lib/felecs/entity_manager.rb
# frozen_string_literal: true
module FelECS
class Entities
# Creating a new Entity
# @param components [Components] Can be any number of components, identical duplicates will be automatically purged however different components from the same component manager are allowed.
# @return [Entity]
def initialize(*components)
# Add each component
add(*components)
self.class._data.push self
end
# A hash that uses component manager constant names as keys, and where the values of those keys are arrays that contain the the components attached to this entity.
# @return [Hash<Component_Manager, Array<Integer>>]
def components
@components ||= {}
end
# A single component from a component manager. Use this if you expect the component to only belong to one entity and you want to access it. Access the component using either parameter notation or array notation. Array notation is conventional for better readablility.
# @example
# @entity.component[@component_manager] # array notation(the standard)
# @entity.component(@component_manager) # method notation
# @param manager [ComponentManager] If you pass nil you can then use array notation to access the same value.
# @return [Component]
def component(manager = nil)
if manager.nil?
FelECS::Entities.component_redirect.entity = self
FelECS::Entities.component_redirect
else
if components[manager].nil?
raise "This entity(#{self}) doesnt have any components of this type: #{manager}"
elsif components[manager].length > 1
Warning.warn("This entity has MANY of this component but you called the method that is intended for having a single of this component type.\nYou may have a bug in your logic.")
end
components[manager].first
end
end
# Removes this Entity from the list and purges all references to this Entity from other Components, as well as its data.
# @return [Boolean] +true+
def delete
components.each do |_component_manager, component_array|
component_array.reverse_each do |component|
component.entities.delete(self)
end
end
FelECS::Entities._data.delete self
@components = {}
true
end
# Add any number components to the Entity.
# @param components_to_add [Component] Any number of components created from any component manager
# @return [Boolean] +true+
def add(*components_to_add)
components_to_add.each do |component|
if components[component.class].nil?
components[component.class] = [component]
component.entities.push self
check_systems component, :addition_triggers
elsif !components[component.class].include? component
components[component.class].push component
component.entities.push self
check_systems component, :addition_triggers
end
end
true
end
# triggers every system associated with this component's trigger
# @return [Boolean] +true+
# @!visibility private
def check_systems(component, trigger_type)
component_calls = component.class.send(trigger_type)
component.send(trigger_type).each do |system|
component_calls |= [system]
end
component_calls.sort_by(&:priority).reverse.each(&:call)
true
end
# Remove a component from the Entity
# @param components_to_remove [Component] A component created from any component manager
# @return [Boolean] +true+
def remove(*components_to_remove)
components_to_remove.each do |component|
check_systems component, :removal_triggers if component.entities.include? self
component.entities.delete self
components[component.class].delete component
components.delete component.class if components[component.class].empty?
end
true
end
# Export all data into a JSON String which can then be saved into a file
# TODO: This function is not yet complete
# @return [String] A JSON formatted String
# def to_json() end
class << self
# Selects every entity that has components of they type passed into
# this function and then executes the code block for those components
# and entities.
# @return [Nil]
def group(*component_managers, &block)
return nil if component_managers.empty?
if component_managers.length == 1
component_managers.first.each do |cmp|
block.call(cmp, cmp.entity)
end
else
arry = component_managers.first.select do |cmp|
ent = cmp.entity
keep = true
component_managers.drop(1).each do |mgr|
next unless ent.components[mgr].nil?
keep = false
break
end
keep
end
arry.each do |cmp|
ent = cmp.entity
cmp_arry = [cmp]
component_managers.drop(1).each do |cmp_mgr|
cmp_arry.push ent.component[cmp_mgr]
end
block.call(*cmp_arry, ent)
end
end
nil
end
# Makes component managers behave like arrays with additional
# methods for managing the array
# @!visibility private
def respond_to_missing?(method, *)
if _data.respond_to? method
true
else
super
end
end
# Makes component managers behave like arrays with additional
# methods for managing the array
# @!visibility private
def method_missing(method, *args, **kwargs, &block)
if _data.respond_to? method
_data.send(method, *args, **kwargs, &block)
else
super
end
end
# Fancy method redirection for when the `component` method is called
# in an Entity
# WARNING: This method will not correctly work with multithreading
# @!visibility private
def component_redirect
if @component_redirect
else
@component_redirect = Object.new
@component_redirect.instance_variable_set(:@entity, nil)
@component_redirect.define_singleton_method(:entity) do
instance_variable_get(:@entity)
end
@component_redirect.define_singleton_method(:entity=) do |value|
instance_variable_set(:@entity, value)
end
@component_redirect.define_singleton_method(:[]) do |component_manager|
entity.component(component_manager)
end
end
@component_redirect
end
# @return [Array<Entity>] Array of all Entities that exist
# @!visibility private
def _data
@data ||= []
end
# Creates a new entity using the data from a JSON string
# TODO: This function is not yet complete
# @param json_string [String] A string that was exported originally using the {FelECS::Entities#to_json to_json} function
# @param opts [Keywords] What values(its {FelECS::Entities#id ID} or the {FelECS::ComponentManager#id component IDs}) should be overwritten TODO: this might change
# def from_json(json_string, **opts) end
end
end
end