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from operator import itemgetter
import prolog.engine
import prolog.util
import socket
from server.hints import Hint, HintPopup
import server.problems
id = 110
number = 4
visible = True
facts = None
solution = '''\
dup([], []).
dup([H|T], [H,H|TT]) :-
dup(T, TT).
'''
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'),
'timeout': Hint('timeout'),
'recursive_case': Hint('recursive_case'),
'forcing_result_onto_recursion': Hint('forcing_result_onto_recursion'),
'base_case_arbitrary': Hint('base_case_arbitrary'),
'base_case_missing_[]': Hint('base_case_missing_[]'),
}
test_cases = [
('dup([], X)',
[{'X': '[]'}]),
('dup([y], X)',
[{'X': '[y, y]'}]),
('dup([k, f, f, g, a], X)',
[{'X': '[k, k, f, f, f, f, g, g, a, a]'}]),
('dup(X, [k, k, f, f, f, f, g, g, a, a])',
[{'X': '[k, f, f, g, a]'}]),
]
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'}]
# recursion is getting bigger and bigger
# base case succeeds with arbitrary result
if prolog.engine.ask_truthTO(engine_id, 'dup([], L), var(L)'):
return [{'id': 'base_case_arbitrary'}]
# base case does not work for empty list
if prolog.engine.ask_truthTO(engine_id, 'dup([q], [q,q]), \+ dup([], [])'):
return [{'id': 'base_case_missing_[]'}]
# forcing result onto recursion; case of dup(T, [H,H|L]) or dup(T, [H,H|T])
if not prolog.engine.ask_truthTO(engine_id, 'dup([a,b,c,d,e], _)') and \
(prolog.engine.ask_truth(engine_id,
'asserta( dup([b], [a,a,yowza]) ), dup([a,b], [yowza]), retract( dup([b], [a,a,yowza]) )') or \
prolog.engine.ask_truth(engine_id,
'asserta( dup([b], [a,a,b]) ), dup([a,b], [b]), retract( dup([b], [a,a,b]) )')):
return [{'id': 'forcing_result_onto_recursion'}]
# missing/failed base case
if not prolog.engine.ask_one(engine_id, 'dup([], [])'):
return [{'id': 'base_case'}]
# target predicate seems to always be false
if not prolog.engine.ask_truth(engine_id, 'dup([_,_,_], _)'):
return [{'id': 'predicate_always_false'}]
# 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, 'dup([qa,qb,qc], [qa,qa,qb,qb,qc,qc])'):
return [{'id': 'recursive_case'}]
except socket.timeout as ex:
return [{'id': 'timeout'}]
finally:
if engine_id:
prolog.engine.destroy(engine_id)
return []
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