/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2016-2019 OpenCFD Ltd.
-------------------------------------------------------------------------------
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::ddt2

Group
    grpFieldFunctionObjects

Description
    This function object calculates the magnitude squared
    of d(scalarField)/dt.

    The result can be used further for determining variance or RMS values
    (for example).

Usage
    Example of function object specification:
    \verbatim
    dpdt2
    {
        type        ddt2;
        libs        ("libfieldFunctionObjects.so");
        fields      (p);
        result      d@@dt2;
        ...
    }
    \endverbatim

    Where the entries comprise:
    \table
        Property | Description                | Required  | Default value
        type     | type name: ddt2            | yes       |
        fields   | Name of fields to process  | yes       |
        result   | Name of results            | no        | magSqr(ddt(@@))
        log      | Log to standard output     | no        | yes
        mag      | Use 'mag' instead of 'magSqr' | no     | false
    \endtable

    Note that the optional 'mag' entry cannot be changed during the simulation
    since it alters the dimensions of the output field.

    A list of fields can contain exact names or regular expressions.
    The token '\@\@' in the result name is replaced by the name of the source
    field. In the special case of a single source field (specified as
    a non-regex), the '\@\@' token checking is suppressed.

    The function object will skip over fields that appear to have
    already been processed (ie, their names are similar to the output names).

SourceFiles
    ddt2.C
    ddt2Templates.C

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

#ifndef functionObjects_ddt2_H
#define functionObjects_ddt2_H

#include "fvMeshFunctionObject.H"
#include "volFieldsFwd.H"
#include "OFstream.H"
#include "regExp.H"
#include "HashSet.H"
#include "wordRes.H"

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

namespace Foam
{
namespace functionObjects
{

/*---------------------------------------------------------------------------*\
                            Class ddt2 Declaration
\*---------------------------------------------------------------------------*/

class ddt2
:
    public fvMeshFunctionObject
{
    // Private data

        //- Name of fields to process.
        wordRes selectFields_;

        //- Formatting for the result fields.
        word resultName_;

        //- Avoid processing the same field twice.
        mutable regExp blacklist_;

        //- Hashed names of result fields.
        wordHashSet results_;

        //- Use 'mag' instead of 'magSqr'.
        //  Cannot be adjusted during the simulation since it alters the
        //  dimensions of the output field.
        const bool mag_;


    // Private Member Functions

        //- Check that string contains the appropriate substitution token(s).
        static bool checkFormatName(const std::string& str);


        //- Accept unless field name appears to have already been processed
        bool accept(const word& fieldName) const;

        //- Apply for the volume field type
        template<class FieldType>
        int apply(const word& inputName, int& state);

        //- Process by trying to apply for various volume field types.
        int process(const word& inputName);


        //- No copy construct
        ddt2(const ddt2&) = delete;

        //- No copy assignment
        void operator=(const ddt2&) = delete;


public:

    //- Runtime type information
    TypeName("ddt2");


    // Constructors

        //- Construct from Time and dictionary
        ddt2
        (
            const word& name,
            const Time& runTime,
            const dictionary& dict
        );


    //- Destructor
    virtual ~ddt2() = default;


    // Member Functions

        //- Read the ddt2 specification
        virtual bool read(const dictionary&);

        //- Calculate the ddt2 fields
        virtual bool execute();

        //- Write the ddt fields
        virtual bool write();
};


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

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

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

#ifdef NoRepository
    #include "ddt2Templates.C"
#endif

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

#endif

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