StaticAssert.H

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::StaticAssertionFailed
 
Description
    Macros and classes to provide static (compile-time) assertions.
 
    Ideas from various sources
    (http://www.ddj.com/cpp/184401547, http://www.boost.org)
 
\*---------------------------------------------------------------------------*/
 
#ifndef StaticAssert_H
#define StaticAssert_H
 
namespace Foam
{
 
//- Forward declaration of StaticAssertionFailed.
//  Leave as an incomplete class so that sizeof(..) fails
template<bool Truth> class StaticAssertionFailed;
 
/*---------------------------------------------------------------------------*\
                    Class StaticAssertionFailed Declaration
\*---------------------------------------------------------------------------*/
 
//- Specialization for successful assertions
template<>
class StaticAssertionFailed<true>
{};
 
 
//- Helper class for handling static assertions
template<unsigned Test>
class StaticAssertionTest {};
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
// Internal use:
// ~~~~~~~~~~~~~
 
// Paste together strings, even if an argument is itself a macro
#define StaticAssertMacro(X,Y)  StaticAssertMacro1(X,Y)
#define StaticAssertMacro1(X,Y) StaticAssertMacro2(X,Y)
#define StaticAssertMacro2(X,Y) X##Y
 
// External use:
// ~~~~~~~~~~~~~
 
//- Assert that some test is true at compile-time
#define StaticAssert(Test)                                                   \
    typedef ::Foam::StaticAssertionTest                                      \
    <                                                                        \
        sizeof( ::Foam::StaticAssertionFailed< ((Test) ? true : false) > )   \
    > StaticAssertMacro(StaticAssertionTest, __LINE__)
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //