From 69461f2cbed186c1fb1c0c6d9df1c80b412c1299 Mon Sep 17 00:00:00 2001
From: Shai Berger <shai@platonix.com>
Date: Tue, 20 Feb 2018 18:30:53 +0200
Subject: [PATCH] Add support for the --output-dir and --add-suffix options
 from 2to3

These options were added to 2to3 in Python 2.7 and 3.2. This commit
adds the options always, with descriptive errors if the user attempts
to use them with a version of Python that is too old.

Most of the code here was shamelessly stolen from lib2to3's source.
---
 libmodernize/main.py | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/libmodernize/main.py b/libmodernize/main.py
index 5d38e0d..0243b0e 100644
--- a/libmodernize/main.py
+++ b/libmodernize/main.py
@@ -27,6 +27,8 @@ def format_usage(usage):
     """Method that doesn't output "Usage:" prefix"""
     return usage
 
+_lib2to3_has_output_dir = hasattr(StdoutRefactoringTool([], {}, False, False, False), '_output_dir')
+
 def main(args=None):
     """Main program.
 
@@ -56,6 +58,15 @@ def main(args=None):
                       help="Write back modified files.")
     parser.add_option("-n", "--nobackups", action="store_true", default=False,
                       help="Don't write backups for modified files.")
+    parser.add_option("-o", "--output-dir", action="store", default="",
+                      help="Put output files in this directory "
+                           "instead of overwriting the input files.  Requires -n.  "
+                           "Available on Python==2.7 and Python>=3.2.")
+    parser.add_option("--add-suffix", action="store", default="",
+                      help="Append this string to all output filenames."
+                           " Requires -n if non-empty.  "
+                           "Available on Python==2.7 and Python>=3.2.  "
+                           "ex: --add-suffix='3' will generate .py3 files.")
     parser.add_option("--six-unicode", action="store_true", default=False,
                       help="Wrap unicode literals in six.u().")
     parser.add_option("--future-unicode", action="store_true", default=False,
@@ -96,6 +107,16 @@ def main(args=None):
             return 2
     if options.print_function:
         flags["print_function"] = True
+    if not _lib2to3_has_output_dir and (options.output_dir or options.add_suffix):
+        print("--output-dir and --add-suffix are not supported "
+              "with this version of Python.", file=sys.stderr)
+        return 2
+    # If we allowed these, the original files would be renamed to backup names
+    # but not replaced.
+    if options.output_dir and not options.nobackups:
+        parser.error("Can't use --output-dir/-o without -n.")
+    if options.add_suffix and not options.nobackups:
+        parser.error("Can't use --add-suffix without -n.")
 
     # Set up logging handler
     level = logging.DEBUG if options.verbose else logging.INFO
@@ -128,8 +149,11 @@ def main(args=None):
     else:
         requested = default_fixes
     fixer_names = requested.difference(unwanted_fixes)
+    newer_options = {}
+    if (options.output_dir or options.add_suffix):
+        newer_options = dict(output_dir=options.output_dir, append_suffix=options.add_suffix)
     rt = StdoutRefactoringTool(sorted(fixer_names), flags, sorted(explicit),
-                               options.nobackups, not options.no_diffs)
+                               options.nobackups, not options.no_diffs, **newer_options)
 
     # Refactor all files and directories passed as arguments
     if not rt.errors: