From 5e6b98523be3de71363eb17aeabbbc305569487f Mon Sep 17 00:00:00 2001
From: Kistaro Windrider <kistaro@gmail.com>
Date: Mon, 23 Jun 2025 00:47:02 -0700
Subject: [PATCH] delete linked lists and use optimized array impls.

Also removes "suppress" table from collider, use candidate.dead instead
because the set of dead ships and the set of non-colliding ships is
identical.
---
 vacuum_gambit.p8 | 205 +++++++++++++++++------------------------------
 1 file changed, 72 insertions(+), 133 deletions(-)

diff --git a/vacuum_gambit.p8 b/vacuum_gambit.p8
index 6e3e997..67852b2 100644
--- a/vacuum_gambit.p8
+++ b/vacuum_gambit.p8
@@ -59,90 +59,48 @@ function mknew(tt)
  return tt
 end
 
--- intrusive singly-linked list.
--- cannot be nested or crossed!
-linked_list = mknew{
- is_linked_list=true,
- init = 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 is empty.
-function linked_list:vore(x)
- if (not x.next) return
- self.tail.next = x.next
- self.tail = x.tail
- x.next = nil
- x.tail = x
-end
-
--- strip calls f(x) for each
--- node, removing each node for
--- which f(x) returns true.
-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
+-- call f on everything on list
+-- and return a new list of
+-- items for which f was false.
+function stripped(list, f)
+ local ret, n = {}, 0
+ for i=1,#list do
+  local v = list[i]
+  if not f(v) then
+   n += 1
+   ret[n] = v
   end
-  n = n.next
  end
- self.tail = p
+ return ret
 end
 
--- stripmove calls x:move() for
--- each node, removing each node
--- for which x:move() is true.
-function linked_list:stripmove()
- local p, n = self, self.next
- while n do
-  if n:move() then
-   p.next = n.next
-  else
-   p = n
+-- call :move on everything on
+-- src and dump everything
+-- for which it returned false
+-- onto dest.
+function appendmove(dest, src)
+ local n = #dest
+ for i=1, #src do
+  local v = src[i]
+  if not v:move() then
+   n += 1
+   dest[n] = v
   end
-  n = n.next
- end
- self.tail = p
-end
-
--- optimized special case -
--- could be done with strip but
--- this avoids extra function
--- calls and comparisions since
--- draw isn't allowed to kill
--- the item
-function linked_list:draw()
- local n = self.next
- while n do
-  n:draw()
-  n = n.next
  end
 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
+-- like stripped, but calls
+-- :move on stuff in the list
+-- instead of taking a func arg.
+function stripmoved(list)
+ local ret, n = {}, 0
+ for i=1,#list do
+  local v = list[i]
+  if not v:move() then
+   n += 1
+   ret[n] = v
+  end
+ end
  return ret
 end
 
@@ -156,12 +114,12 @@ function _init()
 end
 
 function once_next_frame(f)
- new_events:push_back{
+ add(new_events, {
   move = function()
    f()
    return true
   end,
- }
+ })
 end
 
 -- health gradients for 1..5 hp
@@ -182,13 +140,13 @@ function wipe_game()
  xpwhoosh = nil
  primary_ship = player.new()
  init_hpcols()
- eships = linked_list.new()
- pbullets = linked_list.new()
- ebullets = linked_list.new()
- intangibles_fg = linked_list.new()
- intangibles_bg = linked_list.new()
- events = linked_list.new()
- new_events = linked_list.new()
+ eships = {}
+ pbullets ={}
+ ebullets ={}
+ intangibles_fg = {}
+ intangibles_bg = {}
+ events = {}
+ new_events = {}
 	primary_ship.main_gun = zap_gun_p.new()
  primary_ship.main_gun:peel()
  gframe = 0
@@ -241,10 +199,11 @@ function updategame()
   current_wave = flotilla.new()
   current_wave:load(rnd() > 0.5 and 7 or 0, 0, min(ones(waves_complete)\2, 4))
  end
- events:vore(new_events)
- for _, lst in ipairs{events, intangibles_bg, eships} do
-  lst:stripmove()
- end
+ events = stripmoved(events)
+ appendmove(events, new_events)
+ new_events = {}
+ intangibles_big = stripmoved(intangibles_bg)
+ eships = stripmoved(eships)
 
 	-- eship collider will be used
  -- both for pship and pbullets.
@@ -255,9 +214,9 @@ function updategame()
   local pbox = hurtbox(ps)
   for es in eship_collider:iterate_collisions(pbox) do
    ps:hitship(es)
-   if(es:hitship(ps)) eship_collider:yoink(es)
+   es:hitship(ps)
   end
-  ebullets:strip(function(eb)
+  ebullets = stripped(ebullets, function(eb)
    if (eb:move()) return true
    if (not collides(pbox, hurtbox(eb))) return
    ps:hitbullet(eb)
@@ -267,17 +226,17 @@ function updategame()
   ebullets:stripmove()
  end
 
- pbullets:strip(function(pb)
+ pbullets = stripped(pbullets, function(pb)
   if (pb:move()) return true
   for es in eship_collider:iterate_collisions(hurtbox(pb)) do
-   if (es:hitbullet(pb)) eship_collider:yoink(es)
+   es:hitbullet(pb)
    if (pb:hitship(es)) return true
   end
  end)
  
  intangibles_fg:stripmove()
 
-	if waves_complete == 32767 and not eships.next and not ebullets.next and not events.next then
+	if waves_complete == 32767 and #eships == 0 and #ebullets == 0 and #events == 0 then
 	  game_state = win
 	end
 	if (ps.dead) game_state = lose
@@ -345,15 +304,6 @@ function puke(item, indent, seen, hidekey)
  end
  local xpfx = pfx.." "
 
- if item.is_linked_list then
-  local ret,n = "linked_list <",0
-  item:strip(function(x)
-   n += 1
-   ret ..= xpfx..tostr(n)..": "..puke(x, indent+2, seen, "next")
-  end)
-  return ret..pfx..">"
- end
-
  local ret = "{"
  for k, v in pairs(item) do
   if (k ~= hidekey) ret ..= xpfx..tostr(k)..": "..puke(v, indent+2, seen)
@@ -373,8 +323,10 @@ end
 function drawgame()
  clip(0,0,112,128)
  rectfill(0,0,112,128,0)
- for drawable in all{intangibles_bg, pbullets, primary_ship, eships, ebullets, intangibles_fg} do
-  drawable:draw()
+ for drawables in all{intangibles_bg, pbullets, {primary_ship}, eships, ebullets, intangibles_fg} do
+  for item in all(drawables) do
+   item:draw()
+  end
  end
  clip(0,0,128,128)
  drawhud()
@@ -586,6 +538,7 @@ function ship_m:constrain(p, dp, pmin, pmax, want)
 end
 
 function ship_m:move()
+ if (self.dead) return true;
  self:refresh_shield()
  local dx, dy, shoot_spec1, shoot_spec2 = self:act()
  local sg, xm, ym = self.special_guns, self.xmomentum, self.ymomentum
@@ -842,7 +795,7 @@ end
 function bullet_base:spawn_at(x, y)
  self.x = x - self.x_off
  self.y = y - self.y_off
- self.category():push_back(self)
+ add(self.category(), self)
 end
 
 function gun_base:shoot(x, y)
@@ -954,7 +907,7 @@ blast = mknew(bullet_base.new{
   if self.damage > 0 and not self.awaitcancel then
    self.awaitcancel = true
    once_next_frame(function()
-    new_events:push_back{
+    add(new_events, {
      wait = 4,
      obj = self,
      saved_dmg = self.damage,
@@ -965,7 +918,7 @@ blast = mknew(bullet_base.new{
        return true
       end
      end,
-    }
+    })
     self.damage = 0
     self.awaitcancel = false
    end)
@@ -1418,10 +1371,10 @@ end
 
 collider = mknew{
  init = function(x)
-  x.suppress = {}
-  local p, n = x.from, x.from.next
-  while n do
+  local from = x.from
+  for k=1,#from do
    -- insert
+   local n = from[k]
    for i in all(collider_indexes(hurtbox(n))) do
     local a = x[i]
     if not a then
@@ -1430,35 +1383,21 @@ collider = mknew{
     end
     add(a, n)
    end
-   -- prepare yoink
-   n.prev = p
-   p = n
-   n = n.next
   end
  end,
 }
 
 function collider_indexes(box)
- local ret = {}
+ local ret,i = {}, 0
  for x = box.x\8, (box.x+box.width)\8 do
   for y = box.y\8, (box.y+box.height)\8 do
-   add(ret, x+256*y)
+   i += 1
+   ret[i] = x+256*y
   end
  end
  return ret
 end
 
-function collider:yoink(item)
- self.suppress[item]=true
- local p,n = item.prev,item.next
- p.next = n
- if n then
-  n.prev = p
- else
-  self.from.tail = p
- end
-end
-
 function collider:iterate_collisions(box)
  local seen = { }
  local bucket_ids = collider_indexes(box)
@@ -1474,7 +1413,7 @@ function collider:iterate_collisions(box)
     bi += 1
     if not seen[candidate] then
      seen[candidate] = true
-     if (not self.suppress[candidate] and collides(box, hurtbox(candidate))) return candidate
+     if (not candidate.dead and collides(box, hurtbox(candidate))) return candidate
     end
    end -- done with this bucket
    bi=1
@@ -1561,7 +1500,7 @@ function flotilla:load(ulc_cx, ulc_cy, lvl)
    for s in all(row) do
     counts[s.ship_t] += 1
     s.x,s.y=rnd_spawn_loc()
-    eships:push_back(s)
+    add(eships, s)
    end
    add(rows, row)
   end
@@ -1675,7 +1614,7 @@ end
 function blip(obj, col)
  obj.fx_pal = blip_pals[col]
  if (obj.___fx_pal_event) obj.___fx_pal_event:abort() 
- events:push_back(blip_fx.new{frames=3, obj=obj})
+ add(events, blip_fx.new{frames=3, obj=obj})
 end
 
 bossspark = split"7,7,10,10,9,9,9,8,8,8,2,2,5,5"
@@ -1712,14 +1651,14 @@ end
 function spark(sprs, x, y, dx, dy, odds, fg)
  if (sprs==nil or flr(rnd(odds) or (abs(dx) < 0.5 and abs(dy))) ~= 0) return
  local target = fg and intangibles_fg or intangibles_bg
- target:push_back(spark_particle.new{
+ target[#target+1] = spark_particle.new{
   x = x + rnd(4) - 2,
   y = y + rnd(4) - 2,
   sprs = sprs,
   sidx = 1,
   dx = dx * rnd(2),
   dy = dy * rnd(2),
- })
+ }
 end
 -->8
 -- powerups