feat: defined state and state machine concepts

modules/wave_survival/register_types.cpp

@@ -6,6 +6,8 @@
 #include "wave_survival/player_body.h"
 #include "wave_survival/player_camera.h"
 #include "wave_survival/player_input.h"
+#include "wave_survival/state.h"
+#include "wave_survival/state_machine.h"
 #include "wave_survival/weapon_base.h"
 #include "wave_survival/weapon_inventory.h"
 #include "wave_survival/weapons/rifle.h"
@@ -22,6 +24,8 @@ void initialize_wave_survival_module(ModuleInitializationLevel p_level) {
 	GDREGISTER_CLASS(WeaponInventory);
 	GDREGISTER_CLASS(HitscanMuzzle);
 	GDREGISTER_CLASS(HealthStatus);
+	GDREGISTER_CLASS(StateMachine);
+	GDREGISTER_CLASS(State);
 }
 
 void uninitialize_wave_survival_module(ModuleInitializationLevel p_level) {

modules/wave_survival/state.cpp

@@ -0,0 +1,16 @@
+#include "state.h"
+
+void State::_bind_methods() {
+}
+
+String State::get_next_state() const {
+	return this->get_class();
+}
+
+void State::set_state_machine(StateMachine *machine) {
+	this->state_machine = machine;
+}
+
+StateMachine *State::get_state_machine() const {
+	return this->state_machine;
+}

modules/wave_survival/state.h

@@ -0,0 +1,26 @@
+#ifndef STATE_H
+#define STATE_H
+
+#include "core/object/class_db.h"
+#include "core/object/object.h"
+class StateMachine;
+class Node;
+
+class State : public Object {
+	GDCLASS(State, Object);
+	static void _bind_methods();
+
+public:
+	virtual void set_target(Node *target) {}
+	virtual void enter_state() {}
+	virtual void exit_state() {}
+	virtual void process(double delta) {}
+	virtual String get_next_state() const;
+	void set_state_machine(StateMachine *machine);
+	StateMachine *get_state_machine() const;
+
+private:
+	StateMachine *state_machine{ nullptr };
+};
+
+#endif // !STATE_H

modules/wave_survival/state_machine.cpp

@@ -0,0 +1,55 @@
+#include "state_machine.h"
+#include "state.h"
+
+void StateMachine::_bind_methods() {}
+
+void StateMachine::add_state(State *state) {
+	state->set_state_machine(this);
+	state->set_target(this->get_parent());
+	this->states.insert(state->get_class(), state);
+	if (this->current_state == nullptr) {
+		this->switch_to_state(state);
+	}
+}
+
+void StateMachine::switch_to_state(State *state) {
+	if (this->current_state) {
+		this->current_state->exit_state();
+	}
+	this->current_state = state;
+	if (this->current_state) {
+		this->current_state->enter_state();
+	} else {
+		print_error("StateMachine::switch_to_state: New state is nullptr, StateMachine will now stop working");
+	}
+}
+
+void StateMachine::ready() {
+}
+
+void StateMachine::process(double delta) {
+	if (this->current_state) {
+		this->current_state->process(delta);
+		String new_state{ this->current_state->get_next_state() };
+		if (new_state != this->current_state->get_class()) {
+			this->switch_to_state(this->states[new_state]);
+		}
+	}
+}
+
+void StateMachine::_notification(int what) {
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+	switch (what) {
+		default:
+			return;
+		case NOTIFICATION_READY:
+			set_process(true);
+			ready();
+			return;
+		case NOTIFICATION_PROCESS:
+			process(get_process_delta_time());
+			return;
+	}
+}

modules/wave_survival/state_machine.h

@@ -0,0 +1,23 @@
+#ifndef STATE_MACHINE_H
+#define STATE_MACHINE_H
+
+#include "scene/main/node.h"
+class State;
+
+class StateMachine : public Node {
+	GDCLASS(StateMachine, Node);
+	static void _bind_methods();
+	void add_state(State *state);
+	void switch_to_state(State *state);
+	void ready();
+	void process(double delta);
+
+protected:
+	void _notification(int what);
+
+private:
+	State *current_state{ nullptr };
+	HashMap<StringName, State *> states{};
+};
+
+#endif // !STATE_MACHINE_H