kstd: implement default allocator

1 files changed, 64 insertions, 0 deletions

diff --git a/libs/kstd/include/kstd/allocator b/libs/kstd/include/kstd/allocator
new file mode 100644
index 0000000..0de0e10
--- /dev/null
+++ b/libs/kstd/include/kstd/allocator
@@ -0,0 +1,64 @@
+#ifndef KSTD_ALLOCATOR_HPP
+#define KSTD_ALLOCATOR_HPP
+
+#include <cstddef>
+#include <new>
+#include <type_traits>
+
+#if __has_builtin(__builtin_operator_new) >= 201'802L
+#define KSTD_OPERATOR_NEW __builtin_operator_new
+#define KSTD_OPERATOR_DELETE __builtin_operator_delete
+#else
+#define KSTD_OPERATOR_NEW ::operator new
+#define KSTD_OPERATOR_DELETE ::operator delete
+#endif
+
+namespace kstd
+{
+
+  template<typename T>
+  struct allocator
+  {
+    using value_type = T;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
+    using propagate_on_container_move_assignment = std::true_type;
+    using is_always_equal = std::true_type;
+
+    constexpr allocator() noexcept = default;
+
+    template<typename U>
+    constexpr allocator(allocator<U> const &) noexcept
+    {}
+
+    constexpr auto allocate(std::size_t n) -> T *
+    {
+      if (alignof(T) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
+      {
+        return static_cast<T *>(KSTD_OPERATOR_NEW(n * sizeof(T), std::align_val_t{alignof(T)}));
+      }
+      return static_cast<T *>(KSTD_OPERATOR_NEW(n * sizeof(T)));
+    }
+
+    constexpr void deallocate(T * p, std::size_t n) noexcept
+    {
+      if (alignof(T) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
+      {
+        KSTD_OPERATOR_DELETE(p, n * sizeof(T), std::align_val_t{alignof(T)});
+      }
+      KSTD_OPERATOR_DELETE(p, n * sizeof(T));
+    }
+  };
+
+  template<typename T, typename U>
+  constexpr auto operator==(allocator<T> const &, allocator<U> const &) noexcept -> bool
+  {
+    return true;
+  }
+
+}  // namespace kstd
+
+#undef KSTD_OPERATOR_NEW
+#undef KSTD_OPERATOR_DELETE
+
+#endif
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