git-visualize

#!/usr/bin/env python3
# show the entire history of a Git repo as a colored tree in the terminal
import re, signal, subprocess, sys

def process_lines(lines, out):
    starred_col = None
    for line in lines:
        plain_line = re.sub(r"\x1b\[[\d;]*m", "", line)
        m = re.match(r"(\| *)+$", plain_line)
        if m:
            if (starred_col is None
                or plain_line[starred_col:starred_col + 1] == "|"):
                continue
        out.write(line)
        plain_head, = re.match(r"([\|* ]*)", plain_line).groups()
        starred_col = plain_head.index("*") if "*" in plain_head else None

git_version = subprocess.check_output(["git", "--version"],
                                      universal_newlines=True)
git_version = re.search("(\d+)\.(\d+)\.(\d+)", git_version).groups()
git_version = tuple(map(int, git_version))

def col(s):
    if s == "auto":
        # %C(auto) is only supported on git >= 1.8.3
        return "%C(auto)" if git_version >= (1, 8, 3) else ""
    return "%C{}".format(s)

# the %n introduces a gap between each entry,
# but most of them gets removed by the filter
# except gaps that occur between disjoint components
fmt = "{}%h {}%ad{}{}%d %s%n".format(
    col("auto"), col("green"), col("reset"), col("auto"))

signal.signal(signal.SIGPIPE, signal.SIG_DFL)

args = sys.argv[1:] or ["--all"]
git = subprocess.Popen(["git", "log", "--color",
                         "--date=short", "--decorate", "--full-history",
                         "--graph", "--pretty=format:" + fmt] +
                        args,
                        stdout=subprocess.PIPE,
                        universal_newlines=True)
try:
    less = subprocess.Popen(["less", "-R"],
                            stdin=subprocess.PIPE,
                            universal_newlines=True)
    while True:
        try:
            process_lines(git.stdout, less.stdin)
            less.stdin.close()
            less.wait()
            break
        except KeyboardInterrupt:
            # SIGINT is not fatal to less so we need to keep going
            less.send_signal(getattr(signal, "SIGINT", signal.SIGTERM))
        except:
            less.stdin.close()
            less.terminate()
            less.wait()
            raise
except:
    git.terminate()
    git.wait()
    raise