command_parser.py

import argparse
import os
import string
import sys

from itertools import chain


def clean_words(readlines):
	'''
		list -> list of str
		
		Remove the punctuation from input list: readlines.
		
	'''

	cleaned = []
	for line in readlines:
		for word in line.split():
			cleaned.append((word.strip(string.punctuation) + ' '))
	return cleaned


class ParserResult:
	"""docstring for ClassName"""
	

	def __init__(self, input_file):
		self._input_file = input_file


	def output_file(self, filename, input_file):
		'''
			str, list -> None
			
			Outputs a file with given content and the name given if
			the file does not exists, otherwise prints an error message.

		'''

		if os.path.exists(filename):
			sys.stdout.write('The file already exists, cannot be created!\n')
			sys.exit()
		else:
			_output_file = file('{}'.format(filename), 'wt')
			[_output_file.write(i) for i in input_file]
			_output_file.close()


	def sort_file(self):
		'''
			file -> list

			Read the input file in a list and return the sorted version of it.
		'''
		try:		
			#  added method for testcase, when a file-like object it's used instead
			#  of a real file.
			return sorted(clean_words(self._input_file),
							key=lambda s:s.lower())		
		except AttributeError:
			with self._input_file as f:
				return sorted(clean_words(f.readlines()),
								key=lambda s: s.lower())


	def sort_lines(self):
		pass


	def sort_lines_and_words(self):
		pass


def main():

	parser = argparse.ArgumentParser(description='''Takes in
									as an argument the name of a file.''')

	parser.add_argument('sort', type=argparse.FileType('r'),
						help='''Output the lines from file 
						in sorted alphabetical order.''')

	parser.add_argument('-r', '--reversed', action='store_true', help='''Output the
						lines in reversed order.''')

	parser.add_argument('-o', '--output', type=str, help='''Output
						the result in a new file''')

	args = parser.parse_args()
	results = ParserResult(args.sort)

	if args.reversed:
		if args.output:
			results.output_file(args.output, reversed(results.sort_file()))
			sys.stdout.write('%s is now reversed.\n' % args.output)
		
		else:
			[sys.stdout.write(item) for item in reversed(results.sort_file())]

	elif args.output:
		results.output_file(args.output, results.sort_file())

	else:
		output = chain(results.sort_file())
		try:
			while True:
				sys.stdout.write(output.next())
		except StopIteration:
			sys.stdout.write('\n')


if __name__ == '__main__':
	main()