
# The contents of this file are subject to the Mozilla Public License
# (MPL) Version 1.1 (the "License"); you may not use this file except
# in compliance with the License. You may obtain a copy of the License
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#
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# limitations under the License.
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# The Original Code is LEPL (http://www.acooke.org/lepl)
# The Initial Developer of the Original Code is Andrew Cooke.
# Portions created by the Initial Developer are Copyright (C) 2009-2010
# Andrew Cooke (andrew@acooke.org). All Rights Reserved.
#
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'''
Illustrate some of the finer points of lexing.
'''

#from logging import basicConfig, DEBUG

from lepl import Token, Integer, Eos, Literal
from lepl._example.support import Example


class Limitations(Example):
    '''
    These are used in the lexer part of the manual.
    '''

    def test_ambiguity(self):
        '''
        A (signed) integer will consume a - sign. 
        '''
        tokens = (Token(Integer()) | Token(r'\-'))[:] & Eos()
        self.examples([(lambda: list(tokens.parse_all('1-2')), 
                        "[['1', '-2']]")])
        matchers = (Integer() | Literal('-'))[:] & Eos()
        self.examples([(lambda: list(matchers.parse_all('1-2')), 
                        "[['1', '-2'], ['1', '-', '2']]")])
    
    def test_complete(self):
        '''
        The complete flag indicates whether the entire token must be consumed.
        '''
        #basicConfig(level=DEBUG)
        abc = Token('abc')
        incomplete = abc(Literal('ab'))
        incomplete.config.no_full_first_match()
        self.examples([(lambda: incomplete.parse('abc'), "None")])
        abc = Token('abc')
        incomplete = abc(Literal('ab'), complete=False)
        incomplete.config.no_full_first_match()
        self.examples([(lambda: incomplete.parse('abc'), "['ab']")])
