Commented group_identifier_list()

1 files changed, 16 insertions, 5 deletions

diff --git a/sqlparse/engine/grouping.py b/sqlparse/engine/grouping.py
index 8f5ccd9..37e029b 100644
--- a/sqlparse/engine/grouping.py
+++ b/sqlparse/engine/grouping.py
@@ -185,6 +185,7 @@ def group_identifier(tlist):
 
 
 def group_identifier_list(tlist):
+    # First group the `tlist` sublists
     for sgroup in tlist.get_sublists():
         if not isinstance(sgroup, sql.IdentifierList):
             group_identifier_list(sgroup)
@@ -204,13 +205,14 @@ def group_identifier_list(tlist):
                    lambda t: isinstance(t, sql.Comment),
                    ]
 
-    tcomma = tlist.token_next_match(0, T.Punctuation, ',')
     start = None
+
+    tcomma = tlist.token_next_match(0, T.Punctuation, ',')
     while tcomma:
         before = tlist.token_prev(tcomma)
         after = tlist.token_next(tcomma)
 
-        # Check if the tokens around tcomma belong to a list
+        # Check if the tokens around tcomma belong to an identifier list
         bpassed = apassed = False
         for func in fend1_funcs:
             if before and func(before):
@@ -218,22 +220,31 @@ def group_identifier_list(tlist):
             if after and func(after):
                 apassed = True
 
+        # Both tokens around tcomma belong to a list
         if bpassed and apassed:
-            if start is None:
+            # Set the start of the identifier list if not defined before
+            if start == None:
                 start = before
 
+            # Look if the next token is another comma
             next_ = tlist.token_next(after)
             if next_ and next_.match(T.Punctuation, ','):
                 tcomma = next_
+
+            # Reached the end of the list
             else:
-                # Reached the end of the list
+                # Create and group the identifiers list
                 tokens = tlist.tokens_between(start, after)
                 group = tlist.group_tokens(sql.IdentifierList, tokens)
+
+                # Skip ahead to next ","
                 start = None
                 tcomma = tlist.token_next_match(tlist.token_index(group) + 1,
                                                 T.Punctuation, ',')
+
+        # At least one of the tokens around tcomma don't belong to an
+        # identifier list. Something's wrong here, skip ahead to next ","
         else:
-            # Something's wrong here, skip ahead to next ","
             start = None
             tcomma = tlist.token_next_match(tlist.token_index(tcomma) + 1,
                                             T.Punctuation, ',')