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from operator import itemgetter
import socket
import prolog.engine
import prolog.util
from server.hints import Hint, HintPopup
id = 119
number = 60
visible = True
facts = None
solution = '''\
len([], 0).
len([_|T], Len) :-
len(T, LenT),
Len is LenT + 1.
'''
hint_type = {
'eq_instead_of_equ_markup': HintPopup('eq_instead_of_equ_markup'),
'eq_instead_of_equ': Hint('eq_instead_of_equ'),
'predicate_always_false': Hint('predicate_always_false'),
'base_case': Hint('base_case'),
'recursive_case': Hint('recursive_case'),
'timeout': Hint('timeout'),
'arbitrary_base_case': Hint('arbitrary_base_case'),
'args_not_instantiated': Hint('arbitrary_base_case'),
'=_instead_of_is': Hint('=_instead_of_is'),
'+H_instead_of_+1': Hint('+H_instead_of_+1'),
'forcing_result_onto_recursion': Hint('forcing_result_onto_recursion'),
'same_var_on_both_sides_of_is': Hint('same_var_on_both_sides_of_is'),
}
test_cases = [
('len([8, 3, 5, 1], X)',
[{'X': '4'}]),
('len([2, -3, 5, 0, 3], X)',
[{'X': '5'}]),
('len([], X)',
[{'X': '0'}]),
]
def test(code, aux_code):
n_correct = 0
engine_id = None
try:
engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
if engine_id is not None and 'error' not in map(itemgetter(0), output):
# Engine successfully created, and no syntax error in program.
for query, answers in test_cases:
if prolog.engine.check_answers(engine_id, query=query, answers=answers, timeout=1.0):
n_correct += 1
except socket.timeout:
pass
finally:
if engine_id:
prolog.engine.destroy(engine_id)
hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': len(test_cases)}}]
return n_correct, len(test_cases), hints
def hint(code, aux_code):
tokens = prolog.util.tokenize(code)
try:
engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
# strict equality testing instead of simple matching
# this is usually (but not necessarily) wrong
targets = [prolog.util.Token('EQ', '==')]
marks = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
if marks:
return [{'id': 'eq_instead_of_equ_markup', 'start': m[0], 'end': m[1]} for m in marks] + \
[{'id': 'eq_instead_of_equ'}]
# target predicate seems to always be false
if not prolog.engine.ask_truthTO(engine_id, 'len(_, _)'):
return [{'id': 'predicate_always_false'}]
# arbitrary base case: len([], _)
if prolog.engine.ask_truthTO(engine_id, 'len([], q), len([], child(Q, q))'):
return [{'id': 'arbitrary_base_case'}]
# missing/failed base case
if not prolog.engine.ask_truthTO(engine_id, 'len([], 0)'):
return [{'id': 'base_case'}]
# arguments not instantiated
reply, output = prolog.engine.ask(engine_id, 'len([a, b, c], Len)', timeout=1)
if reply.get('code') == 'instantiation_error':
return [{'id': 'args_not_instantiated'}]
# = instead of is
if prolog.engine.ask_truthTO(engine_id, 'len([qa, qb, qc, qd], _+_)'):
return [{'id': '=_instead_of_is'}]
# +H instead of +1
if prolog.engine.ask_truthTO(engine_id, 'len([1, 3, 9, 27, 81], 121)'):
return [{'id': '+H_instead_of_+1'}]
# forcing result onto recursion
if prolog.engine.ask_truthTO(engine_id, '''\
asserta(len([9, 81], 2+1)), len([27, 9, 81], 2), retract(len([9, 81], 2+1))
;
asserta(len([9, 81], 1+2)), len([27, 9, 81], 2), retract(len([9, 81], 1+2))'''):
return [{'id': 'forcing_result_onto_recursion'}]
# same var on both sides of is
if prolog.engine.ask_truth(engine_id, 'len([], 0), \+ len([a, b, c], _)'):
return [{'id': 'same_var_on_both_sides_of_is'}]
# base case works, the recursive doesn't (but it doesn't timeout)
# this may be left as the last, most generic hint
if not prolog.engine.ask_truth(engine_id, 'len([2, 41, -22], 3)'):
return [{'id': 'recursive_case'}]
except socket.timeout as ex:
return [{'id': 'timeout'}]
finally:
if engine_id:
prolog.engine.destroy(engine_id)
return []
|
