memory/buffer/traits: add a simple buffer concept

CMakeLists.txt

@@ -351,6 +351,7 @@ list (
     matrix.hpp
     memory/buffer/simple.cpp
     memory/buffer/simple.hpp
+    memory/buffer/traits.hpp
     memory/deleter.cpp
     memory/deleter.hpp
     nocopy.hpp

memory/buffer/traits.hpp

@@ -0,0 +1,43 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2018 Danny Robson <danny@nerdcruft.net>
+ */
+
+#pragma once
+
+#include <type_traits>
+
+
+namespace cruft::memory::buffer {
+    ///////////////////////////////////////////////////////////////////////////
+    /// A trait that evaluates to true if the queried type models cruft::allocator
+    template <
+        typename BufferT,
+        typename = std::void_t<>
+    >
+    struct is_buffer
+        : public std::false_type
+    { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename BufferT>
+    struct is_buffer<BufferT,
+        std::void_t<
+            // Provides aligned and unaligned allocation
+            decltype(std::declval<BufferT> ().begin ()),
+            decltype(std::declval<BufferT> ().end   ()),
+            decltype(std::declval<BufferT> ().size  ()),
+            void
+        >
+    > : public std::true_type
+    { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename BufferT>
+    constexpr auto is_buffer_v = is_buffer<BufferT>::value;
+}