Behavior tree: add repeat_while primitive

libs/util/include/psemek/util/behavior_tree.hpp

@@ -414,6 +414,81 @@ namespace psemek::util
 			}
 		};
 
+		template <typename Condition, typename Child>
+		struct repeat_while
+		{
+			Condition condition;
+			Child child;
+			bool current_started = false;
+			int current = 0;
+
+			repeat_while(Condition condition, Child child)
+				: condition(std::move(condition))
+				, child(std::move(child))
+			{}
+
+			void start(Args ...)
+			{
+				current = 0;
+				current_started = false;
+			}
+
+			status update(Time dt, Args ... args)
+			{
+				if (current == 0)
+				{
+					if (!current_started)
+					{
+						condition.start(args...);
+						current_started = true;
+					}
+
+					auto result = condition.update(dt, args...);
+					if (auto f = std::get_if<finished>(&result))
+					{
+						if (!(f->result))
+							return finished{true};
+						else
+						{
+							current = 1;
+							current_started = false;
+							dt = 0;
+						}
+					}
+					else
+						return result;
+				}
+
+				// current == 1
+
+				if (!current_started)
+				{
+					child.start(args...);
+					current_started = true;
+				}
+
+				auto result = child.update(dt, args...);
+				if (auto f = std::get_if<finished>(&result))
+				{
+					if (!(f->result))
+						return finished{false};
+					else
+					{
+						current = 0;
+						current_started = false;
+						return running{};
+					}
+				}
+				else
+					return result;
+			}
+
+			bool event(Event const & e, Args ... args)
+			{
+				return condition.event(e, args...) || child.event(e, args...);
+			}
+		};
+
 		template <typename Child>
 		struct retry
 		{