Changed lib layout once more

lib/system.lua

@@ -0,0 +1,167 @@
+local PATH = (...):gsub('%.[^%.]+$', '')
+
+local Component = require(PATH..".component")
+local Pool      = require(PATH..".pool")
+
+local System = {}
+System.mt    = {
+   __index = System,
+   __call  = function(systemProto, ...)
+      local system = setmetatable({
+         __all      = {},
+         __pools    = {},
+         __instance = nil,
+
+         __isSystem = true,
+      }, systemProto)
+
+      for _, filter in pairs(systemProto.__filter) 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
+
+      system:init(...)
+      return system
+   end,
+}
+
+--- Creates a new System prototype.
+-- @param ... Variable amounts of filters
+-- @return A new System prototype
+function System.new(...)
+   local systemProto = setmetatable({
+      __filter = {...},
+   }, System.mt)
+   systemProto.__index = systemProto
+
+   return systemProto
+end
+
+--- Default initialization function.
+-- @param ... Varags
+function System:init(...)
+end
+
+--- Builds a Pool for the System.
+-- @param baseFilter The 'raw' Filter
+-- @return A new Pool
+function System:__buildPool(baseFilter)
+   local name   = "pool"
+   local filter = {}
+
+   for i, v in ipairs(baseFilter) do
+      if type(v) == "table" then
+         filter[#filter + 1] = v
+      elseif type(v) == "string" then
+         name = v
+      end
+   end
+
+   return Pool(name, filter)
+end
+
+--- Checks and applies an Entity to the System's pools.
+-- @param e The Entity to check
+-- @return True if the Entity was added, false if it was removed. Nil if nothing happend
+function System:__check(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)
+      elseif poolHas and not eligible then
+         pool:remove(e)
+         self:entityRemovedFrom(e, pool)
+         self:__tryRemove(e)
+      end
+   end
+end
+
+--- Removed an Entity from the System.
+-- @param e The Entity to remove
+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
+
+--- Tries to add an Entity to the System.
+-- @param e The Entity to add
+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
+
+--- Tries to remove an Entity from the System.
+-- @param e The Entity to remove
+function System:__tryRemove(e)
+   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
+
+--- Returns the Instance the System is in.
+-- @return The Instance
+function System:getInstance()
+   return self.__instance
+end
+
+--- Returns if the System has the Entity.
+-- @param The Entity to check for
+-- @return True if the System has the Entity. False otherwise
+function System:__has(e)
+   return self.__all[e] and true
+end
+
+--- Default callback for adding an Entity.
+-- @param e The Entity that was added
+function System:entityAdded(e)
+end
+
+--- Default callback for adding an Entity to a pool.
+-- @param e The Entity that was added
+-- @param pool The pool the Entity was added to
+function System:entityAddedTo(e, pool)
+end
+
+--- Default callback for removing an Entity.
+-- @param e The Entity that was removed
+function System:entityRemoved(e)
+end
+
+--- Default callback for removing an Entity from a pool.
+-- @param e The Entity that was removed
+-- @param pool The pool the Entity was removed from
+function System:entityRemovedFrom(e, pool)
+end
+
+return setmetatable(System, {
+   __call = function(_, ...) return System.new(...) end,
+})