ENH: provide lookupOrDefault for NamedEnum - makes for easier use.

applications/test/NamedEnum/Test-NamedEnum.C

@@ -66,6 +66,9 @@ int main(int argc, char *argv[])
     const List<namedEnumTest::option> options
         = namedEnumTest::namedEnum.enums();
 
+    dictionary testDict;
+    testDict.add("lookup1", "c");
+
     Info<< "enums: " << options << nl;
 
     Info<< "loop over enums (as list):" << nl;
@@ -88,6 +91,30 @@ int main(int argc, char *argv[])
         << namedEnumTest::namedEnum["a"] << nl
         << namedEnumTest::namedEnum[namedEnumTest::a] << nl;
 
+    Info<< "--- test dictionary lookup ---" << endl;
+    {
+        Info<< "dict: " << testDict << endl;
+
+        namedEnumTest::option gotOpt =
+            namedEnumTest::namedEnum.lookupOrDefault
+            (
+                "test",
+                testDict,
+                namedEnumTest::option::a
+            );
+
+        Info<< "got: " << gotOpt << endl;
+
+        gotOpt = namedEnumTest::namedEnum.lookupOrDefault
+        (
+            "lookup1",
+            testDict,
+            namedEnumTest::option::a
+        );
+
+        Info<< "got: " << gotOpt << endl;
+    }
+
     Info<< "--- test read construction ---" << endl;
 
     namedEnumTest::option dummy(namedEnumTest::namedEnum.read(Sin));

src/OpenFOAM/containers/NamedEnum/NamedEnum.C

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -24,33 +24,60 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "NamedEnum.H"
+#include "dictionary.H"
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+template<class Enum, int nEnum>
+template<class StringType>
+Foam::List<StringType> Foam::NamedEnum<Enum, nEnum>::getNamesList()
+{
+    List<StringType> lst(nEnum);
+
+    label count = 0;
+    for (int enumi=0; enumi < nEnum; ++enumi)
+    {
+        if (names[enumi] && names[enumi][0])
+        {
+            lst[count++] = names[enumi];
+        }
+    }
+
+    lst.setSize(count);
+    return lst;
+}
+
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template<class Enum, int nEnum>
 Foam::NamedEnum<Enum, nEnum>::NamedEnum()
 :
-    HashTable<int>(2*nEnum)
+    table_type(2*nEnum)
 {
-    for (int enumI = 0; enumI < nEnum; ++enumI)
+    for (int enumi=0; enumi < nEnum; ++enumi)
     {
-        if (!names[enumI] || names[enumI][0] == '\0')
+        if (names[enumi] && names[enumi][0])
+        {
+            insert(names[enumi], enumi);
+        }
+        else
         {
-            stringList goodNames(enumI);
+            // Bad name - generate error message
+            stringList goodNames(enumi);
 
-            for (int i = 0; i < enumI; ++i)
+            for (int i = 0; i < enumi; ++i)
             {
                 goodNames[i] = names[i];
             }
 
             FatalErrorInFunction
-                << "Illegal enumeration name at position " << enumI << endl
-                << "after entries " << goodNames << ".\n"
+                << "Illegal enumeration name at position " << enumi << nl
+                << "after entries " << goodNames << nl
                 << "Possibly your NamedEnum<Enum, nEnum>::names array"
                 << " is not of size " << nEnum << endl
                 << abort(FatalError);
         }
-        insert(names[enumI], enumI);
     }
 }
 
@@ -60,14 +87,13 @@ Foam::NamedEnum<Enum, nEnum>::NamedEnum()
 template<class Enum, int nEnum>
 Enum Foam::NamedEnum<Enum, nEnum>::read(Istream& is) const
 {
-    const word name(is);
-
-    HashTable<int>::const_iterator iter = find(name);
+    const word enumName(is);
+    table_type::const_iterator iter = find(enumName);
 
     if (!iter.found())
     {
         FatalIOErrorInFunction(is)
-            << name << " is not in enumeration: "
+            << enumName << " is not in enumeration: "
             << sortedToc() << exit(FatalIOError);
     }
 
@@ -78,45 +104,47 @@ Enum Foam::NamedEnum<Enum, nEnum>::read(Istream& is) const
 template<class Enum, int nEnum>
 void Foam::NamedEnum<Enum, nEnum>::write(const Enum e, Ostream& os) const
 {
-    os  << operator[](e);
+    os  << names[int(e)];
 }
 
 
 template<class Enum, int nEnum>
-Foam::stringList Foam::NamedEnum<Enum, nEnum>::strings()
+Enum Foam::NamedEnum<Enum, nEnum>::lookup
+(
+    const word& key,
+    const dictionary& dict
+) const
 {
-    stringList lst(nEnum);
+    const word enumName(dict.lookup(key));
+    table_type::const_iterator iter = find(enumName);
 
-    label nElem = 0;
-    for (int enumI = 0; enumI < nEnum; ++enumI)
+    if (!iter.found())
     {
-        if (names[enumI] && names[enumI][0])
-        {
-            lst[nElem++] = names[enumI];
-        }
+        FatalIOErrorInFunction(dict)
+            << enumName << " is not in enumeration: "
+            << sortedToc() << exit(FatalIOError);
     }
 
-    lst.setSize(nElem);
-    return lst;
+    return Enum(iter.object());
 }
 
 
 template<class Enum, int nEnum>
-Foam::wordList Foam::NamedEnum<Enum, nEnum>::words()
+Enum Foam::NamedEnum<Enum, nEnum>::lookupOrDefault
+(
+    const word& key,
+    const dictionary& dict,
+    const enum_type deflt
+) const
 {
-    wordList lst(nEnum);
-
-    label nElem = 0;
-    for (int enumI = 0; enumI < nEnum; ++enumI)
+    if (dict.found(key))
     {
-        if (names[enumI] && names[enumI][0])
-        {
-            lst[nElem++] = names[enumI];
-        }
+        return lookup(key, dict);
+    }
+    else
+    {
+        return deflt;
     }
-
-    lst.setSize(nElem);
-    return lst;
 }
 
 
@@ -125,18 +153,32 @@ Foam::List<Enum> Foam::NamedEnum<Enum, nEnum>::enums()
 {
     List<Enum> lst(nEnum);
 
-    label nElem = 0;
-    for (int enumI = 0; enumI < nEnum; ++enumI)
+    label count = 0;
+    for (int enumi = 0; enumi < nEnum; ++enumi)
     {
-        if (names[enumI] && names[enumI][0])
+        if (names[enumi] && names[enumi][0])
         {
-            lst[nElem++] = Enum(enumI);
+            lst[count++] = Enum(enumi);
         }
     }
 
-    lst.setSize(nElem);
+    lst.setSize(count);
     return lst;
 }
 
 
+template<class Enum, int nEnum>
+Foam::stringList Foam::NamedEnum<Enum, nEnum>::strings()
+{
+    return getNamesList<string>();
+}
+
+
+template<class Enum, int nEnum>
+Foam::wordList Foam::NamedEnum<Enum, nEnum>::words()
+{
+    return getNamesList<word>();
+}
+
+
 // ************************************************************************* //

src/OpenFOAM/containers/NamedEnum/NamedEnum.H

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -25,7 +25,9 @@ Class
     Foam::NamedEnum
 
 Description
-    Initialise the NamedEnum HashTable from the static list of names.
+    A NamedEnum is a wrapper around a static list of names that represent
+    a particular enumeration. Internally it uses a HashTable for quicker
+    lookups.
 
 SourceFiles
     NamedEnum.C
@@ -44,6 +46,7 @@ SourceFiles
 
 namespace Foam
 {
+class dictionary;
 
 // Forward declaration
 template<class Enum, int> class NamedEnum;
@@ -57,11 +60,19 @@ class NamedEnum
 :
     public HashTable<int>
 {
-    //- nEnum must be positive (non-zero)
+    //- The nEnum must be positive (non-zero)
     static_assert(nEnum > 0, "nEnum must be positive (non-zero)");
 
+    //- The type of HashTable used for the lookup.
+    typedef HashTable<int> table_type;
+
+
     // Private Member Functions
 
+        //- The names as a list of strings
+        template<class StringType>
+        static List<StringType> getNamesList();
+
         //- Disallow default bitwise copy construct
         NamedEnum(const NamedEnum&) = delete;
 
@@ -71,6 +82,10 @@ class NamedEnum
 
 public:
 
+    //- The type of enumeration wrapped by NamedEnum
+    typedef Enum enum_type;
+
+
     // Static data members
 
         //- The set of names corresponding to the enumeration Enum
@@ -87,10 +102,33 @@ public:
 
         //- Read a word from Istream and return the corresponding
         //  enumeration element
-        Enum read(Istream& is) const;
+        enum_type read(Istream& is) const;
 
         //- Write the name representation of the enumeration to an Ostream
-        void write(const Enum e, Ostream& os) const;
+        void write(const enum_type e, Ostream& os) const;
+
+        //- Lookup the key in the dictionary and return the corresponding
+        // enumeration element based on its name.
+        // Fatal if anything is incorrect.
+        enum_type lookup
+        (
+            const word& key,
+            const dictionary& dict
+        ) 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.
+        //  Fatal if enumerated name was incorrect.
+        enum_type lookupOrDefault
+        (
+            const word& key,
+            const dictionary& dict,
+            const enum_type deflt
+        ) const;
+
+        //- List of enumerations
+        static List<enum_type> enums();
 
         //- The set of names as a list of strings
         static stringList strings();
@@ -98,26 +136,23 @@ public:
         //- The set of names as a list of words
         static wordList words();
 
-        //- List of enumerations
-        static List<Enum> enums();
-
 
     // Member Operators
 
         //- Return the enumeration element corresponding to the given name
-        const Enum operator[](const char* name) const
+        inline const enum_type operator[](const char* name) const
         {
-            return Enum(HashTable<int>::operator[](name));
+            return enum_type(table_type::operator[](name));
         }
 
         //- Return the enumeration element corresponding to the given name
-        const Enum operator[](const word& name) const
+        inline const enum_type operator[](const word& name) const
         {
-            return Enum(HashTable<int>::operator[](name));
+            return enum_type(table_type::operator[](name));
         }
 
         //- Return the name of the given enumeration element
-        const char* operator[](const Enum e) const
+        inline const char* operator[](const enum_type e) const
         {
             return names[int(e)];
         }