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         if not session.filters then
  15                 local filters = {};
  16                 session.filters = filters;
  17
  18                 function session.filter(type, data)
  19                         local filter_list = filters[type];
  20                         if filter_list then
  21                                 for i = 1, #filter_list do
  22                                         data = filter_list[i](data);
  23                                         if data == nil then break; end
  24                                 end
  25                         end
  26                         return data;
  27                 end
  28         end
  29         return session.filter;
  30 end
  31
  32 function add_filter(session, type, callback, priority)
  33         if not session.filters then
  34                 initialize(session);
  35         end
  36
  37         local filter_list = session.filters[type];
  38         if not filter_list then
  39                 filter_list = {};
  40                 session.filters[type] = filter_list;
  41         end
  42
  43         priority = priority or 0;
  44
  45         local i = 0;
  46         repeat
  47                 i = i + 1;
  48         until not filter_list[i] or filter_list[filter_list[i]] >= priority;
  49
  50         t_insert(filter_list, i, callback);
  51         filter_list[callback] = priority;
  52 end
  53
  54 function remove_filter(session, type, callback)
  55         if not session.filters then return; end
  56         local filter_list = session.filters[type];
  57         if filter_list and filter_list[callback] then
  58                 for i=1, #filter_list do
  59                         if filter_list[i] == callback then
  60                                 t_remove(filter_list, i);
  61                                 filter_list[callback] = nil;
  62                                 return true;
  63                         end
  64                 end
  65         end
  66 end
  67
  68 return _M;