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 # <1,3-6> => 1, 3, 4, 5, 6
  27 # <1> => 1
  28
  29 syntax_pattern = re.compile('<([0-9,-]+)>')
  30 interval_pattern = re.compile('([0-9]+)(-[0-9]+)?')
  31
  32 def _iter_numbers(start, end):
  33     int_start = int(start)
  34     int_end = int(end)
  35     if int_start < int_end:
  36         increment = 1
  37     else:
  38         increment = -1
  39     zero_pad = len(start) > 1 and start.startswith('0') or \
  40                len(end) > 1 and end.startswith('0')
  41     if zero_pad:
  42         length = max(len(start), len(end))
  43     for i in xrange(int_start, int_end + increment, increment):
  44         s = str(i)
  45         if zero_pad:
  46             s = s.zfill(length)
  47         yield s
  48
  49 def expand_syntax(string):
  50     """Iterator over all the strings in the expansion of the argument"""
  51     match = syntax_pattern.search(string)
  52     if match:
  53         prefix = string[:match.start()]
  54         suffix = string[match.end():]
  55         intervals = match.group(1).split(',')
  56         for interval in intervals:
  57             interval_match = interval_pattern.match(interval)
  58             if interval_match:
  59                 start = interval_match.group(1)
  60                 end = (interval_match.group(2) or start).strip('-')
  61                 for i in _iter_numbers(start, end):
  62                     for expanded in expand_syntax(prefix + i + suffix):
  63                         yield expanded
  64     else:
  65         yield string