ENH: add filtering version of dictionary copy

- can be useful when extracting portions of larger field files

src/OpenFOAM/Make/files

@@ -274,6 +274,8 @@ $(dictionary)/dictionaryIO.C
 $(dictionary)/dictionarySearch.C
 $(dictionary)/dictionaryCompat.C
 
+$(dictionary)/dictionaryContent/dictionaryContent.C
+
 entry = $(dictionary)/entry
 $(entry)/entry.C
 $(entry)/entryIO.C

src/OpenFOAM/db/dictionary/dictionaryContent/dictionaryContent.C

@@ -0,0 +1,86 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2021 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "dictionaryContent.H"
+
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+Foam::dictionary
+Foam::dictionaryContent::copyDict
+(
+    const dictionary& input,
+    const wordRes& allow,
+    const wordRes& deny
+)
+{
+    if (allow.empty() && deny.empty())
+    {
+        return dictionary(input);
+    }
+
+    dictionary dict;
+    dict.name() = input.name();  // rename
+
+    for (const entry& e : input)
+    {
+        const keyType& key = e.keyword();
+
+        bool accept = false;
+
+        if (key.isPattern())
+        {
+            // Non-trivial to filter a regex itself - so just accept it
+            // - could also have a "pruneRegex" flag (for example)
+            accept = true;
+        }
+        else if (allow.size())
+        {
+            const auto result = allow.matched(key);
+
+            accept =
+            (
+                result == wordRe::LITERAL
+              ? true
+              : (result == wordRe::REGEX && !deny.match(key))
+            );
+        }
+        else
+        {
+            accept = !deny.match(key);
+        }
+
+        if (accept)
+        {
+            dict.add(e, false);  // No merge - entries are already unique
+        }
+    }
+
+    return dict;
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/db/dictionary/dictionaryContent/dictionaryContent.H

@@ -36,6 +36,7 @@ Description
 #define dictionaryContent_H
 
 #include "dictionary.H"
+#include "wordRes.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -85,6 +86,28 @@ public:
 
     // Member Functions
 
+        //- Copy construct a dictionary,
+        //- filtered by a combination of allow/deny lists
+        //
+        //  An empty 'allow' list accepts everything not in the 'deny' list.
+        //  A literal match has higher priority over a regex match.
+        //
+        //  \verbatim
+        //     input:  ( abc apple wall wall1 wall2 )
+        //     allow:  ( abc def "wall.*" )
+        //     deny:   ( "[ab].*" wall )
+        //
+        //     result: (abc wall1 wall2)
+        //  \endverbatim
+        //
+        //  \return filtered dictionary copy
+        static dictionary copyDict
+        (
+            const dictionary& input,
+            const wordRes& allow = wordRes(),
+            const wordRes& deny = wordRes()
+        );
+
         //- Read-access to the content
         const dictionary& dict() const noexcept
         {