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 local _ENV = nil;
  12 -- luacheck: std none
  13
  14 local new_filter_hooks = {};
  15
  16 local function initialize(session)
  17         if not session.filters then
  18                 local filters = {};
  19                 session.filters = filters;
  20
  21                 function session.filter(type, data)
  22                         local filter_list = filters[type];
  23                         if filter_list then
  24                                 for i = 1, #filter_list do
  25                                         data = filter_list[i](data, session);
  26                                         if data == nil then break; end
  27                                 end
  28                         end
  29                         return data;
  30                 end
  31         end
  32
  33         for i=1,#new_filter_hooks do
  34                 new_filter_hooks[i](session);
  35         end
  36
  37         return session.filter;
  38 end
  39
  40 local function add_filter(session, type, callback, priority)
  41         if not session.filters then
  42                 initialize(session);
  43         end
  44
  45         local filter_list = session.filters[type];
  46         if not filter_list then
  47                 filter_list = {};
  48                 session.filters[type] = filter_list;
  49         elseif filter_list[callback] then
  50                 return; -- Filter already added
  51         end
  52
  53         priority = priority or 0;
  54
  55         local i = 0;
  56         repeat
  57                 i = i + 1;
  58         until not filter_list[i] or filter_list[filter_list[i]] < priority;
  59
  60         t_insert(filter_list, i, callback);
  61         filter_list[callback] = priority;
  62 end
  63
  64 local function remove_filter(session, type, callback)
  65         if not session.filters then return; end
  66         local filter_list = session.filters[type];
  67         if filter_list and filter_list[callback] then
  68                 for i=1, #filter_list do
  69                         if filter_list[i] == callback then
  70                                 t_remove(filter_list, i);
  71                                 filter_list[callback] = nil;
  72                                 return true;
  73                         end
  74                 end
  75         end
  76 end
  77
  78 local function add_filter_hook(callback)
  79         t_insert(new_filter_hooks, callback);
  80 end
  81
  82 local function remove_filter_hook(callback)
  83         for i=1,#new_filter_hooks do
  84                 if new_filter_hooks[i] == callback then
  85                         t_remove(new_filter_hooks, i);
  86                 end
  87         end
  88 end
  89
  90 return {
  91         initialize = initialize;
  92         add_filter = add_filter;
  93         remove_filter = remove_filter;
  94         add_filter_hook = add_filter_hook;
  95         remove_filter_hook = remove_filter_hook;
  96 };