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 local _ENV = nil;
  18
  19 local 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 get_handlers(event)
  57                 return handlers[event];
  58         end;
  59         local function add_handlers(handlers)
  60                 for event, handler in pairs(handlers) do
  61                         add_handler(event, handler);
  62                 end
  63         end;
  64         local function remove_handlers(handlers)
  65                 for event, handler in pairs(handlers) do
  66                         remove_handler(event, handler);
  67                 end
  68         end;
  69         local function _fire_event(event_name, event_data)
  70                 local h = handlers[event_name];
  71                 if h then
  72                         for i=1,#h do
  73                                 local ret = h[i](event_data);
  74                                 if ret ~= nil then return ret; end
  75                         end
  76                 end
  77         end;
  78         local function fire_event(event_name, event_data)
  79                 local w = wrappers[event_name] or global_wrappers;
  80                 if w then
  81                         local curr_wrapper = #w;
  82                         local function c(event_name, event_data)
  83                                 curr_wrapper = curr_wrapper - 1;
  84                                 if curr_wrapper == 0 then
  85                                         if global_wrappers == nil or w == global_wrappers then
  86                                                 return _fire_event(event_name, event_data);
  87                                         end
  88                                         w, curr_wrapper = global_wrappers, #global_wrappers;
  89                                         return w[curr_wrapper](c, event_name, event_data);
  90                                 else
  91                                         return w[curr_wrapper](c, event_name, event_data);
  92                                 end
  93                         end
  94                         return w[curr_wrapper](c, event_name, event_data);
  95                 end
  96                 return _fire_event(event_name, event_data);
  97         end
  98         local function add_wrapper(event_name, wrapper)
  99                 local w;
 100                 if event_name == false then
 101                         w = global_wrappers;
 102                         if not w then
 103                                 w = {};
 104                                 global_wrappers = w;
 105                         end
 106                 else
 107                         w = wrappers[event_name];
 108                         if not w then
 109                                 w = {};
 110                                 wrappers[event_name] = w;
 111                         end
 112                 end
 113                 w[#w+1] = wrapper;
 114         end
 115         local function remove_wrapper(event_name, wrapper)
 116                 local w;
 117                 if event_name == false then
 118                         w = global_wrappers;
 119                 else
 120                         w = wrappers[event_name];
 121                 end
 122                 if not w then return; end
 123                 for i = #w, 1 do
 124                         if w[i] == wrapper then
 125                                 t_remove(w, i);
 126                         end
 127                 end
 128                 if #w == 0 then
 129                         if event_name == nil then
 130                                 global_wrappers = nil;
 131                         else
 132                                 wrappers[event_name] = nil;
 133                         end
 134                 end
 135         end
 136         return {
 137                 add_handler = add_handler;
 138                 remove_handler = remove_handler;
 139                 add_handlers = add_handlers;
 140                 remove_handlers = remove_handlers;
 141                 get_handlers = get_handlers;
 142                 wrappers = {
 143                         add_handler = add_wrapper;
 144                         remove_handler = remove_wrapper;
 145                 };
 146                 add_wrapper = add_wrapper;
 147                 remove_wrapper = remove_wrapper;
 148                 fire_event = fire_event;
 149                 _handlers = handlers;
 150                 _event_map = event_map;
 151         };
 152 end
 153
 154 return {
 155         new = new;
 156 };