start replacing arrays with intrusive slists

`add` costs ten cycles. `push_back` isn't actually any better, but bury_the_dead can get pretty bad, especially for large arrays (like the bullets collections). also replacing the kill loop structure with the `strip` call removes a massive amount of code repetition that's costing me a lot of tokens. I think the final result is _probably_ actually slower because of function call overhead per iteration except when there are collisions on many frames; hopefully the headroom bought by the bucket collider is enough because I'm definitely going to need the tokens.

updatedshmup.p8

@@ -21,6 +21,95 @@ function csv(s)
  return ret
 end
 
+-- generate standard "overlay"
+-- constructor for type tt.
+-- if more is defined, generated
+-- new calls more(ret) after
+-- ret is definitely not nil
+-- before calling setmetatable.
+-- use to initialize mutables.
+function mknew(tt, more)
+ local mt = {__index=tt}
+ -- check "more" only once ever
+ if more then
+  tt.new = function(ret)
+   if (not ret) ret = {}
+   more(ret)
+   setmetatable(ret, mt)
+   return ret
+  end
+ else
+  tt.new=function(ret)
+   if (not ret) ret = {}
+   setmetatable(ret, mt)
+   return ret
+  end
+ end
+end
+
+linked_list = {}
+mknew(linked_list, function(x)
+  x.next=nil
+  x.tail=x
+ end)
+
+function linked_list:push_back(x)
+ self.tail.next = x
+ self.tail = x
+end
+
+function linked_list:push_front(x)
+ if (not self.next) self.tail = x
+ x.next = self.next
+ self.next = x
+end
+
+-- vore eats another linked list
+-- by appending its contents.
+-- the ingested linked
+-- list is no longer valid.
+function linked_list:vore(x)
+ if (not x.next) return
+ self.tail.next = x.next
+ self.tail = x.tail
+end
+
+-- strip calls f(x) for each
+-- node, removing each node for
+-- which f(x) returns true. it
+-- returns the new tail; nil
+-- if the list is now empty.
+function linked_list:strip(f)
+ local p, n = self, self.next
+ while n do
+  if f(n) then
+   p.next = n.next
+  else
+   p = n
+  end
+  n = n.next
+ end
+ self.tail = p
+ return p
+end
+
+function linked_list:pop_front()
+ local ret = self.next
+ if (not ret) return
+ self.next = ret.next
+ if (not ret.next) ret.tail = nil
+ return ret
+end
+
+function linked_list:fix_tail()
+ local p, n = self, self.next
+ while n do
+  p = n
+  n = n.next
+ end
+ self.tail = p
+end
+
 function _init()
  init_bullet_mt()
  init_powerup_mt()
@@ -47,124 +136,98 @@ function init_hpcols()
  hpcols = hpcols_lut[min(primary_ship.maxhp,6)]
 end
 
+function new_linked()
+ local ret = {}
+ ret.tail = ret
+ return ret
+end
+
 function wipe_level()
  primary_ship = new_p1()
  init_hpcols()
- pships = {primary_ship}
+ pships = linked_list:new()
- eships = {}
+ pships:push_back(primary_ship)
- pbullets = {}
+ eships = linked_list:new()
- ebullets = {}
+ pbullets = linked_list:new()
- intangibles_fg = {}
+ ebullets = linked_list:new()
- intangibles_bg = {}
+ intangibles_fg = linked_list:new()
- events = {}
+ intangibles_bg = linked_list:new()
+ events = linked_list:new()
 end
 
 function _update60()
  updategame()
 end
 
+function call_f(x)
+ return x:f()
+end
+
+function call_move(x)
+ return x:move()
+end
+
 function updategame()
  leveldone = level_frame()
-	new_events = {}
+	new_events = new_linked()
-	local deaths = {}
+ events:strip(call_f)
-	for i, e in ipairs(events) do
+ events:vore(new_events)
-	 if (e()) add(deaths, i)
+ for _, lst in ipairs{intangibles_bg, pships, eships, pbullets, ebullets} do
+  lst:strip(call_move)
  end
-	bury_the_dead(events, deaths)
+
-	foreach(new_events, function(e)
+ pships:strip(
-	 add(events, e)
+  function(ps)
-	end)
+   local pbox, pded = hurtbox(ps), false
-	deaths = {}
+   eships:strip(
-	for i, x in ipairs(intangibles_bg) do
+    function(es)
-	 if (x:move()) add(deaths, i)
+     if (~collides(pbox, hurtbox(es))) return
+     pded = pded or ps:hitship(es)
+     return es:hitship(ps)
     end
-	bury_the_dead(intangibles_bg, deaths)
+   )
- for _, tbl in ipairs({pships, eships, pbullets, ebullets, intangibles}) do
+   return pded
-	 local deaths = {}
-	 for i, x in ipairs(tbl) do
-	  if (x:move()) add(deaths, i)
   end
-	 bury_the_dead(tbl, deaths)
+ )
+ pships:strip(
+  function(ps)
+   local pbox, pded = hurtbox(ps), false
+   ebullets:strip(
+    function(eb)
+     if (~collides(pbox, hurtbox(eb))) return
+     pded = pded or ps:hitbullet(eb)
+     return eb:hitship(ps)
     end
-	--then, calculate collisions
+   )
-	local pdeaths = {}
+   return pded
-	local edeaths = {}
-	local eskips = {}
-	-- todo: always use a collider,
-	-- it saves if pships is as low as 2s
- -- pships usually contians 1 thing, 
- -- so don't bother with a bucket collider
-	for ip, ps in ipairs(pships) do
-	 for ie, es in ipairs(eships) do
-	  if not eskips[ie] then
-		  if collides(hurtbox(ps), hurtbox(es)) then
-		   if (es:hitship(ps)) then
-		    add(edeaths, ie)
-		    eskips[ie] = true
   end
-		   if ps:hitship(es) then
+ )
-		    add(pdeaths, ip)
+
-		    break
-		   end
-		  end
-		 end
-	 end
-	end
-	bury_the_dead(pships, pdeaths)
-	bury_the_dead(eships, edeaths)
-	pdeaths = {}
-	edeaths = {}
-	eskips = {}
-	for ip, ps in ipairs(pships) do
-	 for ie, eb in ipairs(ebullets) do
-	  if not eskips[ie] then
-		  if collides(hurtbox(ps), hurtbox(eb)) then
-		   local dead = false
-		   if ps:hitbullet(eb) then
-		    add(pdeaths, ip)
-		    dead = true
-		   end
-		   if (eb:hitship(ps)) then
-		    add(edeaths, ie)
-		    eskips[ie] =true
-		   end
-		   if (dead) break
-		  end
-		 end
-	 end
-	end
-	bury_the_dead(pships, pdeaths)
-	bury_the_dead(ebullets, edeaths)
-	pdeaths = {}
-	edeaths = {}
 	-- many bullets and many enemy ships;
 	-- use bucket collider for efficiency
  local pbullet_collider = new_collider()
-	for idx, pb in ipairs(pbullets) do
+ local p, n := pbullets, pbullets.next
-  pb.___pbullets_idx = idx
+ while n do
-  pbullet_collider:insert(pb)
+  n.prev = p
+  pbullet_collider:insert(n)
+  p = n
+  n = p.next
  end
 
- for es_idx, es in ipairs(eships) do
+ eships:strip(
+  function(es)
    for pb in all(pbullet_collider:get_collisions(es)) do
-   local dead = false
-   if es:hitbullet(pb) then
-    add(edeaths, es_idx)
-    dead=true
-   end
     if pb:hitship(es) then
-    add(pdeaths, pb.___pbullets_idx)
      pbullet_collider:hide(pb)
+     pb.prev.next = pb.next
+     if (pb.next) pb.next.prev = pb.prev
     end
-   if (dead) break
+    if (es:hitbullet(pb)) return true
    end
   end
-	bury_the_dead(eships, edeaths)
+ )
-	bury_the_dead(pbullets, pdeaths)
+ 
-	for i, x in ipairs(intangibles_fg) do
+ intangibles_fg:strip(call_move)
-	 if (x:move()) add(deaths, i)
-	end
-	bury_the_dead(intangibles_fg, deaths)
 
 	if leveldone and ((#eships + #ebullets + #events) == 0) then
 	  state = win
@@ -174,6 +237,8 @@ function updategame()
 	end
 end
 
+-- XXX BOOKMARK XXX
+
 function _draw()
  drawgame()
  draw_debug()