#	tabfix.py              by Joe Strout
#
#	converts a file built with 4-space tabs into a
#	similar file made with 8-space tabs and strings of 4 spaces.

import sys
import string
import regex

TAB = '\t'
endspace = regex.compile('  * $')

def fixTabs(str):
	# first, replace all tabs with spaces
	str = string.expandtabs(str,4)	# assuming 4-space tabs

	# now collapse spaces to tabs, where possible
	tabsize = 8
	col = (len(str)/tabsize)*tabsize
	while col >= 0:
		# check for at least spaces ending before the next tab stop;
		# if found, replace with tabs
		pos = col + endspace.search( str[col:col+tabsize] )
		if pos >= col:
			str = str[:pos] + TAB + str[col+tabsize:]
		col = col - tabsize
	return str


def processFile(filename):

	try:
		file = open( filename, 'r' )	# open the file
	except:
		print "Error opening",filename
		return
		
	lines = file.readlines()			# read it
	for i in range(0,len(lines)):		# process it...
		lines[i] = fixTabs(lines[i])
	file = open( filename, 'w' )		# open it again
	file.writelines(lines)				# write it

	print len(lines), "lines processed in",filename

# end of processFile() function

def run(filename=''):
	if filename=='':
		filename = raw_input('Enter name of a textfile to read: ')

	processFile(filename)
	
# end of run() function

# immediate-mode commands, for drag-and-drop or execfile() execution
if __name__ == '__main__':
	if len(sys.argv) == 2:
		processFile(sys.argv[1])		# accept a command-line filename
	else:
		run()
	print
	raw_input("press Return>")
else:
	print "Module tabfix imported."
	print "To run, type: tabfix.run()"
	print "To reload after changes to the source, type: reload(tabfix)"

# end of tabfix.py