Squashed 'third_party/immer/' content from commit ad3e3556d

git-subtree-dir: third_party/immer
git-subtree-split: ad3e3556d38bb75966dd24c61a774970a7c7957e

immer/heap/cpp_heap.hpp

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+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#pragma once
+
+#include <memory>
+
+namespace immer {
+
+/*!
+ * A heap that uses `operator new` and `operator delete`.
+ */
+struct cpp_heap
+{
+    /*!
+     * Returns a pointer to a memory region of size `size`, if the
+     * allocation was successful, and throws otherwise.
+     */
+    template <typename... Tags>
+    static void* allocate(std::size_t size, Tags...)
+    {
+        return ::operator new(size);
+    }
+
+    /*!
+     * Releases a memory region `data` that was previously returned by
+     * `allocate`.  One must not use nor deallocate again a memory
+     * region that once it has been deallocated.
+     */
+    static void deallocate(std::size_t size, void* data)
+    {
+        ::operator delete(data);
+    }
+};
+
+} // namespace immer