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