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module FelFlame
class Systems
# How early this System should be executed in a list of Systems
attr_accessor :priority
# The Constant name assigned to this System
attr_reader :const_name
# Allows overwriting the storage of triggers, such as for clearing.
# This method should generally only need to be used internally and
# not by a game developer.
# @!visibility private
attr_writer :addition_triggers, :removal_triggers, :attr_triggers
def priority=(priority)
@priority = priority
FelFlame::Stage.systems = FelFlame::Stage.systems.sort_by(&:priority)
end
# Stores references to components or their managers that trigger
# this component when a component or component from that manager
# is added to an entity.
# Do not edit this hash as it is managed by FelFlame automatically.
# @return [Array<Component>]
def addition_triggers
@addition_triggers ||= []
end
# Stores references to components or their managers that trigger
# this component when a component or component from that manager
# is removed from an entity.
# Do not edit this hash as it is managed by FelFlame automatically.
# @return [Array<Component>]
def removal_triggers
@removal_triggers ||= []
end
# Stores references to systems that should be triggered when an
# attribute from this manager is changed
# Do not edit this hash as it is managed by FelFlame automatically.
# @return [Hash<Symbol, Array<Symbol>>]
def attr_triggers
@attr_triggers ||= {}
end
class <<self
include Enumerable
# Iterate over all Systems, sorted by their priority. You also call other enumerable methods instead of each, such as +each_with_index+ or +select+
# @return [Enumerator]
def each(&block)
constants.map { |sym| const_get(sym) }.sort_by(&:priority).reverse.each(&block)
end
end
# Creates a new System which can be accessed as a constant under the namespace {FelFlame::Systems}.
# The name given is what constant the system is assigned to
#
# @example
# FelFlame::Systems.new('PassiveHeal', priority: -2) do
# FelFlame::Components::Health.each do |component|
# component.hp += 5
# end
# end
# # Give it a low priority so other systems such as a
# # Poison system would kill the player first
#
# @param name [String] The name this system will use. Needs to to be in the Ruby Constant format.
# @param priority [Integer] Which priority order this system should be executed in relative to other systems. Higher means executed earlier.
# @param block [Proc] The code you wish to be executed when the system is triggered. Can be defined by using a +do end+ block or using +{ }+ braces.
def initialize(name, priority: 0, &block)
FelFlame::Systems.const_set(name, self)
@const_name = name
@priority = priority
@block = block
end
# Manually execute the system a single time
def call
@block.call
end
# Redefine what code is executed by this System when it is called upon.
# @param block [Proc] The code you wish to be executed when the system is triggered. Can be defined by using a +do end+ block or using +{ }+ braces.
def redefine(&block)
@block = block
end
# Removes triggers from this system. This function is fairly flexible so it can accept a few different inputs
# For addition and removal triggers, you can optionally pass in a component, or a manager to clear specifically
# the relevant triggers for that one component or manager. If you do not pass a component or manager then it will
# clear triggers for all components and managers.
# For attr_triggers
# @example
# # To clear all triggers that execute this system when a component is added:
# FelFlame::Systems::ExampleSystem.clear_triggers :addition_triggers
# # Same as above but for when a component is removed instead
# FelFlame::Systems::ExampleSystem.clear_triggers :removal_triggers
# # Same as above but for when a component has a certain attribute changed
# FelFlame::Systems::ExampleSystem.clear_triggers :attr_triggers
#
# # Clear a trigger from a specific component
# FelFlame::Systems::ExampleSystem.clear_triggers :addition_triggers, FelFlame::Component::ExampleComponent[0]
# # Clear a trigger from a specific component manager
# FelFlame::Systems::ExampleSystem.clear_triggers :addition_triggers, FelFlame::Component::ExampleComponent
#
# # Clear the trigger that executes a system when the ':example_attr' is changes
# FelFlame::Systems::ExampleSystem.clear_triggers :attr_triggers, :example_attr
# @param trigger_types [:Symbols] One or more of the following trigger types: +:addition_triggers+, +:removal_triggers+, or +:attr_triggers+. If attr_triggers is used then you may pass attributes you wish to be cleared as symbols in this parameter as well
# @param component_or_manager [Component or ComponentManager] The object to clear triggers from. Use Nil to clear triggers from all components associated with this system.
# @return [Boolean] +true+
def clear_triggers(*trigger_types, component_or_manager: nil)
trigger_types = [:addition_triggers, :removal_triggers, :attr_triggers] if trigger_types.empty?
if trigger_types.include? :attr_triggers
if (trigger_types - [:addition_triggers,
:removal_triggers,
:attr_triggers]).empty?
if component_or_manager.nil?
#remove all attrs
self.attr_triggers.each do |cmp_or_mgr, attrs|
attrs.each do |attr|
next if cmp_or_mgr.attr_triggers[attr].nil?
cmp_or_mgr.attr_triggers[attr].delete self
end
self.attr_triggers = {}
end
else
#remove attrs relevant to comp_or_man
unless self.attr_triggers[component_or_manager].nil?
self.attr_triggers[component_or_manager].each do |attr|
component_or_manager.attr_triggers[attr].delete self
end
self.attr_triggers[component_or_manager] = []
end
end
else
if component_or_manager.nil?
(trigger_types - [:addition_triggers, :removal_triggers, :attr_triggers]).each do |attr|
#remove attr
self.attr_triggers.each do |cmp_or_mgr, attrs|
cmp_or_mgr.attr_triggers[attr].delete self
end
end
self.attr_triggers.delete (trigger_types - [:addition_triggers,
:removal_triggers,
:attr_triggers])
else
#remove attr from component_or_manager
(trigger_types - [:addition_triggers, :removal_triggers, :attr_triggers]).each do |attr|
next if component_or_manager.attr_triggers[attr].nil?
component_or_manager.attr_triggers[attr].delete self
end
self.attr_triggers[component_or_manager] -= trigger_types unless self.attr_triggers[component_or_manager].nil?
end
end
end
(trigger_types & [:removal_triggers, :addition_triggers] - [:attr_triggers]).each do |trigger_type|
if component_or_manager.nil?
#remove all removal triggers
self.send(trigger_type).each do |trigger|
trigger.send(trigger_type).delete self
end
self.send("#{trigger_type.to_s}=", [])
else
#remove removal trigger relevant to comp/man
self.send(trigger_type).delete component_or_manager
component_or_manager.send(trigger_type).delete self
end
end
true
end
# Add a component or component manager so that it triggers this system when the component or a component from the component manager is added to an entity
# @param component_or_manager [Component or ComponentManager] The component or component manager to trigger this system when added
# @return [Boolean] +true+
def trigger_when_added(component_or_manager)
self.addition_triggers |= [component_or_manager]
component_or_manager.addition_triggers |= [self]
true
end
# Add a component or component manager so that it triggers this system when the component or a component from the component manager is removed from an entity
# @param component_or_manager [Component or ComponentManager] The component or component manager to trigger this system when removed
# @return [Boolean] +true+
def trigger_when_removed(component_or_manager)
self.removal_triggers |= [component_or_manager]
component_or_manager.removal_triggers |= [self]
true
end
# Add a component or component manager so that it triggers this system when a component's attribute is changed.
# @return [Boolean] +true+
def trigger_when_is_changed(component_or_manager, attr)
if component_or_manager.attr_triggers[attr].nil?
component_or_manager.attr_triggers[attr] = [self]
else
component_or_manager.attr_triggers[attr] |= [self]
end
if self.attr_triggers[component_or_manager].nil?
self.attr_triggers[component_or_manager] = [attr]
else
self.attr_triggers[component_or_manager] |= [attr]
end
true
end
end
end
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