self._fix_name(fullname)
          return self.etc[2]==imp.PKG_DIRECTORY
  
      def get_code(self, fullname=None):
          fullname = self._fix_name(fullname)
          if self.code is None:
              mod_type = self.etc[2]
              if mod_type==imp.PY_SOURCE:
                  source = self.get_source(fullname)
                  self.code = compile(source, self.filename, 'exec')
              elif mod_type==imp.PY_COMPILED:
                  self._reopen()
                  try:
                      self.code = read_code(self.file)
                  finally:
                      self.file.close()
              elif mod_type==imp.PKG_DIRECTORY:
                  self.code = self._get_delegate().get_code()
          return self.code
  
      def get_source(self, fullname=None):
          fullname = self._fix_name(fullname)
          if self.source is None:
              mod_type = self.etc[2]
              if mod_type==imp.PY_SOURCE:
                  self._reopen()
                  try:
                      self.source = self.file.read()
                  finally:
                      self.file.close()
              elif mod_type==imp.PY_COMPILED:
                  if os.path.exists(self.filename[:-1]):
                      f = open(self.filename[:-1], 'rU')
                      self.source = f.read()
                      f.close()
              elif mod_type==imp.PKG_DIRECTORY:
                  self.source = self._get_delegate().get_source()
          return self.source
  
  
      def _get_delegate(self):
          return ImpImporter(self.filename).find_module('__init__')
  
      def get_filename(self, fullname=None):
          fullname = self._fix_name(fullname)
          mod_type = self.etc[2]
          if self.etc[2]==imp.PKG_DIRECTORY:
              return self._get_delegate().get_filename()
          elif self.etc[2] in (imp.PY_SOURCE, imp.PY_COMPILED, imp.C_EXTENSION):
              return self.filename
          return None
  
  
  try:
      import zipimport
      from zipimport import zipimporter
  
      def iter_zipimport_modules(importer, prefix=''):
          dirlist = zipimport._zip_directory_cache[importer.archive].keys()
          dirlist.sort()
          _prefix = importer.prefix
          plen = len(_prefix)
          yielded = {}
          import inspect
          for fn in dirlist:
              if not fn.startswith(_prefix):
                  continue
  
              fn = fn[plen:].split(os.sep)
  
              if len(fn)==2 and fn[1].startswith('__init__.py'):
                  if fn[0] not in yielded:
                      yielded[fn[0]] = 1
                      yield fn[0], True
  
              if len(fn)!=1:
                  continue
  
              modname = inspect.getmodulename(fn[0])
              if modname=='__init__':
                  continue
  
              if modname and '.' not in modname and modname not in yielded:
                  yielded[modname] = 1
                  yield prefix + modname, False
  
      iter_importer_modules.register(zipimporter, iter_zipimport_modules)
  
  except ImportError:
      pass
  
  
  def get_importer(path_item):
      """Retrieve a PEP 302 importer for the given path item
  
      The returned importer is cached in sys.path_importer_cache
      if it was newly created by a path hook.
  
      If there is no importer, a wrapper around the basic import
      machinery is returned. This wrapper is never inserted into
      the importer cache (None is inserted instead).
  
      The cache (or part of it) can be cleared manually if a
      rescan of sys.path_hooks is necessary.
      """
      try:
          importer = sys.path_importer_cache[path_item]
      except KeyError:
          for path_hook in sys.path_hooks:
              try:
                  importer = path_hook(path_item)
                  break
              except ImportError:
                  pass
          else:
              importer = None
          sys.path_importer_cache.setdefault(path_item, importer)
  
      if importer is None:
          try:
              importer = ImpImporter(path_item)
          except ImportError:
              importer = None
      return importer
  
  
  def iter_importers(fullname=""):
      """Yield PEP 302 importers for the given module name
  
      If fullname contains a '.', the importers will be for the package
      containing fullname, otherwise they will be importers for sys.meta_path,
      sys.path, and Python's "classic" import machinery, in that order.  If
      the named module is in a package, that package is imported as a side
      effect of invoking this function.
  
      Non PEP 302 mechanisms (e.g. the Windows registry) used by the
      standard import machinery to find files in alternative locations
      are partially supported, but are searched AFTER sys.path. Normally,
      these locations are searched BEFORE sys.path, preventing sys.path
      entries from shadowing them.
  
      For this to cause a visible difference in behaviour, there must
      be a module or package name that is accessible via both sys.path
      and one of the non PEP 302 file system mechanisms. In this case,
      the emulation will find the former version, while the builtin
      import mechanism will find the latter.
  
      Items of the following types can be affected by this discrepancy:
          imp.C_EXTENSION, imp.PY_SOURCE, imp.PY_COMPILED, imp.PKG_DIRECTORY
      """
      if fullname.startswith('.'):
          raise ImportError("Relative module names not supported")
      if '.' in fullname:
          # Get the containing package's __path__
          pkg = '.'.join(fullname.split('.')[:-1])
          if pkg not in sys.modules:
              __import__(pkg)
          path = getattr(sys.modules[pkg], '__path__', None) or []
      else:
          for importer in sys.meta_path:
              yield importer
          path = sys.path
      for item in path:
          yield get_importer(item)
      if '.' not in fullname:
          yield ImpImporter()
  
  def get_loader(module_or_name):
      """Get a PEP 302 "loader" object for module_or_name
  
      If the module or package is accessible via the normal import
      mechanism, a wrapper around the relevant part of that machinery
      is returned.  Returns None if the module cannot be found or imported.
      If the named module is not already imported, its containing package
      (if any) is imported, in order to establish the package __path__.
  
      This function uses iter_importers(), and is thus subject to the same
      limitations regarding platform-specific special import locations such
      as the Windows registry.
      """
      if module_or_name in sys.modules:
          module_or_name = sys.modules[module_or_name]
      if isinstance(module_or_name, ModuleType):
          module = module_or_name
          loader = getattr(module, '__loader__', None)
          if loader is not None:
              return loader
          fullname = module.__name__
      else:
          fullname = module_or_name
      return find_loader(fullname)
  
  def find_loader(fullname):
      """Find a PEP 302 "loader" object for fullname
  
      If fullname contains dots, path must be the containing package's __path__.
      Returns None if the module cannot be found or imported. This function uses
      iter_importers(), and is thus subject to the same limitations regarding
      platform-specific special import locations such as the Windows registry.
      """
      for importer in iter_importers(fullname):
          loader = importer.find_module(fullname)
          if loader is not None:
              return loader
  
      return None
  
  
  def extend_path(path, name):
      """Extend a package's path.
  
      Intended use is to place the following code in a package's __init__.py:
  
          from pkgutil import extend_path
          __path__ = extend_path(__path__, __name__)
  
      This will add to the package's __path__ all subdirectories of
      directories on sys.path named after the package.  This is useful
      if one wants to distribute different parts of a single logical
      package as multiple directories.
  
      It also looks for *.pkg files beginning where * matches the name
      argument.  This feature is similar to *.pth files (see site.py),
      except that it doesn't special-case lines starting with 'import'.
      A *.pkg file is trusted at face value: apart from checking for
      duplicates, all entries found in a *.pkg file are added to the
      path, regardless of whether they are exist the filesystem.  (This
      is a feature.)
  
      If the input path is not a list (as is the case for frozen
      packages) it is returned unchanged.  The input path is not
      modified; an extended copy is returned.  Items are only appended
      to the copy at the end.
  
      It is assumed that sys.path is a sequence.  Items of sys.path that
      are not (unicode or 8-bit) strings referring to existing
      directories are ignored.  Unicode items of sys.path that cause
      errors when used as filenames may cause this function to raise an
      exception (in line with os.path.isdir() behavior).
      """
  
      if not isinstance(path, list):
          # This could happen e.g. when this is called from inside a
          # frozen package.  Return the path unchanged in that case.
          return path
  
      pname = os.path.join(*name.split('.')) # Reconstitute as relative path
      # Just in case os.extsep != '.'
      sname = os.extsep.join(name.split('.'))
      sname_pkg = sname + os.extsep + "pkg"
      init_py = "__init__" + os.extsep + "py"
  
      path = path[:] # Start with a copy of the existing path
  
      for dir in sys.path:
          if not isinstance(dir, basestring) or not os.path.isdir(dir):
              continue
          subdir = os.path.join(dir, pname)
          # XXX This may still add duplicate entries to path on
          # case-insensitive filesystems
          initfile = os.path.join(subdir, init_py)
          if subdir not in path and os.path.isfile(initfile):
              path.append(subdir)
          # XXX Is this the right thing for subpackages like zope.app?
          # It looks for a file named "zope.app.pkg"
          pkgfile = os.path.join(dir, sname_pkg)
          if os.path.isfile(pkgfile):
              try:
                  f = open(pkgfile)
              except IOError, msg:
                  sys.stderr.write("Can't open %s: %s\n" %
                                   (pkgfile, msg))
              else:
                  for line in f:
                      line = line.rstrip('\n')
                      if not line or line.startswith('#'):
                          continue
                      path.append(line) # Don't check for existence!
                  f.close()
  
      return path
  
  def get_data(package, resource):
      """Get a resource from a package.
  
      This is a wrapper round the PEP 302 loader get_data API. The package
      argument should be the name of a package, in standard module format
      (foo.bar). The resource argument should be in the form of a relative
      filename, using '/' as the path separator. The parent directory name '..'
      is not allowed, and nor is a rooted name (starting with a '/').
  
      The function returns a binary string, which is the contents of the
      specified resource.
  
      For packages located in the filesystem, which have already been imported,
      this is the rough equivalent of
  
          d = os.path.dirname(sys.modules[package].__file__)
          data = open(os.path.join(d, resource), 'rb').read()
  
      If the package cannot be located or loaded, or it uses a PEP 302 loader
      which does not support get_data(), then None is returned.
      """
  
      loader = get_loader(package)
      if loader is None or not hasattr(loader, 'get_data'):
          return None
      mod = sys.modules.get(package) or loader.load_module(package)
      if mod is None or not hasattr(mod, '__file__'):
          return None
  
      # Modify the resource name to be compatible with the loader.get_data
      # signature - an os.path format "filename" starting with the dirname of
      # the package's __file__
      parts = resource.split('/')
      parts.insert(0, os.path.dirname(mod.__file__))
      resource_name = os.path.join(*parts)
      return loader.get_data(resource_name)
  