/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2012-2026 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
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
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    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::functionObjects::fieldExpression

Description

See also
    Foam::functionObjects::fvMeshFunctionObject

SourceFiles
    fieldExpression.C

\*---------------------------------------------------------------------------*/

#ifndef fieldExpression_functionObject_H
#define fieldExpression_functionObject_H

#include "fvMeshFunctionObject.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{
namespace functionObjects
{

/*---------------------------------------------------------------------------*\
                       Class fieldExpression Declaration
\*---------------------------------------------------------------------------*/

class fieldExpression
:
    public fvMeshFunctionObject
{
protected:

    // Protected Data

        //- Word indicating that this fieldExpression has no field name
        static const word noFieldName_;

        //- Word indicating that this fieldExpression has no default field
        //  name, so the user must provide one
        static const word noDefaultFieldName_;

        //- Name of field to process
        const word fieldName_;

        //- Name of result field
        word resultName_;


    // Protected Member Functions

        virtual bool calc() = 0;


public:

    //- Runtime type information
    TypeName("fieldExpression");


    // Constructors

        //- Construct from Time and dictionary
        fieldExpression
        (
            const word& name,
            const Time& runTime,
            const dictionary& dict,
            const word& functionName,
            const word& defaultFieldName = noDefaultFieldName_
        );

        //- Disallow default bitwise copy construction
        fieldExpression(const fieldExpression&) = delete;


    //- Destructor
    virtual ~fieldExpression();


    // Member Functions

        //- Return the field required
        virtual wordList fields() const;

        //- Calculate the result field
        virtual bool execute();

        //- Write the result field
        virtual bool write();

        //- Clear the result field from the objectRegistry
        virtual bool clear();


    // Member Operators

        //- Disallow default bitwise assignment
        void operator=(const fieldExpression&) = delete;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace functionObjects
} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //