ENH: Added new demandDrivenEntry for dictionary

src/OpenFOAM/primitives/demandDrivenEntry/demandDrivenEntry.C

+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2013 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "demandDrivenEntry.H"
+
+// * * * * * * * * * * * * * * * Constructor * * * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::demandDrivenEntry<Type>::demandDrivenEntry
+(
+    const dictionary& dict,
+    const Type& value
+)
+:
+    dict_(dict),
+    keyword_("unknown-keyword"),
+    value_(value),
+    stored_(true)
+{}
+
+
+template<class Type>
+Foam::demandDrivenEntry<Type>::demandDrivenEntry
+(
+    const dictionary& dict,
+    const word& keyword
+)
+:
+    dict_(dict),
+    keyword_(keyword),
+    value_(pTraits<Type>::zero),
+    stored_(false)
+{}
+
+
+template<class Type>
+Foam::demandDrivenEntry<Type>::demandDrivenEntry
+(
+    const dictionary& dict,
+    const word& keyword,
+    const Type& defaultValue,
+    const bool readIfPresent
+)
+:
+    dict_(dict),
+    keyword_(keyword),
+    value_(defaultValue),
+    stored_(true)
+{
+    if (readIfPresent)
+    {
+        dict_.readIfPresent<Type>(keyword, value_);
+    }
+}
+
+
+template<class Type>
+Foam::demandDrivenEntry<Type>::demandDrivenEntry(const demandDrivenEntry& dde)
+:
+    dict_(dde.dict_),
+    keyword_(dde.keyword_),
+    value_(dde.value_),
+    stored_(dde.stored_)
+{}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/demandDrivenEntry/demandDrivenEntry.H

+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2013 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::demandDrivenEntry
+
+Description
+    Class for demand-driven dictionary entries
+
+    Holds a reference to a dictionary, which is then queried if the value
+    is requested and has not already been cached
+
+SourceFiles
+    demandDrivenEntry.C
+    demandDrivenEntryI.H
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef demandDrivenEntry_H
+#define demandDrivenEntry_H
+
+#include "dictionary.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                      Class demandDrivenEntry Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class Type>
+class demandDrivenEntry
+{
+private:
+
+    // Private data
+
+        //- Reference to the dictionary
+        const dictionary& dict_;
+
+        //- Keyword to look up
+        const word keyword_;
+
+        //- Value
+        mutable Type value_;
+
+        //- Flag to say that the value has been stored
+        mutable bool stored_;
+
+
+public:
+
+    //- Constructors
+
+        //- Construct from dictionary and value - cannot be re-read
+        demandDrivenEntry
+        (
+            const dictionary& dict,
+            const Type& value
+        );
+
+
+        //- Construct from dictionary and keyword
+        demandDrivenEntry
+        (
+            const dictionary& dict,
+            const word& keyword
+        );
+
+
+        //- Construct from dictionary, keyword and default value
+        demandDrivenEntry
+        (
+            const dictionary& dict,
+            const word& keyword,
+            const Type& defaultValue,
+            const bool readIfPresent = true
+        );
+
+        //- Copy constructor
+        demandDrivenEntry(const demandDrivenEntry& dde);
+
+
+    // Public Member Functions
+
+        //- Return the value
+        inline const Type& value() const;
+
+        //- Set the value
+        inline void setValue(const Type& value);
+
+        //- Reset the demand-driven entry
+        inline void reset();
+};
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "demandDrivenEntryI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "demandDrivenEntry.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/demandDrivenEntry/demandDrivenEntryI.H

+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2013 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "demandDrivenEntry.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<class Type>
+inline const Type& Foam::demandDrivenEntry<Type>::value() const
+{
+    if (!stored_)
+    {
+        dict_.lookup(keyword_) >> value_;
+        stored_ = true;
+    }
+
+    return value_;
+}
+
+
+template<class Type>
+inline void Foam::demandDrivenEntry<Type>::setValue(const Type& value)
+{
+//    dict_.set<Type>(keyword_, value);
+    value_ = value;
+    stored_ = true;
+}
+
+
+template<class Type>
+inline void Foam::demandDrivenEntry<Type>::reset()
+{
+    stored_ = false;
+}
+
+
+// ************************************************************************* //