From eecf27fdf5de5d3e7bee4a47f5ce4d1628fc0c90 Mon Sep 17 00:00:00 2001
From: Serhii Snitsaruk <limbonaut@pm.me>
Date: Thu, 29 Sep 2022 22:44:51 +0200
Subject: [PATCH] Implement guard func

---
 limbo_hsm.cpp   | 15 +++++++++++++--
 limbo_state.cpp | 19 +++++++++++++++++++
 limbo_state.h   | 15 ++++++++++++---
 3 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/limbo_hsm.cpp b/limbo_hsm.cpp
index 491a6ff..4fd4e8e 100644
--- a/limbo_hsm.cpp
+++ b/limbo_hsm.cpp
@@ -129,8 +129,19 @@ bool LimboHSM::dispatch(const String &p_event, const Variant &p_cargo) {
 		uint64_t key = _get_transition_key(active_state, p_event);
 		if (transitions.has(key)) {
 			LimboState *to_state = transitions[key];
-			_change_state(to_state);
-			event_consumed = true;
+			bool permitted = true;
+			if (to_state->guard.obj != nullptr) {
+				Variant result = to_state->guard.obj->callv(to_state->guard.func, to_state->guard.binds);
+				if (unlikely(result.get_type() != Variant::BOOL)) {
+					ERR_PRINT_ONCE(vformat("State guard func \"%s()\" returned non-boolean value (%s).", to_state->guard.func, to_state));
+				} else {
+					permitted = bool(result);
+				}
+			}
+			if (permitted) {
+				_change_state(to_state);
+				event_consumed = true;
+			}
 		}
 	}
 
diff --git a/limbo_state.cpp b/limbo_state.cpp
index 4eb854a..78ce1be 100644
--- a/limbo_state.cpp
+++ b/limbo_state.cpp
@@ -109,6 +109,21 @@ LimboState *LimboState::call_on_update(Object *p_object, const StringName &p_met
 	return this;
 }
 
+void LimboState::set_guard_func(Object *p_object, const StringName &p_func, const Array &p_binds) {
+	ERR_FAIL_COND(p_object == nullptr);
+	ERR_FAIL_COND(!p_object->has_method(p_func));
+
+	guard.obj = p_object;
+	guard.func = p_func;
+	guard.binds = p_binds;
+}
+
+void LimboState::clear_guard_func() {
+	guard.obj = nullptr;
+	guard.func = "";
+	guard.binds.clear();
+}
+
 void LimboState::_notification(int p_what) {
 	switch (p_what) {
 		case NOTIFICATION_EXIT_TREE: {
@@ -134,6 +149,8 @@ void LimboState::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("call_on_enter", "p_object", "p_method"), &LimboState::call_on_enter);
 	ClassDB::bind_method(D_METHOD("call_on_exit", "p_object", "p_method"), &LimboState::call_on_exit);
 	ClassDB::bind_method(D_METHOD("call_on_update", "p_object", "p_method"), &LimboState::call_on_update);
+	ClassDB::bind_method(D_METHOD("set_guard_func", "p_object", "p_func", "p_binds"), &LimboState::set_guard_func, Array());
+	ClassDB::bind_method(D_METHOD("clear_guard_func"), &LimboState::clear_guard_func);
 
 	BIND_VMETHOD(MethodInfo("_setup"));
 	BIND_VMETHOD(MethodInfo("_enter"));
@@ -150,6 +167,8 @@ LimboState::LimboState() {
 	agent = nullptr;
 	active = false;
 
+	guard.obj = nullptr;
+
 	set_process(false);
 	set_physics_process(false);
 	set_process_input(false);
diff --git a/limbo_state.h b/limbo_state.h
index fa9dee9..fefd4ac 100644
--- a/limbo_state.h
+++ b/limbo_state.h
@@ -4,22 +4,29 @@
 #define LIMBO_STATE_H
 
 #include "blackboard.h"
+#include "core/class_db.h"
+#include "core/object.h"
 #include "core/string_name.h"
 #include "core/ustring.h"
 #include "core/variant.h"
 #include "scene/main/node.h"
 
-// TODO Implement guards
 class LimboHSM;
 
 class LimboState : public Node {
 	GDCLASS(LimboState, Node);
 
 private:
+	struct GuardCallback {
+		Object *obj = nullptr;
+		StringName func;
+		Array binds;
+	};
+
 	Object *agent;
 	Ref<Blackboard> blackboard;
 	Map<String, StringName> handlers;
-	// Guard *guard;
+	GuardCallback guard;
 
 protected:
 	friend LimboHSM;
@@ -51,7 +58,9 @@ public:
 	String event_finished() const { return EVENT_FINISHED; }
 	LimboState *get_root() const;
 	bool is_active() const { return active; }
-	uint32_t hash() const;
+
+	void set_guard_func(Object *p_object, const StringName &p_func, const Array &p_binds = Array());
+	void clear_guard_func();
 
 	LimboState();
 };