From def67bba57e7cfdf9942bc2c88a4ce484963f9d2 Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Fri, 6 Sep 2024 23:22:18 +0200
Subject: maybe_uninit

---
 asl/maybe_uninit.hpp | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 asl/maybe_uninit.hpp

(limited to 'asl/maybe_uninit.hpp')

diff --git a/asl/maybe_uninit.hpp b/asl/maybe_uninit.hpp
new file mode 100644
index 0000000..ffbbb1c
--- /dev/null
+++ b/asl/maybe_uninit.hpp
@@ -0,0 +1,44 @@
+#pragma once
+
+#include "asl/annotations.hpp"
+#include "asl/layout.hpp"
+#include "asl/memory.hpp"
+#include "asl/meta.hpp"
+
+namespace asl
+{
+
+template<is_object T>
+class alignas(align_of<T>) maybe_uninit
+{
+    char m_storage[size_of<T>];
+
+public:
+    constexpr void* uninit_ptr() const { return m_storage; }
+
+    // @Safety Pointer must only be accessed when in initialized state.
+    constexpr const T* init_ptr(unsafe) const { return reinterpret_cast<const T*>(m_storage); }
+    constexpr       T* init_ptr(unsafe)       { return reinterpret_cast<      T*>(m_storage); }
+
+    // @Safety Reference must only be accessed when in initialized state.
+    constexpr const T& as_init(unsafe) const { return *reinterpret_cast<const T*>(m_storage); }
+    constexpr       T& as_init(unsafe)       { return *reinterpret_cast<      T*>(m_storage); }
+
+    // @Safety Must be called only when in uninitialized state.
+    template<typename... Args>
+    inline void init(unsafe, Args&&... args)
+    {
+        new(uninit_ptr()) T(ASL_FWD(args)...);
+    }
+
+    // @Safety Must be called only when in initialized state.
+    inline void uninit(unsafe)
+    {
+        if constexpr (!trivially_destructible<T>)
+        {
+            init_ptr(unsafe("Caller has checked init state"))->~T();
+        }
+    }
+};
+
+} // namespace asl
-- 
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