util/filters.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8
   9 local t_insert, t_remove = table.insert, table.remove;
  10
  11 module "filters"
  12
  13 function initialize(session)
  14         local filters = {};
  15         session.filters = filters;
  16
  17         function session.filter(type, data)
  18                 local filter_list = filters[type];
  19                 for i = 1, #filter_list do
  20                         data = filter_list[i](data);
  21                 end
  22                 return data;
  23         end
  24 end
  25
  26 function add_filter(session, type, callback, priority)
  27         if not session.filters then
  28                 initialize(session);
  29         end
  30
  31         local filter_list = session.filters[type];
  32         if not filter_list then
  33                 filter_list = {};
  34                 session.filters[type] = filter_list;
  35         end
  36
  37         priority = priority or 0;
  38
  39         local i = 0;
  40         repeat
  41                 i = i + 1;
  42         until not filter_list[i] or filter_list[filter_list[i]] >= priority;
  43
  44         t_insert(filter_list, i, callback);
  45         filter_list[callback] = priority;
  46 end
  47
  48 function remove_filter(session, type, callback)
  49         if not session.filters then return; end
  50         local filter_list = session.filters[type];
  51         if filter_list and filter_list[callback] then
  52                 for i=1, #filter_list do
  53                         if filter_list[i] == callback then
  54                                 t_remove(filter_list, i);
  55                                 filter_list[callback] = nil;
  56                                 return true;
  57                         end
  58                 end
  59         end
  60 end
  61
  62 return _M;