Convert .h files using ifdef guard to use pragma once

ifdef_guard_to_pragma_once.py

#!/usr/bin/python

import sys
import os
import tempfile
import re

starts_with_ifndef = re.compile(r'^\s*#ifndef.*\n#define.*\n')
ends_with_endif = re.compile(r'#endif.*$')


def topragmaonce(filename):
    "topragmaonce will remove #ifndef...#endif guard, and put #pragma once instead"
    tmp = tempfile.NamedTemporaryFile(delete=False)
    with open(filename, 'r') as fp:
        data = fp.read()
    if not starts_with_ifndef.match(data):
        return
    data = starts_with_ifndef.sub('', data)
    data = ends_with_endif.sub('', data)
    tmp.write('#pragma once\n')
    tmp.write(data)
    tmp.close()
    os.rename(tmp.name, filename)


for arg in sys.argv[1:]:
    topragmaonce(arg)