ENH: provide Enum failsafe lookup

- if the enum name is not found, then warn and return the default.

src/OpenFOAM/primitives/enums/Enum.C

@@ -215,10 +215,37 @@ EnumType Foam::Enum<EnumType>::lookupOrDefault
     {
         return lookup(key, dict);
     }
+
+    return deflt;
+}
+
+
+template<class EnumType>
+EnumType Foam::Enum<EnumType>::lookupOrFailsafe
+(
+    const word& key,
+    const dictionary& dict,
+    const EnumType deflt
+) const
+{
+    if (dict.found(key))
+    {
+        const word enumName(dict.lookup(key));
+        const label idx = getIndex(enumName);
+
+        if (idx < 0)
+        {
+            IOWarningInFunction(dict)
+                << "bad " << key <<" specifier " << enumName
+                << " using " << getName(deflt) << endl;
+        }
         else
         {
-        return deflt;
+            return EnumType(values_[idx]);
         }
+    }
+
+    return deflt;
 }
 
 

src/OpenFOAM/primitives/enums/Enum.H

@@ -161,6 +161,18 @@ public:
         ) const;
 
 
+        //- Find the key in the dictionary and return the corresponding
+        //  enumeration element based on its name.
+        //  Return the default value if the key was not found in the dictionary
+        //  or if the enumerated name was incorrect (emit warning)
+        EnumType lookupOrFailsafe
+        (
+            const word& key,
+            const dictionary& dict,
+            const EnumType deflt
+        ) const;
+
+
       // IO
 
         //- Read a word from Istream and return the corresponding enumeration