From 633e34c1e89b882868a4b74ff14b4110662c4218 Mon Sep 17 00:00:00 2001
From: jyxiong <jingyu.xiong@foxmail.com>
Date: Mon, 22 Sep 2025 20:13:54 +0800
Subject: [PATCH] feat: construct_at & destroy_at

---
 source/tinystl/memory.h                  |  5 ++-
 source/tinystl/memory/allocator_traits.h | 57 ++++++++++++++----------
 source/tinystl/memory/construct.h        | 13 ++++++
 source/tinystl/memory/destroy.h          | 20 +++++++++
 source/tinystl/type_traits.h             |  5 ++-
 5 files changed, 75 insertions(+), 25 deletions(-)
 create mode 100644 source/tinystl/memory/construct.h
 create mode 100644 source/tinystl/memory/destroy.h

diff --git a/source/tinystl/memory.h b/source/tinystl/memory.h
index 7d02056..778d4ee 100644
--- a/source/tinystl/memory.h
+++ b/source/tinystl/memory.h
@@ -1,6 +1,9 @@
 #pragma once
 
+#include <tinystl/memory/addressof.h>
 #include <tinystl/memory/allocator.h>
 #include <tinystl/memory/allocator_traits.h>
-#include <tinystl/memory/addressof.h>
+#include <tinystl/memory/construct.h>
+#include <tinystl/memory/destroy.h>
 #include <tinystl/memory/pointer_traits.h>
+
diff --git a/source/tinystl/memory/allocator_traits.h b/source/tinystl/memory/allocator_traits.h
index 1dcf342..b4daa8e 100644
--- a/source/tinystl/memory/allocator_traits.h
+++ b/source/tinystl/memory/allocator_traits.h
@@ -1,13 +1,17 @@
 #pragma once
 
-#include <utility>
 #include <limits>
+#include <utility>
 
+
+#include "tinystl/memory/construct.h"
+#include "tinystl/memory/destroy.h"
 #include "tinystl/memory/pointer_traits.h"
-#include "tinystl/type_traits/void_t.h"
-#include "tinystl/type_traits/is_empty.h"
 #include "tinystl/type_traits/enable_if.h"
+#include "tinystl/type_traits/is_empty.h"
 #include "tinystl/type_traits/make_unsigned.h"
+#include "tinystl/type_traits/void_t.h"
+
 
 // https://en.cppreference.com/w/cpp/memory/allocator_traits.html
 
@@ -44,8 +48,7 @@ struct get_void_pointer {
     typename tinystl::pointer_traits<pointer_type>::template rebind<void>;
 };
 template <class Alloc>
-struct get_void_pointer<
-  Alloc, tinystl::void_t<typename Alloc::void_pointer>> {
+struct get_void_pointer<Alloc, tinystl::void_t<typename Alloc::void_pointer>> {
   using type = typename Alloc::void_pointer;
 };
 
@@ -66,24 +69,26 @@ struct get_const_void_pointer<
 // get_difference_type
 template <class Alloc, class = void>
 struct get_difference_type {
-    using _Ptrty = typename get_pointer<Alloc>::type;
-    using type   = typename tinystl::pointer_traits<_Ptrty>::difference_type;
+  using _Ptrty = typename get_pointer<Alloc>::type;
+  using type = typename tinystl::pointer_traits<_Ptrty>::difference_type;
 };
 
 template <class Alloc>
-struct get_difference_type<Alloc, tinystl::void_t<typename Alloc::difference_type>> {
-    using type = typename Alloc::difference_type;
+struct get_difference_type<
+  Alloc, tinystl::void_t<typename Alloc::difference_type>> {
+  using type = typename Alloc::difference_type;
 };
 
 // get_size_type
 template <class Alloc, class = void>
 struct get_size_type {
-    using type = tinystl::make_unsigned_t<typename get_difference_type<Alloc>::type>;
+  using type =
+    tinystl::make_unsigned_t<typename get_difference_type<Alloc>::type>;
 };
 
 template <class Alloc>
 struct get_size_type<Alloc, tinystl::void_t<typename Alloc::size_type>> {
-    using type = typename Alloc::size_type;
+  using type = typename Alloc::size_type;
 };
 
 // propagate_on_container_copy_assignment
@@ -144,7 +149,7 @@ template <
   template <class, class...> class Alloc, class First, class... Rest,
   class Newfirst>
 struct get_rebind_get_impl<Alloc<First, Rest...>, Newfirst> {
-// given Alloc<First, Rest...>, replace First with Newfirst
+  // given Alloc<First, Rest...>, replace First with Newfirst
   using type = Alloc<Newfirst, Rest...>;
 };
 
@@ -165,9 +170,9 @@ template <class, class Alloc, class... Args>
 const bool has_construct_impl = false;
 
 template <class Alloc, class... Args>
-const bool
-    has_construct_impl<decltype((void)std::declval<Alloc>().construct(std::declval<Args>()...)), Alloc, Args...> =
-        true;
+const bool has_construct_impl<
+  decltype((void)std::declval<Alloc>().construct(std::declval<Args>()...)),
+  Alloc, Args...> = true;
 
 template <class Alloc, class... Args>
 const bool has_construct = has_construct_impl<void, Alloc, Args...>;
@@ -177,15 +182,19 @@ template <class Alloc, class Pointer, class = void>
 const bool has_destroy = false;
 
 template <class Alloc, class Pointer>
-const bool
-    has_destroy<Alloc, Pointer, decltype((void)std::declval<Alloc>().destroy(std::declval<Pointer>()))> = true;
+const bool has_destroy<
+  Alloc, Pointer,
+  decltype((void)std::declval<Alloc>().destroy(std::declval<Pointer>()))> =
+  true;
 
 // has_max_size
 template <class Alloc, class = void>
 const bool has_max_size = false;
 
 template <class Alloc>
-const bool has_max_size<Alloc, decltype((void)std::declval<Alloc&>().max_size())> = true;
+const bool
+  has_max_size<Alloc, decltype((void)std::declval<Alloc &>().max_size())> =
+    true;
 
 // has_select_on_container_copy_construction
 template <class Alloc, class = void>
@@ -193,8 +202,8 @@ const bool has_select_on_container_copy_construction = false;
 
 template <class Alloc>
 const bool has_select_on_container_copy_construction<
-    Alloc,
-    decltype((void)std::declval<Alloc>().select_on_container_copy_construction())> = true;
+  Alloc, decltype((void)std::declval<Alloc>()
+                    .select_on_container_copy_construction())> = true;
 
 } // namespace detail
 
@@ -253,7 +262,7 @@ struct allocator_traits {
     class T, class... Args,
     enable_if_t<!detail::has_construct<Alloc, T *, Args...>, int> = 0>
   static void construct(Alloc &, T *p, Args &&...args) {
-    std::construct_at(p, std::forward<Args>(args)...);
+    construct_at(p, std::forward<Args>(args)...);
   }
 
   template <class T, enable_if_t<detail::has_destroy<Alloc, T *>, int> = 0>
@@ -263,11 +272,13 @@ struct allocator_traits {
 
   template <class T, enable_if_t<!detail::has_destroy<Alloc, T *>, int> = 0>
   static void destroy(Alloc &, T *p) {
-    std::destroy_at(p);
+    destroy_at(p);
   }
 
   template <class U = Alloc, enable_if_t<detail::has_max_size<U>, int> = 0>
-  static size_type max_size(const Alloc &a) noexcept { return a.max_size(); }
+  static size_type max_size(const Alloc &a) noexcept {
+    return a.max_size();
+  }
 
   template <class U = Alloc, enable_if_t<!detail::has_max_size<U>, int> = 0>
   static size_type max_size(const Alloc &) noexcept {
diff --git a/source/tinystl/memory/construct.h b/source/tinystl/memory/construct.h
new file mode 100644
index 0000000..103b59c
--- /dev/null
+++ b/source/tinystl/memory/construct.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <utility>
+
+namespace tinystl {
+template <
+  class T, class... Args,
+  class = decltype(::new (std::declval<void *>()) T(std::declval<Args>()...))>
+constexpr T *construct_at(T *location, Args &&...args) {
+  return ::new (static_cast<void *>(location)) T(std::forward<Args>(args)...);
+}
+
+} // namespace tinystl
\ No newline at end of file
diff --git a/source/tinystl/memory/destroy.h b/source/tinystl/memory/destroy.h
new file mode 100644
index 0000000..5ec5916
--- /dev/null
+++ b/source/tinystl/memory/destroy.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include "tinystl/memory/addressof.h"
+#include "tinystl/type_traits/enable_if.h"
+#include "tinystl/type_traits/is_array.h"
+
+namespace tinystl {
+template <class T, enable_if_t<!is_array_v<T>, int> = 0>
+void destroy_at(T *p) {
+  p->~T();
+}
+
+template <class T, enable_if_t<is_array_v<T>, int> = 0>
+void destroy_at(T *p) {
+  for (auto &elem : *p) {
+    (destroy_at)(addressof(elem));
+  }
+}
+
+} // namespace tinystl
\ No newline at end of file
diff --git a/source/tinystl/type_traits.h b/source/tinystl/type_traits.h
index 8720b38..c16ee84 100644
--- a/source/tinystl/type_traits.h
+++ b/source/tinystl/type_traits.h
@@ -3,12 +3,13 @@
 // https://en.cppreference.com/w/cpp/header/type_traits.html
 
 // composite_type_categories
-
 #include <tinystl/type_traits/is_arithmetic.h>
 #include <tinystl/type_traits/is_member_pointer.h>
 #include <tinystl/type_traits/is_object.h>
+#include <tinystl/type_traits/is_reference.h>
 #include <tinystl/type_traits/is_scalar.h>
 
+
 // const_volatility_specifiers
 #include <tinystl/type_traits/remove_cv.h>
 
@@ -23,8 +24,10 @@
 #include <tinystl/type_traits/is_enum.h>
 #include <tinystl/type_traits/is_floating_point.h>
 #include <tinystl/type_traits/is_integral.h>
+#include <tinystl/type_traits/is_lvalue_reference.h>
 #include <tinystl/type_traits/is_null_pointer.h>
 #include <tinystl/type_traits/is_pointer.h>
+#include <tinystl/type_traits/is_rvalue_reference.h>
 #include <tinystl/type_traits/is_union.h>
 #include <tinystl/type_traits/is_void.h>