text: # #########################     LICENSE     ############################ #
  
  # Copyright (c) 2005-2018, Michele Simionato
  # 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 bytecode 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.
  
  # 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
  # HOLDERS 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.
  
  """
  Decorator module, see http://pypi.python.org/pypi/decorator
  for the documentation.
  """
  from __future__ import print_function
  
  import re
  import sys
  import inspect
  import operator
  import itertools
  import collections
  
  __version__ = '4.3.2'
  
  if sys.version >= '3':
      from inspect import getfullargspec
  
      def get_init(cls):
          return cls.__init__
  else:
      FullArgSpec = collections.namedtuple(
          'FullArgSpec', 'args varargs varkw defaults '
          'kwonlyargs kwonlydefaults annotations')
  
      def getfullargspec(f):
          "A quick and dirty replacement for getfullargspec for Python 2.X"
          return FullArgSpec._make(inspect.getargspec(f) + ([], None, {}))
  
      def get_init(cls):
          return cls.__init__.__func__
  
  try:
      iscoroutinefunction = inspect.iscoroutinefunction
  except AttributeError:
      # let's assume there are no coroutine functions in old Python
      def iscoroutinefunction(f):
          return False
  try:
      from inspect import isgeneratorfunction
  except ImportError:
      # assume no generator function in old Python versions
      def isgeneratorfunction():
          return False
  
  
  DEF = re.compile(r'\s*def\s*([_\w][_\w\d]*)\s*\(')
  
  
  # basic functionality
  class FunctionMaker(object):
      """
      An object with the ability to create functions with a given signature.
      It has attributes name, doc, module, signature, defaults, dict and
      methods update and make.
      """
  
      # Atomic get-and-increment provided by the GIL
      _compile_count = itertools.count()
  
      # make pylint happy
      args = varargs = varkw = defaults = kwonlyargs = kwonlydefaults = ()
  
      def __init__(self, func=None, name=None, signature=None,
                   defaults=None, doc=None, module=None, funcdict=None):
          self.shortsignature = signature
          if func:
              # func can be a class or a callable, but not an instance method
              self.name = func.__name__
              if self.name == '<lambda>':  # small hack for lambda functions
                  self.name = '_lambda_'
              self.doc = func.__doc__
              self.module = func.__module__
              if inspect.isfunction(func):
                  argspec = getfullargspec(func)
                  self.annotations = getattr(func, '__annotations__', {})
                  for a in ('args', 'varargs', 'varkw', 'defaults', 'kwonlyargs',
                            'kwonlydefaults'):
                      setattr(self, a, getattr(argspec, a))
                  for i, arg in enumerate(self.args):
                      setattr(self, 'arg%d' % i, arg)
                  allargs = list(self.args)
                  allshortargs = list(self.args)
                  if self.varargs:
                      allargs.append('*' + self.varargs)
                      allshortargs.append('*' + self.varargs)
                  elif self.kwonlyargs:
                      allargs.append('*')  # single star syntax
                  for a in self.kwonlyargs:
                      allargs.append('%s=None' % a)
                      allshortargs.append('%s=%s' % (a, a))
                  if self.varkw:
                      allargs.append('**' + self.varkw)
                      allshortargs.append('**' + self.varkw)
                  self.signature = ', '.join(allargs)
                  self.shortsignature = ', '.join(allshortargs)
                  self.dict = func.__dict__.copy()
          # func=None happens when decorating a caller
          if name:
              self.name = name
          if signature is not None:
              self.signature = signature
          if defaults:
              self.defaults = defaults
          if doc:
              self.doc = doc
          if module:
              self.module = module
          if funcdict:
              self.dict = funcdict
          # check existence required attributes
          assert hasattr(self, 'name')
          if not hasattr(self, 'signature'):
              raise TypeError('You are decorating a non function: %s' % func)
  
      def update(self, func, **kw):
          "Update the signature of func with the data in self"
          func.__name__ = self.name
          func.__doc__ = getattr(self, 'doc', None)
          func.__dict__ = getattr(self, 'dict', {})
          func.__defaults__ = self.defaults
          func.__kwdefaults__ = self.kwonlydefaults or None
          func.__annotations__ = getattr(self, 'annotations', None)
          try:
              frame = sys._getframe(3)
          except AttributeError:  # for IronPython and similar implementations
              callermodule = '?'
          else:
              callermodule = frame.f_globals.get('__name__', '?')
          func.__module__ = getattr(self, 'module', callermodule)
          func.__dict__.update(kw)
  
      def make(self, src_templ, evaldict=None, addsource=False, **attrs):
          "Make a new function from a given template and update the signature"
          src = src_templ % vars(self)  # expand name and signature
          evaldict = evaldict or {}
          mo = DEF.search(src)
          if mo is None:
              raise SyntaxError('not a valid function template\n%s' % src)
          name = mo.group(1)  # extract the function name
          names = set([name] + [arg.strip(' *') for arg in
                                self.shortsignature.split(',')])
          for n in names:
              if n in ('_func_', '_call_'):
                  raise NameError('%s is overridden in\n%s' % (n, src))
  
          if not src.endswith('\n'):  # add a newline for old Pythons
              src += '\n'
  
          # Ensure each generated function has a unique filename for profilers
          # (such as cProfile) that depend on the tuple of (<filename>,
          # <definition line>, <function name>) being unique.
          filename = '<%s:decorator-gen-%d>' % (
              __file__, next(self._compile_count))
          try:
              code = compile(src, filename, 'single')
              exec(code, evaldict)
          except Exception:
              print('Error in generated code:', file=sys.stderr)
              print(src, file=sys.stderr)
              raise
          func = evaldict[name]
          if addsource:
              attrs['__source__'] = src
          self.update(func, **attrs)
          return func
  
      @classmethod
      def create(cls, obj, body, evaldict, defaults=None,
                 doc=None, module=None, addsource=True, **attrs):
          """
          Create a function from the strings name, signature and body.
          evaldict is the evaluation dictionary. If addsource is true an
          attribute __source__ is added to the result. The attributes attrs
          are added, if any.
          """
          if isinstance(obj, str):  # "name(signature)"
              name, rest = obj.strip().split('(', 1)
              signature = rest[:-1]  # strip a right parens
              func = None
          else:  # a function
              name = None
              signature = None
              func = obj
          self = cls(func, name, signature, defaults, doc, module)
          ibody = '\n'.join('    ' + line for line in body.splitlines())
          caller = evaldict.get('_call_')  # when called from `decorate`
          if caller and iscoroutinefunction(caller):
              body = ('async def %(name)s(%(signature)s):\n' + ibody).replace(
                  'return', 'return await')
          else:
              body = 'def %(name)s(%(signature)s):\n' + ibody
          return self.make(body, evaldict, addsource, **attrs)
  
  
  def decorate(func, caller, extras=()):
      """
      decorate(func, caller) decorates a function using a caller.
      If the caller is a generator function, the resulting function
      will be a generator function.
      """
      evaldict = dict(_call_=caller, _func_=func)
      es = ''
      for i, extra in enumerate(extras):
          ex = '_e%d_' % i
          evaldict[ex] = extra
          es += ex + ', '
  
      if '3.5' <= sys.version < '3.6':
          # with Python 3.5 isgeneratorfunction returns True for all coroutines
          # however we know that it is NOT possible to have a generator
          # coroutine in python 3.5: PEP525 was not there yet
          generatorcaller = isgeneratorfunction(
              caller) and not iscoroutinefunction(caller)
      else:
          generatorcaller = isgeneratorfunction(caller)
      if generatorcaller:
          fun = FunctionMaker.create(
              func, "for res in _call_(_func_, %s%%(shortsignature)s):\n"
                    "    yield res" % es, evaldict, __wrapped__=func)
      else:
          fun = FunctionMaker.create(
              func, "return _call_(_func_, %s%%(shortsignature)s)" % es,
              evaldict, __wrapped__=func)
      if hasattr(func, '__qualname__'):
          fun.__qualname__ = func.__qualname__
      return fun
  
  
  def decorator(caller, _func=None):
      """decorator(caller) converts a caller function into a decorator"""
      if _func is not None:  # return a decorated function
          # this is obsolete behavior; you should use decorate instead
          return decorate(_func, caller)
      # else return a decorator function
      defaultargs, defaults = '', ()
      if inspect.isclass(caller):
          name = caller.__name__.lower()
          doc = 'decorator(%s) converts functions/generators into ' \
              'factories of %s objects' % (caller.__name__, caller.__name__)
      elif inspect.isfunction(caller):
          if caller.__name__ == '<lambda>':
              name = '_lambda_'
          else:
              name = caller.__name__
          doc = caller.__doc__
          nargs = caller.__code__.co_argcount
          ndefs = len(caller.__defaults__ or ())
          defaultargs = ', '.join(caller.__code__.co_varnames[nargs-ndefs:nargs])
          if defaultargs:
              defaultargs += ','
          defaults = caller.__defaults__
      else:  # assume caller is an object with a __call__ method
          name = caller.__class__.__name__.lower()
          doc = caller.__call__.__doc__
      evaldict = dict(_call=caller, _decorate_=decorate)
      dec = FunctionMaker.create(
          '%s(%s func)' % (name, defaultargs),
          'if func is None: return lambda func:  _decorate_(func, _call, (%s))\n'
          'return _decorate_(func, _call, (%s))' % (defaultargs, defaultargs),
          evaldict, doc=doc, module=caller.__module__, __wrapped__=caller)
      if defaults:
          dec.__defaults__ = defaults + (None,)
      return dec
  
  
  # ####################### contextmanager ####################### #
  
  try:  # Python >= 3.2
      from contextlib import _GeneratorContextManager
  except ImportError:  # Python >= 2.5
      from contextlib import GeneratorContextManager as _GeneratorContextManager
  
  
  class ContextManager(_GeneratorContextManager):
      def __call__(self, func):
          """Context manager decorator"""
          return FunctionMaker.create(
              func, "with _self_: return _func_(%(shortsignature)s)",
              dict(_self_=self, _func_=func), __wrapped__=func)
  
  
  init = getfullargspec(_GeneratorContextManager.__init__)
  n_args = len(init.args)
  if n_args == 2 and not init.varargs:  # (self, genobj) Python 2.7
      def __init__(self, g, *a, **k):
          return _GeneratorContextManager.__init__(self, g(*a, **k))
      ContextManager.__init__ = __init__
  elif n_args == 2 and init.varargs:  # (self, gen, *a, **k) Python 3.4
      pass
  elif n_args == 4:  # (self, gen, args, kwds) Python 3.5
      def __init__(self, g, *a, **k):
          return _GeneratorContextManager.__init__(self, g, a, k)
      ContextManager.__init__ = __init__
  
  _contextmanager = decorator(ContextManager)
  
  
  def contextmanager(func):
      # Enable Pylint config: contextmanager-decorators=decorator.contextmanager
      return _contextmanager(func)
  
  
  # ############################ dispatch_on ############################ #
  
  def append(a, vancestors):
      """
      Append ``a`` to the list of the virtual ancestors, unless it is already
      included.
      """
      add = True
      for j, va in enumerate(vancestors):
          if issubclass(va, a):
              add = False
              break
          if issubclass(a, va):
              vancestors[j] = a
              add = False
      if add:
          vancestors.append(a)
  
  
  # inspired from simplegeneric by P.J. Eby and functools.singledispatch
  def dispatch_on(*dispatch_args):
      """
      Factory of decorators turning a function into a generic function
      dispatching on the given arguments.
      """
      assert dispatch_args, 'No dispatch args passed'
      dispatch_str = '(%s,)' % ', '.join(dispatch_args)
  
      def check(arguments, wrong=operator.ne, msg=''):
          """Make sure one passes the expected number of arguments"""
          if wrong(len(arguments), len(dispatch_args)):
              raise TypeError('Expected %d arguments, got %d%s' %
                              (len(dispatch_args), len(arguments), msg))
  
      def gen_func_dec(func):
          """Decorator turning a function into a generic function"""
  
          # first check the dispatch arguments
          argset = set(getfullargspec(func).args)
          if not set(dispatch_args) <= argset:
              raise NameError('Unknown dispatch arguments %s' % dispatch_str)
  
          typemap = {}
  
          def vancestors(*types):
              """
              Get a list of sets of virtual ancestors for the given types
              """
              check(types)
              ras = [[] for _ in range(len(dispatch_args))]
              for types_ in typemap:
                  for t, type_, ra in zip(types, types_, ras):
                      if issubclass(t, type_) and type_ not in t.mro():
                          append(type_, ra)
              return [set(ra) for ra in ras]
  
          def ancestors(*types):
              """
              Get a list of virtual MROs, one for each type
              """
              check(types)
              lists = []
              for t, vas in zip(types, vancestors(*types)):
                  n_vas = len(vas)
                  if n_vas > 1:
                      raise RuntimeError(
                          'Ambiguous dispatch for %s: %s' % (t, vas))
                  elif n_vas == 1:
                      va, = vas
                      mro = type('t', (t, va), {}).mro()[1:]
                  else:
                      mro = t.mro()
                  lists.append(mro[:-1])  # discard t and object
              return lists
  
          def register(*types):
              """
              Decorator to register an implementation for the given types
              """
              check(types)
  
              def dec(f):
                  check(getfullargspec(f).args, operator.lt, ' in ' + f.__name__)
                  typemap[types] = f
                  return f
              return dec
  
          def dispatch_info(*types):
              """
              An utility to introspect the dispatch algorithm
              """
              check(types)
              lst = []
              for anc in itertools.product(*ancestors(*types)):
                  lst.append(tuple(a.__name__ for a in anc))
              return lst
  
          def _dispatch(dispatch_args, *args, **kw):
              types = tuple(type(arg) for arg in dispatch_args)
              try:  # fast path
                  f = typemap[types]
              except KeyError:
                  pass
              else:
                  return f(*args, **kw)
              combinations = itertools.product(*ancestors(*types))
              next(combinations)  # the first one has been already tried
              for types_ in combinations:
                  f = typemap.get(types_)
                  if f is not None:
                      return f(*args, **kw)
  
              # else call the default implementation
              return func(*args, **kw)
  
          return FunctionMaker.create(
              func, 'return _f_(%s, %%(shortsignature)s)' % dispatch_str,
              dict(_f_=_dispatch), register=register, default=func,
              typemap=typemap, vancestors=vancestors, ancestors=ancestors,
              dispatch_info=dispatch_info, __wrapped__=func)
  
      gen_func_dec.__name__ = 'dispatch_on' + dispatch_str
      return gen_func_dec
  