streamEntry.H

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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
    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::functionEntries::streamEntry
 
Description
    Compiles and executes C++ OpenFOAM code string expressions
 
    inserting the result into the dictionary or dictionary entry.  The
    functionality of \c #stream is equivalent to \c #codeStream but with a
    simpler syntax, relying on separate \c #codeInclude entries to provide
    required include files.  For more details see
    Foam::functionEntries::codeStream.
 
Usage
    Example to find the root of f(x) = x + B*x/sqrt(1 + sqr(x)) - A
    using Newton-Raphson iteration
 
    \verbatim
        A       1;
        B       1;
 
        x       #stream
        #{
            // Lookup the coefficients
            const scalar A = $A;
            const scalar B = $B;
 
            // Initial guess for x
            scalar x = 0;
 
            scalar x0 = x;
 
            do
            {
                // Store the previous iteration x for the convergence check
                x0 = x;
 
                // Temporary sub-function evaluations
                const scalar f1 = 1 + sqr(x);
                const scalar f2 = sqrt(f1);
 
                // Evaluate the function
                const scalar f = x + B*x/f2 - A;
 
                // Evaluate the derivative
                const scalar df = 1 + B/(f1*f2);
 
                // Update x
                x = x0 - f/df;
 
                // Test for convergence
            } while (mag(x - x0) > 1e-6);
 
            os << x;
        #};
    \endverbatim
 
See also
    Foam::functionEntries::codeIncludeEntry
    Foam::functionEntries::codeStream
    Foam::functionEntries::calc
 
SourceFiles
    streamEntry.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef streamEntry_H
#define streamEntry_H
 
#include "functionEntry.H"
#include "OTstream.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace functionEntries
{
 
// Forward declaration of friend classes
class codeBlockEntry;
 
/*---------------------------------------------------------------------------*\
                          Class streamEntry Declaration
\*---------------------------------------------------------------------------*/
 
class streamEntry
:
    public functionEntry
{
protected:
 
    // Protected Member Functions
 
        //- Return the code string
        static string codeString
        (
            const label index,
            const dictionary& codeDict,
            Istream&,
            const string& startString = string::null,
            const string& endString = string::null
        );
 
        //- Perform the calculation and return the result in an OTstream
        static OTstream resultStream
        (
            const dictionary& dict,
            Istream& is,
            const string& startString = string::null,
            const string& endString = string::null
        );
 
 
public:
 
    // Related types
 
        //- Declare friendship with the streamEntry class
        friend class codeBlockEntry;
 
 
    //- Runtime type information
    FunctionTypeName("#stream");
 
 
    // Constructors
 
        //- Construct from line number, dictionary and Istream
        streamEntry
        (
            const label lineNumber,
            const dictionary& parentDict,
            Istream& is
        );
 
        //- Copy construct
        streamEntry(const streamEntry&) = default;
 
        //- Clone
        virtual autoPtr<entry> clone(const dictionary&) const
        {
            return autoPtr<entry>(new streamEntry(*this));
        }
 
 
    // Member Functions
 
        //- Expand the functionEntry into the contextDict
        virtual bool execute(dictionary& contextDict, Istream&);
 
        //- Expand the functionEntry into the contextEntry
        static bool execute
        (
            const dictionary& contextDict,
            primitiveEntry& contextEntry,
            Istream&
        );
 
 
    // Member Operators
 
        //- Disallow default bitwise assignment
        void operator=(const streamEntry&) = delete;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace functionEntries
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //