def parse():
import io
source = """% Equality test
ancestor(A, B) :-
parent(A, B).
ancestor(A, B) :-
parent(A, C),
D = C, % Unification required
ancestor(D, B).
sibling(A, B) :-
parent(P, A),
parent(P, B),
A != B. % negation required
parent(john, douglas).
parent(john, mary).
parent(bob, john).
parent(ebbon, bob).
ancestor(A, B)?
"""
expected = """assert{ ancestor(A, B) :- parent(A, B) }
assert{ ancestor(A, B) :- parent(A, C), D = C, ancestor(D, B) }
assert{ sibling(A, B) :- parent(P, A), parent(P, B), A != B }
assert{ parent(john, douglas) }
assert{ parent(john, mary) }
assert{ parent(bob, john) }
assert{ parent(ebbon, bob) }
query{ ancestor(A, B) }"""
tokens = tokenizer.tokenize(io.StringIO(source))
buffer = []
for e in parser._parse(tokens):
buffer.append("{}{{ {} }}".format(e[1], e[0]))
result = '\n'.join(buffer)
assert result == expected
def parse(reader):
"""Helper function to act as single point of entry for simple parses."""
yield from _parse(tokenizer.tokenize(reader))
