def test_rule_from_function(self):
""" Check the operation of custom rules. """
def parse_hello(string):
""" A rule that grabs the literal 'hello'. """
w = STANDARD[0]
if string.startswith(w):
return w, string[len(w):]
return None, string
p = ParserBase()
p.from_function(parse_hello, main=True)
self.check(p, *STANDARD)
def test_ignore(self):
""" Test the 'ignore' whitespace handling technique. """
# set up parser with new grammar and the digit_run function
p = ParserBase(ws_handler=ignore)
p.from_function(digit_run, ws_handling=True)
p.grammar(GRAMMAR, main='programme')
# trial various combinations of whitespace
# single spacing
p.parse('if 34 > 33 then 44 + 3')
# no spacing
p.parse('if34>33then44+3')
# random spacing, including a tab
p.parse('if34 > 33 then 44+\t3')
def test_require_with_ignore(self):
""" Test the 'require' whitespace handling technique, using
the 'ignore' option. """
# set up parser with new grammar and the digit_run function
p = ParserBase(ws_handler=require(' ', ignore=True))
p.from_function(digit_run, ws_handling=True)
p.grammar(GRAMMAR, main='programme')
# trial various combinations of whitespace
# single spacing - should work
p.parse('if 34 > 33 then 44 + 3')
# double spacing - should now work
p.parse('if 34 > 33 then 44 + 3')
# no spacing - should fail
with self.assertRaises(DelimiterError):
p.parse('if34>33then44+3')
def test_ignore_specific(self):
""" Test the 'ignore_specific' whitespace handling
technique.
"""
# set up parser with new grammar and the digit_run function
p = ParserBase(ws_handler=ignore_specific(' '))
p.from_function(digit_run, ws_handling=True)
p.grammar(GRAMMAR, main='programme')
# trial various combinations of whitespace
# single spacing
p.parse('if 34 > 33 then 44 + 3')
# no spacing
p.parse('if34>33then44+3')
# random spacing, including a tab - should fail
with self.assertRaises(NotFoundError, msg='should ignore tab'):
p.parse('if34 > 33 then 44+\t3')