Ignore attributes starting with dunder in _TokenType (fixes #672).

This issue came up, when trying to deepcopy a parsed statement.
deepcopy uses getattr(obj, '__deepcopy__', None) to get a method
for copying an object. Before this change a new attribute
'__deepcopy__' was created as a new instance of _TokenType (a tuple).

CHANGELOG

@@ -6,6 +6,10 @@ Notable Changes
 * Drop support for Python 3.5.
 * Python 3.12 is now supported (pr725, by hugovk).
 
+Bug Fixes
+
+* Ignore dunder attributes when creating Tokens (issue672).
+
 
 Release 0.4.4 (Apr 18, 2023)
 ----------------------------

sqlparse/tokens.py

@@ -19,6 +19,9 @@ def __contains__(self, item):
         return item is not None and (self is item or item[:len(self)] == self)
 
     def __getattr__(self, name):
+        # don't mess with dunder
+        if name.startswith('__'):
+            return super().__getattr__(self, name)
         new = _TokenType(self + (name,))
         setattr(self, name, new)
         new.parent = self

tests/test_regressions.py

@@ -1,3 +1,5 @@
+import copy
+
 import pytest
 
 import sqlparse
@@ -436,3 +438,9 @@ def test_comment_between_cte_clauses_issue632():
              baz AS ()
         SELECT * FROM baz;""")
     assert p.get_type() == "SELECT"
+
+
+def test_copy_issue672():
+    p = sqlparse.parse('select * from foo')[0]
+    copied = copy.deepcopy(p)
+    assert str(p) == str(copied)