Bazaar's patience diff as GIT_EXTERNAL_DIFF

[Adeodato Simó <dato@xxxxxxxxxxxxxx>]

* Jeff King [Fri, 02 Jan 2009 14:39:04 -0500]:

> If you just want to see the results on some real-world cases (and don't
> care about measuring performance), try installing bzr and using their
> patiencediff test program as a GIT_EXTERNAL_DIFF.

> On Debian, it's:

>   $ sudo apt-get install bzr
>   $ cat >$HOME/patience <<'EOF'
>     #!/bin/sh
>     exec python /usr/share/pyshared/bzrlib/patiencediff.py "$2" "$5"
>     EOF
>   $ chmod 755 patience
>   $ GIT_EXTERNAL_DIFF=$HOME/patience git diff

In case somebody's interested, I have this script lying around that does
that, and knows how to colorize the output using bzrtools, and honoring
color.{diff,ui}. No support for color.diff.<slot>, though.

-- 
Adeodato Simó                                     dato at net.com.org.es
Debian Developer                                  adeodato at debian.org
 
- Oh my God, you're pimping me out for a new roof?
- And windows!
                -- Andrew and Bree Van De Kamp

#! /usr/bin/python

import os
import sys
import stat
import subprocess

from bzrlib.patiencediff import unified_diff, PatienceSequenceMatcher
try:
    from bzrlib.plugins.bzrtools.colordiff import DiffWriter
except ImportError:
    _have_colordiff = False
else:
    _have_colordiff = True

##

def main():
    path = sys.argv[1]
    file1 = open(sys.argv[2], 'rb')
    file2 = open(sys.argv[5], 'rb')

    if use_color():
        writer = DiffWriter(sys.stdout, check_style=True)
    else:
        writer = sys.stdout

    for line in unified_diff(
            file1.readlines(), file2.readlines(),
            path, path, sequencematcher=PatienceSequenceMatcher):
        writer.write(line)

##

def use_color():
    if not _have_colordiff:
        return False

    for c in ['color.diff', 'color.ui']:
        p = subprocess.Popen(
                ['git', 'config', '--get', c], stdout=subprocess.PIPE)
        if p.wait() == 0:
            when = p.stdout.readline().strip()
            break
    else:
        return False

    if when == 'always':
        return True
    elif when in ['false', 'never']:
        return False
    elif when in ['true', 'auto']:
        stdout = sys.stdout.fileno()
        return (os.isatty(stdout) or
                stat.S_ISFIFO(os.fstat(sys.stdout.fileno()).st_mode))
    else:
        return False

##

if __name__ == '__main__':
    sys.exit(main())