From c1cc16c4088cb68d205342450493957f17a71c9a Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@fri.uni-lj.si>
Date: Thu, 17 Mar 2016 15:41:44 +0100
Subject: Prolog: add generic recursion hints for lists_advanced problems

TODO modify texts in */sl.py where appropriate.
---
 .../problems/lists_advanced/shiftright_2/common.py | 39 +++++++++++++++++++---
 1 file changed, 35 insertions(+), 4 deletions(-)

(limited to 'prolog/problems/lists_advanced/shiftright_2/common.py')

diff --git a/prolog/problems/lists_advanced/shiftright_2/common.py b/prolog/problems/lists_advanced/shiftright_2/common.py
index d8a4c9f..d689b95 100644
--- a/prolog/problems/lists_advanced/shiftright_2/common.py
+++ b/prolog/problems/lists_advanced/shiftright_2/common.py
@@ -1,8 +1,9 @@
-# coding=utf-8
-
 from operator import itemgetter
+import socket
+
 import prolog.engine
-import server.problems
+import prolog.util
+from server.hints import Hint, HintPopup
 
 id = 114
 number = 21
@@ -17,6 +18,13 @@ shiftright(L1, [H|T]) :-
   conc114(T, [H], L1).
 '''
 
+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'),
+    'timeout': Hint('timeout'),
+}
+
 test_cases = [
     ('shiftright([i], X)',
         [{'X': '[i]'}]),
@@ -46,5 +54,28 @@ def test(code, aux_code):
     return n_correct, len(test_cases), hints
 
 def hint(code, aux_code):
-    # TODO
+    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, 'shiftright(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
+    except socket.timeout as ex:
+        return [{'id': 'timeout'}]
+
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
     return []
-- 
cgit v1.2.1