Initial release

engine/vendor/vst3sdk/public.sdk/source/vst/utility/optional.h

@@ -0,0 +1,115 @@
+//-----------------------------------------------------------------------------
+// Project     : VST SDK
+//
+// Category    : Helpers
+// Filename    : public.sdk/source/vst/utility/optional.h
+// Created by  : Steinberg, 08/2016
+// Description : optional helper
+//
+//-----------------------------------------------------------------------------
+// This file is part of a Steinberg SDK. It is subject to the license terms
+// in the LICENSE file found in the top-level directory of this distribution
+// and at www.steinberg.net/sdklicenses.
+// No part of the SDK, including this file, may be copied, modified, propagated,
+// or distributed except according to the terms contained in the LICENSE file.
+//-----------------------------------------------------------------------------
+
+#pragma once
+
+#include <cassert>
+#include <memory>
+#include <utility>
+
+//------------------------------------------------------------------------
+namespace VST3 {
+
+//------------------------------------------------------------------------
+template <typename T>
+struct Optional
+{
+	Optional () noexcept : valid (false) {}
+	explicit Optional (const T& v) noexcept : _value (v), valid (true) {}
+	Optional (T&& v) noexcept : _value (std::move (v)), valid (true) {}
+
+	Optional (Optional&& other) noexcept { *this = std::move (other); }
+	Optional& operator= (Optional&& other) noexcept
+	{
+		valid = other.valid;
+		_value = std::move (other._value);
+		return *this;
+	}
+
+	explicit operator bool () const noexcept
+	{
+		setValidationChecked ();
+		return valid;
+	}
+
+	const T& operator* () const noexcept
+	{
+		checkValid ();
+		return _value;
+	}
+
+	const T* operator-> () const noexcept
+	{
+		checkValid ();
+		return &_value;
+	}
+
+	T& operator* () noexcept
+	{
+		checkValid ();
+		return _value;
+	}
+
+	T* operator-> () noexcept
+	{
+		checkValid ();
+		return &_value;
+	}
+
+	T&& value () noexcept
+	{
+		checkValid ();
+		return std::move (_value);
+	}
+
+	const T& value () const noexcept
+	{
+		checkValid ();
+		return _value;
+	}
+
+	void swap (T& other) noexcept
+	{
+		checkValid ();
+		auto tmp = std::move (other);
+		other = std::move (_value);
+		_value = std::move (tmp);
+	}
+
+private:
+	T _value {};
+	bool valid;
+
+#if !defined(NDEBUG)
+	mutable bool validationChecked {false};
+#endif
+
+	void setValidationChecked () const
+	{
+#if !defined(NDEBUG)
+		validationChecked = true;
+#endif
+	}
+	void checkValid () const
+	{
+#if !defined(NDEBUG)
+		assert (validationChecked);
+#endif
+	}
+};
+
+//------------------------------------------------------------------------
+}