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

   1 # This Python file uses the following encoding: utf-8
   2 '''
   3 Created on Jun 16, 2011
   4
   5 @author: mjacob
   6 '''
   7 from abc import abstractmethod, ABCMeta
   8
   9 class TreeBuilderI(object, metaclass=ABCMeta):
  10     def __init__(self, chart, type, *edges):
  11         self.__chart = chart
  12         self.__type = type
  13         self.__edges = edges
  14
  15     def build(self, working_on):
  16         return self._build(working_on, self.__chart, *self.__edges)
  17
  18     @abstractmethod
  19     def _build(self, chart, *edges): pass
  20
  21     def __eq__(self, othr):
  22         return self.__type == othr.__type and self.__edges == othr.__edges
  23
  24     def __hash__(self):
  25         return hash((self.__type, self.__edges))
  26
  27     def __str__(self):
  28         return "%s Tree Builder: %s" % (self.__type, self.__edges)
  29
  30     def __repr__(self):
  31         return "%r Tree Builder: %r" % (self.__type, self.__edges)
  32
  33 class InitialTreeBuilder(TreeBuilderI):
  34     def _build(self, working_on, chart, new_edge):
  35         return frozenset((new_edge.production().as_tree(),))
  36
  37 class PassthroughTreeBuilder(TreeBuilderI):
  38     def _build(self, working_on, chart, edge):
  39         if edge in working_on:
  40             return frozenset()
  41
  42         return chart.get_trees(edge, working_on)