Initial release

engine/vendor/vst3sdk/vstgui4/vstgui/lib/optional.h

@@ -0,0 +1,135 @@
+// This file is part of VSTGUI. It is subject to the license terms 
+// in the LICENSE file found in the top-level directory of this
+// distribution and at http://github.com/steinbergmedia/vstgui/LICENSE
+
+#pragma once
+
+#include <utility>
+
+//------------------------------------------------------------------------
+namespace VSTGUI {
+
+//------------------------------------------------------------------------
+/** simplified optional 
+ *
+ *	@ingroup new_in_4_5
+ */
+template <typename T>
+struct Optional
+{
+	static_assert (std::is_default_constructible<T>::value, "Type T must be default constructible");
+
+	Optional (T&& v);
+	explicit Optional (const T& v);
+	Optional ();
+
+	Optional (Optional&&) = default;
+	Optional& operator= (Optional&&) = default;
+	Optional (const Optional&) = delete;
+	Optional& operator= (const Optional&) = delete;
+
+	explicit operator bool () const;
+
+	const T* operator-> () const;
+	T* operator-> ();
+
+	const T& operator* () const&;
+	T& operator* () &;
+
+	T&& value ();
+	const T& value () const;
+
+	void reset ();
+private:
+	std::pair<bool, T> _value;
+};
+
+//------------------------------------------------------------------------
+template <typename T>
+inline Optional<typename std::decay<T>::type> makeOptional (T&& value)
+{
+	return Optional<typename std::decay<T>::type> (std::forward<T> (value));
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline Optional<T>::Optional (T&& v)
+: _value {true, std::move (v)}
+{
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline Optional<T>::Optional (const T& v)
+: _value {true, v}
+{
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline Optional<T>::Optional ()
+{
+	_value.first = false;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline Optional<T>::operator bool () const
+{
+	return _value.first;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline const T* Optional<T>::operator-> () const
+{
+	return _value.second;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline T* Optional<T>::operator-> ()
+{
+	return &_value.second;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline const T& Optional<T>::operator* () const&
+{
+	return _value.second;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline T& Optional<T>::operator* () &
+{
+	return _value.second;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline T&& Optional<T>::value ()
+{
+	assert (_value.first);
+	return std::move (_value.second);
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline const T& Optional<T>::value () const
+{
+	assert (_value.first);
+	return _value.second;
+}
+
+//------------------------------------------------------------------------
+template <typename T>
+inline void Optional<T>::reset ()
+{
+	_value.first = false;
+	_value.second = {};
+}
+
+//------------------------------------------------------------------------
+} // VSTGUI