pointer: add thin pointer wrapper

pointer.hpp

@@ -13,6 +13,57 @@
 #include <cstdint>
 
 
+namespace cruft::ptr {
+    /// A utiliity function that deletes the provided pointer.
+    ///
+    /// Useful as a means of moving `delete` calls inside a translation unit
+    /// and hence removing the need to include implementation headers for a
+    /// type that needs deletion.
+    template <typename ValueT>
+    void destroy (ValueT*);
+
+
+    /// A smart pointer that defers deletion to `destroy`.
+    ///
+    /// This is solely useful as a way of avoid undefined type errors when
+    /// using std::unique_ptr and forward declarations.
+    template <typename ValueT>
+    class thin {
+    public:
+        explicit thin (ValueT *_value) { m_value = _value; }
+        ~thin () { destroy (m_value); }
+
+        thin (thin const&) = delete;
+        thin& operator= (thin const&) = delete;
+
+        thin (thin &&rhs)
+           : m_value (rhs.m_value)
+       { rhs.m_value = nullptr; }
+
+        thin& operator= (thin &&rhs) noexcept
+        {
+            std::swap (m_value, rhs.m_value);
+        }
+
+        ValueT      & operator* (void)       &{ return *m_value; }
+        ValueT const& operator* (void) const &{ return *m_value; }
+        ValueT      * operator->(void)       &{ return  m_value; }
+        ValueT const* operator->(void) const &{ return  m_value; }
+
+    private:
+        ValueT *m_value;
+    };
+
+
+    template <typename ValueT, typename ...ArgsT>
+    thin<ValueT>
+    make_thin (ArgsT &&...args)
+    {
+        return thin (new ValueT (std::forward<ArgsT> (args)...));
+    }
+}
+
+
 namespace cruft::align {
     ///////////////////////////////////////////////////////////////////////////
     /// round the pointer upwards to satisfy the provided alignment