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                 if filter_list then
  20                         for i = 1, #filter_list do
  21                                 data = filter_list[i](data);
  22                         end
  23                 end
  24                 return data;
  25         end
  26 end
  27
  28 function add_filter(session, type, callback, priority)
  29         if not session.filters then
  30                 initialize(session);
  31         end
  32
  33         local filter_list = session.filters[type];
  34         if not filter_list then
  35                 filter_list = {};
  36                 session.filters[type] = filter_list;
  37         end
  38
  39         priority = priority or 0;
  40
  41         local i = 0;
  42         repeat
  43                 i = i + 1;
  44         until not filter_list[i] or filter_list[filter_list[i]] >= priority;
  45
  46         t_insert(filter_list, i, callback);
  47         filter_list[callback] = priority;
  48 end
  49
  50 function remove_filter(session, type, callback)
  51         if not session.filters then return; end
  52         local filter_list = session.filters[type];
  53         if filter_list and filter_list[callback] then
  54                 for i=1, #filter_list do
  55                         if filter_list[i] == callback then
  56                                 t_remove(filter_list, i);
  57                                 filter_list[callback] = nil;
  58                                 return true;
  59                         end
  60                 end
  61         end
  62 end
  63
  64 return _M;