exprTraits.H

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    Copyright (C) 2021-2023 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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    under the terms of the GNU General Public License as published by
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    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::exprTypeTraits
 
Description
    Simple type identifiers for polymorphic expression values.
    The definitions are similar to std::integral_constant in that they
    provide value, value_type (and name).
 
SourceFiles
    exprTraits.C
 
Namespace
    Foam::expressions
 
Description
    A namespace for expression-related classes/traits etc.
 
Namespace
    Foam::expressions::Detail
 
Description
    A namespace for implementation details related to expressions.
 
\*---------------------------------------------------------------------------*/
 
#ifndef Foam_expressions_exprTraits_H
#define Foam_expressions_exprTraits_H
 
// Regular field types
#include "label.H"
#include "scalar.H"
//TBD: #include "complex.H"
#include "vector.H"
#include "sphericalTensor.H"
#include "symmTensor.H"
#include "tensor.H"
#include "word.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace expressions
{
 
//- An enumeration of known and expected expression value types.
//  Do not rely on the enumeration values for any direct coding.
//
//  \note NONE used when initializing types, whereas INVALID is used
//  for unsupported types (never as a stored type).
//  This avoids false positives when testing.
//
//  Except NONE and INVALID, the enumerations will mostly not be used
//  directly, but through exprTypeTraits :: value
 
enum class valueTypeCode : unsigned char
{
    NONE = 0,               
    INVALID,                
 
    // Rank 0 types
    type_bool,              
    type_label,             
    type_scalar,            
//TBD: type_complex,           //!< Type is 'complex'
 
    // Rank 1 types
    type_vector,            
 
    // Rank 2 types
    type_sphericalTensor,   
    type_symmTensor,        
    type_tensor             
};
 
 
// Global Functions
 
//- From string to valueTypeCode (if any)
valueTypeCode valueTypeCodeOf
(
    const word& dataTypeName,
    // Fallback for unknown
    const expressions::valueTypeCode deflt = expressions::valueTypeCode::INVALID
);
 
 
// Some implementation detail
namespace Detail
{
 
//- The number of components associated with given valueTypeCode
::Foam::direction nComponents(const expressions::valueTypeCode) noexcept;
 
//- The vector-space rank associated with given valueTypeCode
::Foam::direction rank(const expressions::valueTypeCode) noexcept;
 
} // End namespace Detail
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace expressions
 
 
/*---------------------------------------------------------------------------*\
                       Class exprTypeTraits Declaration
\*---------------------------------------------------------------------------*/
 
// Generic enumerated traits is INVALID (unknown)
template<class Type>
struct exprTypeTraits
{
    // The value type
    typedef Type value_type;
    // The type name (similar to pTraits typeName)
    static constexpr const char* const name = "";
    // The enumeration number associated with the type
    static constexpr
        ::Foam::expressions::valueTypeCode value =
        ::Foam::expressions::valueTypeCode::INVALID;
    // The rank of the type
    static constexpr ::Foam::direction rank = 0;
    // The number of components
    static constexpr ::Foam::direction nComponents = 0;
};
 
 
#undef  defineExprTypeTraits
#define defineExprTypeTraits(Type, Name, Rank, NumCmpts)                      \
                                   \
    template<>                                                                \
    struct exprTypeTraits<Type>                                               \
    {                                                                         \
        typedef Type value_type;                                              \
        static constexpr const char* const name = #Name ;                     \
        static constexpr                                                      \
            ::Foam::expressions::valueTypeCode value =                        \
            ::Foam::expressions::valueTypeCode::type_##Name ;                 \
        static constexpr ::Foam::direction rank = Rank ;                      \
        static constexpr ::Foam::direction nComponents = NumCmpts ;           \
    };
 
 
// Define with name to match pTraits::typeName, with rank/nComponents
defineExprTypeTraits(bool, bool, 0, 1);
defineExprTypeTraits(::Foam::label, label, 0, 1);
defineExprTypeTraits(::Foam::scalar, scalar, 0, 1);
//TBD: defineExprTypeTraits(::Foam::complex, complex, 0, 2);
defineExprTypeTraits(::Foam::vector, vector, 1, 3);
defineExprTypeTraits(::Foam::tensor, tensor, 2, 9);
defineExprTypeTraits(::Foam::sphericalTensor, sphericalTensor, 2, 1);
defineExprTypeTraits(::Foam::symmTensor, symmTensor, 2, 6);
 
#undef defineExprTypeTraits
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
//- A word representation of a valueTypeCode.
//- Empty for expressions::valueTypeCode::INVALID
word name(const expressions::valueTypeCode typeCode);
 
 
//- A word representation of a valueTypeCode.
//- Empty for expressions::valueTypeCode::INVALID
template<>
struct nameOp<expressions::valueTypeCode>
{
    word operator()(const expressions::valueTypeCode typeCode) const
    {
        return Foam::name(typeCode);
    }
};
 
// No IOstream Operators for valueTypeCode at the moment (Nov 2021)
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //