From 92c702a913c2b83b74c7d25732f119d21f90dce2 Mon Sep 17 00:00:00 2001
From: OEOTYAN <OEOTYAN@outlook.com>
Date: Sun, 27 Oct 2024 03:13:10 +0800
Subject: [PATCH] chore: add UntypedStorage

---
 src/ll/api/base/Alias.h     | 28 ++++++++++++++++++++++++++++
 src/ll/api/coro/Generator.h |  6 +++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/ll/api/base/Alias.h b/src/ll/api/base/Alias.h
index 8f956728b5..9736896cc4 100644
--- a/src/ll/api/base/Alias.h
+++ b/src/ll/api/base/Alias.h
@@ -1,5 +1,10 @@
 #pragma once
 
+#include <bit>
+#include <cstddef>
+#include <type_traits>
+#include <utility>
+
 namespace ll {
 template <class T, size_t N>
 struct CArray {
@@ -11,4 +16,27 @@ struct CArray<T, 0> {
 };
 template <class T, size_t N = 0>
 using CArrayT = typename CArray<T, N>::type;
+
+template <size_t Len, size_t Align = (std::min)((1ull << std::countr_zero(Len)), 8ull)>
+struct UntypedStorage {
+    alignas(Align) std::byte data[Len];
+
+    template <class T>
+    [[nodiscard]] T& as() & {
+        return *reinterpret_cast<T*>(this);
+    }
+    template <class T>
+    [[nodiscard]] T const& as() const& {
+        return *reinterpret_cast<T const*>(this);
+    }
+    template <class T>
+    [[nodiscard]] T&& as() && {
+        return std::move(*reinterpret_cast<T*>(this));
+    }
+    template <class T>
+    [[nodiscard]] T const&& as() const&& {
+        return std::move(*reinterpret_cast<T const*>(this));
+    }
+};
+
 } // namespace ll
diff --git a/src/ll/api/coro/Generator.h b/src/ll/api/coro/Generator.h
index ba5a61a940..7dec1a7990 100644
--- a/src/ll/api/coro/Generator.h
+++ b/src/ll/api/coro/Generator.h
@@ -12,7 +12,7 @@ template <class T>
 struct Generator {
     using value     = std::remove_cvref_t<T>;
     using reference = T&&;
-    using yielded   = std::conditional_t<std::is_reference_v<reference>, reference, reference const&>;
+    using yielded   = reference;
 
 
     struct promise_type {
@@ -60,8 +60,8 @@ struct Generator {
     struct iterator {
         using iterator_category = std::input_iterator_tag;
         using difference_type   = ptrdiff_t;
-        using value_type        = value;
-        using reference         = reference;
+        using value_type        = Generator::value;
+        using reference         = Generator::reference;
         using pointer           = std::add_pointer_t<yielded>;
 
         std::coroutine_handle<promise_type> handle = nullptr;