Squashed 'third_party/immer/' content from commit ad3e3556d

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

immer/heap/malloc_heap.hpp

@@ -0,0 +1,44 @@
+//
+// 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 <immer/config.hpp>
+
+#include <cstdlib>
+#include <memory>
+
+namespace immer {
+
+/*!
+ * A heap that uses `std::malloc` and `std::free` to manage memory.
+ */
+struct malloc_heap
+{
+    /*!
+     * Returns a pointer to a memory region of size `size`, if the
+     * allocation was successful and throws `std::bad_alloc` otherwise.
+     */
+    template <typename... Tags>
+    static void* allocate(std::size_t size, Tags...)
+    {
+        auto p = std::malloc(size);
+        if (IMMER_UNLIKELY(!p))
+            throw std::bad_alloc{};
+        return p;
+    }
+
+    /*!
+     * 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, void* data) { std::free(data); }
+};
+
+} // namespace immer