def test_seplist5(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(
eval(
begin(set_text('a,b,cd'), seplist(char(_), char(','), _, y),
char(_), eoi, getvalue(y))), ['a', 'b', 'c'])
def test_greedy_some5(self):
_ = DummyVar('_')
y = LogicVar('y')
assert_raises(
NoSolution, eval,
begin(set_text('aaa'), greedy_some(char(_), _, y), char(_), eoi,
y))
def test_right_recursive1(self):
function1 = function( ((), and_p(char('a'), f())),
((),char('b')))
eq_(eval(letr([(f,function1)],
parse_text(f(),'b'), parse_text(f(),'ab'), parse_text(f(),'aab'))),
'b')
assert_raises(NoSolution, eval, letr([(f,function1)], parse_text(f(), 'a')))
def test_some5(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(
eval(
begin(set_text('abc'), some(char(_), _, y), char(_), eoi,
getvalue(y))), ['a', 'b'])
def test_some(self):
X, Y = Var('X'), Var('Y')
eq_(eval(begin(parse_text(some(char(X), X, Y), '222'), Y)),
['2', '2', '2'])
eq_(eval(begin(parse_text(some(char(X), X, Y), '234'), Y)), ['2'])
assert_raises(NoSolution, eval,
begin(parse_text(some(char(X), X, Y), ''), Y))
def test_any5(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(
eval(
begin(set_text('aaa'), any(char(_), _, y), char(_), eoi,
getvalue(y))), ['a', 'a'])
def testoptionalcut(self):
x, s = Var('x'), Var('s')
ruleList = [(s, function(((x, ), and_p(-char('a'), cut, char(x)))))]
eq_(eval(let(ruleList, parse_text(s(x), 'aa'), x)), 'a')
eq_(eval(let(ruleList, parse_text(s(x), 'b'), x)), 'b')
assert_raises(NoSolution, eval, let(ruleList, parse_text(s(x), 'a'),
x))
def test_greedy_seplist5(self):
_ = DummyVar('_')
y = LogicVar('y')
assert_raises(
NoSolution, eval,
begin(set_text('a,a,a'), greedy_seplist(char(_), char(','), _, y),
char(_), eoi, getvalue(y)))
def test_right_recursive2(self):
x, p = Var('x'), Var('p')
function1 = [(p,function( ((), and_p(char(x), p())),
((),char(x))))]
eq_(eval(letr(function1, parse_text(p(),'a'), parse_text(p(),'ab'), parse_text(p(),'abc'))),
'c')
assert_raises(NoSolution, eval, letr(function1, parse_text(p(), '')))
def test_dummy_times_between(self):
_, Y = DummyVar('_'), Var('Y')
eq_(eval(begin(parse_text(times_between(char(_), 2, 3, _, Y), '234'), Y)), ['2','3', '4'])
eq_(eval(begin(parse_text(times_between(char(_), 2, 3, _, Y), '23'), Y)), ['2','3'])
eq_(eval(begin(parse_text(times_between(char(_), 2, 3, _, Y), '2345'), Y)), ['2','3', '4'])
assert_raises(NoSolution, eval, begin(parse_text(times_between(char(_), 2, 3, _, Y), '2'), Y))
assert_raises(NoSolution, eval, begin(parse_text((and_p, times_between(char(_), 2, 3, _, Y), eoi), '2345'), Y))
def test_dummy_any(self):
_, Y = DummyVar('_'), Var('Y')
eq_(eval(begin(parse_text(any(char(_), _, Y), '222'), Y)),
['2', '2', '2'])
eq_(eval(begin(parse_text(any(char(_), _, Y), '234'), Y)),
['2', '3', '4'])
eq_(eval(begin(parse_text(any(char(_), _, Y), ''), Y)), [])
def test_any_some(self):
X, Y = Var('X'), Var('Y')
eq_(
eval(
begin(
parse_text(
char(X) + any(~char('b') + some(char(X))) + eoi,
'abaaaa'), X)), 'a')
def test_right_recursive2(self):
x, p = Var('x'), Var('p')
function1 = [(p, function(((), and_p(char(x), p())), ((), char(x))))]
eq_(
eval(
letr(function1, parse_text(p(), 'a'), parse_text(p(), 'ab'),
parse_text(p(), 'abc'))), 'c')
assert_raises(NoSolution, eval, letr(function1, parse_text(p(), '')))
def test_right_recursive1(self):
function1 = function(((), and_p(char('a'), f())), ((), char('b')))
eq_(
eval(
letr([(f, function1)], parse_text(f(), 'b'),
parse_text(f(), 'ab'), parse_text(f(), 'aab'))), 'b')
assert_raises(NoSolution, eval,
letr([(f, function1)], parse_text(f(), 'a')))
def test_unify_right_recursive(self):
x, p = Var('x'), Var('p')
function1 = [(p,function( ((x,), and_p(char(x), p(x))),
((x,),char(x))))]
eq_(eval(letr(function1, parse_text(p(x), 'aa'))), 'a')
eq_(eval(letr(function1, parse_text(p(x), 'a'))), 'a')
assert_raises(NoSolution, eval, letr(function1, parse_text(and_p(p(x), eoi), 'xy')))
assert_raises(NoSolution, eval, letr(function1, parse_text(p(x), '')))
def test_greedy_seplist4(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(
eval(
begin(set_text('a,a,a'),
greedy_seplist(char(_), char(','), _, y), eoi,
getvalue(y))), ['a', 'a', 'a'])
def testABCD(self):
A, B, C, D = vars('A, B, C, D')
ruleList = [(A,function(((), B()|C()))),
(B,function(((), D()+char('b')))),
(C,function(((), D()+char('c')))),
(D,function(((), char('d')))),
]
eq_(eval(letr(ruleList, parse_text(A()+eoi, 'dc'))), True)
def test_dummy_times_more(self):
_, Y = DummyVar('_'), Var('Y')
eq_(eval(begin(parse_text((times_more, char(_), 3, _, Y), '234'), Y)),
['2', '3', '4'])
eq_(eval(begin(parse_text((times_more, char(_), 3, _, Y), '2345'), Y)),
['2', '3', '4', '5'])
assert_raises(NoSolution, eval,
begin(parse_text(times_more(char(_), 3, _, Y), '23'), Y))
def test_dumy_some(self):
_, Y = DummyVar('_'), Var('Y')
eq_(eval(begin(parse_text(some(char(_), _, Y), '222'), Y)),
['2', '2', '2'])
eq_(eval(begin(parse_text(some(char(_), _, Y), '234'), Y)),
['2', '3', '4'])
assert_raises(NoSolution, eval,
begin(parse_text(some(char(_), _, Y), ''), Y))
def testIndentUndent(self):
_, n, s, line = DummyVar('_'), Var('n'), Var('s'), Var('line')
space = char(' ')
ruleList = [(s,function( ((n,), some(line(n)),s(add(n,1))),
((n,), some(line(n))))),
(line,function( ((n,), times(space, n),some(letter(_)),any(space),char('\n'))))
]
eq_(eval(letr(ruleList, parse_text(s(0), 'a\n b\n c\n'))), True)
eq_(eval(letr(ruleList, parse_text(s(0), 'asd\n bdf\n cdfh\n'))), True)
def testparallelRule(self):
x, s, gt, lt = Var('x'), Var('s'), Var('>'), Var('<')
ruleList = [(s,function( ((x,), parallel(gt(x, 3), lt(x, 5))))),
(gt,function( ((4, 3),char('4')))),
(lt,function( ((4, 5),char('4'))))]
eq_(eval(letr(ruleList, parse_text(s(x), '4'), x)), 4)
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '6'), x))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(s(x), eoi), '41'), x))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), ''), x))
def test_dummy_times_less_lazy(self):
_, Y = DummyVar('_'), Var('Y')
eq_(
eval(
preparse(
begin(
parse_text(
times_less(char(_), 3, _, Y, lazy) + char('4'),
'234'), Y))), ['2', '3'])
def testABCD(self):
A, B, C, D = vars('A, B, C, D')
ruleList = [
(A, function(((), B() | C()))),
(B, function(((), D() + char('b')))),
(C, function(((), D() + char('c')))),
(D, function(((), char('d')))),
]
eq_(eval(letr(ruleList, parse_text(A() + eoi, 'dc'))), True)
def testOr(self):
x, s, one, two = Var('x'), Var('s'), Var('one'), Var('two')
ruleList = [(s, function( ((x,), or_p(one(x), two(x))))),
(one, function( (('1',),char('1')))),
(two, function( (('2',),char('2'))))]
eq_(eval(letr(ruleList, parse_text(s(x), '1'))), '1')
eq_(eval(letr(ruleList, parse_text(s(y), '2'))), '2')
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '3')))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(s(x), eoi), '12')))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '')))
def test_unify_right_recursive(self):
x, p = Var('x'), Var('p')
function1 = [(p,
function(((x, ), and_p(char(x), p(x))),
((x, ), char(x))))]
eq_(eval(letr(function1, parse_text(p(x), 'aa'))), 'a')
eq_(eval(letr(function1, parse_text(p(x), 'a'))), 'a')
assert_raises(NoSolution, eval,
letr(function1, parse_text(and_p(p(x), eoi), 'xy')))
assert_raises(NoSolution, eval, letr(function1, parse_text(p(x), '')))
def testIndirectLeftRecursive(self):
#assert 0, 'temporary mask'
A, B, C = vars('A, B, C')
ruleList = [(A, function(((), B()))),
(B, function(
((), A() + char('a')),
((), char('b')),
))]
eq_(eval(letr(ruleList, parse_text(A() + eoi, 'b'))), True)
eq_(eval(letr(ruleList, parse_text(A() + eoi, 'ba'))), True)
eq_(eval(letr(ruleList, parse_text(A() + eoi, 'baa'))), True)
def testOr(self):
x, s, one, two = Var('x'), Var('s'), Var('one'), Var('two')
ruleList = [(s, function(((x, ), or_p(one(x), two(x))))),
(one, function((('1', ), char('1')))),
(two, function((('2', ), char('2'))))]
eq_(eval(letr(ruleList, parse_text(s(x), '1'))), '1')
eq_(eval(letr(ruleList, parse_text(s(y), '2'))), '2')
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '3')))
assert_raises(NoSolution, eval,
letr(ruleList, parse_text(and_p(s(x), eoi), '12')))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '')))
def testIndirectLeftRecursive(self):
#assert 0, 'temporary mask'
A, B, C = vars('A, B, C')
ruleList = [(A, function(((), B()))),
(B, function(
((), A()+char('a')),
((), char('b')),
))]
eq_(eval(letr(ruleList, parse_text(A()+eoi, 'b'))), True)
eq_(eval(letr(ruleList, parse_text(A()+eoi, 'ba'))), True)
eq_(eval(letr(ruleList, parse_text(A()+eoi, 'baa'))), True)
def testIndentUndent(self):
_, n, s, line = DummyVar('_'), Var('n'), Var('s'), Var('line')
space = char(' ')
ruleList = [(s,
function(((n, ), some(line(n)), s(add(n, 1))),
((n, ), some(line(n))))),
(line,
function(((n, ), times(space, n), some(letter(_)),
any(space), char('\n'))))]
eq_(eval(letr(ruleList, parse_text(s(0), 'a\n b\n c\n'))), True)
eq_(eval(letr(ruleList, parse_text(s(0), 'asd\n bdf\n cdfh\n'))), True)
def xxxtest_left_recursive(self):
assert 0, 'a good idea is waiting to be implemented'
assert 0, 'googd idea failed!'
engine = Engine()
X = Var()
f = userTerm("f")
engine.add_rule(rule(f(X), f(X)+char('1')))
engine.add_rule(rule(f(X),char('2')))
X = Var()
engine.run(f(X), '21')
engine.run(f(X), '2')
assert_raises(UnifyFail, engine.run, f(X), '1')
def testparallelRule(self):
x, s, gt, lt = Var('x'), Var('s'), Var('>'), Var('<')
ruleList = [(s, function(((x, ), parallel(gt(x, 3), lt(x, 5))))),
(gt, function(((4, 3), char('4')))),
(lt, function(((4, 5), char('4'))))]
eq_(eval(letr(ruleList, parse_text(s(x), '4'), x)), 4)
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), '6'),
x))
assert_raises(NoSolution, eval,
letr(ruleList, parse_text(and_p(s(x), eoi), '41'), x))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(s(x), ''),
x))
def xxxtest_left_recursive(self):
assert 0, 'a good idea is waiting to be implemented'
assert 0, 'googd idea failed!'
engine = Engine()
X = Var()
f = userTerm("f")
engine.add_rule(rule(f(X), f(X) + char('1')))
engine.add_rule(rule(f(X), char('2')))
X = Var()
engine.run(f(X), '21')
engine.run(f(X), '2')
assert_raises(UnifyFail, engine.run, f(X), '1')
def testExpressionByRightRecursiveList(self):
E, e, e1, e2 = Var('E'), Var('e'), Var('e1'), Var('e2')
ruleList = [(E,function(
(((e1, '/', e2), 1), E(e1,2), char('/'), E(e2, 1)),
((1, 2), char('1')),
((e, 1), E(e, 2))))]
eq_(eval(letr(ruleList, parse_text(E(e, 1), '1/1/1'), e)), (1, '/', (1, '/', 1)))
eq_(eval(letr(ruleList, parse_text(E(e, 1), '1/1'), e)), (1, '/', 1))
eq_(eval(letr(ruleList, parse_text(E(e, 1), '1'), e)), 1)
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(E(e, 1), eoi), '1+1/1'), e))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(E(e, 1), eoi), '2'), e))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(E(e, 1), eoi), '1/'), e))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(E(e, 1), eoi), '/'), e))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(E(e, 1), eoi), ''), e))
def testRecursiveReturnValue3(self):
E, e, e1, e2 = Var('E'), Var('e'), Var('e1'), Var('e2')
ruleList = [(E,
function(((e, 1), E(e, 2)), ((e, 2), char(e)),
(((e1, e2), 1), E(e1, 2), E(e2, 1))))]
eq_(eval(letr(ruleList, parse_text(E(e, 1) + eoi, '12'), e)),
('1', '2'))
def test_lazy_some4(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(
eval(
begin(set_text('aaa'), lazy_some(char(_), _, y), eoi,
getvalue(y))), ['a', 'a', 'a'])
def test_times4(self):
_ = DummyVar('_')
x = LogicVar('x')
eq_(
eval(
begin(set_text('aaa'), times(char(_), 3, _, x), eoi,
getvalue(x))), ['a', 'a', 'a'])
def testRecursiveReturnValue3(self):
E, e, e1, e2 = Var('E'), Var('e'), Var('e1'), Var('e2')
ruleList = [(E,function(
((e, 1), E(e, 2)),
((e, 2), char(e)),
(((e1, e2), 1), E(e1,2), E(e2, 1))
))]
eq_(eval(letr(ruleList, parse_text(E(e, 1)+eoi, '12'), e)), ('1', '2'))
def testDirectLeftRecursive(self):
#assert 0, 'temporary mask'
E = Var('E')
ruleList = [(E,function(
((), #println('e1'),
E(),
#println('e2'),
char('a'),
#println('e3')
),
((), char('b'),
#println('eb')
),
))]
eq_(eval(letr(ruleList, parse_text(E()+eoi, 'b'))), True)
eq_(eval(letr(ruleList, parse_text(E()+eoi, 'ba'))), True)
eq_(eval(letr(ruleList, parse_text(E()+eoi, 'baa'))), True)
def test_times_a2(self):
X, Y, S = Var('X'), Var('Y'), Var('S')
function1 = function(((Y, ), times(char('a'), 2, 'a', Y)))
eq_(eval(begin(parse_text(function1(X), 'aa'), X)), ['a', 'a'])
assert_raises(NoSolution, eval, begin(parse_text(function1(X), 'a'),
X))
assert_raises(NoSolution, eval,
begin(parse_text(and_p(function1(X), eoi), 'aaa'), X))
def test_chars(self):
x, cs, chars = LogicVar('x'), Var('cs'), MacroVar('chars')
x1 = Var('x')
eq_(
eval(
let([(chars, lamda(
(x1, cs), begin(char(x1), contain(cs, x1))))],
parse_text(chars(x, 'a'), 'a'), getvalue(x))), 'a')
def test_kleene2(self):
f, kleene = MacroVar('f'), MacroVar('kleene')
_ = DummyVar('_')
item = Var('item')
fun = macro((item, ),
letrec([(f, macrorules(((), item, f()), ((), nullword)))],
f()))
eq_(eval(let([(kleene, fun)], set_text('ab'), kleene(char(_)))), True)
def test_some2(self):
X = Var('X')
eq_(eval(parse_text(and_p(some(char(X)), char('4')), '224')), '4')
eq_(eval(parse_text(and_p(some(char(X)), cut, char('4')), '224')), '4')
assert_raises(
NoSolution, eval,
parse_text(and_p(some(char(X)), char('3'), char('5')), '2234'))
def test_dummy_times_less(self):
_, Y = DummyVar('_'), Var('Y')
eq_(
eval(
preparse(
begin(
parse_text(
times_less(char(_), 3, _, Y) + char('4'), '234'),
Y))), ['2', '3'])
eq_(eval(begin(parse_text(times_less(char(_), 3, _, Y), '234'), Y)),
['2', '3', '4'])
eq_(eval(begin(parse_text(times_less(char(_), 3, _, Y), '23'), Y)),
['2', '3'])
assert_raises(
NoSolution, eval,
preparse(
begin(parse_text(times_less(char(_), 3, _, Y) + eoi, '2345'),
Y)))
def testKleene1(self): #occurs_check
x, s, kleene = Var('x'), Var('s'), Var('kleene')
x1 = Var('x')
result = LogicVar('result')
ruleList = [(kleene, rules(
((cons('a', x),), begin(char('a'), kleene(x))),
((nil,), nullword)))]
eq_(eval(letrec(ruleList,
parse_text(kleene(result), 'aa'), getvalue(result))), L('a', 'a'))
def test_kleene1(self):
f, kleene = MacroVar('f'), MacroVar('kleene')
item = Var('item')
fun = macro((item,),
letrec([(f, macrorules(
((), item, f()),
((), nullword)))],
f()))
eq_(eval(let([(kleene, fun)], set_text('aa'), kleene(char('a')))), True)
def testKleene3(self):
x, c, kleene = Var('x'), Var('c'), Var('kleene')
ruleList = [(kleene,function(
((Cons(c, x),), char(c),kleene(x)),
((nil,), nullword)))]
eq_(eval(letr(ruleList, parse_text(kleene(x), 'a'), x)), L('a'))
eq_(eval(letr(ruleList, parse_text(kleene(x), 'aa'), x)), L('a', 'a'))
eq_(eval(letr(ruleList, parse_text(kleene(x), 'aaa'), x)), L('a', 'a', 'a'))
eq_(eval(letr(ruleList, parse_text(kleene(x), 'bbb'), x)), L('b', 'b', 'b'))
eq_(eval(letr(ruleList, parse_text(kleene(x), 'abc'), x)), L('a', 'b', 'c'))
eq_(eval(letr(ruleList, parse_text(kleene(x), ''), x)), nil)
def testKleene4(self):
x, _, c, s, kleene = Var('x'), DummyVar('_'), Var('c'), Var('s'), Var('kleene')
ruleList = [(s,function( ((x,), kleene(_, x)))),
(kleene,function(
((_, Cons(c, x)), char(c)&kleene(_, x)),
((_, nil), nullword)))]
eq_(eval(letr(ruleList, parse_text(s(x), 'a'), x)), L('a'))
eq_(eval(letr(ruleList, parse_text(s(x), 'aa'), x)), L('a', 'a'))
eq_(eval(letr(ruleList, parse_text(s(x), 'aaa'), x)), L('a', 'a', 'a'))
eq_(eval(letr(ruleList, parse_text(s(x), 'bbb'), x)), L('b', 'b', 'b'))
eq_(eval(letr(ruleList, parse_text(s(x), 'abc'), x)), L('a', 'b', 'c'))
eq_(eval(letr(ruleList, parse_text(s(x), ''), x)), nil)
def testKleene2(self):
x, c, s, kleene = Var('x'), Var('c'), Var('s'), Var('kleene')
ruleList = [(s,function( ((x,), kleene(c, x)))),
(kleene,function(
((c, Cons(c, x)), and_p(char(c), kleene(c, x))),
((c, nil), nullword)))]
eq_(eval(letr(ruleList, parse_text(s(x), 'aa'), x)), L('a', 'a'))
eq_(eval(letr(ruleList, parse_text(s(x), 'aaa'), x)), L('a', 'a', 'a'))
eq_(eval(letr(ruleList, parse_text(s(x), 'bbb'), x)), L('b', 'b', 'b'))
eq_(eval(letr(ruleList, parse_text(s(x), ''), x)), nil)
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(s(x), eoi), 'aab'), x))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(s(x), eoi), 'abc'), x))
assert_raises(NoSolution, eval, letr(ruleList, parse_text(and_p(s(x), eoi), '41'), x))
def testDirectLeftRecursiveWithArguments(self):
#assert 0, 'temporary mask'
E, X = Var('E'), Var('X')
ruleList = [(E,function(
((), #println('e1'),
E(),
#println('e2'),
digit(X),
#println('e3', X)
),
((), char('b'),
#println('eb')
),
))]
#eq_(eval(letr(ruleList, parse_text(E()+eoi, 'b'))), True)
#eq_(eval(letr(ruleList, parse_text(E()+eoi, 'b1'))), True)
eq_(eval(letr(ruleList, parse_text(E()+eoi, 'b123'))), True)
def test_any2(self):
text, pos = il.Var('text'), il.Var('pos')
any_cont = il.Var('any_cont')
result = cps(any(char('1')))
expect = 1
eq_(result, expect)
def test_char2(self):
x = Var('x')
text, pos = il.Var('text'), il.Var('pos')
result = cps(char(x))
expect = 2
eq_(result, expect)
def test_char(self):
text, pos = il.Var('text'), il.Var('pos')
result = cps(char('a'))
expect = 1
eq_(result, expect)
def test_lazy_any4(self):
_ = DummyVar('_')
y = LogicVar('y')
eq_(eval(begin(set_text('aaa'), lazy_any(char(_), _, y), eoi, getvalue(y))), ['a', 'a', 'a'])
def test_lazy_any3(self):
eq_(eval(begin(set_text('aaa'), lazy_any(char('a')), char('a'), eoi)), True)
def test_any3(self):
eq_(eval(begin(set_text('aaa'), any(char('a')))), True)
def test_repeat(self):
#return
# the code below loops for ever, after modifie the behaviour of solver.parse_state and terminals.
x = LogicVar('x')
eq_(eval(and_(set_text('123'), repeat, char(x), unify(x, '3'))), True)
def test_char_eoi(self):
eq_(eval(begin(set_text('a'), char('a'), eoi)), True)
assert_raises(NoSolution, eval, begin(set_text('ab'), char('a'), eoi))
def testRecursiveReturnValue2(self):
E, F, e, e1 = Var('E'), Var('F'), Var('e'), Var('e1')
ruleList = [(E,function((((e, e),), F(e)))),
(F,function(((1,), char('1'))))]
eq_(eval(letr(ruleList, parse_text(E(e), '1'), e)), (1, 1))
def test_repeat2(self):
#return
# the code below loops for ever.
x = LogicVar('x')
eq_(eval(and_(set_text('123'), repeat, char(x), unify(x, '4'))), True)
def test_follew_char(self):
eq_(eval(begin(set_text('a'), follow(char('a')), char('a'))), 'a')