Introduce clang-format-diff.py

This script can be used to format a diff to adhere to clang-format

contrib/devtools/clang-format-diff.py

@@ -0,0 +1,166 @@
+#!/usr/bin/env python3
+#
+#===- clang-format-diff.py - ClangFormat Diff Reformatter ----*- python -*--===#
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License.
+#
+#           ============================================================
+#
+# University of Illinois/NCSA
+# Open Source License
+#
+# Copyright (c) 2007-2015 University of Illinois at Urbana-Champaign.
+# All rights reserved.
+#
+# Developed by:
+#
+#     LLVM Team
+#
+#     University of Illinois at Urbana-Champaign
+#
+#     http://llvm.org
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal with
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is furnished to do
+# so, subject to the following conditions:
+#
+#     * Redistributions of source code must retain the above copyright notice,
+#       this list of conditions and the following disclaimers.
+#
+#     * Redistributions in binary form must reproduce the above copyright notice,
+#       this list of conditions and the following disclaimers in the
+#       documentation and/or other materials provided with the distribution.
+#
+#     * Neither the names of the LLVM Team, University of Illinois at
+#       Urbana-Champaign, nor the names of its contributors may be used to
+#       endorse or promote products derived from this Software without specific
+#       prior written permission.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+# CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+# SOFTWARE.
+#
+#           ============================================================
+#
+#===------------------------------------------------------------------------===#
+
+r"""
+ClangFormat Diff Reformatter
+============================
+
+This script reads input from a unified diff and reformats all the changed
+lines. This is useful to reformat all the lines touched by a specific patch.
+Example usage for git/svn users:
+
+  git diff -U0 HEAD^ | clang-format-diff.py -p1 -i
+  svn diff --diff-cmd=diff -x-U0 | clang-format-diff.py -i
+
+"""
+
+import argparse
+import difflib
+import io
+import re
+import subprocess
+import sys
+
+
+# Change this to the full path if clang-format is not on the path.
+binary = 'clang-format'
+
+
+def main():
+  parser = argparse.ArgumentParser(description=
+                                   'Reformat changed lines in diff. Without -i '
+                                   'option just output the diff that would be '
+                                   'introduced.')
+  parser.add_argument('-i', action='store_true', default=False,
+                      help='apply edits to files instead of displaying a diff')
+  parser.add_argument('-p', metavar='NUM', default=0,
+                      help='strip the smallest prefix containing P slashes')
+  parser.add_argument('-regex', metavar='PATTERN', default=None,
+                      help='custom pattern selecting file paths to reformat '
+                      '(case sensitive, overrides -iregex)')
+  parser.add_argument('-iregex', metavar='PATTERN', default=
+                      r'.*\.(cpp|cc|c\+\+|cxx|c|cl|h|hpp|m|mm|inc|js|ts|proto'
+                      r'|protodevel|java)',
+                      help='custom pattern selecting file paths to reformat '
+                      '(case insensitive, overridden by -regex)')
+  parser.add_argument('-sort-includes', action='store_true', default=False,
+                      help='let clang-format sort include blocks')
+  parser.add_argument('-v', '--verbose', action='store_true',
+                      help='be more verbose, ineffective without -i')
+  args = parser.parse_args()
+
+  # Extract changed lines for each file.
+  filename = None
+  lines_by_file = {}
+  for line in sys.stdin:
+    match = re.search('^\+\+\+\ (.*?/){%s}(\S*)' % args.p, line)
+    if match:
+      filename = match.group(2)
+    if filename is None:
+      continue
+
+    if args.regex is not None:
+      if not re.match('^%s$' % args.regex, filename):
+        continue
+    else:
+      if not re.match('^%s$' % args.iregex, filename, re.IGNORECASE):
+        continue
+
+    match = re.search('^@@.*\+(\d+)(,(\d+))?', line)
+    if match:
+      start_line = int(match.group(1))
+      line_count = 1
+      if match.group(3):
+        line_count = int(match.group(3))
+      if line_count == 0:
+        continue
+      end_line = start_line + line_count - 1
+      lines_by_file.setdefault(filename, []).extend(
+          ['-lines', str(start_line) + ':' + str(end_line)])
+
+  # Reformat files containing changes in place.
+  for filename, lines in lines_by_file.items():
+    if args.i and args.verbose:
+      print('Formatting {}'.format(filename))
+    command = [binary, filename]
+    if args.i:
+      command.append('-i')
+    if args.sort_includes:
+      command.append('-sort-includes')
+    command.extend(lines)
+    command.extend(['-style=file', '-fallback-style=none'])
+    p = subprocess.Popen(command,
+                         stdout=subprocess.PIPE,
+                         stderr=None,
+                         stdin=subprocess.PIPE,
+                         universal_newlines=True)
+    stdout, stderr = p.communicate()
+    if p.returncode != 0:
+      sys.exit(p.returncode)
+
+    if not args.i:
+      with open(filename, encoding="utf8") as f:
+        code = f.readlines()
+      formatted_code = io.StringIO(stdout).readlines()
+      diff = difflib.unified_diff(code, formatted_code,
+                                  filename, filename,
+                                  '(before formatting)', '(after formatting)')
+      diff_string = ''.join(diff)
+      if len(diff_string) > 0:
+        sys.stdout.write(diff_string)
+
+if __name__ == '__main__':
+  main()