Scans the local directory if it's a git repository and adds the ID line to all header comments.

versid.py

#!/usr/bin/env python
# ID: versid.py [] benjamin@bengfort.com $

import re
import os
import git
import fileinput


IDRE = re.compile(r'^#\s*ID:\s+([\w\.\-]+)\s+\[([a-f0-8]*)\]\s+([\w\@\.\+\-]*)\s+\$\s*$', re.I)


def versionize(path, branch='master', num_lines=20, modify=False):
    """
    Primary utility for performing the versionization.
    """
    try:
        path = os.path.abspath(path)

        if not os.path.isdir(path):
            raise Exception("'{}' is not a directory!".format(path))

        repo = git.Repo(path)
    except git.InvalidGitRepositoryError:
        raise Exception("'{}' is not a Git repository!".format(path))


    # Construct the path version tree.
    versions = {}
    for commit in repo.iter_commits(branch):
        for blob in commit.tree.traverse():
            versions[blob.abspath] = commit

    # Track required modifications
    output = []

    # Walk the directory path
    for root, dirs, files in os.walk(path):

        # Ignore hidden directories (.git)
        dirs[:] = [d for d in dirs if not d.startswith('.')]

        for name in files:
            name = os.path.join(root, name)
            if name not in versions: continue
            output.append(
                read_head(name, versions[name], maxlines=num_lines)
            )

    # Remove any non-matched files.
    output = filter(None, output)

    # Make the modifications if the args specifies to
    if modify:
        for path, vers in output:
            modify_inplace(path, vers)

    # Return the output
    return [
        "{}  {}".format(path, vers)
        for path, vers in output
    ] if output else ["No files require an ID header."]


def read_head(path, commit, maxlines=None):
    """
    Reads the first maxlines of the file (or all lines if None) and looks
    for the version string. If it exists, it replaces it with the commit
    and author information.
    """

    with open(path, 'r') as f:
        for idx, line in enumerate(f.readlines()):
            if maxlines and idx >= maxlines:
                break

            match = IDRE.match(line)
            if match and not match.groups()[1]:
                vers = "# ID: {} [{}] {} $".format(
                    os.path.basename(path), commit.hexsha[:7], commit.author.email
                )
                return path, vers


def modify_inplace(path, vers):
    """
    Modifies the ID line by writing all lines except the match line.
    """
    matched = False
    for line in fileinput.input(path, inplace=1):
        if not matched and IDRE.match(line):
            matched = True
            sys.stdout.write(vers + "\n")
        else:
            sys.stdout.write(line)