rename folder src to concord

concord/entity.lua

@@ -0,0 +1,180 @@
+--- Entity
+-- Entities are the concrete objects that exist in your project.
+-- An Entity have Components and are processed by Systems.
+-- An Entity is contained by a maximum of 1 World.
+
+local PATH = (...):gsub('%.[^%.]+$', '')
+
+local Type = require(PATH..".type")
+
+local Entity = {}
+Entity.__mt = {
+   __index = Entity,
+}
+
+--- Creates a new Entity. Optionally adds it to a World.
+-- @param world Optional World to add the entity to
+-- @return 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)
+   end
+
+   local e = setmetatable({
+      __world      = nil,
+      __components = {},
+
+      __isEntity = true,
+   }, Entity.__mt)
+
+   if (world) then
+      world:addEntity(e)
+   end
+
+   return e
+end
+
+local function give(e, componentClass, ...)
+   local component = componentClass:__initialize(...)
+
+   e[componentClass] = component
+   e.__components[componentClass] = component
+
+   e:__dirty()
+end
+
+local function remove(e, componentClass)
+   e[componentClass] = nil
+   e.__components[componentClass] = nil
+
+   e:__dirty()
+end
+
+--- Gives an Entity a Component.
+-- If the Component already exists, it's overridden by this new Component
+-- @param componentClass ComponentClass to add an instance of
+-- @param ... varargs passed to the Component's populate function
+-- @return self
+function Entity:give(componentClass, ...)
+   if not Type.isComponentClass(componentClass) then
+      error("bad argument #1 to 'Entity:give' (ComponentClass expected, got "..type(componentClass)..")", 2)
+   end
+
+   give(self, componentClass, ...)
+
+   return self
+end
+
+--- Ensures an Entity to have a Component.
+-- If the Component already exists, no action is taken
+-- @param componentClass ComponentClass to add an instance of
+-- @param ... varargs passed to the Component's populate function
+-- @return self
+function Entity:ensure(componentClass, ...)
+   if not Type.isComponentClass(componentClass) then
+      error("bad argument #1 to 'Entity:ensure' (ComponentClass expected, got "..type(componentClass)..")", 2)
+   end
+
+   if self[componentClass] then
+      return self
+   end
+
+   give(self, componentClass, ...)
+
+   return self
+end
+
+--- Removes a Component from an Entity.
+-- @param componentClass ComponentClass of the Component to remove
+-- @return self
+function Entity:remove(componentClass)
+   if not Type.isComponentClass(componentClass) then
+      error("bad argument #1 to 'Entity:remove' (ComponentClass expected, got "..type(componentClass)..")")
+   end
+
+   remove(self, componentClass)
+
+   return self
+end
+
+--- Assembles an Entity.
+-- @param assemblage Assemblage to assemble with
+-- @param ... Varargs to pass to the Assemblage's assemble function.
+function Entity:assemble(assemblage, ...)
+   if not Type.isAssemblage(assemblage) then
+      error("bad argument #1 to 'Entity:assemble' (Assemblage expected, got "..type(assemblage)..")")
+   end
+
+   assemblage:assemble(self, ...)
+
+   return self
+end
+
+--- Destroys the Entity.
+-- Removes the Entity from it's World if it's in one.
+-- @return self
+function Entity:destroy()
+   if self.__world then
+      self.__world:removeEntity(self)
+   end
+
+   return self
+end
+
+--- Internal: Tells the World it's in that this Entity is dirty.
+-- @return self
+function Entity:__dirty()
+   if self.__world then
+      self.__world:__dirtyEntity(self)
+   end
+
+   return self
+end
+
+--- Returns true if the Entity has a Component.
+-- @param componentClass ComponentClass of the Component to check
+-- @return True if the Entity has the Component, false otherwise
+function Entity:has(componentClass)
+   if not Type.isComponentClass(componentClass) then
+      error("bad argument #1 to 'Entity:has' (ComponentClass expected, got "..type(componentClass)..")")
+   end
+
+   return self[componentClass] ~= nil
+end
+
+--- Gets a Component from the Entity.
+-- @param componentClass ComponentClass of the Component to get
+-- @return The Component
+function Entity:get(componentClass)
+   if not Type.isComponentClass(componentClass) then
+      error("bad argument #1 to 'Entity:get' (ComponentClass expected, got "..type(componentClass)..")")
+   end
+
+   return self[componentClass]
+end
+
+--- Returns a table of all Components the Entity has.
+-- Warning: Do not modify this table.
+-- Use Entity:give/ensure/remove instead
+-- @return Table of all Components the Entity has
+function Entity:getComponents()
+   return self.__components
+end
+
+--- Returns true if the Entity is in a World.
+-- @return True if the Entity is in a World, false otherwise
+function Entity:inWorld()
+   return self.__world and true or false
+end
+
+--- Returns the World the Entity is in.
+-- @return The World the Entity is in.
+function Entity:getWorld()
+   return self.__world
+end
+
+return setmetatable(Entity, {
+   __call = function(_, ...)
+      return Entity.new(...)
+   end,
+})