git-patch-to-hg-patch

#!/usr/bin/python

"""Git format-patch to hg importable patch.
"""

# Original author: bholley

import sys
import re
import fileinput

def process(lines):

  # Discard the first line.
  lines.pop(0);

  # Read the second line, and extract the author.
  author = re.sub(r'^From: (.*)$', r'# User \1', lines.pop(0))

  # Discard the third line.
  lines.pop(0)

  # Read the subject line, filtering out the gunk and unwrapping.
  subject = re.sub(r'^Subject: (.*)', r'\1', lines.pop(0))
  nextline = lines.pop(0)
  while nextline[0] == ' ':
    subject = subject.rstrip('\n') + nextline
    nextline = lines.pop(0)

  # Filter a version (ie, v3, v12) out of the subject.
  subject = re.sub(r'\s?v\d\d?', '', subject)

  # Write the header.
  lines.insert(0, subject)
  lines.insert(0, '\n')
  lines.insert(0, author)
  lines.insert(0, '# HG changeset patch\n')

if __name__ == "__main__":

  # If there were no arguments, do stdin->stdout.
  filelist = sys.argv[1:]
  if not filelist:
    lines = sys.stdin.readlines()
    process(lines)
    sys.stdout.writelines(lines)
    sys.exit(0)

  # Otherwise, we take a list of files.
  for filename in filelist:

    # Read the lines.
    f = open(filename, 'r')
    lines = f.readlines()
    f.close()

    # Process.
    process(lines)

    # Write them back to the same file.
    f = open(filename, 'w')
    f.writelines(lines)
    f.close()