Issue 6945 - Add script to make filter list diffs

abp/filters/diff_script.py

Index: abp/filters/diff_script.py
===================================================================
new file mode 100644
--- /dev/null
+++ b/abp/filters/diff_script.py
@@ -0,0 +1,60 @@
+# This file is part of Adblock Plus <https://adblockplus.org/>,
+# Copyright (C) 2006-present eyeo GmbH
+#
+# Adblock Plus is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3 as
+# published by the Free Software Foundation.
+#
+# Adblock Plus is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Command line script for rendering Adblock Plus filter list diffs."""
+
+from __future__ import print_function
+import argparse

[Sebastian Noack, 2018/09/21 11:51:21]

Nit: __future__ imports are special, so I would seperate them from corelib
imports with a blank line.

[rhowell, 2018/09/24 22:05:21]

Done.

+import io
+import sys
+
+from .sources import NotFound
+from .renderer import render_diff
+__all__ = ['main']

[Sebastian Noack, 2018/09/21 11:51:21]

Nit: There should be blank link above, here as well.

[rhowell, 2018/09/24 22:05:21]

Done.

+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description='Render a filter list diff.')
+    parser.add_argument(
+        'base', help='the older filter list that needs to be updated',
+        nargs='?')
+    parser.add_argument(
+        'latest', help='the most recent version of the filter list',
+        nargs='?')
+    parser.add_argument(
+        'outfile', help='output file for filter list diff',
+        default='-', nargs='?')
+    return parser.parse_args()
+
+
+def main(args_in=None):

[Sebastian Noack, 2018/09/21 11:51:20]

The args_in argument seems to be unused, and I don't see such an argument in
render_script.py either.

[rhowell, 2018/09/24 22:05:21]

Oops, I should've removed this when removing the extraneous test on the last
patch set. Done!

+    """Entry point for the diff rendering script (diffrender)."""
+    args = parse_args()
+
+    with io.open(args.base, 'r') as base, io.open(args.latest, 'r') as latest:

[Sebastian Noack, 2018/09/21 11:51:21]

Unlike below, you don't specify an encoding when calling io.open() here. On
Linux (at least) it will still work as intended as it defaults to UTF-8. But
according to the documentation the default encoding depends on the platform. So
we should explicitly specify encoding='utf-8' here as well.

[rhowell, 2018/09/24 22:05:21]

Done.

+        try:
+            lines = render_diff(base, latest)
+            if args.outfile == '-':
+                outfile = io.open(sys.stdout.fileno(), 'w',
+                                  closefd=False,
+                                  encoding=sys.stdout.encoding or 'utf-8')
+            else:
+                outfile = io.open(args.outfile, 'w', encoding='utf-8')
+
+            with outfile:
+                for line in lines:
+                    print(line, file=outfile)
+        except NotFound as exc:

[Sebastian Noack, 2018/09/21 11:51:20]

Can we even run into this exception since we neither load the input files
through the sources module nor do we render includes.

[rhowell, 2018/09/24 22:05:21]

I guess not. Removed it.

+            sys.exit(exc)