source: misc/tictac.py @ 37:f34e74fdbd0e

#!/usr/bin/env python
#
# tictac.py
# http://mornie.org/code/browser/misc/tictac.py
#
# Copyright (C) 2007  Daniele Tricoli aka Eriol <eriol@mornie.org>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
#
# A present for crash ;)
##

import atexit
import os.path
import StringIO

from optparse import OptionParser
from sys import stdin, stdout

def backread(afile, buffer_size=1024):

    afile.seek(0, 2)
    eof = afile.tell()

    seek_positon = range(eof, 0, -buffer_size) + [0]
    blocks_size = [buffer_size for _ in range(len(seek_positon) - 1)]
    blocks_size.append(seek_positon[-2])

    blocks = zip(seek_positon, blocks_size)

    for pos, size in blocks:
        afile.seek(pos)
        data = afile.read(size)
        yield ''.join(reversed(data))

def _print(data):
    for l in backread(data):
        stdout.write(l)
    stdout.write('\n')

def main():
    interactive = False
    data = StringIO.StringIO()
    usage = '''usage: %prog [FILE]

    With no FILE read standard input
'''
    parser = OptionParser(usage)
    (options, args) = parser.parse_args()

    if len(args) < 1:
        interactive = True
    elif not os.path.isfile(args[0]):
        parser.error('No such file')

    if interactive:
        while True:
            line = stdin.readline()
            if not line: break
            data.write(line)
        atexit.register(_print, data)
    else:
        fin = open(args[0], 'r')
        try:
            _print(fin)
        finally:
            fin.close()

if __name__ == '__main__':
    main()