Remove all trailing punctuation from lines

Remove trailing sequences of COMMAs and PERIODs when extracting edits
from a trace. This is because subgoal order is rarely important in
Prolog, and we don't care if the edit happened on the last line or not.
This means that we treat for example

  "conc(A,B)," → "conc(A,B,C)." the same as
  "conc(A,B)"  → "conc(A,B,C)".

1 files changed, 4 insertions, 2 deletions

diff --git a/prolog/util.py b/prolog/util.py
index 7fb81e3..c762f23 100644
--- a/prolog/util.py
+++ b/prolog/util.py
@@ -66,13 +66,15 @@ def decompose(code):
     rule_start = 0
     for t in tokens:
         if t.type == 'SEMI':
-            if line != []:
+            if line:
                 lines.append(tuple(line))
                 line = []
             lines.append((t,))
             continue
         if not parens:
             if t.type in ('PERIOD', 'FROM', 'COMMA', 'EOF'):
+                if t.type == 'FROM':
+                    line.append(t)
                 if line != []:
                     lines.append(tuple(line))
                     line = []
@@ -104,7 +106,7 @@ def compose(lines, rules):
             if i == end-1:
                 code += '.\n'
             elif i == start:
-                code += ' :-\n'
+                code += '\n'
             else:
                 if line and line[-1].type != 'SEMI' and lines[i+1][-1].type != 'SEMI':
                     code += ','