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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 = 10000
number = 6
visible = True
facts = None
solution = '''\
last_elem([X], X).
last_elem([_|T], X) :-
last_elem(T, X).
'''
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'),
'final_hint': Hint('final_hint'),
'[]_should_not_succeed': Hint('[]_should_not_succeed'),
'list_returned': Hint('list_returned'),
'clumsy_conc_use': Hint('clumsy_conc_use'),
'unsuccessful_conc_use': Hint('unsuccessful_conc_use'),
}
test_cases = [
('last_elem([X], c)',
[{'X': 'c'}]),
('last_elem([y, l, r, g, a], X)',
[{'X': '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)}}]
if n_correct == len(test_cases):
tokens = prolog.util.tokenize(code)
if prolog.util.Token('NAME', 'conc') not in tokens or prolog.util.Token('NAME', 'append') not in tokens:
hints += [{'id': 'final_hint'}]
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
# using conc, but clumsily: conc(_, X, L) instead of conc(_, [X], L)
if prolog.util.Token('NAME', 'conc') in tokens and \
prolog.engine.ask_truthTO(engine_id, 'last_elem([q,a,b,c], [q,a,b,c])'):
return [{'id': 'clumsy_conc_use'}]
# general unsuccessful use of conc, but not specifically detected
# return general_conc hint, not to confuse/force the student into a non-conc solution
if prolog.util.Token('NAME', 'conc') in tokens:
return [{'id': 'unsuccessful_conc_use'}]
# succeeds when asked to return the last element of an empty list
if prolog.engine.ask_truthTO(engine_id, 'last_elem([], _)'):
return [{'id': '[]_should_not_succeed'}]
# returns a list, not an element as required
if prolog.engine.ask_one(engine_id, 'last_elem([qQ], [qQ])'): # 'last_elem([qQ], X), is_list(X)' with ask_one?
return [{'id': 'list_returned'}]
# missing/failed base case
if not prolog.engine.ask_truth(engine_id, 'last_elem([qQ], qQ)'):
return [{'id': 'base_case'}]
# target predicate seems to always be false
if not prolog.engine.ask_truthTO(engine_id, 'last_elem(_, _)') and \
not prolog.engine.ask_truthTO(engine_id, 'last_elem([_,_,_,_,_,_], _)'):
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, 'last_elem([qa,qb,qQ,qc], qc)'):
return [{'id': 'recursive_case'}]
except socket.timeout as ex:
return [{'id': 'timeout'}]
finally:
if engine_id:
prolog.engine.destroy(engine_id)
return []
|
