cleanup the swap implementation

KRM7 · Feb 7, 2024 · 888a268 · 888a268
1 parent 571c51d
commit 888a268
Showing 1 changed file with 15 additions and 16 deletions.
diff --git a/src/small_unique_ptr.hpp b/src/small_unique_ptr.hpp
@@ -228,7 +228,7 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
             this->data_ = std::exchange(other.data_, nullptr);
             return;
         }
-        if constexpr (!detail::is_always_heap_allocated_v<U>) // other.is_stack_allocated()
+        if constexpr (!other.is_always_heap_allocated()) // other.is_stack_allocated()
         {
             other.move_buffer_to(*this);
             this->data_ = this->buffer(other.template offsetof_base<T>());
@@ -238,8 +238,6 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
 
     constexpr small_unique_ptr& operator=(small_unique_ptr&& other) noexcept
     {
-        if (std::addressof(other) == this) [[unlikely]] return *this;
-
         return operator=<T>(std::move(other));
     }
 
@@ -248,12 +246,14 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
     {
         static_assert(!detail::is_proper_base_of_v<T, U> || std::has_virtual_destructor_v<T>);
 
+        if (std::addressof(other) == this) [[unlikely]] return *this;
+
         if (!other.is_stack_allocated() || std::is_constant_evaluated())
         {
             reset(std::exchange(other.data_, nullptr));
             return *this;
         }
-        if constexpr (!detail::is_always_heap_allocated_v<U>) // other.is_stack_allocated()
+        if constexpr (!other.is_always_heap_allocated()) // other.is_stack_allocated()
         {
             reset();
             other.move_buffer_to(*this);
@@ -281,14 +281,17 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
         this->data_ = new_data;
     }
 
-    constexpr void swap(small_unique_ptr& other) noexcept requires(detail::is_always_heap_allocated_v<T>)
+    constexpr void swap(small_unique_ptr& other) noexcept
     {
-        std::swap(this->data_, other.data_);
-    }
-
-    constexpr void swap(small_unique_ptr& other) noexcept requires(!detail::is_always_heap_allocated_v<T>)
-    {
-        if (is_stack_allocated() && other.is_stack_allocated())
+        if constexpr (is_always_heap_allocated())
+        {
+            std::swap(this->data_, other.data_);
+        }
+        else if (!is_stack_allocated() && !other.is_stack_allocated())
+        {
+            std::swap(this->data_, other.data_);
+        }
+        else if (is_stack_allocated() && other.is_stack_allocated())
         {
             const std::ptrdiff_t other_offset = other.offsetof_base();
             const std::ptrdiff_t this_offset  = this->offsetof_base();
@@ -306,10 +309,6 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
             this->data_ = this->buffer(other_offset);
             other.data_ = other.buffer(this_offset);
         }
-        else if (!is_stack_allocated() && !other.is_stack_allocated())
-        {
-            std::swap(this->data_, other.data_);
-        }
         else if (!is_stack_allocated() && other.is_stack_allocated())
         {
             const pointer new_data = this->buffer(other.offsetof_base());
@@ -328,7 +327,7 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
     pointer release() noexcept = delete;
 
     [[nodiscard]]
-    constexpr static bool is_always_heap_allocated() noexcept
+    static constexpr bool is_always_heap_allocated() noexcept
     {
         return detail::is_always_heap_allocated_v<T>;
     }