WTF NPAPI extension. Early draft.

tools/nixysa/third_party/gflags-1.0/python/gflags.py

+#!/usr/bin/env python
+
+# Copyright (c) 2007, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# ---
+# Author: Chad Lester
+# Design and style contributions by:
+#   Amit Patel, Bogdan Cocosel, Daniel Dulitz, Eric Tiedemann,
+#   Eric Veach, Laurence Gonsalves, Matthew Springer
+# Code reorganized a bit by Craig Silverstein
+
+"""
+This module is used to define and parse command line flags.
+
+This module defines a *distributed* flag-definition policy: rather
+than an application having to define all flags in or near main(), each
+python module defines flags that are useful to it.  When one python
+module imports another, it gains access to the other's flags.  (This
+is implemented by having all modules share a common, global registry
+object containing all the flag information.)
+
+Flags are defined through the use of one of the DEFINE_xxx functions.
+The specific function used determines how the flag is parsed, checked,
+and optionally type-converted, when it's seen on the command line.
+
+
+IMPLEMENTATION: DEFINE_* creates a 'Flag' object and registers it with
+a 'FlagValues' object (typically the global FlagValues FLAGS, defined
+here).  The 'FlagValues' object can scan the command line arguments
+and pass flag arguments to the corresponding 'Flag' objects for
+value-checking and type conversion.  The converted flag values are
+available as members of the 'FlagValues' object.
+
+Code can access the flag through a FlagValues object, for instancee
+gflags.FLAGS.myflag.  Typically, the __main__ module passes the
+command line arguments to gflags.FLAGS for parsing.
+
+At bottom, this module calls getopt(), so getopt functionality is
+supported, including short- and long-style flags, and the use of -- to
+terminate flags.
+
+Methods defined by the flag module will throw 'FlagsError' exceptions.
+The exception argument will be a human-readable string.
+
+
+FLAG TYPES:  This is a list of the DEFINE_*'s that you can do.  All
+flags take a name, default value, help-string, and optional 'short'
+name (one-letter name).  Some flags have other arguments, which are
+described with the flag.
+
+DEFINE_string: takes any input, and interprets it as a string.
+
+DEFINE_boolean: typically does not take an argument: say --myflag to
+                set FLAGS.myflag to true, or --nomyflag to set
+                FLAGS.myflag to false.  Alternately, you can say
+                   --myflag=true  or --myflag=t or --myflag=1  or
+                   --myflag=false or --myflag=f or --myflag=0
+
+DEFINE_float: takes an input and interprets it as a floating point
+              number.  Takes optional args lower_bound and
+              upper_bound; if the number specified on the command line
+              is out of range, it will raise a FlagError.
+
+DEFINE_integer: takes an input and interprets it as an integer.  Takes
+                optional args lower_bound and upper_bound as for floats.
+
+DEFINE_enum: takes a list of strings which represents legal values.  If
+             the command-line value is not in this list, raise a flag
+             error.  Otherwise, assign to FLAGS.flag as a string.
+
+DEFINE_list: Takes a comma-separated list of strings on the commandline.
+             Stores them in a python list object.
+
+DEFINE_spaceseplist: Takes a space-separated list of strings on the
+                     commandline.  Stores them in a python list object.
+
+DEFINE_multistring: The same as DEFINE_string, except the flag can be
+                    specified more than once on the commandline.  The
+                    result is a python list object (list of strings),
+                    even if the flag is only on the command line once.
+
+DEFINE_multi_int: The same as DEFINE_integer, except the flag can be
+                  specified more than once on the commandline.  The
+                  result is a python list object (list of ints),
+                  even if the flag is only on the command line once.
+
+
+SPECIAL FLAGS: There are a few flags that have special meaning:
+   --help (or -?)  prints a list of all the flags in a human-readable fashion
+   --helpshort     prints a list of all the flags in the 'main' .py file only
+   --flagfile=foo  read flags from foo.
+   --undefok=f1,f2 ignore unrecognized option errors for f1,f2
+   --              as in getopt(), terminates flag-processing
+
+Note on --flagfile:
+
+Flags may be loaded from text files in addition to being specified on
+the commandline.
+
+Any flags you don't feel like typing, throw them in a file, one flag
+per line, for instance:
+   --myflag=myvalue
+   --nomyboolean_flag
+You then specify your file with the special flag
+'--flagfile=somefile'.  You CAN recursively nest flagfile= tokens OR
+use multiple files on the command line.  Lines beginning with a single
+hash '#' or a double slash '//' are comments in your flagfile.
+
+Any flagfile=<file> will be interpreted as having a relative path from
+the current working directory rather than from the place the file was
+included from:
+   myPythonScript.py --flagfile=config/somefile.cfg
+
+If somefile.cfg includes further --flagfile= directives, these will be
+referenced relative to the original CWD, not from the directory the
+including flagfile was found in!
+
+The caveat applies to people who are including a series of nested
+files in a different dir than they are executing out of.  Relative
+path names are always from CWD, not from the directory of the parent
+include flagfile. We do now support '~' expanded directory names.
+
+Absolute path names ALWAYS work!
+
+
+EXAMPLE USAGE:
+
+  import gflags
+  FLAGS = gflags.FLAGS
+
+  # Flag names are globally defined!  So in general, we need to be
+  # careful to pick names that are unlikely to be used by other libraries.
+  # If there is a conflict, we'll get an error at import time.
+  gflags.DEFINE_string('name', 'Mr. President', 'your name')
+  gflags.DEFINE_integer('age', None, 'your age in years', lower_bound=0)
+  gflags.DEFINE_boolean('debug', 0, 'produces debugging output')
+  gflags.DEFINE_enum('gender', 'male', ['male', 'female'], 'your gender')
+
+  def main(argv):
+    try:
+      argv = FLAGS(argv)  # parse flags
+    except gflags.FlagsError, e:
+      print '%s\\nUsage: %s ARGS\\n%s' % (e, sys.argv[0], FLAGS)
+      sys.exit(1)
+    if FLAGS.debug: print 'non-flag arguments:', argv
+    print 'Happy Birthday', FLAGS.name
+    if FLAGS.age is not None:
+      print 'You are a %s, who is %d years old' % (FLAGS.gender, FLAGS.age)
+
+  if __name__ == '__main__':
+    main(sys.argv)
+"""
+
+import getopt
+import os
+import re
+import sys
+
+# Are we running at least python 2.2?
+try:
+  if tuple(sys.version_info[:3]) < (2,2,0):
+    raise NotImplementedError("requires python 2.2.0 or later")
+except AttributeError:   # a very old python, that lacks sys.version_info
+  raise NotImplementedError("requires python 2.2.0 or later")
+
+# If we're not running at least python 2.2.1, define True, False, and bool.
+# Thanks, Guido, for the code.
+try:
+  True, False, bool
+except NameError:
+  False = 0
+  True = 1
+  def bool(x):
+    if x:
+      return True
+    else:
+      return False
+
+# Are we running under pychecker?
+_RUNNING_PYCHECKER = 'pychecker.python' in sys.modules
+
+
+def _GetCallingModule():
+  """
+  Get the name of the module that's calling into this module; e.g.,
+  the module calling a DEFINE_foo... function.
+  """
+  # Walk down the stack to find the first globals dict that's not ours.
+  for depth in range(1, sys.getrecursionlimit()):
+    if not sys._getframe(depth).f_globals is globals():
+      return __GetModuleName(sys._getframe(depth).f_globals)
+  raise AssertionError, "No module was found"
+
+
+# module exceptions:
+class FlagsError(Exception):
+  """The base class for all flags errors"""
+
+class DuplicateFlag(FlagsError):
+  """Raised if there is a flag naming conflict"""
+
+# A DuplicateFlagError conveys more information than
+# a DuplicateFlag. Since there are external modules
+# that create DuplicateFlags, the interface to
+# DuplicateFlag shouldn't change.
+class DuplicateFlagError(DuplicateFlag):
+  def __init__(self, flagname, flag_values):
+    self.flagname = flagname
+    message = "The flag '%s' is defined twice." % self.flagname
+    flags_by_module = flag_values.__dict__['__flags_by_module']
+    for module in flags_by_module:
+      for flag in flags_by_module[module]:
+        if flag.name == flagname:
+          message = message + " First from " + module + ","
+          break
+    message = message + " Second from " + _GetCallingModule()
+    Exception.__init__(self, message)
+
+class IllegalFlagValue(FlagsError): "The flag command line argument is illegal"
+
+class UnrecognizedFlag(FlagsError):
+  """Raised if a flag is unrecognized"""
+
+# An UnrecognizedFlagError conveys more information than
+# an UnrecognizedFlag. Since there are external modules
+# that create DuplicateFlags, the interface to
+# DuplicateFlag shouldn't change.
+class UnrecognizedFlagError(UnrecognizedFlag):
+  def __init__(self, flagname):
+    self.flagname = flagname
+    Exception.__init__(self, "Unknown command line flag '%s'" % flagname)
+
+# Global variable used by expvar
+_exported_flags = {}
+_help_width = 80  # width of help output
+
+
+def GetHelpWidth():
+  """
+  Length of help to be used in TextWrap
+  """
+  global _help_width
+  return _help_width
+
+
+def CutCommonSpacePrefix(text):
+  """
+  Cut out a common space prefix. If the first line does not start with a space
+  it is left as is and only in the remaining lines a common space prefix is
+  being searched for. That means the first line will stay untouched. This is
+  especially useful to turn doc strings into help texts. This is because some
+  people prefer to have the doc comment start already after the apostrophy and
+  then align the following lines while others have the apostrophies on a
+  seperately line. The function also drops trailing empty lines and ignores
+  empty lines following the initial content line while calculating the initial
+  common whitespace.
+
+  Args:
+    text:  text to work on
+
+  Returns:
+    the resulting text
+  """
+  text_lines = text.splitlines()
+  # Drop trailing empty lines
+  while text_lines and not text_lines[-1]:
+    text_lines = text_lines[:-1]
+  if text_lines:
+    # We got some content, is the first line starting with a space?
+    if text_lines[0] and text_lines[0][0].isspace():
+      text_first_line = []
+    else:
+      text_first_line = [text_lines.pop(0)]
+    # Calculate length of common leading whitesppace (only over content lines)
+    common_prefix = os.path.commonprefix([line for line in text_lines if line])
+    space_prefix_len = len(common_prefix) - len(common_prefix.lstrip())
+    # If we have a common space prefix, drop it from all lines
+    if space_prefix_len:
+      for index in xrange(len(text_lines)):
+        if text_lines[index]:
+          text_lines[index] = text_lines[index][space_prefix_len:]
+    return '\n'.join(text_first_line + text_lines)
+  return ''
+
+
+def TextWrap(text, length=None, indent='', firstline_indent=None, tabs='    '):
+  """
+  Wrap a given text to a maximum line length and return it.
+  We turn lines that only contain whitespace into empty lines.
+  We keep new lines.
+  We also keep tabs (e.g. we do not treat tabs as spaces).
+
+  Args:
+    text:             text to wrap
+    length:           maximum length of a line, includes indentation
+                      if this is None then use GetHelpWidth()
+    indent:           indent for all but first line
+    firstline_indent: indent for first line, if None then fall back to indent
+    tabs:             replacement for tabs
+
+  Returns:
+    wrapped text
+
+  Raises:
+    CommandsError: if indent not shorter than length
+    CommandsError: if firstline_indent not shorter than length
+  """
+  # Get defaults where callee used None
+  if length is None:
+    length = GetHelpWidth()
+  if indent is None:
+    indent = ''
+  if len(indent) >= length:
+    raise CommandsError('Indent must be shorter than length')
+  # In line we will be holding the current line which is to be started with
+  # indent (or firstline_indent if available) and then appended with words.
+  if firstline_indent is None:
+    firstline_indent = ''
+    line = indent
+  else:
+    line = firstline_indent
+    if len(firstline_indent) >= length:
+      raise CommandsError('First iline indent must be shorter than length')
+
+  # If the callee does not care about tabs we simply convert them to spaces
+  # If callee wanted tabs to be single space then we do that already here.
+  if not tabs or tabs == ' ':
+    text = text.replace('\t', ' ')
+  else:
+    tabs_are_whitespace = not tabs.strip()
+
+  line_regex = re.compile('([ ]*)(\t*)([^ \t]+)', re.MULTILINE)
+
+  # Split the text into lines and the lines with the regex above. The resulting
+  # lines are collected in result[]. For each split we get the spaces, the tabs
+  # and the next non white space (e.g. next word).
+  result = []
+  for text_line in text.splitlines():
+    # Store result length so we can find out whether processing the next line
+    # gave any new content
+    old_result_len = len(result)
+    # Process next line with line_regex. For optimization we do an rstrip().
+    # - process tabs (changes either line or word, see below)
+    # - process word (first try to squeeze on line, then wrap or force wrap)
+    # Spaces found on the line are ignored, they get added while wrapping as
+    # needed.
+    for spaces, current_tabs, word in line_regex.findall(text_line.rstrip()):
+      # If tabs weren't converted to spaces, handle them now
+      if current_tabs:
+        # If the last thing we added was a space anyway then drop it. But
+        # let's not get rid of the indentation.
+        if (((result and line != indent) or
+            (not result and line != firstline_indent)) and line[-1] == ' '):
+          line = line[:-1]
+        # Add the tabs, if that means adding whitespace, just add it at the
+        # line, the rstrip() code while shorten the line down if necessary
+        if tabs_are_whitespace:
+          line += tabs * len(current_tabs)
+        else:
+          # if not all tab replacement is whitespace we prepend it to the word
+          word = tabs * len(current_tabs) + word
+      # Handle the case where word cannot be squeezed onto current last line
+      if len(line) + len(word) > length and len(indent) + len(word) <= length:
+        result.append(line.rstrip())
+        line = indent + word
+        word = ''
+        # No space left on line or can we append a space?
+        if len(line) + 1 >= length:
+          result.append(line.rstrip())
+          line = indent
+        else:
+          line += ' '
+      # Add word and shorten it up to allowed line length. Restart next line
+      # with indent and repeat, or add a space if we're done (word finished)
+      # This deals with words that caanot fit on one line (e.g. indent + word
+      # longer than allowed line length).
+      while len(line) + len(word) >= length:
+        line += word
+        result.append(line[:length])
+        word = line[length:]
+        line = indent
+      # Default case, simply append the word and a space
+      if word:
+        line += word + ' '
+    # End of input line. If we have content we finish the line. If the
+    # current line is just the indent but we had content in during this
+    # original line then we need to add an emoty line.
+    if (result and line != indent) or (not result and line != firstline_indent):
+      result.append(line.rstrip())
+    elif len(result) == old_result_len:
+      result.append('')
+    line = indent
+
+  return '\n'.join(result)
+
+
+def DocToHelp(doc):
+  """
+  Takes a __doc__ string and reformats it as help.
+  """
+  # Get rid of starting and ending white space. Using lstrip() or even strip()
+  # could drop more than maximum of first line and right space of last line.
+  doc = doc.strip()
+
+  # Get rid of all empty lines
+  whitespace_only_line = re.compile('^[ \t]+$', re.M)
+  doc = whitespace_only_line.sub('', doc)
+
+  # Cut out common space at line beginnings
+  doc = CutCommonSpacePrefix(doc)
+
+  # Just like this module's comment, comments tend to be aligned somehow.
+  # In other words they all start with the same amount of white space
+  # 1) keep double new lines
+  # 2) keep ws after new lines if not empty line
+  # 3) all other new lines shall be changed to a space
+  # Solution: Match new lines between non white space and replace with space.
+  doc = re.sub('(?<=\S)\n(?=\S)', ' ', doc, re.M)
+
+  return doc
+
+
+def __GetModuleName(globals_dict):
+  """Given a globals dict, find the module in which it's defined."""
+  for name, module in sys.modules.iteritems():
+    if getattr(module, '__dict__', None) is globals_dict:
+      if name == '__main__':
+        return sys.argv[0]
+      return name
+  raise AssertionError, "No module was found"
+
+def _GetMainModule():
+  """Get the module name from which execution started."""
+  for depth in range(1, sys.getrecursionlimit()):
+    try:
+      globals_of_main = sys._getframe(depth).f_globals
+    except ValueError:
+      return __GetModuleName(globals_of_main)
+  raise AssertionError, "No module was found"
+
+
+class FlagValues:
+  """
+  Used as a registry for 'Flag' objects.
+
+  A 'FlagValues' can then scan command line arguments, passing flag
+  arguments through to the 'Flag' objects that it owns.  It also
+  provides easy access to the flag values.  Typically only one
+  'FlagValues' object is needed by an application:  gflags.FLAGS
+
+  This class is heavily overloaded:
+
+  'Flag' objects are registered via __setitem__:
+       FLAGS['longname'] = x   # register a new flag
+
+  The .value member of the registered 'Flag' objects can be accessed as
+  members of this 'FlagValues' object, through __getattr__.  Both the
+  long and short name of the original 'Flag' objects can be used to
+  access its value:
+       FLAGS.longname          # parsed flag value
+       FLAGS.x                 # parsed flag value (short name)
+
+  Command line arguments are scanned and passed to the registered 'Flag'
+  objects through the __call__ method.  Unparsed arguments, including
+  argv[0] (e.g. the program name) are returned.
+       argv = FLAGS(sys.argv)  # scan command line arguments
+
+  The original registered Flag objects can be retrieved through the use
+  of the dictionary-like operator, __getitem__:
+       x = FLAGS['longname']   # access the registered Flag object
+
+  The str() operator of a 'FlagValues' object provides help for all of
+  the registered 'Flag' objects.
+  """
+
+  def __init__(self):
+    # Since everything in this class is so heavily overloaded,
+    # the only way of defining and using fields is to access __dict__
+    # directly.
+    self.__dict__['__flags'] = {}
+    self.__dict__['__flags_by_module'] = {} # A dict module -> list of flag
+
+  def FlagDict(self):
+    return self.__dict__['__flags']
+
+  def _RegisterFlagByModule(self, module_name, flag):
+    """We keep track of which flag is defined by which module so that
+       we can later sort the flags by module.
+    """
+    flags_by_module = self.__dict__['__flags_by_module']
+    flags_by_module.setdefault(module_name, []).append(flag)
+
+  def AppendFlagValues(self, flag_values):
+    """Append flags registered in another FlagValues instance.
+
+    Args:
+      flag_values: registry to copy from
+    """
+    for flag_name, flag in flag_values.FlagDict().iteritems():
+      # Flags with shortnames will appear here twice (once with under
+      # its normal name, and again with its short name).  To prevent
+      # problems (DuplicateFlagError) that occur when doubly
+      # registering flags, we perform a check to make sure that the
+      # entry we're looking at is for its normal name.
+      if flag_name == flag.name:
+        self[flag_name] = flag
+
+  def __setitem__(self, name, flag):
+    """
+    Register a new flag variable.
+    """
+    fl = self.FlagDict()
+    if not isinstance(flag, Flag):
+      raise IllegalFlagValue, flag
+    if not isinstance(name, type("")):
+      raise FlagsError, "Flag name must be a string"
+    if len(name) == 0:
+      raise FlagsError, "Flag name cannot be empty"
+    # If running under pychecker, duplicate keys are likely to be defined.
+    # Disable check for duplicate keys when pycheck'ing.
+    if (fl.has_key(name) and not flag.allow_override and
+        not fl[name].allow_override and not _RUNNING_PYCHECKER):
+      raise DuplicateFlagError(name, self)
+    short_name = flag.short_name
+    if short_name is not None:
+      if (fl.has_key(short_name) and not flag.allow_override and
+          not fl[short_name].allow_override and not _RUNNING_PYCHECKER):
+        raise DuplicateFlagError(short_name, self)
+      fl[short_name] = flag
+    fl[name] = flag
+    global _exported_flags
+    _exported_flags[name] = flag
+
+  def __getitem__(self, name):
+    """
+    Retrieve the flag object.
+    """
+    return self.FlagDict()[name]
+
+  def __getattr__(self, name):
+    """
+    Retrieve the .value member of a flag object.
+    """
+    fl = self.FlagDict()
+    if not fl.has_key(name):
+      raise AttributeError, name
+    return fl[name].value
+
+  def __setattr__(self, name, value):
+    """
+    Set the .value member of a flag object.
+    """
+    fl = self.FlagDict()
+    fl[name].value = value
+    return value
+
+  def __delattr__(self, name):
+    """
+    Delete a previously-defined flag from a flag object.
+    """
+    fl = self.FlagDict()
+    if not fl.has_key(name):
+      raise AttributeError, name
+    del fl[name]
+
+  def SetDefault(self, name, value):
+    """
+    Change the default value of the named flag object.
+    """
+    fl = self.FlagDict()
+    if not fl.has_key(name):
+      raise AttributeError, name
+    fl[name].SetDefault(value)
+
+  def __contains__(self, name):
+    """
+    Return True if name is a value (flag) in the dict.
+    """
+    return name in self.FlagDict()
+
+  has_key = __contains__  # a synonym for __contains__()
+
+  def __iter__(self):
+    return self.FlagDict().iterkeys()
+
+  def __call__(self, argv):
+    """
+    Searches argv for flag arguments, parses them and then sets the flag
+    values as attributes of this FlagValues object.  All unparsed
+    arguments are returned.  Flags are parsed using the GNU Program
+    Argument Syntax Conventions, using getopt:
+
+    http://www.gnu.org/software/libc/manual/html_mono/libc.html#Getopt
+
+    Args:
+       argv: argument list. Can be of any type that may be converted to a list.
+
+    Returns:
+       The list of arguments not parsed as options, including argv[0]
+
+    Raises:
+       FlagsError: on any parsing error
+    """
+    # Support any sequence type that can be converted to a list
+    argv = list(argv)
+
+    shortopts = ""
+    longopts = []
+
+    fl = self.FlagDict()
+
+    # This pre parses the argv list for --flagfile=<> options.
+    argv = self.ReadFlagsFromFiles(argv)
+
+    # Correct the argv to support the google style of passing boolean
+    # parameters.  Boolean parameters may be passed by using --mybool,
+    # --nomybool, --mybool=(true|false|1|0).  getopt does not support
+    # having options that may or may not have a parameter.  We replace
+    # instances of the short form --mybool and --nomybool with their
+    # full forms: --mybool=(true|false).
+    original_argv = list(argv)  # list() makes a copy
+    shortest_matches = None
+    for name, flag in fl.items():
+      if not flag.boolean:
+        continue
+      if shortest_matches is None:
+        # Determine the smallest allowable prefix for all flag names
+        shortest_matches = self.ShortestUniquePrefixes(fl)
+      no_name = 'no' + name
+      prefix = shortest_matches[name]
+      no_prefix = shortest_matches[no_name]
+
+      # Replace all occurences of this boolean with extended forms
+      for arg_idx in range(1, len(argv)):
+        arg = argv[arg_idx]
+        if arg.find('=') >= 0: continue
+        if arg.startswith('--'+prefix) and ('--'+name).startswith(arg):
+          argv[arg_idx] = ('--%s=true' % name)
+        elif arg.startswith('--'+no_prefix) and ('--'+no_name).startswith(arg):
+          argv[arg_idx] = ('--%s=false' % name)
+
+    # Loop over all of the flags, building up the lists of short options and
+    # long options that will be passed to getopt.  Short options are
+    # specified as a string of letters, each letter followed by a colon if it
+    # takes an argument.  Long options are stored in an array of strings.
+    # Each string ends with an '=' if it takes an argument.
+    for name, flag in fl.items():
+      longopts.append(name + "=")
+      if len(name) == 1:  # one-letter option: allow short flag type also
+        shortopts += name
+        if not flag.boolean:
+          shortopts += ":"
+
+    longopts.append('undefok=')
+    undefok_flags = []
+
+    # In case --undefok is specified, loop to pick up unrecognized
+    # options one by one.
+    unrecognized_opts = []
+    args = argv[1:]
+    while True:
+      try:
+        optlist, unparsed_args = getopt.getopt(args, shortopts, longopts)
+        break
+      except getopt.GetoptError, e:
+        if not e.opt or e.opt in fl:
+          # Not an unrecognized option, reraise the exception as a FlagsError
+          raise FlagsError(e)
+        # Handle an unrecognized option.
+        unrecognized_opts.append(e.opt)
+        # Remove offender from args and try again
+        for arg_index in range(len(args)):
+          if ((args[arg_index] == '--' + e.opt) or
+              (args[arg_index] == '-' + e.opt) or
+              args[arg_index].startswith('--' + e.opt + '=')):
+            args = args[0:arg_index] + args[arg_index+1:]
+            break
+        else:
+          # We should have found the option, so we don't expect to get
+          # here.  We could assert, but raising the original exception
+          # might work better.
+          raise FlagsError(e)
+
+    for name, arg in optlist:
+      if name == '--undefok':
+        undefok_flags.extend(arg.split(','))
+        continue
+      if name.startswith('--'):
+        # long option
+        name = name[2:]
+        short_option = 0
+      else:
+        # short option
+        name = name[1:]
+        short_option = 1
+      if fl.has_key(name):
+        flag = fl[name]
+        if flag.boolean and short_option: arg = 1
+        flag.Parse(arg)
+
+    # If there were unrecognized options, raise an exception unless
+    # the options were named via --undefok.
+    for opt in unrecognized_opts:
+      if opt not in undefok_flags:
+        raise UnrecognizedFlagError(opt)
+
+    if unparsed_args:
+      # unparsed_args becomes the first non-flag detected by getopt to
+      # the end of argv.  Because argv may have been modified above,
+      # return original_argv for this region.
+      return argv[:1] + original_argv[-len(unparsed_args):]
+    else:
+      return argv[:1]
+
+  def Reset(self):
+    """
+    Reset the values to the point before FLAGS(argv) was called.
+    """
+    for f in self.FlagDict().values():
+      f.Unparse()
+
+  def RegisteredFlags(self):
+    """
+    Return a list of all registered flags.
+    """
+    return self.FlagDict().keys()
+
+  def FlagValuesDict(self):
+    """
+    Return a dictionary with flag names as keys and flag values as values.
+    """
+    flag_values = {}
+
+    for flag_name in self.RegisteredFlags():
+      flag = self.FlagDict()[flag_name]
+      flag_values[flag_name] = flag.value
+
+    return flag_values
+
+  def __str__(self):
+    """
+    Generate a help string for all known flags.
+    """
+    return self.GetHelp()
+
+  def GetHelp(self, prefix=""):
+    """
+    Generate a help string for all known flags.
+    """
+    helplist = []
+
+    flags_by_module = self.__dict__['__flags_by_module']
+    if flags_by_module:
+
+      modules = flags_by_module.keys()
+      modules.sort()
+
+      # Print the help for the main module first, if possible.
+      main_module = _GetMainModule()
+      if main_module in modules:
+        modules.remove(main_module)
+        modules = [ main_module ] + modules
+
+      for module in modules:
+        self.__RenderOurModuleFlags(module, helplist)
+
+      self.__RenderModuleFlags('google3.pyglib.flags',
+                               _SPECIAL_FLAGS.FlagDict().values(),
+                               helplist)
+
+    else:
+      # Just print one long list of flags.
+      self.__RenderFlagList(
+          self.FlagDict().values() + _SPECIAL_FLAGS.FlagDict().values(),
+          helplist, prefix)
+
+    return '\n'.join(helplist)
+
+  def __RenderModuleFlags(self, module, flags, output_lines, prefix=""):
+    """
+    Generate a help string for a given module.
+    """
+    output_lines.append('\n%s%s:' % (prefix, module))
+    self.__RenderFlagList(flags, output_lines, prefix + "  ")
+
+  def __RenderOurModuleFlags(self, module, output_lines, prefix=""):
+    """
+    Generate a help string for a given module.
+    """
+    flags_by_module = self.__dict__['__flags_by_module']
+    if module in flags_by_module:
+      self.__RenderModuleFlags(module, flags_by_module[module],
+                               output_lines, prefix)
+
+  def MainModuleHelp(self):
+    """
+    Generate a help string for all known flags of the main module.
+    """
+    helplist = []
+    self.__RenderOurModuleFlags(_GetMainModule(), helplist)
+    return '\n'.join(helplist)
+
+  def __RenderFlagList(self, flaglist, output_lines, prefix="  "):
+    fl = self.FlagDict()
+    special_fl = _SPECIAL_FLAGS.FlagDict()
+    flaglist = [(flag.name, flag) for flag in flaglist]
+    flaglist.sort()
+    flagset = {}
+    for (name, flag) in flaglist:
+      # It's possible this flag got deleted or overridden since being
+      # registered in the per-module flaglist.  Check now against the
+      # canonical source of current flag information, the FlagDict.
+      if fl.get(name, None) != flag and special_fl.get(name, None) != flag:
+        # a different flag is using this name now
+        continue
+      # only print help once
+      if flagset.has_key(flag): continue
+      flagset[flag] = 1
+      flaghelp = ""
+      if flag.short_name: flaghelp += "-%s," % flag.short_name
+      if flag.boolean:
+        flaghelp += "--[no]%s" % flag.name + ":"
+      else:
+        flaghelp += "--%s" % flag.name + ":"
+      flaghelp += "  "
+      if flag.help:
+        flaghelp += flag.help
+      flaghelp = TextWrap(flaghelp, indent=prefix+"  ",
+                          firstline_indent=prefix)
+      if flag.default_as_str:
+        flaghelp += "\n"
+        flaghelp += TextWrap("(default: %s)" % flag.default_as_str,
+                             indent=prefix+"  ")
+      if flag.parser.syntactic_help:
+        flaghelp += "\n"
+        flaghelp += TextWrap("(%s)" % flag.parser.syntactic_help,
+                             indent=prefix+"  ")
+      output_lines.append(flaghelp)
+
+  def get(self, name, default):
+    """
+    Retrieve the .value member of a flag object, or default if .value is None
+    """
+
+    value = self.__getattr__(name)
+    if value is not None: # Can't do if not value, b/c value might be '0' or ""
+      return value
+    else:
+      return default
+
+  def ShortestUniquePrefixes(self, fl):
+    """
+    Returns a dictionary mapping flag names to their shortest unique prefix.
+    """
+    # Sort the list of flag names
+    sorted_flags = []
+    for name, flag in fl.items():
+      sorted_flags.append(name)
+      if flag.boolean:
+        sorted_flags.append('no%s' % name)
+    sorted_flags.sort()
+
+    # For each name in the sorted list, determine the shortest unique prefix
+    # by comparing itself to the next name and to the previous name (the latter
+    # check uses cached info from the previous loop).
+    shortest_matches = {}
+    prev_idx = 0
+    for flag_idx in range(len(sorted_flags)):
+      curr = sorted_flags[flag_idx]
+      if flag_idx == (len(sorted_flags) - 1):
+        next = None
+      else:
+        next = sorted_flags[flag_idx+1]
+        next_len = len(next)
+      for curr_idx in range(len(curr)):
+        if (next is None
+            or curr_idx >= next_len
+            or curr[curr_idx] != next[curr_idx]):
+          # curr longer than next or no more chars in common
+          shortest_matches[curr] = curr[:max(prev_idx, curr_idx) + 1]
+          prev_idx = curr_idx
+          break
+      else:
+        # curr shorter than (or equal to) next
+        shortest_matches[curr] = curr
+        prev_idx = curr_idx + 1 # next will need at least one more char
+    return shortest_matches
+
+  def __IsFlagFileDirective(self, flag_string):
+    """ Detects the --flagfile= token.
+    Takes a string which might contain a '--flagfile=<foo>' directive.
+    Returns a Boolean.
+    """
+    if isinstance(flag_string, type("")):
+      if flag_string.startswith('--flagfile='):
+        return 1
+      elif flag_string == '--flagfile':
+        return 1
+      elif flag_string.startswith('-flagfile='):
+        return 1
+      elif flag_string == '-flagfile':
+        return 1
+      else:
+        return 0
+    return 0
+
+  def ExtractFilename(self, flagfile_str):
+    """Function to remove the --flagfile= (or variant) and return just the
+      filename part.  We can get strings that look like:
+        --flagfile=foo, -flagfile=foo.
+      The case of --flagfile foo and  -flagfile foo shouldn't be hitting this
+      function, as they are dealt with in the level above this funciton.
+    """
+    if flagfile_str.startswith('--flagfile='):
+      return os.path.expanduser((flagfile_str[(len('--flagfile=')):]).strip())
+    elif flagfile_str.startswith('-flagfile='):
+      return os.path.expanduser((flagfile_str[(len('-flagfile=')):]).strip())
+    else:
+      raise FlagsError('Hit illegal --flagfile type: %s' % flagfile_str)
+      return ''
+
+
+  def __GetFlagFileLines(self, filename, parsed_file_list):
+    """Function to open a flag file, return its useful (!=comments,etc) lines.
+    Takes:
+        A filename to open and read
+        A list of files we have already read THAT WILL BE CHANGED
+    Returns:
+        List of strings. See the note below.
+
+    NOTE(springer): This function checks for a nested --flagfile=<foo>
+    tag and handles the lower file recursively. It returns a list off
+    all the lines that _could_ contain command flags.  This is
+    EVERYTHING except whitespace lines and comments (lines starting
+    with '#' or '//').
+    """
+    line_list = []  # All line from flagfile.
+    flag_line_list = []  # Subset of lines w/o comments, blanks, flagfile= tags.
+    try:
+      file_obj = open(filename, 'r')
+    except IOError, e_msg:
+      print e_msg
+      print 'ERROR:: Unable to open flagfile: %s' % (filename)
+      return flag_line_list
+
+    line_list = file_obj.readlines()
+    file_obj.close()
+    parsed_file_list.append(filename)
+
+    # This is where we check each line in the file we just read.
+    for line in line_list:
+      if line.isspace():
+        pass
+      # Checks for comment (a line that starts with '#').
+      elif (line.startswith('#') or line.startswith('//')):
+        pass
+      # Checks for a nested "--flagfile=<bar>" flag in the current file.
+      # If we find one, recursively parse down into that file.
+      elif self.__IsFlagFileDirective(line):
+        sub_filename = self.ExtractFilename(line)
+        # We do a little safety check for reparsing a file we've already done.
+        if not sub_filename in parsed_file_list:
+          included_flags = self.__GetFlagFileLines(sub_filename, parsed_file_list)
+          flag_line_list.extend(included_flags)
+        else: # Case of hitting a circularly included file.
+          print >>sys.stderr, ('Warning: Hit circular flagfile dependency: %s'
+                                                                 % sub_filename)
+      else:
+        # Any line that's not a comment or a nested flagfile should
+        # get copied into 2nd position, this leaves earlier arguements
+        # further back in the list, which makes them have higher priority.
+        flag_line_list.append(line.strip())
+    return flag_line_list
+
+  def ReadFlagsFromFiles(self, argv):
+    """Process command line args, but also allow args to be read from file
+    Usage:
+      Takes: a list of strings, usually sys.argv, which may contain one or more
+            flagfile directives of the form --flagfile="./filename"
+      References: Global gflags.FLAG class instance
+      Returns: a new list which has the original list combined with what we
+                 read from any flagfile(s).
+
+      This function should be called  before the normal FLAGS(argv) call.
+      This function simply scans the input list for a flag that looks like:
+         --flagfile=<somefile>
+      Then it opens <somefile>, reads all valid key and value pairs and inserts
+      them into the input list between the first item of the list and any
+      subsequent items in the list.
+      Note that your application's flags are still defined the usual way using
+      gflags DEFINE_flag() type functions.
+
+      Notes (assuming we're getting a commandline of some sort as our input):
+      --> Any flags on the command line we were passed in _should_ always take
+              precedence!!!
+      --> a further "--flagfile=<otherfile.cfg>" CAN be nested in a flagfile.
+              It will be processed after the parent flag file is done.
+      --> For duplicate flags, first one we hit should "win".
+      --> In a flagfile, a line beginning with # or // is a comment
+      --> Entirely blank lines _should_ be ignored
+    """
+    parsed_file_list = []
+    rest_of_args = argv
+    new_argv = []
+    while rest_of_args:
+      current_arg = rest_of_args[0]
+      rest_of_args = rest_of_args[1:]
+      if self.__IsFlagFileDirective(current_arg):
+        # This handles the case of -(-)flagfile foo.  Inthis case the next arg
+        # really is part of this one.
+        if current_arg == '--flagfile' or current_arg =='-flagfile':
+          if not rest_of_args:
+            raise IllegalFlagValue, '--flagfile with no argument'
+          flag_filename = os.path.expanduser(rest_of_args[0])
+          rest_of_args = rest_of_args[1:]
+        else:
+          # This handles the case of (-)-flagfile=foo.
+          flag_filename = self.ExtractFilename(current_arg)
+        new_argv = (new_argv[:1] +
+                self.__GetFlagFileLines(flag_filename, parsed_file_list) +
+                new_argv[1:])
+      else:
+        new_argv.append(current_arg)
+
+    return new_argv
+
+  def FlagsIntoString(self):
+    """
+    Retrieve a string version of all the flags with assignments stored
+    in this FlagValues object.  Should mirror the behavior of the c++
+    version of FlagsIntoString.  Each flag assignment is seperated by
+    a newline.
+    """
+    s = ''
+    for flag in self.FlagDict().values():
+      if flag.value is not None:
+        s += flag.Serialize() + '\n'
+    return s
+
+  def AppendFlagsIntoFile(self, filename):
+    """
+    Appends all flags found in this FlagInfo object to the file
+    specified.  Output will be in the format of a flagfile.  This
+    should mirror the behavior of the c++ version of
+    AppendFlagsIntoFile.
+    """
+    out_file = open(filename, 'a')
+    out_file.write(self.FlagsIntoString())
+    out_file.close()
+# end of FlagValues definition
+
+# The global FlagValues instance
+FLAGS = FlagValues()
+
+
+class Flag:
+  """
+  'Flag' objects define the following fields:
+    .name  - the name for this flag
+    .default - the default value for this flag
+    .default_as_str - default value as repr'd string, e.g., "'true'" (or None)
+    .value  - the most recent parsed value of this flag; set by Parse()
+    .help  - a help string or None if no help is available
+    .short_name  - the single letter alias for this flag (or None)
+    .boolean  - if 'true', this flag does not accept arguments
+    .present  - true if this flag was parsed from command line flags.
+    .parser  - an ArgumentParser object
+    .serializer - an ArgumentSerializer object
+    .allow_override - the flag may be redefined without raising an error
+
+  The only public method of a 'Flag' object is Parse(), but it is
+  typically only called by a 'FlagValues' object.  The Parse() method is
+  a thin wrapper around the 'ArgumentParser' Parse() method.  The parsed
+  value is saved in .value, and the .present member is updated.  If this
+  flag was already present, a FlagsError is raised.
+
+  Parse() is also called during __init__ to parse the default value and
+  initialize the .value member.  This enables other python modules to
+  safely use flags even if the __main__ module neglects to parse the
+  command line arguments.  The .present member is cleared after __init__
+  parsing.  If the default value is set to None, then the __init__
+  parsing step is skipped and the .value member is initialized to None.
+
+  Note: The default value is also presented to the user in the help
+  string, so it is important that it be a legal value for this flag.
+  """
+  def __init__(self, parser, serializer, name, default, help_string,
+               short_name=None, boolean=0, allow_override=0):
+    self.name = name
+
+    if not help_string:
+      help_string = '(no help available)'
+
+    self.help = help_string
+    self.short_name = short_name
+    self.boolean = boolean
+    self.present = 0
+    self.parser = parser
+    self.serializer = serializer
+    self.allow_override = allow_override
+    self.value = None
+
+    self.SetDefault(default)
+
+  def __GetParsedValueAsString(self, value):
+    if value is None:
+      return None
+    if self.serializer:
+      return repr(self.serializer.Serialize(value))
+    if self.boolean:
+      if value:
+        return repr('true')
+      else:
+        return repr('false')
+    return repr(str(value))
+
+  def Parse(self, argument):
+    try:
+      self.value = self.parser.Parse(argument)
+    except ValueError, e:  # recast ValueError as IllegalFlagValue
+      raise IllegalFlagValue, ("flag --%s: " % self.name) + str(e)
+    self.present += 1
+
+  def Unparse(self):
+    if self.default is None:
+      self.value = None
+    else:
+      self.Parse(self.default)
+    self.present = 0
+
+  def Serialize(self):
+    if self.value is None:
+      return ''
+    if self.boolean:
+      if self.value:
+        return "--%s" % self.name
+      else:
+        return "--no%s" % self.name
+    else:
+      if not self.serializer:
+        raise FlagsError, "Serializer not present for flag %s" % self.name
+      return "--%s=%s" % (self.name, self.serializer.Serialize(self.value))
+
+  def SetDefault(self, value):
+    """
+    Change the default value, and current value, of this flag object
+    """
+    # We can't allow a None override because it may end up not being
+    # passed to C++ code when we're overriding C++ flags.  So we
+    # cowardly bail out until someone fixes the semantics of trying to
+    # pass None to a C++ flag.  See swig_flags.Init() for details on
+    # this behavior.
+    if value is None and self.allow_override:
+      raise DuplicateFlag, self.name
+
+    self.default = value
+    self.Unparse()
+    self.default_as_str = self.__GetParsedValueAsString(self.value)
+# End of Flag definition
+
+class ArgumentParser:
+  """
+  This is a base class used to parse and convert arguments.
+
+  The Parse() method checks to make sure that the string argument is a
+  legal value and convert it to a native type.  If the value cannot be
+  converted, it should throw a 'ValueError' exception with a human
+  readable explanation of why the value is illegal.
+
+  Subclasses should also define a syntactic_help string which may be
+  presented to the user to describe the form of the legal values.
+  """
+  syntactic_help = ""
+  def Parse(self, argument):
+    """
+    The default implementation of Parse() accepts any value of argument,
+    simply returning it unmodified.
+    """
+    return argument
+
+class ArgumentSerializer:
+  """
+  This is the base class for generating string representations of a
+  flag value
+  """
+  def Serialize(self, value):
+    return str(value)
+
+class ListSerializer(ArgumentSerializer):
+  def __init__(self, list_sep):
+    self.list_sep = list_sep
+
+  def Serialize(self, value):
+    return self.list_sep.join([str(x) for x in value])
+
+
+# The DEFINE functions are explained in the module doc string.
+
+def DEFINE(parser, name, default, help, flag_values=FLAGS, serializer=None,
+           **args):
+  """
+  This creates a generic 'Flag' object that parses its arguments with a
+  'Parser' and registers it with a 'FlagValues' object.
+
+  Developers who need to create their own 'Parser' classes should call
+  this module function. to register their flags.  For example:
+
+  DEFINE(DatabaseSpec(), "dbspec", "mysql:db0:readonly:hr",
+         "The primary database")
+  """
+  DEFINE_flag(Flag(parser, serializer, name, default, help, **args),
+              flag_values)
+
+def DEFINE_flag(flag, flag_values=FLAGS):
+  """
+  This registers a 'Flag' object with a 'FlagValues' object.  By
+  default, the global FLAGS 'FlagValue' object is used.
+
+  Typical users will use one of the more specialized DEFINE_xxx
+  functions, such as DEFINE_string or DEFINE_integer.  But developers
+  who need to create Flag objects themselves should use this function to
+  register their flags.
+  """
+  # copying the reference to flag_values prevents pychecker warnings
+  fv = flag_values
+  fv[flag.name] = flag
+
+  if flag_values == FLAGS:
+    # We are using the global flags dictionary, so we'll want to sort the
+    # usage output by calling module in FlagValues.__str__ (FLAGS is an
+    # instance of FlagValues). This requires us to keep track
+    # of which module is creating the flags.
+
+    # Tell FLAGS who's defining flag.
+    FLAGS._RegisterFlagByModule(_GetCallingModule(), flag)
+
+
+###############################
+#################  STRING FLAGS
+###############################
+
+def DEFINE_string(name, default, help, flag_values=FLAGS, **args):
+  """
+  This registers a flag whose value can be any string.
+  """
+  parser = ArgumentParser()
+  serializer = ArgumentSerializer()
+  DEFINE(parser, name, default, help, flag_values, serializer, **args)
+
+
+###############################
+################  BOOLEAN FLAGS
+###############################
+####  and the special HELP flag
+###############################
+
+class BooleanParser(ArgumentParser):
+  """
+  A boolean value
+  """
+
+  def Convert(self, argument):
+    """
+    convert the argument to a boolean; raise ValueError on errors
+    """
+    if type(argument) == str:
+      if argument.lower() in ['true', 't', '1']:
+        return True
+      elif argument.lower() in ['false', 'f', '0']:
+        return False
+
+    bool_argument = bool(argument)
+    if argument == bool_argument:
+      # The argument is a valid boolean (True, False, 0, or 1), and not just
+      # something that always converts to bool (list, string, int, etc.).
+      return bool_argument
+
+    raise ValueError('Non-boolean argument to boolean flag', argument)
+
+  def Parse(self, argument):
+    val = self.Convert(argument)
+    return val
+
+class BooleanFlag(Flag):
+  """
+  A basic boolean flag.  Boolean flags do not take any arguments, and
+  their value is either True (1) or False (0).  The false value is
+  specified on the command line by prepending the word 'no' to either
+  the long or short flag name.
+
+  For example, if a Boolean flag was created whose long name was 'update'
+  and whose short name was 'x', then this flag could be explicitly unset
+  through either --noupdate or --nox.
+  """
+  def __init__(self, name, default, help, short_name=None, **args):
+    p = BooleanParser()
+    Flag.__init__(self, p, None, name, default, help, short_name, 1, **args)
+    if not self.help: self.help = "a boolean value"
+
+def DEFINE_boolean(name, default, help, flag_values=FLAGS, **args):
+  """
+  This registers a boolean flag - one that does not take an argument.
+  If a user wants to specify a false value explicitly, the long option
+  beginning with 'no' must be used: i.e. --noflag
+
+  This flag will have a value of None, True or False.  None is possible if
+  default=None and the user does not specify the flag on the command
+  line.
+  """
+  DEFINE_flag(BooleanFlag(name, default, help, **args), flag_values)
+
+class HelpFlag(BooleanFlag):
+  """
+  HelpFlag is a special boolean flag that prints usage information and
+  raises a SystemExit exception if it is ever found in the command
+  line arguments.  Note this is called with allow_override=1, so other
+  apps can define their own --help flag, replacing this one, if they want.
+  """
+  def __init__(self):
+    BooleanFlag.__init__(self, "help", 0, "show this help",
+                         short_name="?", allow_override=1)
+  def Parse(self, arg):
+    if arg:
+      doc = sys.modules["__main__"].__doc__
+      flags = str(FLAGS)
+      print doc or ("\nUSAGE: %s [flags]\n" % sys.argv[0])
+      if flags:
+        print "flags:"
+        print flags
+      sys.exit(1)
+
+class HelpshortFlag(BooleanFlag):
+  """
+  HelpshortFlag is a special boolean flag that prints usage
+  information for the "main" module, and rasies a SystemExit exception
+  if it is ever found in the command line arguments.  Note this is
+  called with allow_override=1, so other apps can define their own
+  --helpshort flag, replacing this one, if they want.
+  """
+  def __init__(self):
+    BooleanFlag.__init__(self, "helpshort", 0,
+                         "show usage only for this module", allow_override=1)
+  def Parse(self, arg):
+    if arg:
+      doc = sys.modules["__main__"].__doc__
+      flags = FLAGS.MainModuleHelp()
+      print doc or ("\nUSAGE: %s [flags]\n" % sys.argv[0])
+      if flags:
+        print "flags:"
+        print flags
+      sys.exit(1)
+
+
+###############################
+##################  FLOAT FLAGS
+###############################
+
+class FloatParser(ArgumentParser):
+  """
+  A floating point value; optionally bounded to a given upper and lower
+  bound.
+  """
+  number_article = "a"
+  number_name = "number"
+  syntactic_help = " ".join((number_article, number_name))
+
+  def __init__(self, lower_bound=None, upper_bound=None):
+    self.lower_bound = lower_bound
+    self.upper_bound = upper_bound
+    sh = self.syntactic_help
+    if lower_bound != None and upper_bound != None:
+      sh = ("%s in the range [%s, %s]" % (sh, lower_bound, upper_bound))
+    elif lower_bound == 1:
+      sh = "a positive %s" % self.number_name
+    elif upper_bound == -1:
+      sh = "a negative %s" % self.number_name
+    elif lower_bound == 0:
+      sh = "a non-negative %s" % self.number_name
+    elif upper_bound != None:
+      sh = "%s <= %s" % (self.number_name, upper_bound)
+    elif lower_bound != None:
+      sh = "%s >= %s" % (self.number_name, lower_bound)
+    self.syntactic_help = sh
+
+  def Convert(self, argument):
+    """
+    convert the argument to a float; raise ValueError on errors
+    """
+    return float(argument)
+
+  def Parse(self, argument):
+    val = self.Convert(argument)
+    if ((self.lower_bound != None and val < self.lower_bound) or
+        (self.upper_bound != None and val > self.upper_bound)):
+      raise ValueError, "%s is not %s" % (val, self.syntactic_help)
+    return val
+
+def DEFINE_float(name, default, help, lower_bound=None, upper_bound=None,
+                 flag_values = FLAGS, **args):
+  """
+  This registers a flag whose value must be a float.  If lower_bound,
+  or upper_bound are set, then this flag must be within the given range.
+  """
+  parser = FloatParser(lower_bound, upper_bound)
+  serializer = ArgumentSerializer()
+  DEFINE(parser, name, default, help, flag_values, serializer, **args)
+
+
+###############################
+################  INTEGER FLAGS
+###############################
+
+class IntegerParser(FloatParser):
+  """
+  An integer value; optionally bounded to a given upper or lower bound.
+  """
+  number_article = "an"
+  number_name = "integer"
+  syntactic_help = " ".join((number_article, number_name))
+  def Convert(self, argument):
+    __pychecker__ = 'no-returnvalues'
+    if type(argument) == str:
+      base = 10
+      if len(argument) > 2 and argument[0] == "0" and argument[1] == "x":
+        base=16
+      try:
+        return int(argument, base)
+      # ValueError is thrown when argument is a string, and overflows an int.
+      except ValueError:
+        return long(argument, base)
+    else:
+      try:
+        return int(argument)
+      # OverflowError is thrown when argument is numeric, and overflows an int.
+      except OverflowError:
+        return long(argument)
+
+def DEFINE_integer(name, default, help, lower_bound=None, upper_bound=None,
+                   flag_values = FLAGS, **args):
+  """
+  This registers a flag whose value must be an integer.  If lower_bound,
+  or upper_bound are set, then this flag must be within the given range.
+  """
+  parser = IntegerParser(lower_bound, upper_bound)
+  serializer = ArgumentSerializer()
+  DEFINE(parser, name, default, help, flag_values, serializer, **args)
+
+
+###############################
+###################  ENUM FLAGS
+###############################
+
+class EnumParser(ArgumentParser):
+  """
+  A string enum value
+  """
+
+  def __init__(self, enum_values=None):
+    self.enum_values = enum_values
+
+  def Parse(self, argument):
+    """
+    If enum_values is not specified, any string is allowed
+    """
+    if self.enum_values and argument not in self.enum_values:
+      raise ValueError, ("value should be one of <%s>"
+                         % "|".join(self.enum_values))
+    return argument
+
+class EnumFlag(Flag):
+  """
+  A basic enum flag. The flag's value can be any string from the list
+  of enum_values.
+  """
+  def __init__(self, name, default, help, enum_values=[],
+               short_name=None, **args):
+    p = EnumParser(enum_values)
+    g = ArgumentSerializer()
+    Flag.__init__(self, p, g, name, default, help, short_name, **args)
+    if not self.help: self.help = "an enum string"
+    self.help = "<%s>: %s" % ("|".join(enum_values), self.help)
+
+def DEFINE_enum(name, default, enum_values, help, flag_values=FLAGS,
+                **args):
+  """
+  This registers a flag whose value can be a string from a set of
+  specified values.
+  """
+  DEFINE_flag(EnumFlag(name, default, help, enum_values, ** args),
+              flag_values)
+
+
+###############################
+###################  LIST FLAGS
+###############################
+
+class BaseListParser(ArgumentParser):
+  """
+  A base class for a string list parser.
+  To extend, inherit from this class, and call
+
+  BaseListParser.__init__(self, token, name)
+
+  where token is a character used to tokenize, and
+  name is a description of the separator
+  """
+
+  def __init__(self, token=None, name=None):
+    assert name
+    self._token = token
+    self._name = name
+    self.syntactic_help = "a %s separated list" % self._name
+
+  def Parse(self, argument):
+    if argument == '':
+      return []
+    else:
+      return [s.strip() for s in argument.split(self._token)]
+
+
+class ListParser(BaseListParser):
+  """
+  A string list parser (comma-separated)
+  """
+
+  def __init__(self):
+    BaseListParser.__init__(self, ',', 'comma')
+
+class WhitespaceSeparatedListParser(BaseListParser):
+  """
+  A string list parser (whitespace-separated)
+  """
+
+  def __init__(self):
+    BaseListParser.__init__(self, None, 'whitespace')
+
+
+def DEFINE_list(name, default, help, flag_values=FLAGS, **args):
+  """
+  This registers a flag whose value is a list of strings, separated by commas
+  """
+  parser = ListParser()
+  serializer = ListSerializer(',')
+  DEFINE(parser, name, default, help, flag_values, serializer, **args)
+
+def DEFINE_spaceseplist(name, default, help, flag_values=FLAGS, **args):
+  """
+  This registers a flag whose value is a list of strings, separated by any
+  whitespace
+  """
+  parser = WhitespaceSeparatedListParser()
+  serializer = ListSerializer(' ')
+  DEFINE(parser, name, default, help, flag_values, serializer, **args)
+
+
+###############################
+##################  MULTI FLAGS
+###############################
+
+class MultiFlag(Flag):
+  """
+  MultiFlag is a specialized subclass of Flag that accumulates
+  multiple values in a list when a command-line option appears
+  multiple times.
+
+  See the __doc__ for Flag for most behavior of this class.  Only
+  differences in behavior are described here:
+   * the default value may be a single value -OR- a list of values
+   * the value of the flag is always a list, even if the option was only
+     supplied once, and even if the default value is a single value
+  """
+  def __init__(self, *args, **kwargs):
+    Flag.__init__(self, *args, **kwargs)
+
+    self.help = (self.help +
+                 ';\n    repeat this option to specify a list of values')
+
+  def Parse(self, arguments):
+    """Parse one or more arguments with the installed parser.
+
+    Arguments:
+      arguments:  a single argument or a list of arguments (typically a list
+        of default values); single arguments will be converted internally into
+        a list containing one item
+    """
+    if not isinstance(arguments, list):
+      # Default value may be a list of values.  Most other arguments will not
+      # be, so convert them into a single-item list to make processing simpler
+      # below.
+      arguments = [ arguments ]
+
+    if self.present:
+      # keep a backup reference to list of previously supplied option values
+      values = self.value
+    else:
+      # "erase" the defaults with an empty list
+      values = []
+
+    for item in arguments:
+      # have Flag superclass parse argument, overwriting self.value reference
+      Flag.Parse(self, item)  # also increments self.present
+      values.append(self.value)
+
+    # put list of option values back in member variable
+    self.value = values
+
+  def Serialize(self):
+    if not self.serializer:
+      raise FlagsError, "Serializer not present for flag %s" % self.name
+    if self.value is None:
+      return ''
+
+    s = ''
+
+    multi_value = self.value
+
+    for self.value in multi_value:
+      if s: s += ' '
+      s += Flag.Serialize(self)
+
+    self.value = multi_value
+
+    return s
+
+
+def DEFINE_multi(parser, serializer, name, default, help, flag_values=FLAGS,
+                 **args):
+  """
+  This creates a generic 'MultiFlag' object that parses its arguments with a
+  'Parser' and registers it with a 'FlagValues' object.
+
+  Developers who need to create their own 'Parser' classes for options which
+  can appear multiple times can call this module function to register their
+  flags.
+  """
+  DEFINE_flag(MultiFlag(parser, serializer, name, default, help, **args), flag_values)
+
+def DEFINE_multistring(name, default, help, flag_values=FLAGS, **args):
+  """
+  This registers a flag whose value can be a list of any strings.  Use the flag
+  on the command line multiple times to place multiple string values into the
+  list.  The 'default' may be a single string (which will be converted into a
+  single-element list) or a list of strings.
+  """
+  parser = ArgumentParser()
+  serializer = ArgumentSerializer()
+  DEFINE_multi(parser, serializer, name, default, help, flag_values, **args)
+
+def DEFINE_multi_int(name, default, help, lower_bound=None, upper_bound=None,
+                     flag_values=FLAGS, **args):
+  """
+  This registers a flag whose value can be a list of any integers.  Use the
+  flag on the command line multiple times to place multiple integer values
+  into the list.  The 'default' may be a single integer (which will be
+  converted into a single-element list) or a list of integers.
+  """
+  parser = IntegerParser(lower_bound, upper_bound)
+  serializer = ArgumentSerializer()
+  DEFINE_multi(parser, serializer, name, default, help, flag_values, **args)
+
+
+# Now register the flags that we want to exist in all applications.
+# These are all defined with allow_override=1, so user-apps can use
+# these flagnames for their own purposes, if they want.
+DEFINE_flag(HelpFlag())
+DEFINE_flag(HelpshortFlag())
+
+# Define special flags here so that help may be generated for them.
+_SPECIAL_FLAGS = FlagValues()
+
+DEFINE_string(
+    'flagfile', "",
+    "Insert flag definitions from the given file into the command line.",
+    _SPECIAL_FLAGS)
+
+DEFINE_string(
+    'undefok', "",
+    "comma-separated list of flag names that it is okay to specify "
+    "on the command line even if the program does not define a flag "
+    "with that name.  IMPORTANT: flags in this list that have "
+    "arguments MUST use the --flag=value format.", _SPECIAL_FLAGS)