gsh/host_syntax.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2006, 2007, 2008 Guillaume Chazarain <guichaz@gmail.com>
  18
  19 import re
  20
  21 # Currently the only expansion is <START_NUMBER-END_NUMBER>
  22 # <1-10> => 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
  23 # <10-1> => 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
  24 # <01-10> => 01, 02, 03, 04, 05, 06, 07, 08, 09, 10
  25 # <1-4,6-10> => 1, 2, 3, 4, 6, 7, 8, 9, 10
  26
  27 syntax_pattern = re.compile('<([0-9,-]+)>')
  28 interval_pattern = re.compile('([0-9]+)-([0-9]+)')
  29
  30 def _iter_numbers(start, end):
  31     if int(start) < int(end):
  32         increment = 1
  33     else:
  34         increment = -1
  35     zero_pad = start.startswith('0') or end.startswith('0')
  36     if zero_pad:
  37         length = max(len(start), len(end))
  38     for i in xrange(int(start), int(end) + increment, increment):
  39         s = str(i)
  40         if zero_pad:
  41             s = '0' * (length - len(s)) + s
  42         yield s
  43
  44 def expand_syntax(string):
  45     """Iterator over all the strings in the expansion of the argument"""
  46     match = syntax_pattern.search(string)
  47     if match:
  48         prefix = string[:match.start()]
  49         suffix = string[match.end():]
  50         intervals = match.group(1).split(',')
  51         for interval in intervals:
  52             interval_match = interval_pattern.match(interval)
  53             if interval_match:
  54                 start = interval_match.group(1)
  55                 end = interval_match.group(2)
  56                 for i in _iter_numbers(start, end):
  57                     for expanded in expand_syntax(prefix + i + suffix):
  58                         yield expanded
  59     else:
  60         yield string