1 files changed, 101 insertions, 0 deletions
diff --git a/prolog/problems/family_relations/ancestor_2/common.py b/prolog/problems/family_relations/ancestor_2/common.py
index 473fa27..873b87b 100644
--- a/prolog/problems/family_relations/ancestor_2/common.py
+++ b/prolog/problems/family_relations/ancestor_2/common.py
@@ -13,3 +13,104 @@ ancestor(X, Y) :-
   parent(X, Z),
   ancestor(Z, Y).
 '''
+
+hint_type = {
+    'gender_is_irrelevant': Hint('gender_is_irrelevant'),
+    'grandparent_used': Hint('grandparent_used'),
+    'base_case': Hint('base_case'),
+    'ancestor_to_oneself': Hint('ancestor_to_oneself'),
+    'descendant_need_not_be_parent': Hint('descendant_need_not_be_parent'),
+    'wrong_direction': Hint('wrong_direction'),
+}
+
+test_cases = [
+    # TODO
+]
+
+def test(program, solved_problems):
+    code = (program + '\n' +
+            server.problems.solutions_for_problems('prolog', solved_problems) + '\n' +
+            server.problems.load_facts('prolog', facts).facts)
+
+    engine_id = None
+    try:
+        engine_id, output = prolog.engine.create(code=code, timeout=1.0)
+        if not engine_id or 'error' in map(itemgetter(0), output):
+            # Engine creation failed, or syntax error in code.
+            return 0, len(test_cases)
+
+        n_correct = 0
+        for query, answers in test_cases:
+            # Limit inferences for each solution to curb unbounded recursion.
+            limited = 'call_with_inference_limit(({}), 100000, _)'.format(query)
+            if prolog.engine.check_answers(engine_id, query=limited, answers=answers, timeout=1.0):
+                n_correct += 1
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
+    passed = n_correct == len(test_cases)
+    hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': len(test_cases)}}]
+    return passed, hints
+
+def hint(program, solved_problems):
+    tokens = prolog.util.tokenize(program)
+
+    code = (program + '\n' +
+            server.problems.solutions_for_problems('prolog', solved_problems) + '\n' +
+            server.problems.load_facts('prolog', facts).facts)
+
+    engine_id = None
+    try:
+        engine_id, output = prolog.engine.create(code=code, timeout=1.0)
+        if not engine_id:
+            raise Exception('Prolog engine failed to create.')
+
+        # gender testing is redundant
+        # this is not necessarily wrong, but worth mentioning anyway
+        targets = [prolog.util.Token('NAME', 'male'), prolog.util.Token('NAME', 'female')]
+        pos = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
+        if pos:
+            # TODO: resolve how highlighting info is communicated
+            return [{'id': 'gender_is_irrelevant', 'highlight': pos}]
+
+        # grandparent is a sign of complications
+        # it's likely used instead of recursion
+        targets = [prolog.util.Token('NAME', 'grandparent')]
+        pos = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
+        if pos:
+            # TODO: resolve how highlighting info is communicated
+            return [{'id': 'grandparent_used', 'highlight': pos}]
+
+        # missing/failed base case
+        # TODO: how will ask_truth handle/return timeouts...
+        # TODO: timeout is the same as fail in this particular case
+        if prolog.engine.ask_truth(engine_id,
+            'parent(X, Y), \+ ancestor(X, Y)'):
+            return [{'id', 'base_case'}]
+
+        # ancestor to oneself
+        if prolog.engine.ask_truth(engine_id, 'ancestor(X, X)'):
+            return [{'id', 'ancestor_to_oneself'}]
+
+        # Y does not necessarily need to be a parent
+        if prolog.engine.ask_one(engine_id,
+            'ancestor(_, Y), \+ parent(Y, _)') == 'false':
+            return [{'id': 'descendant_need_not_be_parent'}]
+
+        # descendant instead of ancestor (wrong direction)
+        # warning: knowledge base dependent
+        if prolog.engine.ask_truth(engine_id,
+            'findall(_, ancestor(william, X), L1), length(L1, 2), \
+             findall(_, ancestor(X, william), L2), length(L2, 6)'):
+            return [{'id', 'wrong_direction'}]
+
+    except socket.timeout as ex:
+        pass
+
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
+    return None
+