Reimplement optional not to require default-constructible value types

1 files changed, 210 insertions, 0 deletions

diff --git a/libbutl/optional.ixx b/libbutl/optional.ixx
new file mode 100644
index 0000000..2c40d30
--- /dev/null
+++ b/libbutl/optional.ixx
@@ -0,0 +1,210 @@
+// file      : libbutl/optional.ixx -*- C++ -*-
+// copyright : Copyright (c) 2014-2018 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+namespace butl
+{
+  namespace details
+  {
+    // optional_data<T, false>
+    //
+
+    template <typename T>
+    inline optional_data<T, false>& optional_data<T, false>::
+    operator= (nullopt_t)
+    {
+      if (v_)
+      {
+        d_.~T ();
+        v_ = false;
+      }
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, false>& optional_data<T, false>::
+    operator= (const T& v)
+    {
+      if (v_)
+      {
+        d_.~T ();
+        v_ = false;
+      }
+
+      new (&d_) T (v);
+      v_ = true;
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, false>& optional_data<T, false>::
+    operator= (T&& v)
+    {
+      if (v_)
+      {
+        d_.~T ();
+        v_ = false;
+      }
+
+      new (&d_) T (std::move (v));
+      v_ = true;
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, false>::
+    optional_data (const optional_data& o)
+        : v_ (o.v_)
+    {
+      if (v_)
+        new (&d_) T (o.d_);
+    }
+
+    template <typename T>
+    inline optional_data<T, false>::
+    optional_data (optional_data&& o)
+        : v_ (o.v_)
+    {
+      if (v_)
+        new (&d_) T (std::move (o.d_));
+    }
+
+    template <typename T>
+    inline optional_data<T, false>& optional_data<T, false>::
+    operator= (const optional_data& o)
+    {
+      if (v_)
+      {
+        d_.~T ();
+        v_ = false;
+      }
+
+      if (o.v_)
+      {
+        new (&d_) T (o.d_);
+        v_ = true;
+      }
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, false>& optional_data<T, false>::
+    operator= (optional_data&& o)
+    {
+      if (v_)
+      {
+        d_.~T ();
+        v_ = false;
+      }
+
+      if (o.v_)
+      {
+        new (&d_) T (std::move (o.d_));
+        v_ = true;
+      }
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, false>::
+    ~optional_data ()
+    {
+      if (v_)
+        d_.~T ();
+    }
+
+    // optional_data<T, true>
+    //
+
+    template <typename T>
+    inline optional_data<T, true>& optional_data<T, true>::
+    operator= (nullopt_t)
+    {
+      if (v_)
+        v_ = false;
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, true>& optional_data<T, true>::
+    operator= (const T& v)
+    {
+      if (v_)
+        v_ = false;
+
+      new (&d_) T (v);
+      v_ = true;
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, true>& optional_data<T, true>::
+    operator= (T&& v)
+    {
+      if (v_)
+        v_ = false;
+
+      new (&d_) T (std::move (v));
+      v_ = true;
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, true>::
+    optional_data (const optional_data& o)
+        : v_ (o.v_)
+    {
+      if (v_)
+        new (&d_) T (o.d_);
+    }
+
+    template <typename T>
+    inline optional_data<T, true>::
+    optional_data (optional_data&& o)
+        : v_ (o.v_)
+    {
+      if (v_)
+        new (&d_) T (std::move (o.d_));
+    }
+
+    template <typename T>
+    inline optional_data<T, true>& optional_data<T, true>::
+    operator= (const optional_data& o)
+    {
+      if (v_)
+        v_ = false;
+
+      if (o.v_)
+      {
+        new (&d_) T (o.d_);
+        v_ = true;
+      }
+
+      return *this;
+    }
+
+    template <typename T>
+    inline optional_data<T, true>& optional_data<T, true>::
+    operator= (optional_data&& o)
+    {
+      if (v_)
+        v_ = false;
+
+      if (o.v_)
+      {
+        new (&d_) T (std::move (o.d_));
+        v_ = true;
+      }
+
+      return *this;
+    }
+  }
+}