ENH: add bitSet::operator() for predicate use (as per HashSet)

src/OpenFOAM/containers/Bits/bitSet/bitSet.H

@@ -493,6 +493,10 @@ public:
 
     // Member Operators
 
+        //- Test value at specified position, same as test()
+        //  Enables use as a predicate
+        inline bool operator()(const label pos) const;
+
         //- Identical to get() - get value at index.
         //  Never auto-vivify entries.
         inline unsigned int operator[](const label i) const;

src/OpenFOAM/containers/Bits/bitSet/bitSetI.H

@@ -621,6 +621,12 @@ inline Foam::bitSet& Foam::bitSet::extend(const bitSet& other)
 
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
+inline bool Foam::bitSet::operator()(const label pos) const
+{
+    return test(pos);
+}
+
+
 inline unsigned int Foam::bitSet::operator[](const label i) const
 {
     return get(i);