Erase destroyed entites after a safe time has elapsed

.gitignore

@@ -2,3 +2,5 @@
 *~
 *.sublime-*
 .DS_Store
+.ackrc
+

colliderwrapper.lua

@@ -1,8 +1,16 @@
 local class = require 'middleclass.middleclass'
 local HC = require 'HardonCollider'
 
+require 'events.eraseevent'
+
 ColliderWrapper = class('ColliderWrapper')
 
+-- number of ticks of slack/buffer to allow when erasing an event
+-- theoretically, this should not be necessary, but using it guarantees
+-- that we will not encounter hard-to-reproduce bugs due to off-by-one
+-- errors on the order of milliseconds
+ColliderWrapper.static.erasureSlack = 10
+
 function ColliderWrapper:initialize(eventLog)
     self.collider = HC(100, function(...) self:onCollide(...) end)
     self.hitboxes = {}
@@ -25,10 +33,12 @@ function ColliderWrapper:onCollide(dt, hitbox1, hitbox2, dx, dy)
 
     if entity1:hit(entity2, dx, dy) then
         self.eventLog:insert(DestroyEvent(id1), self.time)
+        self.eventLog:insert(EraseEvent(id1), self.time + constants.jumpTime + self.class.erasureSlack)
     end
 
     if entity2:hit(entity1, -dx, -dy) then
         self.eventLog:insert(DestroyEvent(id2), self.time)
+        self.eventLog:insert(EraseEvent(id2), self.time + constants.jumpTime + self.class.erasureSlack)
     end
 end
 

events/eraseevent.lua

@@ -0,0 +1,12 @@
+local class = require 'middleclass.middleclass'
+
+require 'events.event'
+require 'utils'
+
+EraseEvent = class('events.EraseEvent', EntityEvent)
+
+
+function EraseEvent:safeApply(state, collider)
+    collider:remove(state[self.entityId].hitbox)
+    state[self.entityId] = nil
+end