#!/usr/bin/env python
import fileinput, optparse, sys

# Command-line parser
parser = optparse.OptionParser(
        usage="""
%prog [options] [files]
Expand tab to spaces, printing to the standard output by default.
When no files are given, read from the standard input.

Examples:
 expand in one file
    % expand_tabs.py -t 4 file.txt

 expand tabs in Python source files
    % find . -name "*.py" | xargs expand_tabs.py -it 4
""".strip(),
        formatter=optparse.IndentedHelpFormatter(max_help_position=30)
    )
parser.add_option("-t", "--tabsize", type="int", metavar="SIZE")
parser.add_option("-i", "--inplace", action="store_true", help="change the files in-place (don't print)")
parser.add_option("-b", "--backupext", default="", metavar="EXT", help="backup extension to use (default: no backup)")

options, args = parser.parse_args()
if options.tabsize is None:
    parser.error("tab size not specified")

# Do the work
for line in fileinput.input(files=args, inplace=options.inplace, backup=options.backupext):
    sys.stdout.write( line.expandtabs(options.tabsize) )
