text: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  #
  # Copyright (c) 2014 Daniel Standage <daniel.standage@gmail.com>
  # Copyright (c) 2008 Sascha Steinbiss <steinbiss@zbh.uni-hamburg.de>
  # Copyright (c) 2008 Center for Bioinformatics, University of Hamburg
  #
  # Permission to use, copy, modify, and distribute this software for any
  # purpose with or without fee is hereby granted, provided that the above
  # copyright notice and this permission notice appear in all copies.
  #
  # THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  #
  
  from gt.dlload import gtlib
  from gt.core.error import Error, gterror
  from gt.extended.genome_node import GenomeNode
  from ctypes import byref, c_void_p
  
  
  class GenomeStream:
  
      def __init__(self, *args):
          raise NotImplementedError("Please call the constructor of a " +
                                    "GenomeStream implementation.")
  
      def __del__(self):
          try:
              gtlib.gt_node_stream_delete(self.gs)
          except AttributeError:
              pass
  
      def from_param(cls, obj):
          if not isinstance(obj, GenomeStream):
              raise TypeError("argument must be a GenomeStream")
          return obj._as_parameter_
  
      from_param = classmethod(from_param)
  
      def next_tree(self):
          err = Error()
          genome_node = c_void_p()
          rval = gtlib.gt_node_stream_next(self.gs, byref(genome_node),
                                           err._as_parameter_)
          if rval != 0:
              gterror(err)
          if genome_node.value == None:
              return None
          else:
              return GenomeNode.create_from_ptr(genome_node.value)
  
      def pull(self):
          err = Error()
          rval = gtlib.gt_node_stream_pull(self.gs, err._as_parameter_)
          if rval != 0:
              gterror(err)
  
      def register(cls, gtlib):
          from ctypes import c_int, c_void_p, POINTER
          gtlib.gt_node_stream_delete.argtypes = [c_void_p]
          gtlib.gt_node_stream_delete.restype = None
          gtlib.gt_node_stream_next.argtypes = [c_void_p, c_void_p, c_void_p]
          gtlib.gt_node_stream_next.restype = c_int
          gtlib.gt_node_stream_pull.argtypes = [c_void_p, c_void_p]
          gtlib.gt_node_stream_pull.restype = c_int
  
      register = classmethod(register)
  