ENH: add low-level polymorphic/boxed exprValue

- primarily for handling expression results,
  but can also be used as a universal value holder.

  Has some characteristics suitable for type-less IO:
  eg, is_integral(), nComponents()

ENH: add is_pointer() check for expression scanToken

applications/test/exprTraits/Test-exprTraits.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2021 OpenCFD Ltd.
+    Copyright (C) 2021-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -17,8 +17,9 @@ Description
 
 #include "IOstreams.H"
 #include "ITstream.H"
-#include "exprTraits.H"
 #include "uLabel.H"
+
+#include "exprTraits.H"
 #include "error.H"
 #include "stringList.H"
 #include "exprScanToken.H"
@@ -27,16 +28,18 @@ using namespace Foam;
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-template<class T>
+template<class Type>
 void printTraits()
 {
-    const auto typeCode = exprTypeTraits<T>::value;
+    const auto typeCode = exprTypeTraits<Type>::value;
 
-    Info<< "type " << pTraits<T>::typeName
-        << " code:" << int(typeCode)
-        << " name:" << exprTypeTraits<T>::name;
+    Info<< "Type '" << pTraits<Type>::typeName
+        << "' = code:" << int(typeCode)
+        << " rank:" << exprTypeTraits<Type>::rank
+        << " cmpt:" << exprTypeTraits<Type>::nComponents
+        << " name:" << exprTypeTraits<Type>::name;
 
-    if (pTraits<T>::typeName != word(exprTypeTraits<T>::name))
+    if (pTraits<Type>::typeName != word(exprTypeTraits<Type>::name))
     {
         Info<< " (UNSUPPORTED)";
     }
@@ -45,6 +48,17 @@ void printTraits()
 }
 
 
+void print(const expressions::scanToken& tok)
+{
+    Info<< "    type:" << int(tok.type_);
+    if (tok.is_pointer())
+    {
+        Info<< " ptr:" << Foam::name(tok.name_);
+    }
+    Info<< nl;
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 int main()
@@ -56,6 +70,7 @@ int main()
     printTraits<bool>();
     printTraits<label>();
     printTraits<scalar>();
+    printTraits<complex>();
     printTraits<vector>();
     printTraits<tensor>();
     printTraits<symmTensor>();
@@ -71,33 +86,27 @@ int main()
     Info<< "Name of typeCode: "
         << getName(expressions::valueTypeCode::type_bool) << nl;
 
-
     {
-        expressions::scanToken tok;
-        expressions::scanToken tok2;
+        expressions::scanToken tok(expressions::scanToken::null());
+        expressions::scanToken tok2(expressions::scanToken::null());
 
         Info<< nl << "sizeof(scanToken): "
             << sizeof(tok) << nl;
 
-        Info<< "    type:" << int(tok.type_) << nl;
-        Info<< "    ptr:" << Foam::name(tok.name_) << nl;
-
-        Info<< "    type:" << int(tok2.type_) << nl;
-        Info<< "    ptr:" << Foam::name(tok2.name_) << nl;
+        print(tok);
+        print(tok2);
 
         tok.setWord("hello");
 
-        Info<< "    type:" << int(tok.type_) << nl;
-        Info<< "    ptr:" << Foam::name(tok.name_) << nl;
+        print(tok);
 
         tok2 = tok;
-        Info<< "    type:" << int(tok2.type_) << nl;
-        Info<< "    ptr:" << Foam::name(tok2.name_) << nl;
+        print(tok2);
 
         tok2.destroy();
 
-        Info<< "    type:" << int(tok2.type_) << nl;
-        Info<< "    ptr:" << Foam::name(tok2.name_) << nl;
+        print(tok);  // Not a leak, but old rubbish
+        print(tok2);
     }
 
     Info<< nl << "Done" << nl;

applications/test/exprValue/Make/files

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

applications/test/exprValue/Make/options

@@ -0,0 +1,2 @@
+/* EXE_INC = */
+/* EXE_LIBS = */

applications/test/exprValue/Test-exprValue.C

@@ -0,0 +1,141 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2021-2023 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
+
+Application
+    Test-exprValue
+
+Description
+    Test low-level polymorphic value container (exprValue)
+
+\*---------------------------------------------------------------------------*/
+
+#include "argList.H"
+#include "IOstreams.H"
+#include "ITstream.H"
+#include "exprValue.H"
+
+using namespace Foam;
+
+void printInfo(const expressions::exprValue& val)
+{
+    Info<< "Boxed type:" << int(val.typeCode())
+        << " (" << val.valueTypeName() << ") good:"
+        << val.good() << " => " << val << nl;
+}
+
+
+expressions::exprValue tryParse(const std::string& str)
+{
+    expressions::exprValue val, val2;
+
+    ITstream is(str);
+
+    const bool ok = val.read(is);
+
+    Info<< "read " << Foam::name(val.typeCode()) << " from " << str;
+
+    if (ok)
+    {
+        Info<< " trailing tokens:" << is.nRemainingTokens() << nl
+            << "value: " << val << nl;
+    }
+    else
+    {
+        Info<< " FAILED" << nl;
+    }
+
+    if (ok)
+    {
+        Info<< "Direct from string: ";
+        if (expressions::exprValue::read(str, val2))
+        {
+            Info<< "good" << nl;
+        }
+        else
+        {
+            Info<< "bad" << nl;
+        }
+    }
+    return val;
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+int main(int argc, char *argv[])
+{
+    argList::noBanner();
+    argList::noParallel();
+
+    #include "setRootCase.H"
+
+    // Aborts
+    // expressions::exprValue value(std::string(""));
+
+    {
+        expressions::exprValue value;
+
+        // Nothing
+        printInfo(value);
+
+        value.set(scalar(100));
+        printInfo(value);
+
+        value.set(vector(1,2,3));
+        printInfo(value);
+
+        value = vector(4,5,6);
+        printInfo(value);
+
+        value = Zero;
+        printInfo(value);
+
+        value.clear();
+        printInfo(value);
+
+        value = 100 * vector(1,0,0);
+        printInfo(value);
+    }
+
+
+    {
+        Info<< nl << "Test parsing" << nl << nl;
+
+        for
+        (
+            const auto& input :
+            stringList
+            ({
+                "()",  // bad
+                "( 1 2  ",  // also bad
+                "(  ",  // really bad
+                "(1 16 12)",
+                "(1 bad)",
+                "(5)",
+                "1.2345",
+                "5.678 trailing",
+                "true",
+                "false",
+                " 1 ",
+                "  yes no "
+            })
+        )
+        {
+            (void) tryParse(input);
+        }
+    }
+
+    return 0;
+}
+
+
+// ************************************************************************* //