Move normalize to prolog.util

1 files changed, 11 insertions, 0 deletions

diff --git a/prolog/util.py b/prolog/util.py
index e5a93e2..48e3345 100644
--- a/prolog/util.py
+++ b/prolog/util.py
@@ -156,6 +156,17 @@ def rename_vars(tokens, names=None):
             tokens[i] = Token('VARIABLE', names[cur_name])
     return tokens
 
+# Helper function to remove trailing punctuation from lines and rename
+# variables to A1,A2,A3,… (potentially using [var_names]). Return a tuple.
+def normalized(line, var_names=None):
+    # Remove trailing punctuation.
+    i = len(line)
+    while i > 0:
+        if line[i-1].type not in ('COMMA', 'PERIOD', 'SEMI'):
+            break
+        i -= 1
+    return tuple(rename_vars(line[:i], var_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