add stl mimalloc wrapper

include/mimalloc-stl-allocator.h

@@ -0,0 +1,44 @@
+#pragma once
+#ifndef MIMALLOC_STL_ALLOCATOR_H
+#define MIMALLOC_STL_ALLOCATOR_H
+
+#ifdef __cplusplus
+/* ----------------------------------------------------------------------------
+This header can be used to hook mimalloc into STL containers in place of 
+std::allocator.
+-----------------------------------------------------------------------------*/
+#include <mimalloc.h>
+#include <type_traits> // true_type
+
+#pragma warning(disable: 4100)
+
+template <class T>
+struct mi_stl_allocator {
+  typedef T value_type;
+  
+  using propagate_on_container_copy_assignment = std::true_type;
+  using propagate_on_container_move_assignment = std::true_type;
+  using propagate_on_container_swap = std::true_type;
+  using is_always_equal = std::true_type;
+
+  mi_stl_allocator() noexcept {}
+  mi_stl_allocator(const mi_stl_allocator& other) noexcept {}
+  template <class U>
+  mi_stl_allocator(const mi_stl_allocator<U>& other) noexcept {}
+
+  T* allocate(size_t n, const void* hint = 0) {
+    return (T*)mi_mallocn(n, sizeof(T));
+  }
+
+  void deallocate(T* p, size_t n) {
+    mi_free(p);
+  }
+};
+
+template <class T1, class T2>
+bool operator==(const mi_stl_allocator<T1>& lhs, const mi_stl_allocator<T2>& rhs) noexcept { return true; }
+template <class T1, class T2>
+bool operator!=(const mi_stl_allocator<T1>& lhs, const mi_stl_allocator<T2>& rhs) noexcept { return false; }
+
+#endif // __cplusplus
+#endif // MIMALLOC_STL_ALLOCATOR_H