git-branch-tree

#!/usr/bin/env python2

"""
A very slow version of 'git branch' that shows a tree, according
to which branch is an ancestor of which other branch.
"""

import os
import pty
import subprocess as sp
import sys
import re

def main():
    master, slave = pty.openpty()
    cmd = ["git", "branch"] + sys.argv[1:]
    tstP = sp.Popen(cmd,
                    stdin=slave, stdout=slave,
                    stderr=sp.STDOUT, close_fds=True)
    os.close(slave)
    f = os.fdopen(master)
    data = f.read()

    branches = []
    for line in data.splitlines():
        m = re.match(r"^([ *]+)([\x1b][\[][^m]+m)?([^\x1b]*)([\x1b][\[][^m]*m)?$", line)
        (prefix, ansi1, branch_name, ansi2) = m.groups()
        if not ansi2:
            ansi2 = ""
        if not ansi1:
            ansi1 = ""
        branches.append((branch_name, (prefix, ansi1, ansi2), []))

    xbranches = []
    for (branch_name, info, lst) in list(branches):
        parents = []
        for (other_branch_name, _, _) in branches:
            if other_branch_name != branch_name:
                cmd = "git merge-base --is-ancestor %s %s" % (other_branch_name, branch_name)
                r = os.system(cmd)
                if r == 0:
                    f = os.popen("git log %s..%s --oneline | wc -l" % (other_branch_name, branch_name), "r")
                    distance = int(f.read())
                    parents.append((distance, other_branch_name))
        if not parents:
            xbranches.append((branch_name, info, lst))
        else:
            parents.sort()
            for (other_branch_name, _, other_lst) in list(branches):
                if other_branch_name == parents[0][1]:
                    other_lst.append((branch_name, info, lst))
                    break

    def f(lst, level):
        for (branch_name, (prefix, ansi1, ansi2), subs) in lst:
            print prefix + level + ansi1 + branch_name + ansi2
            if subs:
                f(subs, level = level + "  ")

    f(xbranches, level="")

if __name__ == "__main__":
    main()