Ring buffer: Use as backing for std::queue uses

src/core/CMakeLists.txt

@@ -29,6 +29,7 @@ add_files(
     random_func.cpp
     random_func.hpp
     ring_buffer.hpp
+    ring_buffer_queue.hpp
     serialisation.cpp
     serialisation.hpp
     smallstack_type.hpp

src/core/ring_buffer.hpp

@@ -192,6 +192,11 @@ public:
 		}
 	};
 
+	using difference_type = std::ptrdiff_t;
+	using size_type = size_t;
+	using value_type = T;
+	using reference = T &;
+	using const_reference = const T &;
 	typedef ring_buffer_iterator<T, false> iterator;
 	typedef ring_buffer_iterator<const T, false> const_iterator;
 	typedef ring_buffer_iterator<T, true> reverse_iterator;

src/core/ring_buffer_queue.hpp

@@ -0,0 +1,20 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file ring_buffer_queue.hpp std::queue backed by a ring buffer. */
+
+#ifndef RING_BUFFER_QUEUE_HPP
+#define RING_BUFFER_QUEUE_HPP
+
+#include "ring_buffer.hpp"
+
+#include <queue>
+
+template<class T>
+using ring_buffer_queue = std::queue<T, ring_buffer<T>>;
+
+#endif /* RING_BUFFER_QUEUE_HPP */