Demonstration of Python standard library textwrap module.

wrap_text.py

#!/usr/bin/env python3

"""
Demonstration of Python standard library textwrap module.

Run "python3 wrap_test.py -h" for command-line options.
"""

import argparse
import sys
import textwrap

def parse_command_line():
  """Parse command line arguments, returning a namespace of argument values."""
  argp = argparse.ArgumentParser(
    description="Wraps text into lines of specified length",
    epilog="See the documentation of the Python argparse module for more info."
  )

  argp.add_argument('filepath', nargs='*',
    help="path to input file (default: standard input)"
  )
  argp.add_argument('-w', '--width',
    type=int, metavar="N", default=70,
    help="maximum length of wrapped lines (default: %(default)s)",
  )
  argp.add_argument('--max-lines', metavar="N", type=int, default=None,
    help="if set, then the output will contain at most this many lines"
  )
  argp.add_argument('--placeholder', metavar="TEXT", default=" [...]",
    help="string that will appear at end of output text if truncated (default: \"%(default)s\")"
  )
  argp.add_argument('--expand-tabs',
    action=argparse.BooleanOptionalAction, default=True,
    help="if true, all tab characters will be expanded to spaces"
  )
  argp.add_argument('--tabsize',
    type=int, metavar="N", default='8',
    help="number of spaces tabs are expanded to if --expand-tabs is set (default: %(default)s)"
  )
  argp.add_argument('--replace-whitespace',
    action=argparse.BooleanOptionalAction, default=True,
    help="after tab expansion, replace each whitespace character with a single space"
  )
  argp.add_argument('--drop-whitespace',
    action=argparse.BooleanOptionalAction, default=True,
    help=" if true, whitespace at the beginning and ending of every line is dropped"
  )
  argp.add_argument('--initial-indent',
    metavar="TEXT", default='',
    help="prefix for first line of wrapped output",
  )
  argp.add_argument('--subsequent-indent',
    metavar="TEXT", default='',
    help="prefix for all lines except the first"
  )
  argp.add_argument('--fix-sentence-endings',
    action=argparse.BooleanOptionalAction, default=False,
    help="if true, ensure sentences are always separated by two spaces"
  )
  argp.add_argument('--break-long-words',
    action=argparse.BooleanOptionalAction, default=True,
    help="if true, then words longer than --width will be broken"
  )
  argp.add_argument('--break-on-hyphens',
    action=argparse.BooleanOptionalAction, default=True,
    help="if true, wrap on whitespace and after hyphens in compound words"
  )

  return argp.parse_args()


def wrap_and_print(text, args):
  """Apply text-wrapping to the given text according to the command-line
  options, then print the result.
  """
  lines = textwrap.wrap(text,
    width=args.width,
    initial_indent=args.initial_indent,
    subsequent_indent=args.subsequent_indent,
    expand_tabs=args.expand_tabs,
    tabsize=args.tabsize,
    replace_whitespace=args.replace_whitespace,
    fix_sentence_endings=args.fix_sentence_endings,
    break_long_words=args.break_long_words,
    break_on_hyphens=args.break_on_hyphens,
    drop_whitespace=args.drop_whitespace,
    max_lines=args.max_lines,
    placeholder=args.placeholder,
  )

  for line in lines:
    print(line)


def main():
  """Main entry point."""
  args = parse_command_line()

  if len(args.filepath) > 0:
    # Process list of input files
    for path in args.filepath:
      with open(path, 'r') as f:
        text = f.read()
        wrap_and_print(text, args)
  else:
    # No filepaths given on command line, so read standard input
    text = sys.stdin.read()
    wrap_and_print(text, args)


if __name__ == '__main__':
  main()