util/events.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
  10 local pairs = pairs;
  11 local t_insert = table.insert;
  12 local t_sort = table.sort;
  13 local setmetatable = setmetatable;
  14 local next = next;
  15
  16 module "events"
  17
  18 function new()
  19         local handlers = {};
  20         local global_wrappers;
  21         local wrappers = {};
  22         local event_map = {};
  23         local function _rebuild_index(handlers, event)
  24                 local _handlers = event_map[event];
  25                 if not _handlers or next(_handlers) == nil then return; end
  26                 local index = {};
  27                 for handler in pairs(_handlers) do
  28                         t_insert(index, handler);
  29                 end
  30                 t_sort(index, function(a, b) return _handlers[a] > _handlers[b]; end);
  31                 handlers[event] = index;
  32                 return index;
  33         end;
  34         setmetatable(handlers, { __index = _rebuild_index });
  35         local function add_handler(event, handler, priority)
  36                 local map = event_map[event];
  37                 if map then
  38                         map[handler] = priority or 0;
  39                 else
  40                         map = {[handler] = priority or 0};
  41                         event_map[event] = map;
  42                 end
  43                 handlers[event] = nil;
  44         end;
  45         local function remove_handler(event, handler)
  46                 local map = event_map[event];
  47                 if map then
  48                         map[handler] = nil;
  49                         handlers[event] = nil;
  50                         if next(map) == nil then
  51                                 event_map[event] = nil;
  52                         end
  53                 end
  54         end;
  55         local function get_handlers(event)
  56                 return handlers[event];
  57         end;
  58         local function add_handlers(handlers)
  59                 for event, handler in pairs(handlers) do
  60                         add_handler(event, handler);
  61                 end
  62         end;
  63         local function remove_handlers(handlers)
  64                 for event, handler in pairs(handlers) do
  65                         remove_handler(event, handler);
  66                 end
  67         end;
  68         local function _fire_event(event_name, event_data)
  69                 local h = handlers[event_name];
  70                 if h then
  71                         for i=1,#h do
  72                                 local ret = h[i](event_data);
  73                                 if ret ~= nil then return ret; end
  74                         end
  75                 end
  76         end;
  77         local function fire_event(event_name, event_data)
  78                 local w = wrappers[event_name] or global_wrappers;
  79                 if w then
  80                         local curr_wrapper = #w;
  81                         local function c(event_name, event_data)
  82                                 curr_wrapper = curr_wrapper - 1;
  83                                 if curr_wrapper == 0 then
  84                                         if global_wrappers == nil or w == global_wrappers then
  85                                                 return _fire_event(event_name, event_data);
  86                                         end
  87                                         w, curr_wrapper = global_wrappers, #global_wrappers;
  88                                         return w[curr_wrapper](c, event_name, event_data);
  89                                 else
  90                                         return w[curr_wrapper](c, event_name, event_data);
  91                                 end
  92                         end
  93                         return w[curr_wrapper](c, event_name, event_data);
  94                 end
  95                 return _fire_event(event_name, event_data);
  96         end
  97         local function add_wrapper(event_name, wrapper)
  98                 local w;
  99                 if event_name == false then
 100                         w = global_wrappers;
 101                         if not w then
 102                                 w = {};
 103                                 global_wrappers = w;
 104                         end
 105                 else
 106                         w = wrappers[event_name];
 107                         if not w then
 108                                 w = {};
 109                                 wrappers[event_name] = w;
 110                         end
 111                 end
 112                 w[#w+1] = wrapper;
 113         end
 114         local function remove_wrapper(event_name, wrapper)
 115                 local w;
 116                 if event_name == false then
 117                         w = global_wrappers;
 118                 else
 119                         w = wrappers[event_name];
 120                 end
 121                 if not w then return; end
 122                 for i = #w, 1 do
 123                         if w[i] == wrapper then
 124                                 table.remove(w, i);
 125                         end
 126                 end
 127                 if #w == 0 then
 128                         if event_name == nil then
 129                                 global_wrappers = nil;
 130                         else
 131                                 wrappers[event_name] = nil;
 132                         end
 133                 end
 134         end
 135         return {
 136                 add_handler = add_handler;
 137                 remove_handler = remove_handler;
 138                 add_handlers = add_handlers;
 139                 remove_handlers = remove_handlers;
 140                 get_handlers = get_handlers;
 141                 wrappers = {
 142                         add_handler = add_wrapper;
 143                         remove_handler = remove_wrapper;
 144                 };
 145                 add_wrapper = add_wrapper;
 146                 remove_wrapper = remove_wrapper;
 147                 fire_event = fire_event;
 148                 _handlers = handlers;
 149                 _event_map = event_map;
 150         };
 151 end
 152
 153 return _M;