ENH: support optional average value when reading rawIOField

ENH: simplify bookkeeping within MappedFile

applications/test/rawIOField/Make/files

@@ -0,0 +1,3 @@
+Test-rawIOField.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-rawIOField

applications/test/rawIOField/Make/options

@@ -0,0 +1,9 @@
+EXE_INC = \
+    -I$(LIB_SRC)/fileFormats/lnInclude \
+    -I$(LIB_SRC)/surfMesh/lnInclude \
+    -I$(LIB_SRC)/meshTools/lnInclude
+
+EXE_LIBS = \
+    -lfileFormats \
+    -lsurfMesh \
+    -lmeshTools

applications/test/rawIOField/Test-rawIOField.C

@@ -0,0 +1,168 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2022 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/>.
+
+Application
+    Test-rawIOField
+
+Description
+    Reading rawIOField from disk
+
+\*---------------------------------------------------------------------------*/
+
+#include "argList.H"
+#include "Time.H"
+#include "Switch.H"
+#include "primitiveFields.H"
+#include "pointField.H"
+#include "rawIOField.H"
+#include "exprTraits.H"
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+using namespace Foam;
+
+#undef  USE_ROOT_CASE
+//#define USE_ROOT_CASE
+
+
+template<class Type>
+tmp<Field<Type>> readRawField
+(
+    const IOobject& io,
+    IOobjectOption::readOption withAverage
+)
+{
+    rawIOField<Type> raw(io, withAverage);
+
+    Info<< "File: " << io.objectPath() << nl
+        << "Read: " << raw.size()
+        << ' ' << pTraits<Type>::typeName << " entries" << nl
+        << "Average: " << Switch::name(raw.hasAverage())
+        << " = " << raw.average() << endl;
+
+    return tmp<Field<Type>>::New(std::move(static_cast<Field<Type>&>(raw)));
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+int main(int argc, char *argv[])
+{
+    argList::addNote
+    (
+        "Test behaviour of rawIOField reading (writing?)"
+    );
+
+    argList::noCheckProcessorDirectories();
+
+    argList::addBoolOption("scalar", "Read scalar field");
+    argList::addBoolOption("vector", "Read vector field");
+    argList::addBoolOption("point", "Read point field");
+    argList::addBoolOption("average", "Require averaged value entry");
+    argList::addBoolOption("try-average", "Optional averaged value entry");
+
+    argList::addArgument("fileName");
+
+    #ifdef USE_ROOT_CASE
+        #include "setRootCase.H"
+        #include "createTime.H"
+    #else
+    // Without root case, or time
+    argList args(argc, argv);
+    #endif
+
+    fileName inputName = args.get<fileName>(1);
+
+    IOobjectOption::readOption withAverage = IOobjectOption::NO_READ;
+
+    if (args.found("average"))
+    {
+        withAverage = IOobjectOption::MUST_READ;
+    }
+    else if (args.found("try-average"))
+    {
+        withAverage = IOobjectOption::READ_IF_PRESENT;
+    }
+
+    Info<< "Using case: " << argList::envGlobalPath() << nl
+        << "Read file:  " << inputName << nl
+        << "with average: " << int(withAverage) << nl
+        << endl;
+
+
+    refPtr<Time> timePtr;
+
+    #ifdef USE_ROOT_CASE
+    timePtr.cref(runTime);
+    #endif
+
+    // Fallback (eg, no runTime)
+    if (!timePtr.good())
+    {
+        timePtr.reset(Time::New(argList::envGlobalPath()));
+    }
+
+
+    const auto& tm = timePtr();
+
+    fileName resolvedName(inputName);
+    resolvedName.toAbsolute();
+
+    IOobject io
+    (
+        resolvedName,   // absolute path
+        tm,
+        IOobject::MUST_READ,
+        IOobject::NO_WRITE,
+        IOobject::NO_REGISTER,
+        true            // is global object (currently not used)
+    );
+
+
+    if (args.found("scalar"))
+    {
+        auto tfield = readRawField<scalar>(io, withAverage);
+    }
+    else if (args.found("point"))
+    {
+        auto tfield = readRawField<point>(io, withAverage);
+    }
+    else if (args.found("vector"))
+    {
+        auto tfield = readRawField<vector>(io, withAverage);
+    }
+    else
+    {
+        Info<< "no data type specified!\n";
+    }
+
+    Info<< nl << "End\n" << endl;
+
+    return 0;
+}
+
+
+// ************************************************************************* //