From 79a91c6a6c4fabf6f3c8949a6735375ceac21989 Mon Sep 17 00:00:00 2001
From: Aleksander Sadikov <aleksander.sadikov@fri.uni-lj.si>
Date: Wed, 9 Mar 2016 19:16:26 +0100
Subject: Hints for del/3 added. And some minor corrections/additions
 elsewhere.

---
 prolog/problems/lists/del_3/common.py | 64 +++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

(limited to 'prolog/problems/lists/del_3/common.py')

diff --git a/prolog/problems/lists/del_3/common.py b/prolog/problems/lists/del_3/common.py
index 23caf08..f3dfcb2 100644
--- a/prolog/problems/lists/del_3/common.py
+++ b/prolog/problems/lists/del_3/common.py
@@ -2,11 +2,14 @@
 
 from operator import itemgetter
 import prolog.engine
+import prolog.util
+import socket
+from server.hints import Hint, HintPopup
 import server.problems
 
 id = 105
 number = 11
-visible = False
+visible = True
 facts = None
 
 solution = '''\
@@ -15,6 +18,17 @@ del(X, [Y|T], [Y|L]) :-
   del(X, T, L).
 '''
 
+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'),
+    'final_hint': Hint('final_hint'),
+    'del_from_empty_list_success': Hint('del_from_empty_list_success'),
+    'lost_heads': Hint('lost_heads'),
+}
+
 test_cases = [
     ('del(1, [1], X)',
         [{'X': '[]'}]),
@@ -41,8 +55,54 @@ def test(code, aux_code):
             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', 'insert') not in tokens:
+            hints += [{'id': 'final_hint'}]
     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'}]
+
+        # recursion is getting bigger and bigger
+
+
+        # deleting from empty list succeeds with an emtpy list result
+        if prolog.engine.ask_truthTO(engine_id, 'del(_, [], _)'):
+            return [{'id': 'del_from_empty_list_success'}]
+
+        # missing/failed base case
+        if not prolog.engine.ask_truthTO(engine_id, 'del(qQ, [qQ,qa,qb,qc], [qa,qb,qc])'):
+            return [{'id': 'base_case'}]
+
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'del(_, [_,_,_,_,_,_], _)'):
+            return [{'id': 'predicate_always_false'}]
+
+        # forgot to put list head(s) back in the list when deleting an element
+        if prolog.engine.ask_truth(engine_id, 'del(q, [a,b,c,d,q,x,y,z], [x,y,z])'):
+            return [{'id': 'lost_heads'}]
+
+        # L=[H|T] at the end of the rule; this can be detected with test cases and can be wrong (in some sense)
+        # TODO: implement it, and provide a good explanation (might be hard)
+
+
+    except socket.timeout as ex:
+        return [{'id': 'timeout'}]
+
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
     return []
-- 
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