Add bt::process helper for nodes without initialization & event processing

libs/bt/include/psemek/bt/process.hpp

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <psemek/bt/node.hpp>
+
+namespace psemek::bt
+{
+
+	template <typename Tree, typename ProcessFn>
+	struct process_node;
+
+	template <typename Time, typename Event, typename ... Args, typename ProcessFn>
+	struct process_node<tree<Time, Event, Args...>, ProcessFn>
+		: node<tree<Time, Event, Args...>>
+	{
+		using tree_type = tree<Time, Event, Args...>;
+		using node_type = node<tree_type>;
+		using typename node_type::finished;
+		using typename node_type::status;
+
+		process_node(ProcessFn && process_fn)
+			: process_fn_(std::move(process_fn))
+		{}
+
+		void start(Args ...) override
+		{}
+
+		status update(Time dt, Args ... args) override
+		{
+			return process_fn_(dt, args...);
+		}
+
+		bool event(Event const &, Args ...) override
+		{
+			return false;
+		}
+
+	private:
+		ProcessFn process_fn_;
+	};
+
+	template <typename Tree, typename ProcessFn>
+	node_ptr<Tree> process(ProcessFn && process_fn)
+	{
+		return std::make_unique<process_node<Tree, ProcessFn>>(std::move(process_fn));
+	}
+
+}