Add bt::conditional node

libs/bt/include/psemek/bt/conditional.hpp

@@ -0,0 +1,85 @@
+#pragma once
+
+#include <psemek/bt/node.hpp>
+#include <psemek/bt/assert.hpp>
+
+#include <optional>
+
+namespace psemek::bt
+{
+
+	template <typename Tree>
+	struct conditional_node;
+
+	template <typename Time, typename Event, typename ... Args>
+	struct conditional_node<tree<Time, Event, Args...>>
+		: node<tree<Time, Event, Args...>>
+	{
+		using tree_type = tree<Time, Event, Args...>;
+		using node_type = node<tree_type>;
+		using typename node_type::running;
+		using typename node_type::finished;
+		using typename node_type::status;
+
+		conditional_node(node_ptr<tree_type> condition, node_ptr<tree_type> true_branch, node_ptr<tree_type> false_branch)
+			: condition_(std::move(condition))
+			, true_branch_(std::move(true_branch))
+			, false_branch_(std::move(false_branch))
+		{}
+
+		void start(Args ... args) override
+		{
+			condition_result_ = std::nullopt;
+			condition_->start(args...);
+		}
+
+		status update(Time dt, Args ... args) override
+		{
+			if (condition_result_)
+			{
+				if (*condition_result_)
+					return true_branch_->update(dt, args...);
+				else
+					return false_branch_->update(dt, args...);
+			}
+			else
+			{
+				auto result = condition_->update(dt, args...);
+
+				if (auto finished = std::get_if<typename node_type::finished>(&result))
+				{
+					condition_result_ = finished->result;
+					return running{};
+				}
+
+				return result;
+			}
+		}
+
+		bool event(Event const & event, Args ... args) override
+		{
+			if (condition_result_)
+			{
+				if (*condition_result_)
+					return true_branch_->event(event, args...);
+				else
+					return false_branch_->event(event, args...);
+			}
+			else
+				return condition_->event(event, args...);
+		}
+
+	private:
+		node_ptr<tree_type> condition_;
+		node_ptr<tree_type> true_branch_;
+		node_ptr<tree_type> false_branch_;
+		std::optional<bool> condition_result_;
+	};
+
+	template <typename Tree>
+	node_ptr<Tree> conditional(node_ptr<Tree> condition, node_ptr<Tree> true_branch, node_ptr<Tree> false_branch)
+	{
+		return std::make_unique<conditional_node<Tree>>(std::move(condition), std::move(true_branch), std::move(false_branch));
+	}
+
+}