Source Code for Module lepl._test.bug_stalled_parser

 1   
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12  # The Original Code is LEPL (http://www.acooke.org/lepl) 
13  # The Initial Developer of the Original Code is Andrew Cooke. 
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15  # Andrew Cooke (andrew@acooke.org). All Rights Reserved. 
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29   
30  ''' 
31  Tests for a regexp bug. 
32  ''' 
33   
34  # pylint: disable-msg=W0614, W0401, C0111, R0201 
35  #@PydevCodeAnalysisIgnore 
36   
37   
38  #from logging import basicConfig, DEBUG 
39  from unittest import TestCase 
40   
41  from lepl import * 
42   
43   
44 -class LeftRecursiveTest(TestCase): 
45       
46  #    def test_limited_lookahead(self): 
47  #        ''' 
48  #        This stalls because Lookahead consumes nothing.  Can we detect this  
49  #        case? 
50  #        ''' 
51  #        #basicConfig(level=DEBUG) 
52  #         
53  #        item     = Delayed() 
54  #        item    += item[1:3] | ~Lookahead('x') 
55  #     
56  #        expr     = item[:2] & Drop(Eos()) 
57  #        expr.config.left_memoize() 
58  #        parser = expr.get_parse_string() 
59  #        print(parser.matcher.tree()) 
60  # 
61  #        parser('abc') 
62   
63  #    def test_plain_lookahead(self): 
64  #        ''' 
65  #        This stalls because Lookahead consumes nothing.  Can we detect this  
66  #        case? 
67  #        ''' 
68  #        #basicConfig(level=DEBUG) 
69  #         
70  #        item     = Delayed() 
71  #        item    += item[1:] | ~Lookahead('\\') 
72  #     
73  #        expr     = item & Drop(Eos()) 
74  #        expr.config.left_memoize() 
75  #        parser = expr.get_parse_string() 
76  #        print(parser.matcher.tree()) 
77  # 
78  #        parser('abc') 
79   
80 -    def test_problem_from_regexp(self): 
81   
82          item     = Delayed() 
83          item    += item[1:]  
84          expr     = item & Drop(Eos()) 
85   
86          expr.config.no_full_first_match() 
87          parser = expr.get_parse_string() 
88          try: 
89              parser('abc') 
90              assert False, 'expcted left recursion error' 
91          except MemoException: 
92              pass 
93          expr.config.left_memoize() 
94          parser = expr.get_parse_string() 
95          parser('abc') 
96