Source Code for Module nltk.parse.util

 1  # Natural Language Toolkit: Parser Utility Functions 
 2  # 
 3  # Author: Ewan Klein <[email protected]> 
 4  #          
 5  # URL: <http://nltk.org> 
 6  # For license information, see LICENSE.TXT 
 7   
 8   
 9  """ 
10  Utility functions for parsers. 
11  """ 
12   
13  ###################################################################### 
14  #{ Test Suites 
15  ###################################################################### 
16   
17   
18  from featurechart import load_earley 
19   
20 -class TestGrammar(object): 
21      """ 
22      Unit tests for  CFG. 
23      """ 
24 -    def __init__(self, grammar, suite, accept=None, reject=None): 
25          self.test_grammar = grammar 
26           
27          self.cp = load_earley(grammar, trace=0) 
28          self.suite = suite 
29          self._accept = accept 
30          self._reject = reject 
31           
32       
33 -    def run(self, show_trees=False): 
34          """ 
35          Sentences in the test suite are divided into two classes: 
36           - grammatical (C{accept}) and 
37           - ungrammatical (C{reject}).  
38          If a sentence should parse accordng to the grammar, the value of 
39          C{trees} will be a non-empty list. If a sentence should be rejected 
40          according to the grammar, then the value of C{trees} will be C{None}. 
41          """ 
42          for test in self.suite: 
43              print test['doc'] + ":", 
44              for key in ['accept', 'reject']: 
45                  for sent in test[key]: 
46                      tokens = sent.split() 
47                      trees = self.cp.parse(tokens) 
48                      if show_trees and trees: 
49                          print 
50                          print sent 
51                          for tree in trees: 
52                              print tree 
53                      if key=='accept': 
54                          if trees == []: 
55                              raise ValueError, "Sentence '%s' failed to parse'" % sent 
56                          else: 
57                              accepted = True 
58                      else: 
59                          if trees: 
60                              raise ValueError, "Sentence '%s' received a parse'" % sent 
61                          else: 
62                              rejected = True 
63              if accepted and rejected: 
64                  print "All tests passed!" 
65