src/mjacob/nltk/parse/tag/strategies.py

   1 # This Python file uses the following encoding: utf-8
   2 '''
   3 Created on May 30, 2011
   4
   5 @author: mjacob
   6 '''
   7 from abc import abstractmethod, ABCMeta
   8
   9 class Strategy(tuple, metaclass=ABCMeta):
  10     """represents a ChartParser strategy"""
  11
  12     def __new__(cls, edge_class, *rules):
  13         return tuple.__new__(cls, rules)
  14
  15     def __init__(self, edge_class, *rules):
  16         super(Strategy, self).__init__(rules)
  17         self.__edge_class = edge_class
  18
  19     def edge_class(self):
  20         return self.__edge_class
  21
  22     @abstractmethod
  23     def goal_edges(self, chart, symbol): pass
  24
  25     def goal_found(self, chart, symbol):
  26         try:
  27             next(self.goal_edges(chart, symbol))
  28             return True
  29         except StopIteration:
  30             return False