Initial commit

fluid/system.lua

@@ -0,0 +1,118 @@
+local PATH = (...):gsub('%.[^%.]+$', '')
+
+local Component = require(PATH..".component")
+local Pool      = require(PATH..".pool")
+
+local System = {}
+System.__index = System
+
+function System.new(...)
+   local system = setmetatable({
+      __all   = {},
+      __pools = {},
+   }, System)
+
+   for _, filter in pairs({...}) do
+      local pool = system:buildPool(filter)
+      if not system[pool.__name] then
+         system[pool.__name]                 = pool
+         system.__pools[#system.__pools + 1] = pool
+      else
+         error("Pool with name '"..pool.__name.."' already exists.")
+      end
+   end
+
+   return system
+end
+
+function System:buildPool(pool)
+   local name   = "pool"
+   local filter = {}
+
+   for i, v in ipairs(pool) do
+      if type(v) == "table" then
+         filter[#filter + 1] = v
+      elseif type(v) == "string" then
+         name = v
+      end
+   end
+
+   return Pool(name, filter)
+end
+
+function System:entityUpdated(e)
+   local systemHas = self:has(e)
+
+   for _, pool in ipairs(self.__pools) do
+      local poolHas  = pool:has(e)
+      local eligible = pool:eligible(e)
+
+      if not poolHas and eligible then
+         pool:add(e)
+         self:entityAddedTo(e, pool)
+         self:tryAdd(e)
+
+         return true
+      elseif poolHas and not eligible then
+         pool:remove(e)
+         self:entityRemovedFrom(e, pool)
+         self:tryRemove(e)
+
+         return false
+      end
+   end
+end
+
+function System:tryAdd(e)
+   if not self:has(e) then
+      self.__all[e] = 0
+      self:entityAdded(e)
+   end
+
+   self.__all[e] = self.__all[e] + 1
+end
+
+function System:tryRemove()
+   if self:has(e) then
+      self.__all[e] = self.__all[e] - 1
+
+      if self.__all[e] == 0 then
+         self.__all[e] = nil
+         self:entityRemoved(e)
+      end
+   end
+end
+
+function System:remove(e)
+   if self:has(e) then
+      for _, pool in ipairs(self.__pools) do
+         if pool:has(e) then
+            pool:remove(e)
+            self:entityRemovedFrom(e, pool)
+         end
+      end
+
+      self.__all[e] = nil
+      self:entityRemoved(e)
+   end
+end
+
+function System:has(e)
+   return self.__all[e] and true
+end
+
+function System:entityAdded(e)
+end
+
+function System:entityAddedTo(e, pool)
+end
+
+function System:entityRemoved(e)
+end
+
+function System:entityRemovedFrom(e, pool)
+end
+
+return setmetatable(System, {
+   __call = function(_, ...) return System.new(...) end,
+})