From 284ddd268604175bd8712804a85bc2c431aa2927 Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@araneo.org>
Date: Tue, 27 May 2014 12:47:52 +0200
Subject: Move PQueue and utility functions into util.py

---
 prolog/util.py | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/prolog/util.py b/prolog/util.py
index 4826f86..438c068 100644
--- a/prolog/util.py
+++ b/prolog/util.py
@@ -1,5 +1,6 @@
 #!/usr/bin/python3
 
+import itertools
 import math
 import re
 
@@ -104,3 +105,41 @@ def rename_vars(tokens, names={}):
                 next_id += 1
             tokens[i] = ('VARIABLE', 'A' + str(names[cur_name]))
     return names
+
+# transformation = before → after; applied on line which is part of rule
+# return mapping from formal vars in before+after to actual vars in rule
+# line and rule should of course not be normalized
+def map_vars(before, after, line, rule):
+    mapping = {}
+    new_index = 0
+    for i in range(len(before)):
+        if line[i][0] == 'VARIABLE':
+            formal_name = before[i][1]
+            if line[i][1] != '_':
+                actual_name = line[i][1]
+            else:
+                actual_name = 'New'+str(new_index)
+                new_index += 1
+            mapping[formal_name] = actual_name
+
+    remaining_formal = set([t[1] for t in after if t[0] == 'VARIABLE' and t[1] not in mapping.keys()])
+    remaining_actual = set([t[1] for t in rule if t[0] == 'VARIABLE' and t[1] != '_' and t[1] not in mapping.values()])
+
+    #for i in range(0, len(remaining_formal)-len(remaining_actual)+2):
+    for var in remaining_formal:
+        remaining_actual.add('New'+str(new_index))
+        new_index += 1
+
+    # cthulhu-inspired horrors continue...
+    # get all possible mappings of remaining transform var. names to actual names
+    def match(a, b):
+        for bc in itertools.combinations(b, min(len(a), len(b))):
+            for bp in itertools.permutations(bc):
+                for ac in itertools.combinations(a, len(bc)):
+                    yield {ac[i]: bp[i] for i in range(len(bc))}
+
+    for more_mapping in match(remaining_formal, remaining_actual):
+        # copy base mapping dict and add remaining vars
+        mapping_all = {k: v for k, v in mapping.items()}
+        mapping_all.update(more_mapping)
+        yield mapping_all
-- 
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