From 9641703375c9fd80b1b5a360a2698e1be5613140 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 23 Oct 2021 10:29:30 +0300
Subject: [PATCH] Behavior trees: implement events in updater & include node
 arguments in event handler

---
 .../include/psemek/util/behavior_tree.hpp     | 111 ++++++++++++++----
 1 file changed, 85 insertions(+), 26 deletions(-)

diff --git a/libs/util/include/psemek/util/behavior_tree.hpp b/libs/util/include/psemek/util/behavior_tree.hpp
index 1d83c288..ea41e43e 100644
--- a/libs/util/include/psemek/util/behavior_tree.hpp
+++ b/libs/util/include/psemek/util/behavior_tree.hpp
@@ -4,6 +4,7 @@
 #include <tuple>
 #include <memory>
 #include <vector>
+#include <optional>
 
 namespace psemek::util
 {
@@ -30,7 +31,7 @@ namespace psemek::util
 		{
 			virtual void start(Args ...) = 0;
 			virtual status update(Time, Args ...) = 0;
-			virtual bool event(Event const &) = 0;
+			virtual bool event(Event const &, Args ...) = 0;
 
 			virtual ~any_node_base() {}
 		};
@@ -55,9 +56,9 @@ namespace psemek::util
 				return node.update(dt, args...);
 			}
 
-			bool event(Event const & e) override
+			bool event(Event const & e, Args ... args) override
 			{
-				return node.event(e);
+				return node.event(e, args...);
 			}
 		};
 
@@ -78,9 +79,9 @@ namespace psemek::util
 				return impl_->update(dt, args...);
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return impl_->event(e);
+				return impl_->event(e, args...);
 			}
 
 		private:
@@ -103,6 +104,27 @@ namespace psemek::util
 				new_.push_back(node_data{std::move(node), {args...}, 0, 0});
 			}
 
+			template <typename Filter>
+			void event(Event const & e, Filter && filter)
+			{
+				for (node_data & n : active_)
+				{
+					if (std::apply(filter, n.args))
+						std::apply([&](Args ... args){ n.node.event(e, args...); }, n.args);
+				}
+
+				for (node_data & n : suspended_)
+				{
+					if (std::apply(filter, n.args))
+					{
+						if (std::apply([&](Args ... args){ return n.node.event(e, args...); }, n.args))
+						{
+							n.duration = n.elapsed;
+						}
+					}
+				}
+			}
+
 			struct update_statistics
 			{
 				int active_count = 0;
@@ -202,7 +224,7 @@ namespace psemek::util
 				return finished{true};
 			}
 
-			bool event(Event const &)
+			bool event(Event const &, Args ...)
 			{
 				return false;
 			}
@@ -232,7 +254,7 @@ namespace psemek::util
 				return suspended{remaining_time};
 			}
 
-			bool event(Event const &)
+			bool event(Event const &, Args ...)
 			{
 				return false;
 			}
@@ -255,12 +277,49 @@ namespace psemek::util
 				return finished{condFn(args...)};
 			}
 
-			bool event(Event const &)
+			bool event(Event const &, Args ...)
 			{
 				return false;
 			}
 		};
 
+		template <typename EventFn, typename Child>
+		struct on_event
+		{
+			EventFn eventFn;
+			Child child;
+
+			std::optional<status> cached_status;
+
+			on_event(EventFn eventFn, Child child)
+				: eventFn(std::move(eventFn))
+				, child(std::move(child))
+			{}
+
+			void start(Args ... args)
+			{
+				child.start(args...);
+			}
+
+			status update(Time dt, Args ... args)
+			{
+				if (cached_status)
+				{
+					auto result = *cached_status;
+					cached_status = std::nullopt;
+					return result;
+				}
+
+				return child.update(dt, std::forward<Args>(args)...);
+			}
+
+			bool event(Event const & e, Args ... args)
+			{
+				cached_status = eventFn(e, args...);
+				return static_cast<bool>(cached_status);
+			}
+		};
+
 		template <typename Child>
 		struct success
 		{
@@ -283,9 +342,9 @@ namespace psemek::util
 				return child_status;
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return child.event(e);
+				return child.event(e, args...);
 			}
 		};
 
@@ -311,9 +370,9 @@ namespace psemek::util
 				return child_status;
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return child.event(e);
+				return child.event(e, args...);
 			}
 		};
 
@@ -347,9 +406,9 @@ namespace psemek::util
 				return result;
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return child.event(e);
+				return child.event(e, args...);
 			}
 		};
 
@@ -383,9 +442,9 @@ namespace psemek::util
 				return result;
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return child.event(e);
+				return child.event(e, args...);
 			}
 		};
 
@@ -418,9 +477,9 @@ namespace psemek::util
 				return update_impl<0>(dt, args...);
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return event_impl<0>(e);
+				return event_impl<0>(e, args...);
 			}
 
 		private:
@@ -461,7 +520,7 @@ namespace psemek::util
 			}
 
 			template <size_t I>
-			bool event_impl(Event const & e)
+			bool event_impl(Event const & e, Args ... args)
 			{
 				if constexpr (I == sizeof...(Children))
 				{
@@ -471,11 +530,11 @@ namespace psemek::util
 				{
 					if (current == I)
 					{
-						return std::get<I>(children).event(e);
+						return std::get<I>(children).event(e, args...);
 					}
 					else
 					{
-						return event_impl<I + 1>(e);
+						return event_impl<I + 1>(e, args...);
 					}
 				}
 			}
@@ -510,9 +569,9 @@ namespace psemek::util
 				return update_impl<0>(dt, args...);
 			}
 
-			bool event(Event const & e)
+			bool event(Event const & e, Args ... args)
 			{
-				return event_impl<0>(e);
+				return event_impl<0>(e, args...);
 			}
 
 		private:
@@ -555,7 +614,7 @@ namespace psemek::util
 			}
 
 			template <size_t I>
-			bool event_impl(Event const & e)
+			bool event_impl(Event const & e, Args ... args)
 			{
 				if constexpr (I == sizeof...(Children))
 				{
@@ -565,11 +624,11 @@ namespace psemek::util
 				{
 					if (current == I)
 					{
-						return std::get<I>(children).event(e);
+						return std::get<I>(children).event(e, args...);
 					}
 					else
 					{
-						return event_impl<I + 1>(e);
+						return event_impl<I + 1>(e, args...);
 					}
 				}
 			}