def test_or():
exp = Group(Literal('+'),
Literal('-'),
OR=True,
repetition=Quantification(min=0, max=1))
assert format(exp) == r'(\+|\-)?'
exp |= Decimal() | Group(Decimal(), Literal('.'), Decimal())
assert format(exp) == r'((\+|\-)?|(\d|(\d\.\d)))'
assert str(
exp
) == "((+<OR>-)<0,1GREATEST><OR>(<D><OR>(<D>.<D>)<1,1GREATEST>)<1,1GREATEST>)<1,1GREATEST>"
def test_and():
exp = StringStart() & 'Title'
assert format(exp) == r'\ATitle'
exp &= Group(Whitespace(), repetition=Quantification(
min=0, max=0)) & ':' & Word()
assert format(exp) == r'(\ATitle(((\s)*:)\w))'
exp &= '\n'
assert format(exp) == '((\ATitle(((\s)*:)\w))\\\n)'
exp &= Group(Whitespace(), repetition=Quantification(
min=1, max=0)) & 'H' & 'e' & 'a' & 'd' & 'e' & 'r'
assert format(
exp) == '(((\ATitle(((\s)*:)\w))\\\n)(((((((\s)+H)e)a)d)e)r))'
exp &= StringEnd()
assert format(
exp) == '((((\ATitle(((\s)*:)\w))\\\n)(((((((\s)+H)e)a)d)e)r))\Z)'
assert str(
exp
) == '((((<SOS>Title(((<SPACE>)<0,GREATEST>:)<1,1GREATEST><WORD>)<1,1GREATEST>)<1,1GREATEST>\n)<1,1GREATEST>(((((((<SPACE>)<1,GREATEST>H)<1,1GREATEST>e)<1,1GREATEST>a)<1,1GREATEST>d)<1,1GREATEST>e)<1,1GREATEST>r)<1,1GREATEST>)<1,1GREATEST><EOS>)<1,1GREATEST>'
def test_building():
colors = Group(Sequence('blue'), Sequence('green'), Sequence('orange'),
Sequence('red'), Sequence('violet'), Sequence('yellow'),
OR=True, repetition=Quantification(min=0, max=1))
assert str(colors) == '(blue<OR>green<OR>orange<OR>red<OR>violet<OR>yellow)<0,1GREATEST>'
sizes = Group(Sequence('huge'), Sequence('large'), Sequence('medium'),
Sequence('small'), Sequence('tiny'), OR=True,
repetition=Quantification(min=0, max=1))
assert str(sizes) == '(huge<OR>large<OR>medium<OR>small<OR>tiny)<0,1GREATEST>'
positions = Group(Sequence('first'), Sequence('last'), Sequence('second'), Sequence('third'), OR=True)
assert str(positions) == '(first<OR>last<OR>second<OR>third)<1,1GREATEST>'
noun = Group(UpperAscii(), Group(LowerAscii(), repetition=Quantification(min=0, max=0)))
assert str(noun) == r'({A,Z}({a,z})<0,GREATEST>)<1,1GREATEST>'
spacing = Group(Whitespace(), repetition=Quantification(min=1, max=0))
assert str(spacing) == r'(<SPACE>)<1,GREATEST>'
entry = Group(positions, spacing, sizes, spacing, colors, spacing, noun)
listing = Group(Group(entry, LineEnd(), repetition=Quantification(min=3)), entry)
def test_range_or():
forward = Range('A') | 'B'
backward = 'A' | Range('B')
assert forward == backward
assert forward == Range('A', 'B')
forward = Range('A') | 'BC'
backward = 'A' | Range('B', 'C')
assert forward != backward
assert forward == Group(Range('A'), Sequence('BC'), OR=True)
assert backward == Range('A', 'B', 'C')
forward = Range('A', 'B') | 'C'
backward = 'AB' | Range('C')
assert forward != backward
assert forward == Range('A', 'B', 'C')
assert backward == Group(Sequence('AB'), Range('C'), OR=True)
forward = Range('A', 'B') | 'CD'
backward = 'AB' | Range('C', 'D')
assert forward != backward
assert forward == Group(Range('A', 'B'), Sequence('CD'), OR=True)
assert backward == Group(Sequence('AB'), Range('C', 'D'), OR=True)
forward = Range('A') | 'BCDE'
backward = 'A' | Range(('B', 'E'))
assert forward != backward
assert forward == Group(Range('A'), Sequence('BCDE'), OR=True)
assert backward == Range('A', ('B', 'E'))
forward = Range(('A', 'D')) | 'E'
backward = 'ABCD' | Range('E')
assert forward != backward
assert forward == Range(('A', 'E'))
assert backward == Group(Sequence('ABCD'), Range('E'), OR=True)
forward = Range(('A', 'C')) | 'DE'
backward = 'AB' | Range(('C', 'E'))
assert forward != backward
assert forward != backward
assert forward == Group(Range(('A', 'C')), Sequence('DE'), OR=True)
assert backward == Group(Sequence('AB'), Range(('C', 'E')), OR=True)
def __init__(self):
self.metachar = '\\p'
self.short_desc = 'TEST'
@pytest.mark.parametrize("illegal", [
Literal('A'),
DummyPosition(),
])
def test_format_abstract_runtime_error(illegal):
with pytest.raises(RuntimeError):
_format_abstract(illegal)
@pytest.mark.parametrize("illegal", [
Quantification(),
Range(('A', 'z')),
Group(Literal('0'), Literal('1')),
])
def test_format_abstract_type_error(illegal):
with pytest.raises(TypeError):
_format_abstract(illegal)
@pytest.mark.parametrize("range,expected", [
(Range('A', invert=False), '[A]'),
(Range('A', 'B', 'z', invert=False), '[ABz]'),
(Range('A', '%', '-', invert=False), r'[%\-A]'),
(Range('z', 'z', '%', '^', invert=False), r'[%\^z]'),
(Range('A', '\u03A9', 'z', '\u03B0', invert=False), '[Az\u03A9\u03B0]'),
(Range('A', invert=True), '[^A]'),
(Range('A', 'B', 'z', invert=True), '[^ABz]'),
(Range('A', '%', '-', invert=True), r'[^%\-A]'),
(Range('z', 'z', '%', '^', invert=True), r'[^%\^z]'),
def test_literal_and():
forward = Literal('R') & 'E'
backward = 'R' & Literal('E')
assert forward == backward
assert forward == Sequence('R', 'E')
forward = Literal('R') & 'ED'
backward = 'RE' & Literal('D')
assert forward == backward
assert forward == Sequence('R', 'E', 'D')
forward = Literal('R') & Literal('E')
assert forward == Sequence('R', 'E')
forward = Literal('R') & Sequence('E')
backward = Sequence('R') & Literal('E')
assert forward == backward
assert forward == Sequence('R', 'E')
forward = Literal('R') & Sequence('E', 'D')
backward = Sequence('R', 'E') & Literal('D')
assert forward == backward
assert forward == Sequence('R', 'E', 'D')
forward = Literal('R') & Range('E')
backward = Range('R') & Literal('E')
assert forward != backward
assert forward == Group(Literal('R'), Range('E'))
assert backward == Group(Range('R'), Literal('E'))
forward = Literal('R') & Range(('E', 'D'))
backward = Range(('R', 'E')) & Literal('D')
assert forward != backward
assert forward == Group(Literal('R'), Range(('E', 'D')))
assert backward == Group(Range(('R', 'E')), Literal('D'))
forward = Literal('R') & Group(*(Literal('E'), ))
backward = Group(*(Literal('R'), )) & Literal('E')
assert forward != backward
assert forward == Group(Literal('R'), Group(*(Literal('E'), )))
assert backward == Group(Group(*(Literal('R'), )), Literal('E'))
forward = Literal('R') & Group(*(Literal('E'), Literal('D')))
backward = Group(*(Literal('R'), Literal('E'))) & Literal('D')
assert forward != backward
assert forward == Group(Literal('R'), Group(*(Literal('E'), Literal('D'))))
assert backward == Group(Group(*(Literal('R'), Literal('E'))),
Literal('D'))
def test_range_and():
forward = Range('A') & 'B'
backward = 'A' & Range('B')
assert forward != backward
assert forward == Group(Range('A'), Literal('B'))
assert backward == Group(Literal('A'), Range('B'))
forward = Range('A') & 'BC'
backward = 'A' & Range('B', 'C')
assert forward != backward
assert forward == Group(Range('A'), Sequence('BC'))
assert backward == Group(Literal('A'), Range('B', 'C'))
forward = Range('A', 'B') & 'C'
backward = 'AB' & Range('C')
assert forward != backward
assert forward == Group(Range('A', 'B'), Literal('C'))
assert backward == Group(Sequence('AB'), Range('C'))
forward = Range('A', 'B') & 'CD'
backward = 'AB' & Range('C', 'D')
assert forward != backward
assert forward == Group(Range('A', 'B'), Sequence('CD'))
assert backward == Group(Sequence('AB'), Range('C', 'D'))
forward = Range('A') & 'BCDE'
backward = 'A' & Range(('B', 'E'))
assert forward != backward
assert forward == Group(Range('A'), Sequence('BCDE'))
assert backward == Group(Literal('A'), Range(('B', 'E')))
forward = Range(('A', 'D')) & 'E'
backward = 'ABCD' & Range('E')
assert forward != backward
assert forward == Group(Range(('A', 'D')), Literal('E'))
assert backward == Group(Sequence('ABCD'), Range('E'))
forward = Range(('A', 'C')) & 'DE'
backward = 'AB' & Range(('C', 'E'))
assert forward != backward
assert forward == Group(Range(('A', 'C')), Sequence('DE'))
assert backward == Group(Sequence('AB'), Range(('C', 'E')))
def test_sequence_or():
forward = Sequence('A') | 'B'
backward = 'A' | Sequence('B')
assert forward != backward
assert forward == Group(Sequence('A'), Literal('B'), OR=True)
assert backward == Group(Literal('A'), Sequence('B'), OR=True)
forward = Sequence('A') | 'BC'
backward = 'A' | Sequence('BC')
assert forward != backward
assert forward == Group(Sequence('A'), Sequence('BC'), OR=True)
assert backward == Group(Literal('A'), Sequence('BC'), OR=True)
forward = Sequence('AB') | 'C'
backward = 'AB' | Sequence('C')
assert forward != backward
assert forward == Group(Sequence('AB'), Literal('C'), OR=True)
assert backward == Group(Sequence('AB'), Sequence('C'), OR=True)
forward = Sequence('AB') | 'CD'
backward = 'AB' | Sequence('CD')
assert forward == backward
assert forward == Group(Sequence('A', 'B'), Sequence('C', 'D'), OR=True)
forward = Sequence('A') | Sequence('B')
assert forward == Group(Sequence('A'), Sequence('B'), OR=True)
forward = Sequence('AB') | Sequence('CD')
assert forward == Group(Sequence('AB'), Sequence('CD'), OR=True)
forward = Sequence('A') | Sequence('BC')
backward = Sequence('AB') | Sequence('C')
assert forward != backward
assert forward == Group(Sequence('A'), Sequence('BC'), OR=True)
assert backward == Group(Sequence('AB'), Sequence('C'), OR=True)
forward = Sequence('A', 'B', 'C') | Sequence('D', 'E')
backward = Sequence('A', 'B') | Sequence('C', 'D', 'E')
assert forward != backward
assert forward == Group(Sequence('ABC'), Sequence('DE'), OR=True)
assert backward == Group(Sequence('AB'), Sequence('CDE'), OR=True)
forward = Sequence('A') | Range('B')
backward = Range('A') | Sequence('B')
assert forward != backward
assert forward == Group(Sequence('A'), Range('B'), OR=True)
assert backward == Group(Range('A'), Sequence('B'), OR=True)
forward = Sequence('A') | Range('B', 'C', 'D')
backward = Range('A') | Sequence('B', 'C', 'D')
assert forward != backward
assert forward == Group(Sequence('A'), Range('B', 'C', 'D'), OR=True)
assert backward == Group(Range('A'), Sequence('B', 'C', 'D'), OR=True)
forward = Sequence('A', 'B', 'C') | Range('D')
backward = Range('A', 'B', 'C') | Sequence('D')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'), Range('D'), OR=True)
assert backward == Group(Range('A', 'B', 'C'), Sequence('D'), OR=True)
forward = Sequence('A', 'B', 'C') | Range('D', 'E', 'F')
backward = Range('A', 'B', 'C') | Sequence('D', 'E', 'F')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'),
Range('D', 'E', 'F'),
OR=True)
assert backward == Group(Range('A', 'B', 'C'),
Sequence('D', 'E', 'F'),
OR=True)
forward = Sequence('A') | Group(Literal('B'))
backward = Group(Literal('A')) | Sequence('B')
assert forward != backward
assert forward == Group(Sequence('A'), Group(Literal('B')), OR=True)
assert backward == Group(Group(Literal('A')), Sequence('B'), OR=True)
forward = Sequence('A') | Group(Sequence('B', 'C', 'D'))
backward = Group(Literal('A')) | Sequence('B', 'C', 'D')
assert forward != backward
assert forward == Group(Sequence('A'),
Group(Sequence('B', 'C', 'D')),
OR=True)
assert backward == Group(Group(Literal('A')),
Sequence('B', 'C', 'D'),
OR=True)
forward = Sequence('A', 'B', 'C') | Group(Literal('D'))
backward = Group(Sequence('A', 'B', 'C')) | Sequence('D')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'),
Group(Literal('D')),
OR=True)
assert backward == Group(Group(Sequence('A', 'B', 'C')),
Sequence('D'),
OR=True)
forward = Sequence('A', 'B', 'C') | Group(Sequence('D', 'E', 'F'))
backward = Group(Sequence('A', 'B', 'C')) | Sequence('D', 'E', 'F')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'),
Group(Sequence('D', 'E', 'F')),
OR=True)
assert backward == Group(Group(Sequence('A', 'B', 'C')),
Sequence('D', 'E', 'F'),
OR=True)
def test_sequence_and():
forward = Sequence('A') & 'B'
backward = 'A' & Sequence('B')
assert forward == backward
assert forward == Sequence('AB')
forward = Sequence('A') & 'BC'
backward = 'A' & Sequence('BC')
assert forward == backward
assert forward == Sequence('ABC')
forward = Sequence('AB') & 'C'
backward = 'AB' & Sequence('C')
assert forward == backward
assert forward == Sequence('ABC')
forward = Sequence('AB') & 'CD'
backward = 'AB' & Sequence('CD')
assert forward == backward
assert forward == Sequence('A', 'B', 'C', 'D')
forward = Sequence('A') & Sequence('B')
assert forward == Sequence('A', 'B')
forward = Sequence('AB') & Sequence('CD')
assert forward == Sequence('AB', 'CD')
forward = Sequence('A') & Sequence('BC')
backward = Sequence('AB') & Sequence('C')
assert forward == backward
assert forward == Sequence('ABC')
forward = Sequence('A', 'B', 'C') & Sequence('D', 'E')
backward = Sequence('A', 'B') & Sequence('C', 'D', 'E')
assert forward == backward
assert forward == Sequence('A', 'B', 'C', 'D', 'E')
forward = Sequence('A') & Range('B')
backward = Range('A') & Sequence('B')
assert forward != backward
assert forward == Group(Sequence('A'), Range('B'))
assert backward == Group(Range('A'), Sequence('B'))
forward = Sequence('A') & Range('B', 'C', 'D')
backward = Range('A') & Sequence('B', 'C', 'D')
assert forward != backward
assert forward == Group(Sequence('A'), Range('B', 'C', 'D'))
assert backward == Group(Range('A'), Sequence('B', 'C', 'D'))
forward = Sequence('A', 'B', 'C') & Range('D')
backward = Range('A', 'B', 'C') & Sequence('D')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'), Range('D'))
assert backward == Group(Range('A', 'B', 'C'), Sequence('D'))
forward = Sequence('A', 'B', 'C') & Range('D', 'E', 'F')
backward = Range('A', 'B', 'C') & Sequence('D', 'E', 'F')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'), Range('D', 'E', 'F'))
assert backward == Group(Range('A', 'B', 'C'), Sequence('D', 'E', 'F'))
forward = Sequence('A') & Group(Literal('B'))
backward = Group(Literal('A')) & Sequence('B')
assert forward != backward
assert forward == Group(Sequence('A'), Group(Literal('B')))
assert backward == Group(Group(Literal('A')), Sequence('B'))
forward = Sequence('A') & Group(Sequence('B', 'C', 'D'))
backward = Group(Literal('A')) & Sequence('B', 'C', 'D')
assert forward != backward
assert forward == Group(Sequence('A'), Group(Sequence('B', 'C', 'D')))
assert backward == Group(Group(Literal('A')), Sequence('B', 'C', 'D'))
forward = Sequence('A', 'B', 'C') & Group(Literal('D'))
backward = Group(Sequence('A', 'B', 'C')) & Sequence('D')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'), Group(Literal('D')))
assert backward == Group(Group(Sequence('A', 'B', 'C')), Sequence('D'))
forward = Sequence('A', 'B', 'C') & Group(Sequence('D', 'E', 'F'))
backward = Group(Sequence('A', 'B', 'C')) & Sequence('D', 'E', 'F')
assert forward != backward
assert forward == Group(Sequence('A', 'B', 'C'),
Group(Sequence('D', 'E', 'F')))
assert backward == Group(Group(Sequence('A', 'B', 'C')),
Sequence('D', 'E', 'F'))
def test_abstract_or():
forward = DummyPosition() | 'E'
backward = 'E' | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Literal('E'), OR=True)
assert backward == Group(Literal('E'), DummyPosition(), OR=True)
forward = DummyPosition() | 'ED'
backward = 'ED' | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Sequence('E', 'D'), OR=True)
assert backward == Group(Sequence('E', 'D'), DummyPosition(), OR=True)
forward = DummyPosition() | DummyPosition()
assert forward == Group(DummyPosition(), DummyPosition(), OR=True)
forward = DummyPosition() | Literal('E')
backward = Literal('E') | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Literal('E'), OR=True)
assert backward == Group(Literal('E'), DummyPosition(), OR=True)
forward = DummyPosition() | Sequence('E')
backward = Sequence('E') | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Sequence('E'), OR=True)
assert backward == Group(Sequence('E'), DummyPosition(), OR=True)
forward = DummyPosition() | Sequence('E', 'D')
backward = Sequence('E', 'D') | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Sequence('E', 'D'), OR=True)
assert backward == Group(Sequence('E', 'D'), DummyPosition(), OR=True)
forward = DummyPosition() | Range('E')
backward = Range('E') | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Range('E'), OR=True)
assert backward == Group(Range('E'), DummyPosition(), OR=True)
forward = DummyPosition() | Range('E', 'D')
backward = Range('E', 'D') | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Range('E', 'D'), OR=True)
assert backward == Group(Range('E', 'D'), DummyPosition(), OR=True)
forward = DummyPosition() | Group(*(DummyPosition(), ))
backward = Group(*(DummyPosition(), )) | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(),
Group(*(DummyPosition(), )),
OR=True)
assert backward == Group(Group(*(DummyPosition(), )),
DummyPosition(),
OR=True)
forward = DummyPosition() | Group(*(DummyPosition(), DummyPosition()))
backward = Group(*(DummyPosition(), DummyPosition())) | DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(),
Group(*(DummyPosition(), DummyPosition())),
OR=True)
assert backward == Group(Group(*(DummyPosition(), DummyPosition())),
DummyPosition(),
OR=True)
def test_abstract_and():
forward = DummyPosition() & 'E'
backward = 'E' & DummyPosition()
assert forward != backward
assert forward == Sequence(DummyPosition(), 'E')
assert backward == Sequence('E', DummyPosition())
forward = DummyPosition() & 'ED'
backward = 'ED' & DummyPosition()
assert forward != backward
assert forward == Sequence(DummyPosition(), 'E', 'D')
assert backward == Sequence('E', 'D', DummyPosition())
forward = DummyPosition() & DummyPosition()
assert forward == Sequence(DummyPosition(), DummyPosition())
forward = DummyPosition() & Literal('E')
backward = Literal('E') & DummyPosition()
assert forward != backward
assert forward == Sequence(DummyPosition(), Literal('E'))
assert backward == Sequence(Literal('E'), DummyPosition())
forward = DummyPosition() & Sequence('E')
backward = Sequence('E') & DummyPosition()
assert forward != backward
assert forward == Sequence(DummyPosition(), 'E')
assert backward == Sequence('E', DummyPosition())
forward = DummyPosition() & Sequence('E', 'D')
backward = Sequence('E', 'D') & DummyPosition()
assert forward != backward
assert forward == Sequence(DummyPosition(), 'E', 'D')
assert backward == Sequence('E', 'D', DummyPosition())
forward = DummyPosition() & Range('E')
backward = Range('E') & DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Range('E'))
assert backward == Group(Range('E'), DummyPosition())
forward = DummyPosition() & Range(('E', 'D'))
backward = Range(('E', 'D')) & DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Range(('E', 'D')))
assert backward == Group(Range(('E', 'D')), DummyPosition())
forward = DummyPosition() & Group(*(DummyPosition(), ))
backward = Group(*(DummyPosition(), )) & DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(), Group(*(DummyPosition(), )))
assert backward == Group(Group(*(DummyPosition(), )), DummyPosition())
forward = DummyPosition() & Group(*(DummyPosition(), DummyPosition()))
backward = Group(*(DummyPosition(), DummyPosition())) & DummyPosition()
assert forward != backward
assert forward == Group(DummyPosition(),
Group(*(DummyPosition(), DummyPosition())))
assert backward == Group(Group(*(DummyPosition(), DummyPosition())),
DummyPosition())
def test_literal_or():
forward = Literal('R') | 'E'
backward = 'R' | Literal('E')
assert forward == backward
assert forward == Range('R', 'E')
forward = Literal('R') | 'ED'
backward = 'RE' | Literal('D')
assert forward != backward
assert forward == Group(Literal('R'), Sequence('E', 'D'), OR=True)
assert backward == Group(Sequence('R', 'E'), Literal('D'), OR=True)
forward = Literal('R') | Literal('E')
assert forward == Range('R', 'E')
forward = Literal('R') | Sequence('E')
backward = Sequence('R') | Literal('E')
assert forward != backward
assert forward == Group(Literal('R'), Sequence('E'), OR=True)
assert backward == Group(Sequence('R'), Literal('E'), OR=True)
forward = Literal('R') | Sequence('E', 'D')
backward = Sequence('R', 'E') | Literal('D')
assert forward != backward
assert forward == Group(Literal('R'), Sequence('E', 'D'), OR=True)
assert backward == Group(Sequence('R', 'E'), Literal('D'), OR=True)
forward = Literal('R') | Range('E')
backward = Range('R') | Literal('E')
assert forward == backward
assert forward == Range('R', 'E')
assert backward == Range('R', 'E')
forward = Literal('R') | Range('E', 'D')
backward = Range('R', 'E') | Literal('D')
assert forward == backward
assert forward == Range('R', 'E', 'D')
assert backward == Range('R', 'E', 'D')
forward = Literal('R') | Group(*(Literal('E'), ))
backward = Group(*(Literal('R'), )) | Literal('E')
assert forward != backward
assert forward == Group(Literal('R'), Group(*(Literal('E'), )), OR=True)
assert backward == Group(Group(*(Literal('R'), )), Literal('E'), OR=True)
forward = Literal('R') | Group(*(Literal('E'), Literal('D')))
backward = Group(*(Literal('R'), Literal('E'))) | Literal('D')
assert forward != backward
assert forward == Group(Literal('R'),
Group(*(Literal('E'), Literal('D'))),
OR=True)
assert backward == Group(Group(*(Literal('R'), Literal('E'))),
Literal('D'),
OR=True)