entities, components, and systems improved

1 files changed, 107 insertions, 3 deletions

diff --git a/system_manager.rb b/system_manager.rb
index 14f37d4..4bd37b2 100644
--- a/system_manager.rb
+++ b/system_manager.rb
@@ -1,7 +1,111 @@
-#require 'app/ECS/systems/00_movement.rb'
-#require 'app/ECS/systems/01_flying.rb'
-
 class 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_accessor :const_name
+
+    # How many frames need to pass before this System is executed when controlled by {FelFlame::Stage}
+    attr_accessor :frame
+
+    attr_writer :addition_triggers
+
+    def addition_triggers
+      @addition_triggers ||= []
+    end
+
+    attr_writer :removal_triggers
+
+    def removal_triggers
+      @removal_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, frame: 2) do
+    #     FelFlame::Components::Health.each do |component|
+    #       component.hp += 5
+    #     end
+    #   end
+    #   # Only heal all characters with health every other frame.
+    #   # 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
+
+    # Attempt to execute the system following the frame parameter set on this system.
+    # @return [Boolean] +true+ if the frame of the {FelFlame::Stage} is a multiple of this System's frame setting and this system has executed, +false+ otherwise where the system has not executed.
+    # For example if a System has its frame set to 3, it will only execute once every third frame that is called in FelFlame::Stage
+    #
+    def step; 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
+    # @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] if trigger_types.empty?
+      trigger_types.each do |trigger_type|
+        if component_or_manager.nil?
+          send(trigger_type).each do |trigger|
+            trigger.send(trigger_type).delete self
+          end
+          self.addition_triggers = []
+        else
+          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
   end
 end