typeInfo: Added dynamicCastNull and refCastNull

These functions dynamic cast a reference to a type, and return a null
object reference if the cast fails. The standard dynamicCast and refCast
functions, by contrast, throw an error if the cast fails.

src/OpenFOAM/db/typeInfo/typeInfo.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -55,6 +55,7 @@ Description
 
 #include "error.H"
 #include "className.H"
+#include "nullObject.H"
 #include <type_traits>
 #include <typeinfo>
 
@@ -105,6 +106,23 @@ inline To& dynamicCast(From& r)
 }
 
 
+//- Reference type cast template function,
+//  wraps dynamic_cast to handle bad_cast exception and generate a null
+//  reference.
+template<class To, class From>
+inline To& dynamicCastNull(From& r)
+{
+    try
+    {
+        return dynamic_cast<To&>(r);
+    }
+    catch (const std::bad_cast&)
+    {
+        return NullObjectNonConstRef<To>();
+    }
+}
+
+
 //- Reference type cast template function.
 //  As per dynamicCast, but handles type names via the virtual type() method.
 template<class To, class From>
@@ -126,6 +144,15 @@ inline To& refCast(From& r)
 }
 
 
+//- Reference type cast template function,
+//  As dynamicCastNull.
+template<class To, class From>
+inline To& refCastNull(From& r)
+{
+    return dynamicCastNull<To, From>(r);
+}
+
+
 //- Check the typeid
 template<class TestType, class Type>
 inline bool isType(const Type& t)

src/OpenFOAM/primitives/nullObject/nullObject.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -72,6 +72,10 @@ extern const NullObject* nullObjectPtr;
 template<class T>
 inline const T& NullObjectRef();
 
+//- Return non-const reference to the nullObject of type T
+template<class T>
+inline T& NullObjectNonConstRef();
+
 //- Return const pointer to the nullObject of type T
 template<class T>
 inline const T* NullObjectConstPtr();

src/OpenFOAM/primitives/nullObject/nullObjectI.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2024 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -30,9 +30,9 @@ inline const T& Foam::NullObjectRef()
 }
 
 template<class T>
-inline T&& Foam::NullObjectMove()
+inline T& Foam::NullObjectNonConstRef()
 {
-    return move(const_cast<T&>(*reinterpret_cast<const T*>(nullObjectPtr)));
+    return const_cast<T&>(*reinterpret_cast<const T*>(nullObjectPtr));
 }
 
 template<class T>
@@ -47,6 +47,12 @@ inline T* Foam::NullObjectPtr()
     return const_cast<T*>(reinterpret_cast<const T*>(nullObjectPtr));
 }
 
+template<class T>
+inline T&& Foam::NullObjectMove()
+{
+    return move(const_cast<T&>(*reinterpret_cast<const T*>(nullObjectPtr)));
+}
+
 
 template<class T>
 inline bool Foam::isNull(const T& t)