Add 3.x try reduction rule

uncompyle6/parsers/reducecheck/__init__.py

@@ -7,6 +7,7 @@ from uncompyle6.parsers.reducecheck.ifstmts_jump import *
 from uncompyle6.parsers.reducecheck.or_check import *
 from uncompyle6.parsers.reducecheck.testtrue import *
 from uncompyle6.parsers.reducecheck.tryelsestmt import *
+from uncompyle6.parsers.reducecheck.tryexcept import *
 from uncompyle6.parsers.reducecheck.tryelsestmtl3 import *
 from uncompyle6.parsers.reducecheck.while1elsestmt import *
 from uncompyle6.parsers.reducecheck.while1stmt import *

uncompyle6/parsers/reducecheck/tryexcept.py

@@ -0,0 +1,59 @@
+#  Copyright (c) 2020 Rocky Bernstein
+
+def tryexcept(self, lhs, n, rule, ast, tokens, first, last):
+    come_from_except = ast[-1]
+    if rule == (
+            "try_except",
+            (
+                "SETUP_EXCEPT",
+                "suite_stmts_opt",
+                "POP_BLOCK",
+                "except_handler",
+                "opt_come_from_except",
+            ),
+    ):
+        if come_from_except[0] == "COME_FROM":
+            # There should be at last two COME_FROMs, one from an
+            # exception handler and one from the try. Otherwise
+            # we have a try/else.
+            return True
+        pass
+
+    elif rule == (
+            'try_except',
+            (
+                'SETUP_EXCEPT',
+                'suite_stmts_opt',
+                'POP_BLOCK',
+                'except_handler',
+                '\\e_opt_come_from_except'
+            ),
+    ):
+        # Find END_FINALLY.
+        for i in range(last, first, -1):
+            if tokens[i] == "END_FINALLY":
+                jump_before_finally = tokens[i-1]
+                if jump_before_finally.kind.startswith("JUMP"):
+                    if jump_before_finally == "JUMP_FORWARD":
+                        # If there is a JUMP_FORWARD before
+                        # the END_FINALLY to some jumps place
+                        # beyond tokens[last].off2int() then
+                        # this is a try/else rather than an
+                        # try (no else).
+                        return tokens[i-1].attr > tokens[last].off2int(prefer_last=True)
+                    elif jump_before_finally == "JUMP_BACK":
+                        # If there is a JUMP_BACK before the
+                        # END_FINALLY then this is a looping
+                        # jump, but then jumps in the except
+                        # handlers have to also be a looping
+                        # jump or this is a try/else rather
+                        # than an try (no else).
+                        except_handler = ast[3]
+                        if (except_handler == "except_handler" and
+                            except_handler[0] == "JUMP_FORWARD"):
+                            return True
+                        return False
+                    pass
+                pass
+            pass
+        return False