1 files changed, 97 insertions, 0 deletions
diff --git a/prolog/problems/family_relations/father_2/common.py b/prolog/problems/family_relations/father_2/common.py
new file mode 100644
index 0000000..e1b46fd
--- /dev/null
+++ b/prolog/problems/family_relations/father_2/common.py
@@ -0,0 +1,97 @@
+# coding=utf-8
+
+id = 999     # TODO: new id has to be defined for this problem
+group = 'family_relations'
+number = 999  # TODO: this should be problem #2
+visible = True
+facts = 'family_relations'
+
+solution = '''\
+father(X, Y) :-
+  parent(X, Y),
+  male(X).
+'''
+
+import prolog.engine
+import prolog.util
+import server.problems
+
+def test(session, program):
+    # TODO: change queries and answers (these are for sister/2)
+    # Test queries and expected answers (values of X).
+    queries = [
+        ('sister(melanie, X)', set(['andrew'])),
+        ('sister(X, andrew)', set(['melanie'])),
+        ('sister(X, _)', set(['michelle', 'daniela', 'patricia', 'luana', 'sally', 'melanie', 'nevia', 'vanessa', 'anna'])),
+    ]
+
+    code = program + '\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:
+            return 0, len(queries)
+
+        n_correct = 0
+        for query, solution in queries:
+            answers, error = prolog.engine.ask_all(engine_id, query=query, timeout=1.0)
+            if answers and answers[-1] != 'timed out':
+                values_x = set([ans.get('X') for ans, constraints in answers])
+                if values_x == solution:
+                    n_correct += 1
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
+    return n_correct, len(queries)
+
+def general_hint():
+    pass
+
+def hint(session, program):
+    tokens = prolog.util.tokenize(program)
+
+    code = program + '\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.')
+
+        # OR (;) instead of AND (,)
+        # this hint has to be before the next two
+        # as otherwise those two would always override it
+        # and not convey the same (amount of) help/information
+        if prolog.util.Token('SEMI', ';') in tokens and prolog.engine.ask_truth(engine_id,
+            'findall(_, father(X, Y), L1), length(L1, N), \
+             findall(_, (parent(X, Y) ; male(X)), L2), length(L2, N)'):
+            return [{'id': 'or_instead_of_and'}]
+
+        # X must be male
+        if prolog.engine.ask_truth(engine_id, 'female(X), father(X, _)'):
+            return [{'id': 'x_must_be_male'}]
+
+        # X must be a parent
+        if prolog.engine.ask_truth(engine_id,
+            'father(X, _), \+ parent(X, _)'):
+            return [{'id': 'x_must_be_parent'}]
+
+        # Y can be of any gender, incl. female
+        if prolog.engine.ask_one(engine_id,
+            'father(_, Y), female(Y)') == 'false':
+            return [{'id': 'y_can_be_of_any_gender'}]
+
+        # Y does not necessarily need to be a parent
+        if prolog.engine.ask_one(engine_id,
+            'father(_, Y), \+ parent(Y, _)') == 'false':
+            return [{'id': 'y_need_not_be_parent'}]
+
+    except socket.timeout as ex:
+        pass
+
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
+    return None