#!/usr/bin/env python
##  $Id: abstfilter.py,v 1.1.1.1 2003/07/01 23:28:27 euske Exp $
##
##  abstfilter.py - A framework for cascade filters.
##


##  AbstractFeeder
##
class AbstractFeeder:

  def __init__(self, next_filter):
    self.next_filter = next_filter
    return

  def feed_next(self, s):
    self.next_filter.feed(s)
    return

  def close(self):
    self.next_filter.close()
    return


##  AbstractFilter
##
class AbstractFilter:

  def __init__(self, next_filter):
    self.next_filter = next_filter
    return

  def process(self, s):
    raise NotImplementedError
  
  def feed(self, s):
    self.feed_next(self.process(s))
    return

  def feed_next(self, s):
    self.next_filter.feed(s)
    return

  def close(self):
    self.next_filter.close()
    return


##  AbstractConsumer
##
class AbstractConsumer:

  def __init__(self):
    return

  def feed(self, s):
    raise NotImplementedError
  
  def close(self):
    return