util.events: Add support for event wrappers, functions which can wrap the calling...

diff --git a/util/events.lua b/util/events.lua
index 40ca39131240c2f9c906021e3fe5a6886361a01d..d5a7359c28b0a4378f2f7bb1002ac9017e8cd008 100644 (file)
--- a/util/events.lua
+++ b/util/events.lua
@@ -17,6 +17,8 @@ module "events"
 
 function new()
        local handlers = {};
+       local global_wrappers;
+       local wrappers = {};
        local event_map = {};
        local function _rebuild_index(handlers, event)
                local _handlers = event_map[event];
@@ -60,7 +62,7 @@ function new()
                        remove_handler(event, handler);
                end
        end;
-       local function fire_event(event_name, event_data)
+       local function _fire_event(event_name, event_data)
                local h = handlers[event_name];
                if h then
                        for i=1,#h do
@@ -69,11 +71,75 @@ function new()
                        end
                end
        end;
+       local function fire_event(event_name, event_data)
+               local w = wrappers[event_name] or global_wrappers;
+               if w then
+                       local curr_wrapper = #w;
+                       local function c(event_name, event_data)
+                               curr_wrapper = curr_wrapper - 1;
+                               if curr_wrapper == 0 then
+                                       if global_wrappers == nil or w == global_wrappers then
+                                               return _fire_event(event_name, event_data);
+                                       end
+                                       w, curr_wrapper = global_wrappers, #global_wrappers;
+                                       return w[curr_wrapper](c, event_name, event_data);
+                               else
+                                       return w[curr_wrapper](c, event_name, event_data);
+                               end
+                       end
+                       return w[curr_wrapper](c, event_name, event_data);
+               end
+               return _fire_event(event_name, event_data);
+       end
+       local function add_wrapper(event_name, wrapper)
+               local w;
+               if event_name == nil then
+                       w = global_wrappers;
+                       if not w then
+                               w = {};
+                               global_wrappers = w;
+                       end
+               else
+                       w = wrappers[event_name];
+                       if not w then
+                               w = {};
+                               wrappers[event_name] = w;
+                       end
+               end
+               w[#w+1] = wrapper;
+       end
+       local function remove_wrapper(event_name, wrapper)
+               local w;
+               if event_name == nil then
+                       w = global_wrappers;
+               else
+                       w = wrappers[event_name];
+               end
+               if not w then return; end
+               for i = #w, 1 do
+                       if w[i] == wrapper then
+                               table.remove(w, i);
+                       end
+               end
+               if #w == 0 then
+                       if event_name == nil then
+                               global_wrappers = nil;
+                       else
+                               wrappers[event_name] = nil;
+                       end
+               end
+       end
        return {
                add_handler = add_handler;
                remove_handler = remove_handler;
                add_handlers = add_handlers;
                remove_handlers = remove_handlers;
+               wrappers = {
+                       add_handler = add_wrapper;
+                       remove_handler = remove_wrapper;
+               };
+               add_wrapper = add_wrapper;
+               remove_wrapper = remove_wrapper;
                fire_event = fire_event;
                _handlers = handlers;
                _event_map = event_map;