Initial commit

fluid/pool.lua

@@ -0,0 +1,57 @@
+local Pool = {}
+Pool.__index = Pool
+
+function Pool.new(name, filter)
+   local pool = setmetatable({
+      __filter = filter,
+      __name   = name,
+   }, Pool)
+
+   return pool
+end
+
+function Pool:eligible(e)
+   for _, component in ipairs(self.__filter) do
+      if not e.components[component] then
+         return false
+      end
+   end
+
+   return true
+end
+
+function Pool:add(e)
+   local key = #self + 1
+
+   self[key] = e
+   e.keys[self] = key
+end
+
+function Pool:has(e)
+   return e.keys[self] and true
+end
+
+function Pool:remove(e, pool)
+   local key = e.keys[self]
+
+   if key then
+      local count = #self
+
+      if key == count then
+         self[key]    = nil
+         e.keys[self] = nil
+      else
+         local swap = self[count]
+
+         self[key]       = swap
+         self[count]     = nil
+         swap.keys[self] = key
+      end
+
+      return true
+   end
+end
+
+return setmetatable(Pool, {
+   __call = function(_, ...) return Pool.new(...) end,
+})