linecleaner.py

#!/usr/bin/env python

# Add this to: .git/hooks/pre-commit
# if ! git diff-index --check $against > /dev/null 2>&1; then 
#     git diff --cached --name-status | $(HOME)/bin/linecleaner.py
# fi

import sys
import re
import fileinput
import subprocess

files = []

for line in sys.stdin:
    if line[0] in ('A', 'M'):
        files.append(line[2:-1])

def edited_line_numbers(contents):
    for line in contents.split('\n'):
        if line.startswith('0000000000000000000000000000000000000000'):
            tokens = line.split(' ')
            yield int(tokens[2]) - 1

for f in files:
    contents = subprocess.Popen(['git', 'blame', '-p', '--line-porcelain', f],
                                stdout=subprocess.PIPE).stdout.read()
    line_numbers = set(edited_line_numbers(contents))
    for number, line in enumerate(fileinput.input(f, inplace=1)):
        if number in line_numbers:
            match = re.match('(.*?)\s+$', line)
            if match:
                sys.stdout.write(match.group(1))
                if line.endswith('\n'):
                    sys.stdout.write('\n')
            else:
                sys.stdout.write(line)
        else:
            sys.stdout.write(line)