polysh/display_names.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) 2008 Guillaume Chazarain <guichaz@gmail.com>
  18
  19 from polysh.rb_tree import RBTree
  20
  21 # {'prefix': <display_name_prefix object>}
  22 PREFIXES = {}
  23
  24 # Red/black tree with key:len(display_name) value:nr of enabled shells with a
  25 # display_name of such a length
  26 NR_ENABLED_DISPLAY_NAMES_BY_LENGTH = RBTree()
  27
  28 # Cache the right most element in the NR_ENABLED_DISPLAY_NAMES_BY_LENGTH tree
  29 max_display_name_length = 0
  30
  31 class display_name_prefix(object):
  32     def __init__(self):
  33         self.next_suffix = 0
  34         self.holes = RBTree()
  35
  36     def new_suffix(self):
  37         if len(self.holes) == 0:
  38             suffix = self.next_suffix
  39             self.next_suffix += 1
  40         else:
  41             first_node = self.holes.firstNode()
  42             suffix = first_node.key
  43             self.holes.deleteNode(first_node)
  44         return suffix
  45
  46     def putback_suffix(self, suffix):
  47         if suffix + 1 != self.next_suffix:
  48             self.holes.insertNode(suffix, suffix)
  49             return
  50
  51         self.next_suffix = suffix
  52         while True:
  53             prev_suffix = self.next_suffix - 1
  54             prev_suffix_node = self.holes.findNode(prev_suffix)
  55             if not prev_suffix_node:
  56                 return
  57             self.holes.deleteNode(prev_suffix_node)
  58             self.next_suffix = prev_suffix
  59
  60     def empty(self):
  61         return self.next_suffix == 0
  62
  63 def make_unique_name(prefix):
  64     prefix_obj = PREFIXES.get(prefix, None)
  65     if prefix_obj is None:
  66         prefix_obj = display_name_prefix()
  67         PREFIXES[prefix] = prefix_obj
  68
  69     suffix = prefix_obj.new_suffix()
  70     if suffix:
  71         name = '%s#%d' % (prefix, suffix)
  72     else:
  73         name = prefix
  74
  75     return name
  76
  77 def update_max_display_name_length():
  78     from polysh import dispatchers
  79     if len(NR_ENABLED_DISPLAY_NAMES_BY_LENGTH) == 0:
  80         new_max = 0
  81     else:
  82         new_max = NR_ENABLED_DISPLAY_NAMES_BY_LENGTH.lastNode().key
  83     global max_display_name_length
  84     if new_max != max_display_name_length:
  85         max_display_name_length = new_max
  86         dispatchers.update_terminal_size()
  87
  88 def change(prev_display_name, new_prefix):
  89     if new_prefix and '#' in new_prefix:
  90         raise Exception('Names cannot contain #')
  91
  92     if prev_display_name is not None:
  93         if new_prefix is not None:
  94             set_enabled(prev_display_name, False)
  95         split = prev_display_name.split('#')
  96         prev_prefix = split[0]
  97         if len(split) == 1:
  98             prev_suffix = 0
  99         else:
 100             prev_suffix = int(split[1])
 101         prefix_obj = PREFIXES[prev_prefix]
 102         prefix_obj.putback_suffix(prev_suffix)
 103         if prefix_obj.empty():
 104             del PREFIXES[prev_prefix]
 105         if new_prefix is None:
 106             return
 107
 108     name = make_unique_name(new_prefix)
 109     set_enabled(name, True)
 110
 111     return name
 112
 113 def set_enabled(display_name, enabled):
 114     length = len(display_name)
 115     node = NR_ENABLED_DISPLAY_NAMES_BY_LENGTH.findNode(length)
 116     if enabled:
 117         if node:
 118             node.value += 1
 119         else:
 120             NR_ENABLED_DISPLAY_NAMES_BY_LENGTH.insertNode(length, 1)
 121     else:
 122         node.value -= 1
 123         if not node.value:
 124             NR_ENABLED_DISPLAY_NAMES_BY_LENGTH.deleteNode(node)
 125
 126     update_max_display_name_length()
 127