ENH: support HashTable erasure via a FixedList

- propagate common erasure methods as HashSet::unset() method,
  for symmetry with HashSet::set()

src/OpenFOAM/containers/HashTables/HashSet/HashSet.H

@@ -64,8 +64,8 @@ class HashSet
 
 public:
 
-    typedef typename HashTable<nil, Key, Hash>::iterator iterator;
-    typedef typename HashTable<nil, Key, Hash>::const_iterator const_iterator;
+    using iterator = typename HashTable<nil, Key, Hash>::iterator;
+    using const_iterator = typename HashTable<nil, Key, Hash>::const_iterator;
 
 
     // Constructors
@@ -154,6 +154,25 @@ public:
             return HashTable<nil, Key, Hash>::erase(key);
         }
 
+        //- Unset the listed keys - same as erase
+        label unset(const UList<Key>& lst)
+        {
+            return HashTable<nil, Key, Hash>::erase(lst);
+        }
+
+        //- Unset the listed keys - same as erase
+        template<unsigned Size>
+        label unset(const FixedList<Key, Size>& lst)
+        {
+            return HashTable<nil, Key, Hash>::erase(lst);
+        }
+
+        //- Unset the listed keys - same as erase
+        label unset(std::initializer_list<Key> lst)
+        {
+            return HashTable<nil, Key, Hash>::erase(lst);
+        }
+
 
     // Member Operators
 

src/OpenFOAM/containers/HashTables/HashTable/HashTable.C

@@ -28,8 +28,34 @@ License
 
 #include "HashTable.H"
 #include "List.H"
+#include "FixedList.H"
 #include "Tuple2.H"
 
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+template<class T, class Key, class Hash>
+template<class InputIter>
+Foam::label Foam::HashTable<T, Key, Hash>::eraseMultiple
+(
+    const InputIter begIter,
+    const InputIter endIter
+)
+{
+    const label nTotal = this->size();
+    label changed = 0;
+
+    // Terminates early if possible
+    for (InputIter iter = begIter; changed < nTotal && iter != endIter; ++iter)
+    {
+        if (this->erase(*iter))
+        {
+            ++changed;
+        }
+    }
+    return changed;
+}
+
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template<class T, class Key, class Hash>
@@ -389,19 +415,28 @@ bool Foam::HashTable<T, Key, Hash>::erase(const Key& key)
 template<class T, class Key, class Hash>
 Foam::label Foam::HashTable<T, Key, Hash>::erase(const UList<Key>& keys)
 {
-    const label nTotal = nElmts_;
-    label count = 0;
+    return eraseMultiple(keys.begin(), keys.end());
+}
 
-    // Remove listed keys from this table - terminates early if possible
-    for (label keyI = 0; count < nTotal && keyI < keys.size(); ++keyI)
-    {
-        if (erase(keys[keyI]))
-        {
-            ++count;
-        }
-    }
 
-    return count;
+template<class T, class Key, class Hash>
+template<unsigned Size>
+Foam::label Foam::HashTable<T, Key, Hash>::erase
+(
+    const FixedList<Key, Size>& keys
+)
+{
+    return eraseMultiple(keys.begin(), keys.end());
+}
+
+
+template<class T, class Key, class Hash>
+Foam::label Foam::HashTable<T, Key, Hash>::erase
+(
+    std::initializer_list<Key> keys
+)
+{
+    return eraseMultiple(keys.begin(), keys.end());
 }
 
 
@@ -412,19 +447,21 @@ Foam::label Foam::HashTable<T, Key, Hash>::erase
     const HashTable<AnyType, Key, AnyHash>& rhs
 )
 {
-    label count = 0;
+    const label nTotal = this->size();
+    label changed = 0;
 
     // Remove rhs keys from this table - terminates early if possible
     // Could optimize depending on which hash is smaller ...
-    for (iterator iter = begin(); iter != end(); ++iter)
+
+    // Terminates early if possible
+    for (iterator iter = begin(); changed < nTotal && iter != end(); ++iter)
     {
         if (rhs.found(iter.key()) && erase(iter))
         {
-            ++count;
+            ++changed;
         }
     }
-
-    return count;
+    return changed;
 }
 
 

src/OpenFOAM/containers/HashTables/HashTable/HashTable.H

@@ -60,6 +60,7 @@ namespace Foam
 
 template<class T> class List;
 template<class T> class UList;
+template<class T, unsigned Size> class FixedList;
 template<class T, class Key, class Hash> class HashTable;
 template<class T, class Key, class Hash> class HashPtrTable;
 
@@ -174,6 +175,18 @@ class HashTable
         bool set(const Key& key, const T& newEntry, const bool protect);
 
 
+protected:
+
+    // Protected Member Functions
+
+        //- Remove using begin/end iterators of listed keys
+        template<class InputIter>
+        inline label eraseMultiple
+        (
+            const InputIter begIter,
+            const InputIter endIter
+        );
+
 public:
 
     // Forward declaration of iterators
@@ -274,6 +287,15 @@ public:
             //  Return the number of elements removed
             label erase(const UList<Key>& keys);
 
+            //- Remove entries given by the listed keys from this HashTable
+            //  Return the number of elements removed
+            template<unsigned Size>
+            label erase(const FixedList<Key, Size>& keys);
+
+            //- Remove entries given by the listed keys from this HashTable
+            //  Return the number of elements removed
+            label erase(std::initializer_list<Key> keys);
+
             //- Remove entries given by the given keys from this HashTable
             //  Return the number of elements removed.
             //  The parameter HashTable needs the same type of key, but the