AndOrNot.h

// Copyright 1998-2018 Epic Games, Inc. All Rights Reserved.

#pragma once

#include "inc.h"

/**
 * Does a boolean AND of the ::Value static members of each type, but short-circuits if any Type::Value == false.
 */
template <typename... Types>
struct TAnd;

template <bool LHSValue, typename... RHS>
struct TAndValue
{
	enum { Value = TAnd<RHS...>::Value };
};

template <typename... RHS>
struct TAndValue<false, RHS...>
{
	enum { Value = false };
};

template <typename LHS, typename... RHS>
struct TAnd<LHS, RHS...> : TAndValue<LHS::Value, RHS...>
{
};

template <>
struct TAnd<>
{
	enum { Value = true };
};

/**
 * Does a boolean OR of the ::Value static members of each type, but short-circuits if any Type::Value == true.
 */
template <typename... Types>
struct TOr;

template <bool LHSValue, typename... RHS>
struct TOrValue
{
	enum { Value = TOr<RHS...>::Value };
};

template <typename... RHS>
struct TOrValue<true, RHS...>
{
	enum { Value = true };
};

template <typename LHS, typename... RHS>
struct TOr<LHS, RHS...> : TOrValue<LHS::Value, RHS...>
{
};

template <>
struct TOr<>
{
	enum { Value = false };
};

/**
 * Does a boolean NOT of the ::Value static members of the type.
 */
template <typename Type>
struct TNot
{
	enum { Value = !Type::Value };
};