Centers banner comments in CS227 programs

center_banners.py

#!/usr/bin/python3

"""
This script finds all banner comments in a Howell (CS227) program and perfectly
centers them, so you won't get any points off on your programs for that.
Prints out the contents of the program just to be safe.

Andrew Teesdale, Jr. (f40c40.com)
"""
import sys

MAX_WIDTH     = 72
BANNER_MARKER = "/"+ ("*" * (MAX_WIDTH - 2)) + "/"

# Banner matcher states
NONE_MATCHED  = 0
OPEN          = 1
CLOSE         = 2

if __name__ == "__main__":
   if len(sys.argv) != 2:
      print("error: Provide at least one file to center")
      sys.exit(1)
   f = open(sys.argv[1], "r")
   
   line_no      = 0  # The current line being read
   banner_lines = [] # The lines center properly
   match_state  = NONE_MATCHED
                     # The current state of the banner matcher
   banner_count = 0

   # Loop marking banner comments and tracking which lines their content
   # is on
   lines = f.readlines()
   for line in lines:
      # Banner comment state machine
      if line.strip() == BANNER_MARKER:
         if match_state == NONE_MATCHED:
            match_state = OPEN
         elif match_state == OPEN:
            match_state   = CLOSE
            banner_count += 1
         elif match_state == CLOSE:
            match_state = OPEN
         else:
            pass
      elif match_state == OPEN:
         if banner_count >= 3:
            lines[line_no] = \
               "/*" + lines[line_no][2:-3].strip().center(MAX_WIDTH - 4) + "*/\n"
      else:
         pass
      
      line_no += 1
   print("".join(lines))
   f.close()