bool.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2025 the Initial Developer.
 *  All Rights Reserved.
 *  
 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
 *  others to use your version of this file under the CPAL, indicate your decision by 
 *  deleting the provisions above and replace them with the notice and other 
 *  provisions required by the GPL License. If you do not delete the provisions above,
 *  a recipient may use your version of this file under either the CPAL or the GPL.
 *  
 *  *** END LICENSE INFORMATION ***
 */
 
 
 
/** @class lass::meta::Bool
 *  @brief meta boolean type
 *  @author Bram de Greve [BdG]
 *
 *  The meta boolean type consists of two types True and False.
 *  Bool<flag> converts an C @c bool @a flag to a @e meta bools True or False
 *
 *  @code
 *  Bool<true>::Type; // resolves to True
 *  @endcode
 */
 
#ifndef LASS_GUARDIAN_OF_INCLUSION_META_BOOL_H
#define LASS_GUARDIAN_OF_INCLUSION_META_BOOL_H
 
#include "meta_common.h"
 
// Clang's -Wunused-private-field will warn that dummy_ and biggerThanTrue_ are not used.
// But GCC <= 11 will then warn that [[maybe_unused]] attribute is ignored.
#if LASS_COMPILER_TYPE == LASS_COMPILER_TYPE_GCC && __GNUC__ <= 11
#   define LASS_META_BOOL_MAYBE_UNUSED
#else
#   define LASS_META_BOOL_MAYBE_UNUSED [[maybe_unused]]
#endif
 
namespace lass
{
namespace meta
{
 
/** meta true
 *  @relates Bool
 */
class True
{
public:
    typedef True Type;
    enum { value = true };
private:
    LASS_META_BOOL_MAYBE_UNUSED char dummy_;
};
 
/** meta false
 *  @relates Bool
 */
struct False
{
public:
    typedef False Type;
    enum { value = false };
private:
    LASS_META_BOOL_MAYBE_UNUSED True biggerThanTrue_[2];
};
 
 
 
template <bool flag> 
struct Bool: 
    public True 
{
};
 
template <> 
struct Bool<false>: 
    public False 
{
};
 
// --- logic operators -----------------------------------------------------------------------------
 
/** meta NOT
 *  @relates Bool
 */
template <typename Operand> struct Not: 
    public Not<typename Operand::Type> 
{
};
template <> struct Not<False>: public True {};
template <> struct Not<True>: public False {};
 
 
 
/** meta AND
 *  @relates Bool
 */
template <typename Operand1, typename Operand2> struct And:
    public And<typename Operand1::Type, typename Operand2::Type> 
{
};
template <> struct And<False, False>: public False {};
template <> struct And<False, True>: public False {};
template <> struct And<True, False>: public False {};
template <> struct And<True, True>: public True {};
 
 
 
/** meta OR
 *  @relates Bool
 */
template <typename Operand1, typename Operand2> struct Or:
    public Or<typename Operand1::Type, typename Operand2::Type> 
{
};
template <> struct Or<False, False>: public False {};
template <> struct Or<False, True>: public True {};
template <> struct Or<True, False>: public True {};
template <> struct Or<True, True>: public True {};
 
 
 
/** meta XOR
 *  @relates Bool
 */
template <typename Operand1, typename Operand2> struct Xor:
    public Xor<typename Operand1::Type, typename Operand2::Type> 
{
};
template <> struct Xor<False, False>: public False {};
template <> struct Xor<False, True>: public True {};
template <> struct Xor<True, False>: public True {};
template <> struct Xor<True, True>: public False {};
 
 
}
 
}
 
#endif
 
// EOF