IOobject: Add support for group name

.group() returns the group name of the object otherwise null
groupName(name, group) returns the constructed group name (currently name.group)

src/OpenFOAM/db/IOobject/IOobject.C

@@ -243,6 +243,21 @@ const Foam::fileName& Foam::IOobject::caseName() const
 }
 
 
+Foam::word Foam::IOobject::group() const
+{
+    word::size_type i = name_.find_last_of('.');
+
+    if (i == word::npos || i == 0)
+    {
+        return word::null;
+    }
+    else
+    {
+        return name_.substr(i+1, word::npos);
+    }
+}
+
+
 const Foam::fileName& Foam::IOobject::rootPath() const
 {
     return time().rootPath();

src/OpenFOAM/db/IOobject/IOobject.H

@@ -154,6 +154,7 @@ private:
         //- IOobject state
         objectState objState_;
 
+
 protected:
 
     // Protected Member Functions
@@ -187,6 +188,9 @@ public:
             word& name
         );
 
+        template<class Name>
+        static inline word groupName(Name name, const word& group);
+
 
     // Constructors
 
@@ -313,6 +317,9 @@ public:
 
         // Path components
 
+            //- Return group (extension part of name)
+            word group() const;
+
             const fileName& rootPath() const;
 
             const fileName& caseName() const;

src/OpenFOAM/db/IOobject/IOobjectI.H

@@ -27,6 +27,20 @@ License
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+template<class Name>
+inline Foam::word Foam::IOobject::groupName(Name name, const word& group)
+{
+    if (group != word::null)
+    {
+        return name + ('.' + group);
+    }
+    else
+    {
+        return name;
+    }
+}
+
+
 template<class Stream>
 inline Stream& Foam::IOobject::writeBanner(Stream& os, bool noHint)
 {