Make example for how to use Concord.utils.loadNamespace for systems more concrete

Fix typo in README.md

.github/workflows/doc.yml

@@ -0,0 +1,38 @@
+name: Build Docs
+
+on: 
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    name: Build docs
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Check out repository
+      uses: actions/checkout@v2
+    
+    - name: Setup Lua
+      uses: leafo/gh-actions-lua@v8
+      with:
+        luaVersion: 5.4
+
+    - name: Install Luarocks
+      uses: leafo/gh-actions-luarocks@v4
+
+    - name: Install LDoc
+      run: luarocks install ldoc
+    
+    - name: Show
+      run: luarocks show ldoc
+
+    - name: Build docs
+      run: ldoc .
+
+    - name: Deploy
+      uses: JamesIves/github-pages-deploy-action@4.1.5
+      with:
+        branch: gh-pages
+        folder: docs

.gitignore

@@ -38,3 +38,6 @@ luac.out
 *.i*86
 *.x86_64
 *.hex
+
+# VSCode
+.vscode/

.luacheckrc

@@ -1 +1,2 @@
+---@diagnostic disable: lowercase-global
 std="love+luajit"

README.md

@@ -7,7 +7,7 @@ With Concord it is possibile to easily write fast and clean code.
 This readme will explain how to use Concord.
 
 Additionally all of Concord is documented using the LDoc format.
-Auto generated docs for Concord can be found in `docs` folder, or on the [Github page](https://tjakka5.github.io/Concord/).
+Auto generated docs for Concord can be found in `docs` folder, or on the [GitHub page](https://keyslam-group.github.io/Concord/).
 
 --- 
 
@@ -133,16 +133,21 @@ Concord does a few things that might not be immediately clear. This segment shou
 Since you'll have lots of Components and Systems in your game Concord makes it a bit easier to load things in.
 
 ```lua
--- Loads all files in the directory, and puts the return value in the table Systems. The key is their filename without any extension
-local Systems = {}
-Concord.utils.loadNamespace("path/to/systems", Systems)
-
-print(Systems.systemName)
-
 -- Loads all files in the directory. Components automatically register into Concord.components, so loading them into a namespace isn't necessary.
 Concord.utils.loadNamespace("path/to/components")
 
 print(Concord.components.componentName)
+
+-- Loads all files in the directory, and puts the return value in the table Systems. The key is their filename without any extension
+local Systems = {}
+Concord.utils.loadNamespace("path/to/systems", Systems)
+
+myWorld:addSystems(
+  Systems.healthSystem
+  Systems.damageSystem,
+  Systems.moveSystem,
+ -- etc
+)
 ```
 
 #### Method chaining
@@ -170,7 +175,7 @@ When defining a ComponentClass you need to pass in a name and usually a `populat
 -- Create the position class with a populate function
 -- The component variable is the actual Component given to an Entity
 -- The x and y variables are values we pass in when we create the Component 
-Concord.component("position" function(component, x, y)
+Concord.component("position", function(component, x, y)
     component.x = x or 0
     component.y = y or 0
 end)
@@ -266,10 +271,10 @@ Systems can have multiple pools.
 
 ```lua
 -- Create a System
-local mySystemClass = Concord.system(pool = {"position"}) -- Pool named 'pool' will contain all Entities with a position Component
+local mySystemClass = Concord.system({pool = {"position"}}) -- Pool named 'pool' will contain all Entities with a position Component
 
 -- Create a System with multiple pools
-local mySystemClass = Concord.system(
+local mySystemClass = Concord.system({
     pool = { -- This pool will be named 'pool'
         "position",
         "velocity",
@@ -278,7 +283,7 @@ local mySystemClass = Concord.system(
         "health",
         "damageable",
     }
-)
+})
 ```
 
 ```lua
@@ -294,14 +299,14 @@ end
 -- Defining a function
 function mySystemClass:update(dt)
     -- Iterate over all entities in the Pool
-    for _, e in ipairs(self.pool) 
+    for _, e in ipairs(self.pool) do
         -- Do something with the Components
         e.position.x = e.position.x + e.velocity.x * dt
         e.position.y = e.position.y + e.velocity.y * dt
     end
 
     -- Iterate over all entities in the second Pool
-    for _, e in ipairs(self.secondPool) 
+    for _, e in ipairs(self.secondPool) do
         -- Do something
     end
 end

concord/builtins/init.lua

@@ -0,0 +1,6 @@
+local PATH = (...):gsub("(%.init)$", "")
+
+return {
+  serializable = require(PATH..".serializable"),
+  key          = require(PATH..".key"),
+}

concord/builtins/key.lua

@@ -0,0 +1,41 @@
+local PATH = (...):gsub('%.builtins%.[^%.]+$', '')
+
+local Component = require(PATH..".component")
+
+local getKey = function (self, key)
+  local entity = self.__entity
+
+  if not entity:inWorld() then
+    error("entity needs to belong to a world")
+  end
+
+  local world = entity:getWorld()
+
+  return world:__assignKey(entity, key)
+end
+
+local Key = Component("key", function (self, key)
+  self.value = getKey(self, key)
+end)
+
+function Key:deserialize (data)
+  self.value = getKey(self, data)
+end
+
+function Key.__mt:__call()
+  return self.value
+end
+
+function Key:removed (replaced)
+  if not replaced then
+    local entity = self.__entity
+
+    if entity:inWorld() then
+      local world = entity:getWorld()
+
+      return world:__clearKey(entity)
+    end
+  end
+end
+
+return Key

concord/builtins/serializable.lua

@@ -0,0 +1,12 @@
+local PATH = (...):gsub('%.builtins%.[^%.]+$', '')
+
+local Component = require(PATH..".component")
+
+local Serializable = Component("serializable")
+
+function Serializable:serialize ()
+  -- Don't serialize this Component
+  return nil
+end
+
+return Serializable

concord/component.lua

@@ -16,15 +16,19 @@ Component.__mt = {
 -- @treturn Component A new ComponentClass
 function Component.new(name, populate)
    if (type(name) ~= "string") then
-      error("bad argument #1 to 'Component.new' (string expected, got "..type(name)..")", 2)
+      Utils.error(2, "bad argument #1 to 'Component.new' (string expected, got %s)", type(name))
+   end
+
+   if (string.match(name, Components.__REJECT_MATCH) ~= "") then
+      Utils.error(2, "bad argument #1 to 'Component.new' (Component names can't start with '%s', got %s)", Components.__REJECT_PREFIX, name)
    end
 
    if (rawget(Components, name)) then
-      error("bad argument #1 to 'Component.new' (ComponentClass with name '"..name.."' was already registerd)", 2) -- luacheck: ignore
+      Utils.error(2, "bad argument #1 to 'Component.new' (ComponentClass with name '%s' was already registerd)", name) -- luacheck: ignore
    end
 
    if (type(populate) ~= "function" and type(populate) ~= "nil") then
-      error("bad argument #1 to 'Component.new' (function/nil expected, got "..type(populate)..")", 2)
+      Utils.error(2, "bad argument #1 to 'Component.new' (function/nil expected, got %s)", type(populate))
    end
 
    local componentClass = setmetatable({
@@ -43,31 +47,40 @@ function Component.new(name, populate)
    return componentClass
 end
 
--- Internal: Populates a Component with values
+-- Internal: Populates a Component with values.
 function Component:__populate() -- luacheck: ignore
 end
 
+-- Callback: When the Component gets removed or replaced in an Entity.
+function Component:removed() -- luacheck: ignore
+end
+
+-- Callback: When the Component gets serialized as part of an Entity.
 function Component:serialize()
    local data = Utils.shallowCopy(self, {})
 
    --This values shouldn't be copied over
-   data.__componentClass = nil
+   data.__componentClass   = nil
-   data.__isComponent = nil
+   data.__entity           = nil
+   data.__isComponent      = nil
    data.__isComponentClass = nil
 
    return data
 end
 
+-- Callback: When the Component gets deserialized from serialized data.
 function Component:deserialize(data)
    Utils.shallowCopy(data, self)
 end
 
 -- Internal: Creates a new Component.
+-- @param entity The Entity that will receive this Component.
 -- @return A new Component
-function Component:__new()
+function Component:__new(entity)
    local component = setmetatable({
       __componentClass = self,
 
+      __entity           = entity,
       __isComponent      = true,
       __isComponentClass = false,
    }, self.__mt)
@@ -76,11 +89,13 @@ function Component:__new()
 end
 
 -- Internal: Creates and populates a new Component.
+-- @param entity The Entity that will receive this Component.
 -- @param ... Varargs passed to the populate function
 -- @return A new populated Component
-function Component:__initialize(...)
+function Component:__initialize(entity, ...)
-   local component = self:__new()
+   local component = self:__new(entity)
 
+   ---@diagnostic disable-next-line: redundant-parameter
    self.__populate(component, ...)
 
    return component

concord/components.lua

@@ -1,12 +1,11 @@
 --- Container for registered ComponentClasses
 -- @module Components
 
-local PATH = (...):gsub('%.[^%.]+$', '')
-
-local Type = require(PATH..".type")
-
 local Components = {}
 
+Components.__REJECT_PREFIX = "!"
+Components.__REJECT_MATCH = "^(%"..Components.__REJECT_PREFIX.."?)(.+)"
+
 --- Returns true if the containter has the ComponentClass with the specified name
 -- @string name Name of the ComponentClass to check
 -- @treturn boolean
@@ -14,22 +13,43 @@ function Components.has(name)
    return rawget(Components, name) and true or false
 end
 
+--- Prefix a component's name with the currently set Reject Prefix
+-- @string name Name of the ComponentClass to reject
+-- @treturn string
+function Components.reject(name)
+   local ok, err = Components.try(name)
+
+   if not ok then error(err, 2) end
+
+   return Components.__REJECT_PREFIX..name
+end
+
 --- Returns true and the ComponentClass if one was registered with the specified name
 -- or false and an error otherwise
 -- @string name Name of the ComponentClass to check
+-- @boolean acceptRejected Whether to accept names prefixed with the Reject Prefix.
 -- @treturn boolean
 -- @treturn Component or error string
-function Components.try(name)
+-- @treturn true if acceptRejected was true and the name had the Reject Prefix, false otherwise.
+function Components.try(name, acceptRejected)
    if type(name) ~= "string" then
       return false, "ComponentsClass name is expected to be a string, got "..type(name)..")"
    end
 
+   local rejected = false
+   if acceptRejected then
+      local prefix
+      prefix, name = string.match(name, Components.__REJECT_MATCH)
+
+      rejected = prefix ~= "" and name
+   end
+
    local value = rawget(Components, name)
    if not value then
       return false, "ComponentClass '"..name.."' does not exist / was not registered"
    end
 
-   return true, value
+   return true, value, rejected
 end
 
 --- Returns the ComponentClass with the specified name

concord/entity.lua

@@ -6,8 +6,16 @@ local PATH = (...):gsub('%.[^%.]+$', '')
 
 local Components = require(PATH..".components")
 local Type       = require(PATH..".type")
+local Utils      = require(PATH..".utils")
+
+-- Initialize built-in Components (as soon as possible)
+local Builtins   = require(PATH..".builtins.init") --luacheck: ignore
+-- Builtins is unused but the require already registers the Components
+
+local Entity = {
+   SERIALIZE_BY_DEFAULT = true,
+}
 
-local Entity = {}
 Entity.__mt = {
    __index = Entity,
 }
@@ -17,12 +25,11 @@ Entity.__mt = {
 -- @treturn Entity A new Entity
 function Entity.new(world)
    if (world ~= nil and not Type.isWorld(world)) then
-      error("bad argument #1 to 'Entity.new' (world/nil expected, got "..type(world)..")", 2)
+      Utils.error(2, "bad argument #1 to 'Entity.new' (world/nil expected, got %s)", type(world))
    end
 
    local e = setmetatable({
       __world      = nil,
-      __components = {},
 
       __isEntity = true,
    }, Entity.__mt)
@@ -31,23 +38,86 @@ function Entity.new(world)
       world:addEntity(e)
    end
 
+   if Entity.SERIALIZE_BY_DEFAULT then
+      e:give("serializable")
+   end
+
    return e
 end
 
-local function give(e, name, componentClass, ...)
+local function createComponent(e, name, componentClass, ...)
-   local component = componentClass:__initialize(...)
+   local component = componentClass:__initialize(e, ...)
+   local hadComponent = not not e[name]
+
+   if hadComponent then
+      e[name]:removed(true)
+   end
 
    e[name] = component
-   e.__components[name] = component
 
-   e:__dirty()
+   if not hadComponent then
+      e:__dirty()
+   end
 end
 
-local function remove(e, name, componentClass)
+local function deserializeComponent(e, name, componentData)
-   e[name] = nil
+   local componentClass = Components[name]
-   e.__components[name] = nil
+   local hadComponent = not not e[name]
 
-   e:__dirty()
+   if hadComponent then
+      e[name]:removed(true)
+   end
+
+   local component = componentClass:__new(e)
+   component:deserialize(componentData)
+
+   e[name] = component
+
+   if not hadComponent then
+      e:__dirty()
+   end
+end
+
+local function giveComponent(e, ensure, name, ...)
+   local component
+   if Type.isComponent(name) then
+      component = name
+      name = component:getName()
+   end
+
+   if ensure and e[name] then
+      return e
+   end
+
+   local ok, componentClass = Components.try(name)
+
+   if not ok then
+      Utils.error(3, "bad argument #1 to 'Entity:%s' (%s)", ensure and 'ensure' or 'give', componentClass)
+   end
+
+   if component then
+      local data = component:deserialize()
+      if data == nil then
+         Utils.error(3, "bad argument #1 to 'Entity:$s' (Component '%s' couldn't be deserialized)", ensure and 'ensure' or 'give', name)
+      end
+
+      deserializeComponent(e, name, data)
+   else 
+      createComponent(e, name, componentClass, ...)
+   end
+
+   return e
+end
+
+
+local function removeComponent(e, name)
+   if e[name] then
+      e[name]:removed(false)
+
+      e[name] = nil
+
+      e:__dirty()
+   end
 end
 
 --- Gives an Entity a Component.
@@ -56,15 +126,7 @@ end
 -- @param ... additional arguments to pass to the Component's populate function
 -- @treturn Entity self
 function Entity:give(name, ...)
-   local ok, componentClass = Components.try(name)
+   return giveComponent(self, false, name, ...)
-
-   if not ok then
-      error("bad argument #1 to 'Entity:get' ("..componentClass..")", 2)
-   end
-
-   give(self, name, componentClass, ...)
-
-   return self
 end
 
 --- Ensures an Entity to have a Component.
@@ -73,19 +135,7 @@ end
 -- @param ... additional arguments to pass to the Component's populate function
 -- @treturn Entity self
 function Entity:ensure(name, ...)
-   local ok, componentClass = Components.try(name)
+   return giveComponent(self, true, name, ...)
-
-   if not ok then
-      error("bad argument #1 to 'Entity:get' ("..componentClass..")", 2)
-   end
-
-   if self[name] then
-      return self
-   end
-
-   give(self, name, componentClass, ...)
-
-   return self
 end
 
 --- Removes a Component from an Entity.
@@ -95,10 +145,10 @@ function Entity:remove(name)
    local ok, componentClass = Components.try(name)
 
    if not ok then
-      error("bad argument #1 to 'Entity:get' ("..componentClass..")", 2)
+      Utils.error(2, "bad argument #1 to 'Entity:remove' (%s)", componentClass)
    end
 
-   remove(self, name, componentClass)
+   removeComponent(self, name)
 
    return self
 end
@@ -109,7 +159,7 @@ end
 -- @treturn Entity self
 function Entity:assemble(assemblage, ...)
    if type(assemblage) ~= "function" then
-      error("bad argument #1 to 'Entity:assemble' (function expected, got "..type(assemblage)..")")
+      Utils.error(2, "bad argument #1 to 'Entity:assemble' (function expected, got %s)", type(assemblage))
    end
 
    assemblage(self, ...)
@@ -145,7 +195,7 @@ function Entity:has(name)
    local ok, componentClass = Components.try(name)
 
    if not ok then
-      error("bad argument #1 to 'Entity:has' ("..componentClass..")", 2)
+      Utils.error(2, "bad argument #1 to 'Entity:has' (%s)", componentClass)
    end
 
    return self[name] and true or false
@@ -158,7 +208,7 @@ function Entity:get(name)
    local ok, componentClass = Components.try(name)
 
    if not ok then
-      error("bad argument #1 to 'Entity:get' ("..componentClass..")", 2)
+      Utils.error(2, "bad argument #1 to 'Entity:get' (%s)", componentClass)
    end
 
    return self[name]
@@ -168,8 +218,13 @@ end
 -- Warning: Do not modify this table.
 -- Use Entity:give/ensure/remove instead
 -- @treturn table Table of all Components the Entity has
-function Entity:getComponents()
+function Entity:getComponents(output)
-   return self.__components
+   output = output or {}
+   local components = Utils.shallowCopy(self, output)
+   components.__world = nil
+   components.__isEntity = nil
+
+   return components
 end
 
 --- Returns true if the Entity is in a World.
@@ -184,11 +239,17 @@ function Entity:getWorld()
    return self.__world
 end
 
-function Entity:serialize()
+function Entity:serialize(ignoreKey)
    local data = {}
 
-   for _, component in pairs(self.__components) do
+   for name, component in pairs(self) do
-      if component.__name then
+      -- The key component needs to be treated separately.
+      if name == "key" and component.__name == "key" then
+         if not ignoreKey then
+            data.key = component.value
+         end
+      --We only care about components that were properly given to the entity
+      elseif Type.isComponent(component) and (component.__name == name) then
          local componentData = component:serialize()
 
          if componentData ~= nil then
@@ -206,18 +267,10 @@ function Entity:deserialize(data)
       local componentData = data[i]
 
       if (not Components.has(componentData.__name)) then
-         error("bad argument #1 to 'Entity:deserialize' (ComponentClass '"..tostring(componentData.__name).."' wasn't yet loaded)") -- luacheck: ignore
+         Utils.error(2, "bad argument #1 to 'Entity:deserialize' (ComponentClass '%s' wasn't yet loaded)", tostring(componentData.__name)) -- luacheck: ignore
       end
 
-      local componentClass = Components[componentData.__name]
+      deserializeComponent(self, componentData.__name, componentData)
-
-      local component = componentClass:__new()
-      component:deserialize(componentData)
-
-      self[componentData.__name] = component
-      self.__components[componentData.__name] = component
-
-      self:__dirty()
    end
 end
 

concord/filter.lua

@@ -0,0 +1,199 @@
+--- Used to filter Entities with specific Components
+-- A Filter has an associated Pool that can contain any amount of Entities.
+-- @classmod Filter
+
+local PATH = (...):gsub('%.[^%.]+$', '')
+
+local List       = require(PATH..".list")
+local Type       = require(PATH..".type")
+local Utils      = require(PATH..".utils")
+local Components = require(PATH..".components")
+
+
+local Filter = {}
+Filter.__mt = {
+   __index = Filter,
+}
+
+--- Validates a Filter Definition to make sure every component is valid.
+-- @string name Name for the Filter.
+-- @tparam table definition Table containing the Filter Definition
+-- @tparam onComponent Optional function, called when a component is valid.
+function Filter.validate (errorLevel, name, def, onComponent)
+   local filter = "World:query filter"
+   if name then
+      filter = ("filter '%s'"):format(name)
+   end
+
+   if type(def) ~= 'table' then
+      Utils.error(3 + errorLevel, "invalid component list for %s (table expected, got %s)", filter, type(def))
+   end
+
+   if not onComponent and def.constructor and not Type.isCallable(def.constructor) then
+      Utils.error(3 + errorLevel, "invalid pool constructor for %s (callable expected, got %s)", filter, type(def.constructor))
+   end
+
+   for n, component in ipairs(def) do
+      local ok, err, reject = Components.try(component, true)
+
+      if not ok then
+         Utils.error(3 + errorLevel, "invalid component for %s at position #%d (%s)", filter, n, err)
+      end
+
+      if onComponent then
+         onComponent(component, reject)
+      end
+   end
+end
+
+--- Parses the Filter Defintion into two tables
+-- required: An array of all the required component names.
+-- rejected: An array of all the components that will be rejected.
+-- @string name Name for the Filter.
+-- @tparam table definition Table containing the Filter Definition
+-- @treturn table required
+-- @treturn table rejected
+function Filter.parse (name, def)
+   local filter = {}
+
+   Filter.validate(1, name, def, function (component, reject)
+      if reject then
+         table.insert(filter, reject)
+         table.insert(filter, false)
+      else
+         table.insert(filter, component)
+         table.insert(filter, true)
+      end
+   end)
+
+   return filter
+end
+
+function Filter.match (e, filter)
+   for i=#filter, 2, -2 do
+      local match = filter[i - 0]
+      local name  = filter[i - 1]
+
+      if (not e[name]) == match then return false end
+   end
+
+   return true
+end
+
+local REQUIRED_METHODS = {"add", "remove", "has", "clear"}
+local VALID_POOL_TYPES = {table=true, userdata=true, lightuserdata=true, cdata=true}
+
+function Filter.isValidPool (name, pool)
+   local poolType = type(pool)
+   --Check that pool is not nil
+   if not VALID_POOL_TYPES[poolType] then
+      Utils.error(3, "invalid value returned by pool '%s' constructor (table expected, got %s).", name, type(pool))
+   end
+
+   --Check if methods are callables
+   for _, method in ipairs(REQUIRED_METHODS) do
+      if not Type.isCallable(pool[method]) then
+         Utils.error(3, "invalid :%s method on pool '%s' (callable expected, got %s).", method, name, type(pool[method]))
+      end
+   end
+end
+
+--- Creates a new Filter
+-- @string name Name for the Filter.
+-- @tparam table definition Table containing the Filter Definition
+-- @treturn Filter The new Filter
+-- @treturn Pool The associated Pool
+function Filter.new (name, def)
+   local pool
+
+   if def.constructor then
+      pool = def.constructor(def)
+      Filter.isValidPool(name, pool)
+   else
+      pool = List()
+   end
+
+   local filter = Filter.parse(name, def)
+
+   local filter = setmetatable({
+      pool = pool,
+
+      __filter = filter,
+      __name   = name,
+   
+      __isFilter = true,
+   }, Filter.__mt)
+
+   return filter, pool
+end
+
+--- Checks if an Entity fulfills the Filter requirements.
+-- @tparam Entity e Entity to check
+-- @treturn boolean
+function Filter:eligible(e)
+   return Filter.match(e, self.__filter)
+end
+
+function Filter:evaluate (e)
+   local has  = self.pool:has(e)
+   local eligible = self:eligible(e)
+
+   if not has and eligible then
+      self.pool:add(e)
+   elseif has and not eligible then
+      self.pool:remove(e)
+   end
+
+   return self
+end
+
+
+-- Adds an Entity to the Pool, if it passes the Filter.
+-- @param e Entity to add
+-- @param bypass Whether to bypass the Filter or not.
+-- @treturn Filter self
+-- @treturn boolean Whether the entity was added or not.
+function Filter:add (e, bypass)
+   if not bypass and not self:eligible(e) then
+      return self, false
+   end
+
+   self.pool:add(e)
+
+   return self, true
+end
+
+-- Remove an Entity from the Pool associated to this Filter.
+-- @param e Entity to remove
+-- @treturn Filter self
+function Filter:remove (e)
+   self.pool:remove(e)
+   return self
+end
+
+-- Clear the Pool associated to this Filter.
+-- @param e Entity to remove
+-- @treturn Filter self
+function Filter:clear (e)
+   self.pool:clear(e)
+   return self
+end
+
+-- Check if the Pool bound to this System contains the passed Entity
+-- @param e Entity to check
+-- @treturn boolean Whether the Entity exists.
+function Filter:has (e)
+   return self.pool:has(e)
+end
+
+--- Gets the name of the Filter
+-- @treturn string
+function Filter:getName()
+   return self.__name
+end
+
+return setmetatable(Filter, {
+  __call  = function(_, ...)
+     return Filter.new(...)
+  end,
+})

concord/list.lua

@@ -16,7 +16,7 @@ end
 
 --- Adds an object to the List.
 -- Object must be of reference type
--- Object may not be the string 'size'
+-- Object may not be the string 'size', 'onAdded' or 'onRemoved'
 -- @param obj Object to add
 -- @treturn List self
 function List:add(obj)
@@ -26,6 +26,7 @@ function List:add(obj)
    self[obj]  = size
    self.size  = size
 
+   if self.onAdded then self:onAdded(obj) end
    return self
 end
 
@@ -51,6 +52,7 @@ function List:remove(obj)
    self[obj] = nil
    self.size = size - 1
 
+   if self.onRemoved then self:onRemoved(obj) end
    return self
 end
 
@@ -94,6 +96,30 @@ function List:indexOf(obj)
    return self[obj]
 end
 
+--- Sorts the List in place, using the order function.
+-- The order function is passed to table.sort internally so documentation on table.sort can be used as reference.
+-- @param order Function that takes two Entities (a and b) and returns true if a should go before than b.
+-- @treturn List self
+function List:sort(order)
+   table.sort(self, order)
+
+   for key, obj in ipairs(self) do
+      self[obj] = key
+   end
+
+   return self
+end
+
+--- Callback for when an item is added to the List.
+-- @param obj Object that was added
+function List:onAdded (obj) --luacheck: ignore
+end
+
+--- Callback for when an item is removed to the List.
+-- @param obj Object that was removed
+function List:onRemoved (obj) --luacheck: ignore
+end
+
 return setmetatable(List, {
    __call = function()
       return List.new()

concord/pool.lua

@@ -1,111 +0,0 @@
---- Used to iterate over Entities with a specific Components
--- A Pool contain a any amount of Entities.
--- @classmod Pool
-
-local PATH = (...):gsub('%.[^%.]+$', '')
-
-local List = require(PATH..".list")
-
-local Pool = {}
-Pool.__mt = {
-   __index = Pool,
-}
-
---- Creates a new Pool
--- @string name Name for the Pool.
--- @tparam table filter Table containing the required BaseComponents
--- @treturn Pool The new Pool
-function Pool.new(name, filter)
-   local pool = setmetatable(List(), Pool.__mt)
-
-   pool.__name   = name
-   pool.__filter = filter
-
-   pool.__isPool = true
-
-   return pool
-end
-
---- Checks if an Entity is eligible for the Pool.
--- @tparam Entity e Entity to check
--- @treturn boolean
-function Pool:eligible(e)
-   for i=#self.__filter, 1, -1 do
-      local component = self.__filter[i].__name
-
-      if not e[component] then return false end
-   end
-
-   return true
-end
-
--- Adds an Entity to the Pool, if it can be eligible.
--- @param e Entity to add
--- @treturn Pool self
--- @treturn boolean Whether the entity was added or not
-function Pool:add(e, bypass)
-   if not bypass and not self:eligible(e) then
-      return self, false
-   end
-
-   List.add(self, e)
-   self:onEntityAdded(e)
-
-   return self, true
-end
-
--- Remove an Entity from the Pool.
--- @param e Entity to remove
--- @treturn Pool self
-function Pool:remove(e)
-   List.remove(self, e)
-   self:onEntityRemoved(e)
-
-   return self
-end
-
---- Evaluate whether an Entity should be added or removed from the Pool.
--- @param e Entity to add or remove
--- @treturn Pool self
-function Pool:evaluate(e)
-   local has  = self:has(e)
-   local eligible = self:eligible(e)
-
-   if not has and eligible then
-      self:add(e, true) --Bypass the check cause we already checked
-   elseif has and not eligible then
-      self:remove(e)
-   end
-
-   return self
-end
-
---- Gets the name of the Pool
--- @treturn string
-function Pool:getName()
-   return self.__name
-end
-
---- Gets the filter of the Pool.
--- Warning: Do not modify this filter.
--- @return Filter of the Pool.
-function Pool:getFilter()
-   return self.__filter
-end
-
---- Callback for when an Entity is added to the Pool.
--- @tparam Entity e Entity that was added.
-function Pool:onEntityAdded(e) -- luacheck: ignore
-end
-
--- Callback for when an Entity is removed from the Pool.
--- @tparam Entity e Entity that was removed.
-function Pool:onEntityRemoved(e)  -- luacheck: ignore
-end
-
-return setmetatable(Pool, {
-   __index = List,
-   __call  = function(_, ...)
-      return Pool.new(...)
-   end,
-})

concord/system.lua

@@ -5,9 +5,8 @@
 
 local PATH = (...):gsub('%.[^%.]+$', '')
 
-local Pool       = require(PATH..".pool")
+local Filter     = require(PATH..".filter")
 local Utils      = require(PATH..".utils")
-local Components = require(PATH..".components")
 
 local System = {
    ENABLE_OPTIMIZATION = true,
@@ -19,7 +18,7 @@ System.mt = {
       local system = setmetatable({
          __enabled = true,
 
-         __pools = {},
+         __filters = {},
          __world = world,
 
          __isSystem = true,
@@ -33,11 +32,11 @@ System.mt = {
          Utils.shallowCopy(systemClass, system)
       end
 
-      for name, filter in pairs(systemClass.__filter) do
+      for name, def in pairs(systemClass.__definition) do
-         local pool = Pool(name, filter)
+         local filter, pool = Filter(name, Utils.shallowCopy(def, {}))
 
          system[name] = pool
-         system.__pools[#system.__pools + 1] = pool
+         table.insert(system.__filters, filter)
       end
 
       system:init(world)
@@ -45,44 +44,23 @@ System.mt = {
       return system
    end,
 }
-
-local validateFilters = function (baseFilters)
-   local filters = {}
-
-   for name, componentsList in pairs(baseFilters) do
-      if type(name) ~= 'string' then
-         error("invalid name for filter (string key expected, got "..type(name)..")", 3)
-      end
-
-      if type(componentsList) ~= 'table' then
-         error("invalid component list for filter '"..name.."' (table expected, got "..type(componentsList)..")", 3)
-      end
-
-      local filter = {}
-      for n, component in ipairs(componentsList) do
-         local ok, componentClass = Components.try(component)
-
-         if not ok then
-            error("invalid component for filter '"..name.."' at position #"..n.." ("..componentClass..")", 3)
-         end
-
-         filter[#filter + 1] = componentClass
-      end
-
-      filters[name] = filter
-   end
-
-   return filters
-end
-
 --- Creates a new SystemClass.
 -- @param table filters A table containing filters (name = {components...})
 -- @treturn System A new SystemClass
-function System.new(filters)
+function System.new(definition)
-   local systemClass = setmetatable({
+   definition = definition or {}
-      __filter = validateFilters(filters),
+
+   for name, def in pairs(definition) do
+      if type(name) ~= 'string' then
+         Utils.error(2, "invalid name for filter (string key expected, got %s)", type(name))
+      end
+
+      Filter.validate(0, name, def)
+   end
+
+   local systemClass = setmetatable({
+      __definition = definition,
 
-      __name          = nil,
       __isSystemClass = true,
    }, System.mt)
    systemClass.__index = systemClass
@@ -101,8 +79,8 @@ end
 -- @param e The Entity to check
 -- @treturn System self
 function System:__evaluate(e)
-   for _, pool in ipairs(self.__pools) do
+   for _, filter in ipairs(self.__filters) do
-      pool:evaluate(e)
+      filter:evaluate(e)
    end
 
    return self
@@ -112,9 +90,9 @@ end
 -- @param e The Entity to remove
 -- @treturn System self
 function System:__remove(e)
-   for _, pool in ipairs(self.__pools) do
+   for _, filter in ipairs(self.__filters) do
-      if pool:has(e) then
+      if filter:has(e) then
-         pool:remove(e)
+         filter:remove(e)
       end
    end
 
@@ -124,8 +102,8 @@ end
 -- Internal: Clears all Entities from the System.
 -- @treturn System self
 function System:__clear()
-   for i = 1, #self.__pools do
+   for _, filter in ipairs(self.__filters) do
-      self.__pools[i]:clear()
+      filter:clear()
    end
 
    return self
@@ -158,18 +136,6 @@ function System:getWorld()
    return self.__world
 end
 
---- Returns true if the System has a name.
--- @treturn boolean
-function System:hasName()
-   return self.__name and true or false
-end
-
---- Returns the name of the System.
--- @treturn string
-function System:getName()
-   return self.__name
-end
-
 --- Callbacks
 -- @section Callbacks
 

concord/type.lua

@@ -3,6 +3,15 @@
 
 local Type = {}
 
+function Type.isCallable(t)
+   if type(t) == "function" then return true end
+
+   local meta = getmetatable(t)
+   if meta and type(meta.__call) == "function" then return true end
+
+   return false
+end
+
 --- Returns if object is an Entity.
 -- @param t Object to check
 -- @treturn boolean
@@ -45,4 +54,11 @@ function Type.isWorld(t)
    return type(t) == "table" and t.__isWorld or false
 end
 
+--- Returns if object is a Filter.
+-- @param t Object to check
+-- @treturn boolean
+function Type.isFilter(t)
+   return type(t) == "table" and t.__isFilter or false
+end
+
 return Type

concord/utils.lua

@@ -3,6 +3,10 @@
 
 local Utils = {}
 
+function Utils.error(level, str, ...)
+    error(string.format(str, ...), level + 1)
+end
+
 --- Does a shallow copy of a table and appends it to a target table.
 -- @param orig Table to copy
 -- @param target Table to append to
@@ -21,39 +25,43 @@ end
 -- @param namespace A table that will hold the required files
 -- @treturn table The namespace table
 function Utils.loadNamespace(pathOrFiles, namespace)
-   if (type(pathOrFiles) ~= "string" and type(pathOrFiles) ~= "table") then
+   if type(pathOrFiles) ~= "string" and type(pathOrFiles) ~= "table" then
-       error("bad argument #1 to 'loadNamespace' (string/table of strings expected, got "..type(pathOrFiles)..")", 2)
+       Utils.error(2, "bad argument #1 to 'loadNamespace' (string/table of strings expected, got %s)", type(pathOrFiles))
    end
 
-   if (type(pathOrFiles) == "string") then
+   if type(pathOrFiles) == "string" then
        local info = love.filesystem.getInfo(pathOrFiles) -- luacheck: ignore
-       if (info == nil or info.type ~= "directory") then
+       if info == nil or info.type ~= "directory" then
-            error("bad argument #1 to 'loadNamespace' (path '"..pathOrFiles.."' not found)", 2)
+            Utils.error(2, "bad argument #1 to 'loadNamespace' (path '%s' not found)", pathOrFiles)
        end
 
        local files = love.filesystem.getDirectoryItems(pathOrFiles)
 
        for _, file in ipairs(files) do
-            local name = file:sub(1, #file - 4)
+            local isFile = love.filesystem.getInfo(pathOrFiles .. "/" .. file).type == "file"
-            local path = pathOrFiles.."."..name
 
-            local value = require(path)
+            if isFile and string.match(file, '%.lua$') ~= nil then
-            if namespace then namespace[name] = value end
+                 local name = file:sub(1, #file - 4)
+                 local path = pathOrFiles.."."..name
+
+                 local value = require(path:gsub("%/", "."))
+                 if namespace then namespace[name] = value end
+            end
        end
-   elseif (type(pathOrFiles == "table")) then
+   elseif type(pathOrFiles) == "table" then
        for _, path in ipairs(pathOrFiles) do
-            if (type(path) ~= "string") then
+            if type(path) ~= "string" then
-                error("bad argument #2 to 'loadNamespace' (string/table of strings expected, got table containing "..type(path)..")", 2) -- luacheck: ignore
+                Utils.error(2, "bad argument #2 to 'loadNamespace' (string/table of strings expected, got table containing %s)", type(path)) -- luacheck: ignore
             end
 
             local name = path
 
             local dotIndex, slashIndex = path:match("^.*()%."), path:match("^.*()%/")
-            if (dotIndex or slashIndex) then
+            if dotIndex or slashIndex then
                 name = path:sub((dotIndex or slashIndex) + 1)
             end
 
-            local value = require(path)
+            local value = require(path:gsub("%/", "."))
             if namespace then namespace[name] = value end
        end
    end

concord/world.lua

@@ -6,10 +6,12 @@
 
 local PATH = (...):gsub('%.[^%.]+$', '')
 
-local Entity = require(PATH..".entity")
+local Filter     = require(PATH..".filter")
-local Type   = require(PATH..".type")
+local Entity     = require(PATH..".entity")
-local List   = require(PATH..".list")
+local Components = require(PATH..".components")
-local Utils  = require(PATH..".utils")
+local Type       = require(PATH..".type")
+local List       = require(PATH..".list")
+local Utils      = require(PATH..".utils")
 
 local World = {
    ENABLE_OPTIMIZATION = true,
@@ -18,6 +20,12 @@ World.__mt = {
    __index = World,
 }
 
+local defaultGenerator = function (state)
+   local current = state
+   state = state +1
+   return string.format("%d", current), state
+end
+
 --- Creates a new World.
 -- @treturn World The new World
 function World.new()
@@ -28,14 +36,24 @@ function World.new()
       __events     = {},
       __emitSDepth = 0,
 
+      __resources = {},
+
+      __hash = {
+         state = -2^53,
+         generator = defaultGenerator,
+         keys = {},
+         entities = {}
+      },
+
       __added   = List(), __backAdded   = List(),
       __removed = List(), __backRemoved = List(),
       __dirty   = List(), __backDirty   = List(),
 
       __systemLookup = {},
 
-      __name    = nil,
       __isWorld = true,
+
+      __ignoreEmits = false
    }, World.__mt)
 
    -- Optimization: We deep copy the World class into our instance of a world.
@@ -53,7 +71,7 @@ end
 -- @treturn World self
 function World:addEntity(e)
    if not Type.isEntity(e) then
-      error("bad argument #1 to 'World:addEntity' (Entity expected, got "..type(e)..")", 2)
+      Utils.error(2, "bad argument #1 to 'World:addEntity' (Entity expected, got %s)", type(e))
    end
 
    if e.__world then
@@ -66,12 +84,47 @@ function World:addEntity(e)
    return self
 end
 
+--- Creates a new Entity and adds it to the World.
+-- @treturn Entity e the new Entity
+function World:newEntity()
+   return Entity(self)
+end
+
+function World:query(def, onMatch)
+   local filter = Filter.parse(nil, def)
+
+   local list = nil
+   if not Type.isCallable(onMatch) then
+      list = type(onMatch) == "table" and onMatch or {}
+   end
+
+   for _, e in ipairs(self.__entities) do
+      if Filter.match(e, filter) then
+         if list then
+            table.insert(list, e)
+         else
+            onMatch(e)
+         end
+      end
+   end
+
+   return list
+end
+
 --- Removes an Entity from the World.
 -- @tparam Entity e Entity to remove
 -- @treturn World self
 function World:removeEntity(e)
    if not Type.isEntity(e) then
-      error("bad argument #1 to 'World:removeEntity' (Entity expected, got "..type(e)..")", 2)
+      Utils.error(2, "bad argument #1 to 'World:removeEntity' (Entity expected, got %s)", type(e))
+   end
+
+   if e.__world ~= self then
+      error("trying to remove an Entity from a World it doesn't belong to", 2)
+   end
+
+   if e:has("key") then
+      e:remove("key")
    end
 
    self.__removed:add(e)
@@ -208,7 +261,7 @@ function World:addSystem(systemClass)
    local ok, err = tryAddSystem(self, systemClass)
 
    if not ok then
-      error("bad argument #1 to 'World:addSystem' ("..err..")", 2)
+      Utils.error(2, "bad argument #1 to 'World:addSystem' (%s)", err)
    end
 
    return self
@@ -226,7 +279,7 @@ function World:addSystems(...)
 
       local ok, err = tryAddSystem(self, systemClass)
       if not ok then
-         error("bad argument #"..i.." to 'World:addSystems' ("..err..")", 2)
+         Utils.error(2, "bad argument #%d to 'World:addSystems' (%s)", i, err)
       end
    end
 
@@ -238,7 +291,7 @@ end
 -- @treturn boolean
 function World:hasSystem(systemClass)
    if not Type.isSystemClass(systemClass) then
-      error("bad argument #1 to 'World:getSystem' (systemClass expected, got "..type(systemClass)..")", 2)
+      Utils.error(2, "bad argument #1 to 'World:hasSystem' (SystemClass expected, got %s)", type(systemClass))
    end
 
    return self.__systemLookup[systemClass] and true or false
@@ -249,7 +302,7 @@ end
 -- @treturn System System to get
 function World:getSystem(systemClass)
    if not Type.isSystemClass(systemClass) then
-      error("bad argument #1 to 'World:getSystem' (systemClass expected, got "..type(systemClass)..")", 2)
+      Utils.error(2, "bad argument #1 to 'World:getSystem' (SystemClass expected, got %s)", type(systemClass))
    end
 
    return self.__systemLookup[systemClass]
@@ -262,14 +315,21 @@ end
 -- @treturn World self
 function World:emit(functionName, ...)
    if not functionName or type(functionName) ~= "string" then
-      error("bad argument #1 to 'World:emit' (String expected, got "..type(functionName)..")")
+      Utils.error(2, "bad argument #1 to 'World:emit' (String expected, got %s)", type(functionName))
    end
 
    local shouldFlush = self.__emitSDepth == 0
 
    self.__emitSDepth = self.__emitSDepth + 1
 
-	local listeners = self.__events[functionName]
+   local listeners = self.__events[functionName]
+
+   if not self.__ignoreEmits and Type.isCallable(self.beforeEmit) then
+      self.__ignoreEmits = true
+      local preventDefaults = self:beforeEmit(functionName, listeners, ...)
+      self.__ignoreEmits = false
+      if preventDefaults then return end
+   end
 
    if listeners then
       for i = 1, #listeners do
@@ -285,6 +345,12 @@ function World:emit(functionName, ...)
       end
    end
 
+   if not self.__ignoreEmits and Type.isCallable(self.afterEmit) then
+      self.__ignoreEmits = true
+      self:afterEmit(functionName, listeners, ...)
+      self.__ignoreEmits = false
+   end
+
    self.__emitSDepth = self.__emitSDepth - 1
 
    return self
@@ -316,49 +382,103 @@ function World:getSystems()
    return self.__systems
 end
 
-function World:serialize()
+function World:serialize(ignoreKeys)
    self:__flush()
 
-   local data = {}
+   local data = { generator = self.__hash.state }
 
    for i = 1, self.__entities.size do
       local entity = self.__entities[i]
 
-      local entityData = entity:serialize()
+      if entity.serializable then
-
+         local entityData = entity:serialize(ignoreKeys)
-      data[i] = entityData
+         table.insert(data, entityData)
+      end
    end
 
    return data
 end
 
-function World:deserialize(data, append)
+function World:deserialize(data, startClean, ignoreGenerator)
-   if (not append) then
+   if startClean then
       self:clear()
    end
 
+   if (not ignoreGenerator) then
+      self.__hash.state = data.generator
+   end
+
+   local entities = {}
+
    for i = 1, #data do
-      local entityData = data[i]
+      local entity = Entity(self)
 
-      local entity = Entity()
+      if data[i].key then
-      entity:deserialize(entityData)
+         local component = Components.key:__new(entity)
+         component:deserialize(data[i].key)
+         entity.key = component
 
-      self:addEntity(entity)
+         entity:__dirty()
+      end
+
+      entities[i] = entity
+   end
+
+   for i = 1, #data do
+      entities[i]:deserialize(data[i])
    end
 
    self:__flush()
+
+   return self
 end
 
---- Returns true if the World has a name.
+function World:setKeyGenerator(generator, initialState)
--- @treturn boolean
+   if not Type.isCallable(generator) then
-function World:hasName()
+      Utils.error(2, "bad argument #1 to 'World:setKeyGenerator' (function expected, got %s)", type(generator))
-   return self.__name and true or false
+   end
+
+   self.__hash.generator = generator
+   self.__hash.state = initialState
+
+   return self
 end
 
---- Returns the name of the World.
+function World:__clearKey(e)
--- @treturn string
+   local key = self.__hash.keys[e]
-function World:getName()
+
-   return self.__name
+   if key then
+      self.__hash.keys[e] = nil
+      self.__hash.entities[key] = nil
+   end
+
+   return self
+end
+
+function World:__assignKey(e, key)
+   local hash = self.__hash
+
+   if not key then
+      key = hash.keys[e]
+      if key then return key end
+
+      key, hash.state = hash.generator(hash.state)
+   end
+
+   if hash.entities[key] and hash.entities[key] ~= e then
+      Utils.error(4, "Trying to assign a key that is already taken (key: '%s').", key)
+   elseif hash.keys[e] and hash.keys[e] ~= key then
+      Utils.error(4, "Trying to assign more than one key to an Entity. (old: '%s', new: '%s')", hash.keys[e], key)
+   end
+
+   hash.keys[e] = key
+   hash.entities[key] = e
+
+   return key
+end
+
+function World:getEntityByKey(key)
+   return self.__hash.entities[key]
 end
 
 --- Callback for when an Entity is added to the World.
@@ -371,8 +491,25 @@ end
 function World:onEntityRemoved(e) -- luacheck: ignore
 end
 
+--- Sets a named resource in the world
+-- @string name Name of the resource
+-- @tparam Any resource Resource to set
+-- @treturn World self
+function World:setResource(name, resource)
+  self.__resources[name] = resource
+  return self
+end
+
+--- Gets a named resource from the world
+-- @string name Name of the resource
+-- @treturn Any resource
+function World:getResource(name)
+  return self.__resources[name]
+end
+
 return setmetatable(World, {
    __call = function(_, ...)
+      ---@diagnostic disable-next-line: redundant-parameter
       return World.new(...)
    end,
 })