ENH: improve/simplify streaming of exprValue

- ensure that operator<< and operator>> behave symmetrically

applications/test/exprValue/Make/files

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

applications/test/exprValue1/Make/files

@@ -0,0 +1,3 @@
+Test-exprValue1.cxx
+
+EXE = $(FOAM_USER_APPBIN)/Test-exprValue1

applications/test/exprValue1/Test-exprValue1.cxx

@@ -11,7 +11,7 @@ License
     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
 
 Application
-    Test-exprValue
+    Test-exprValue1
 
 Description
     Test low-level polymorphic value container (exprValue)
@@ -59,11 +59,11 @@ expressions::exprValue tryParse(const std::string& str)
         Info<< "Direct from string: ";
         if (expressions::exprValue::read(str, val2))
         {
-            Info<< "good" << nl;
+            Info<< "OK" << nl;
         }
         else
         {
-            Info<< "bad" << nl;
+            Info<< "NOK" << nl;
         }
     }
     return val;
@@ -128,21 +128,22 @@ int main(int argc, char *argv[])
 
         expressions::exprValue oldValue(value);
 
-        // Since the IO serialization is not symmetric (in ASCII) there
-        // is no 'operator>>' defined and thus the regular Pstream::broadcast
-        // will not compile.
-        // Even although the data are contiguous and that code branch is never
-        // used.
 
-        // Fails to compile: Pstream::broadcast(value);
+        if (true)
-
+        {
-        // Broadcast manually
+            // Broadcast with serialization
-        UPstream::broadcast
+            Pstream::broadcast(value);
-        (
+        }
-            value.data_bytes(),
+        else
-            value.size_bytes(),
+        {
-            UPstream::worldComm
+            // Broadcast manually
-        );
+            UPstream::broadcast
+            (
+                value.data_bytes(),
+                value.size_bytes(),
+                UPstream::worldComm
+            );
+        }
 
         Pout<< "same values: " << (oldValue == value) << nl;
 

applications/test/exprValue2/Make/files

@@ -0,0 +1,5 @@
+exprValueFieldTag.cxx
+
+Test-exprValue2.cxx
+
+EXE = $(FOAM_USER_APPBIN)/Test-exprValue2

applications/test/exprValue2/Make/options

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

applications/test/exprValue2/Test-exprValue2.cxx

@@ -0,0 +1,143 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 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/>.
+
+Description
+    Test exprValue uniformity checks
+
+\*---------------------------------------------------------------------------*/
+
+#include "argList.H"
+#include "IOobject.H"
+#include "IOstreams.H"
+#include "labelList.H"
+#include "scalarField.H"
+#include "vectorField.H"
+#include "DynamicList.H"
+#include "Random.H"
+#include "exprValue.H"
+#include "exprValueFieldTag.H"
+
+using namespace Foam;
+
+Ostream& printInfo(const expressions::exprValueFieldTag& tag)
+{
+    tag.print(Pout);
+    return Pout;
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+//  Main program:
+
+int main(int argc, char *argv[])
+{
+    using fieldTag = expressions::exprValueFieldTag;
+
+    Random rnd(123456);
+
+    argList::noCheckProcessorDirectories();
+
+    #include "setRootCase.H"
+
+    {
+        scalarField fld1(20);
+        scalarField fld2a(20, Zero);
+        scalarField fld2b(10, 3.10);
+        scalarField fld3;
+
+        forAll(fld1, i)
+        {
+            fld1[i] = rnd.position<scalar>(0, 20);
+        }
+
+        fieldTag tag1(fld1.begin(), fld1.end());
+        fieldTag tag2a(fld2a.begin(), fld2a.end());
+        fieldTag tag2b(fld2b.begin(), fld2b.end());
+        fieldTag tag3(fld3.begin(), fld3.end());
+
+        printInfo(tag1) << nl;
+        printInfo(tag2a) << nl;
+        printInfo(tag2b) << nl;
+        printInfo(tag3) << nl;
+
+        fieldTag result;
+
+        result = fieldTag::combineOp{}(tag1, tag2a);
+        printInfo(result) << nl;
+
+        Info<< "combine: ";
+        printInfo(tag2a) << " and ";
+        printInfo(tag2b) << nl;
+
+        result = fieldTag::combineOp{}(tag2a, tag2b);
+        printInfo(result) << nl;
+    }
+
+    {
+        vectorField fld2a(20, Foam::zero{});
+        vectorField fld2b(10, vector::uniform(3.10));
+
+        fieldTag tag2a(fld2a.begin(), fld2a.end());
+        fieldTag tag2b(fld2b.begin(), fld2b.end());
+
+        printInfo(tag2a) << nl;
+        printInfo(tag2b) << nl;
+
+        fieldTag result;
+
+        Info<< "combine: ";
+        printInfo(tag2a) << " and ";
+        printInfo(tag2b) << nl;
+
+        result = fieldTag::combineOp{}(tag2a, tag2b);
+        printInfo(result) << nl;
+    }
+
+    if (UPstream::parRun())
+    {
+        scalarField fld;
+
+        if (!UPstream::master())
+        {
+            fld.resize(UPstream::myProcNo(), UPstream::myProcNo());
+        }
+
+        fieldTag oldTag(fld.begin(), fld.end());
+
+        printInfo(oldTag) << " input: " << fld << " <- before reduce" << nl;
+
+        fieldTag newTag = returnReduce(oldTag, fieldTag::combineOp());
+
+        printInfo(newTag) << " <- after reduce" << nl;
+    }
+
+
+    Info<< "\nEnd\n" << nl;
+
+    return 0;
+}
+
+
+// ************************************************************************* //

applications/test/exprValue2/exprValueFieldTag.H

@@ -0,0 +1,170 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 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/>.
+
+Class
+    Foam::expressions::exprValueFieldTag
+
+Description
+    A polymorphic single-value container for tracking Field content
+    as uniform etc.
+
+SourceFiles
+    exprValueFieldTag.cxx
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_expressions_exprValueFieldTag_H
+#define Foam_expressions_exprValueFieldTag_H
+
+#include "exprValue.H"
+#include "List.H"  // For ListPolicy
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace expressions
+{
+
+/*---------------------------------------------------------------------------*\
+                      Class exprValueFieldTag Declaration
+\*---------------------------------------------------------------------------*/
+
+class exprValueFieldTag
+{
+    // Private data
+
+        //- Uniformity of field
+        int uniformity_{};
+
+        //- Representative (uniform) value for the field
+        expressions::exprValue value_{};
+
+public:
+
+    // Constructors
+
+        //- Default construct
+        exprValueFieldTag() = default;
+
+        //- Construct from a range of values
+        template<class Type>
+        explicit exprValueFieldTag(const Type* first, const Type* last)
+        {
+            set(first, last);
+        }
+
+
+    // Member Functions
+
+        //- True if the uniformity is "empty"
+        bool empty() const noexcept;
+
+        //- True if the uniformity is "uniform"
+        bool is_uniform() const noexcept;
+
+        //- True if the uniformity is "non-uniform"
+        bool is_nonuniform() const noexcept;
+
+        //- Test for equality of the values
+        bool equal(const exprValueFieldTag& rhs) const;
+
+        //- Set value and uniformity from range of data
+        template<class Type>
+        void set(const Type* first, const Type* last)
+        {
+            uniformity_ =
+                Foam::Detail::ListPolicy::check_uniformity(first, last);
+
+            if (first != last)  // or uniformity_ != EMPTY
+            {
+                value_.set<Type>(*first);
+            }
+            else
+            {
+                value_.set<Type>(Foam::zero{});
+            }
+        }
+
+        //- Set uniform type and value
+        template<class Type>
+        void set_uniform(const Type& val)
+        {
+            uniformity_ = Foam::Detail::ListPolicy::uniformity::UNIFORM;
+            value_.set<Type>(val);
+        }
+
+        //- Set as non-uniform
+        void set_nouniform() noexcept;
+
+
+    // Reduction operations
+
+        //- Combine - eg, for global uniformity
+        void combine(const exprValueFieldTag& b);
+
+        //- Binary operator to be used by reduce function for detecting
+        //- global uniformity
+        struct combineOp
+        {
+            exprValueFieldTag operator()
+            (
+                const exprValueFieldTag& a,
+                const exprValueFieldTag& b
+            ) const
+            {
+                exprValueFieldTag result(a);
+                result.combine(b);
+                return result;
+            }
+        };
+
+
+    // IO Operations
+
+        void read(Istream& is);
+        void write(Ostream& os) const;
+
+        //- Print description to Ostream
+        void print(Ostream& os) const;
+};
+
+} // End namespace expressions
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// IO
+Istream& operator>>(Istream&, expressions::exprValueFieldTag&);
+Ostream& operator<<(Ostream&, const expressions::exprValueFieldTag&);
+
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

applications/test/exprValue2/exprValueFieldTag.cxx

@@ -0,0 +1,160 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 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 "exprValueFieldTag.H"
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::expressions::exprValueFieldTag::empty() const noexcept
+{
+    return
+    (
+        uniformity_ == Foam::Detail::ListPolicy::uniformity::EMPTY
+    );
+}
+
+
+bool Foam::expressions::exprValueFieldTag::is_uniform() const noexcept
+{
+    return
+    (
+        uniformity_ == Foam::Detail::ListPolicy::uniformity::UNIFORM
+    );
+}
+
+
+bool Foam::expressions::exprValueFieldTag::is_nonuniform() const noexcept
+{
+    return
+    (
+        uniformity_ == Foam::Detail::ListPolicy::uniformity::NONUNIFORM
+    );
+}
+
+
+bool Foam::expressions::exprValueFieldTag::equal
+(
+    const exprValueFieldTag& rhs
+) const
+{
+    return (value_ == rhs.value_);
+}
+
+
+void Foam::expressions::exprValueFieldTag::set_nouniform() noexcept
+{
+    uniformity_ = Foam::Detail::ListPolicy::uniformity::NONUNIFORM;
+    value_ = Foam::zero{};
+}
+
+
+void Foam::expressions::exprValueFieldTag::combine
+(
+    const exprValueFieldTag& b
+)
+{
+    if (b.empty())
+    {
+        // no-op
+        return;
+    }
+
+    exprValueFieldTag& a = *this;
+
+    if (a.empty())
+    {
+        a = b;
+    }
+    else if (a.is_nonuniform())
+    {
+        // Already non-uniform/mixed
+        // a.uniformity_ |= b.uniformity_;
+
+        a.value_ = Foam::zero{};
+    }
+    else if (a.is_uniform() && b.is_uniform())
+    {
+        // Both are uniform, but are they the same value?
+        if (!a.equal(b))
+        {
+            a.set_nouniform();
+        }
+    }
+}
+
+
+// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
+
+void Foam::expressions::exprValueFieldTag::read(Istream& is)
+{
+    label uniformTag;
+
+    is >> uniformTag;
+    uniformity_ = int(uniformTag);
+    value_.read(is);
+}
+
+
+void Foam::expressions::exprValueFieldTag::write(Ostream& os) const
+{
+    os << label(uniformity_);
+    value_.write(os, false);  // No pruning
+}
+
+
+void Foam::expressions::exprValueFieldTag::print(Ostream& os) const
+{
+    os  << "{ uniform:"
+        << label(uniformity_)
+        << " type:" << label(value_.typeCode())
+        << " value: " << value_ << " }";
+}
+
+
+Foam::Istream& Foam::operator>>
+(
+    Istream& is,
+    expressions::exprValueFieldTag& tag
+)
+{
+    tag.read(is);
+    return is;
+}
+
+
+Foam::Ostream& Foam::operator<<
+(
+    Ostream& os,
+    const expressions::exprValueFieldTag& tag
+)
+{
+    tag.write(os);
+    return os;
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/expressions/traits/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.
@@ -61,7 +61,37 @@ Foam::expressions::Detail::nComponents
                                                                       \
         case expressions::valueTypeCode::type_##Type :                \
         {                                                             \
-            return pTraits<Type>::nComponents;                        \
+            return exprTypeTraits<Type>::nComponents;                 \
+        }
+
+        FOR_ALL_EXPR_TYPE_CODES(doLocalCode);
+        #undef doLocalCode
+    }
+
+    return 0;
+}
+
+
+Foam::direction
+Foam::expressions::Detail::rank
+(
+    const expressions::valueTypeCode typeCode
+) noexcept
+{
+    switch (typeCode)
+    {
+        case expressions::valueTypeCode::NONE :
+        case expressions::valueTypeCode::INVALID :
+        {
+            break;
+        }
+
+        #undef  doLocalCode
+        #define doLocalCode(Type, UnusedParam)                        \
+                                                                      \
+        case expressions::valueTypeCode::type_##Type :                \
+        {                                                             \
+            return exprTypeTraits<Type>::rank;                        \
         }
 
         FOR_ALL_EXPR_TYPE_CODES(doLocalCode);
@@ -112,7 +142,7 @@ Foam::word Foam::name(const expressions::valueTypeCode typeCode)
 
         case expressions::valueTypeCode::INVALID :
         {
-            // returns ""
+            // returns "", could also return "bad"
             break;
         }
 

src/OpenFOAM/expressions/traits/exprTraits.H

@@ -117,6 +117,9 @@ namespace Detail
 //- The number of components associated with given valueTypeCode
 ::Foam::direction nComponents(const expressions::valueTypeCode) noexcept;
 
+//- The vector-space rank associated with given valueTypeCode
+::Foam::direction rank(const expressions::valueTypeCode) noexcept;
+
 } // End namespace Detail
 
 

src/OpenFOAM/expressions/value/exprValue.C

@@ -129,6 +129,10 @@ Foam::expressions::exprValue::peekType(const ITstream& is)
 
                 switch (endCmpti - firstCmpti)
                 {
+                    case 0:  // Explicitly provided '()' - ie, none
+                        whichCode = expressions::valueTypeCode::NONE;
+                        break;
+
                     case 1:  // pTraits<sphericalTensor>::nComponents
                         whichCode = exprTypeTraits<sphericalTensor>::value;
                         break;
@@ -177,6 +181,13 @@ Foam::expressions::exprValue::peekType(const ITstream& is)
         {
             whichCode = exprTypeTraits<bool>::value;
         }
+
+        // Treat anything else as 'invalid', which also implicitly
+        // includes the token "bad"
+        // else if (tok0.isWord("bad"))
+        // {
+        //     whichCode = expressions::valueTypeCode::INVALID;
+        // }
     }
 
     return whichCode;
@@ -192,7 +203,7 @@ bool Foam::expressions::exprValue::read
     ITstream is(str);
 
     // No trailing non-whitespace!
-    return (val.read(is) && !is.nRemainingTokens());
+    return (val.readTokens(is) && !is.nRemainingTokens());
 }
 
 
@@ -215,10 +226,33 @@ void Foam::expressions::exprValue::deepCopy(const exprValue& rhs)
 }
 
 
-Foam::tokenList Foam::expressions::exprValue::tokens() const
+Foam::tokenList Foam::expressions::exprValue::tokens(bool prune) const
 {
+    // Handling for NONE, INVALID:
+    //   - NONE    => pair of ( ) brackets
+    //   - INVALID => "bad" as a word
+    //
+    // With prune:
+    //   - no output for either
+
     tokenList toks;
 
+    if (!prune)
+    {
+        if (typeCode_ == expressions::valueTypeCode::NONE)
+        {
+            toks.resize(2);
+            toks.front() = token::BEGIN_LIST;
+            toks.back() = token::END_LIST;
+            return toks;
+        }
+        else if (typeCode_ == expressions::valueTypeCode::INVALID)
+        {
+            toks.emplace_back(word("bad"));
+            return toks;
+        }
+    }
+
     switch (typeCode_)
     {
         #undef  doLocalCode
@@ -245,8 +279,29 @@ Foam::tokenList Foam::expressions::exprValue::tokens() const
 }
 
 
-void Foam::expressions::exprValue::print(Ostream& os) const
+void Foam::expressions::exprValue::write(Ostream& os, bool prune) const
 {
+    // Handling for NONE, INVALID:
+    //   - NONE    => pair of ( ) brackets
+    //   - INVALID => "bad" as a word
+    //
+    // With prune:
+    //   - no output for either
+
+    if (!prune)
+    {
+        if (typeCode_ == expressions::valueTypeCode::NONE)
+        {
+            os << token::BEGIN_LIST << token::END_LIST;
+            return;
+        }
+        else if (typeCode_ == expressions::valueTypeCode::INVALID)
+        {
+            os << word("bad");
+            return;
+        }
+    }
+
     switch (typeCode_)
     {
         #undef  doLocalCode
@@ -271,12 +326,87 @@ void Foam::expressions::exprValue::print(Ostream& os) const
 }
 
 
-bool Foam::expressions::exprValue::read(ITstream& is)
+bool Foam::expressions::exprValue::read(Istream& is)
+{
+    ITstream* stream = dynamic_cast<ITstream*>(&is);
+
+    // Reading via tokens - simple for now
+    // Expect either a single token (scalar, label, word etc)
+    // or ( ... ) content
+
+    ITstream toks;
+
+    if (!stream)
+    {
+        token tok(is);
+
+        is.fatalCheck(FUNCTION_NAME);
+
+        if (tok.isPunctuation(token::BEGIN_LIST))
+        {
+            // Expecting "( content )" - eg, (x y z), (xx xy ...)
+            do
+            {
+                toks.add_tokens(tok);
+
+                is >> tok;
+                is.fatalCheck(FUNCTION_NAME);
+            }
+            while (!tok.isPunctuation(token::END_LIST));
+
+            if (tok.isPunctuation(token::END_LIST))
+            {
+                toks.add_tokens(tok);
+            }
+        }
+        else if (tok.good())
+        {
+            toks.add_tokens(tok);
+        }
+
+        // Truncate to number tokens read
+        toks.resize(toks.tokenIndex());
+        toks.seek(0);
+
+        stream = &toks;
+    }
+
+    return readTokens(*stream);
+}
+
+
+bool Foam::expressions::exprValue::readTokens(ITstream& is)
 {
     clear();  // type: none, value: zero
 
     const valueTypeCode whichCode(exprValue::peekType(is));
 
+    if (whichCode == expressions::valueTypeCode::NONE)
+    {
+        typeCode_ = whichCode;
+        is.skip(2);  // Skip tokens: '( )'
+        return true;
+    }
+
+    // This one should be rare or even impossible
+    if (whichCode == expressions::valueTypeCode::INVALID)
+    {
+        typeCode_ = whichCode;
+
+        if (is.bad())
+        {
+            return false;
+        }
+
+        const token& tok0 = is.peek();
+
+        if (tok0.isWord("bad"))
+        {
+            is.skip(1);  // Skip token: "bad"
+            return true;
+        }
+    }
+
     switch (whichCode)
     {
         #undef  doLocalCode
@@ -347,13 +477,24 @@ bool Foam::expressions::exprValue::operator<(const exprValue& rhs) const
 
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
+Foam::Istream& Foam::operator>>
+(
+    Istream& is,
+    expressions::exprValue& val
+)
+{
+    val.read(is);
+    return is;
+}
+
+
 Foam::Ostream& Foam::operator<<
 (
     Ostream& os,
     const expressions::exprValue& val
 )
 {
-    val.print(os);
+    val.write(os, false);  // no pruning
     return os;
 }
 
@@ -367,16 +508,18 @@ Foam::Ostream& Foam::operator<<
 {
     const auto& val = *iproxy;
 
-    if (val.good())
+    if (val.typeCode() == expressions::valueTypeCode::NONE)
     {
-        os  << val.valueTypeName() << ": ";
+        os << "none";
-        val.print(os);
+    }
+    else if (val.typeCode() == expressions::valueTypeCode::INVALID)
+    {
+        os << "bad";
     }
     else
     {
-        // typeCode_ is *never* set to INVALID,
+        os << val.valueTypeName() << ": ";
-        // so NONE is the only remaining non-good type
+        val.write(os);  // pruning is immaterial - !good() already handled
-        os  << "none";
     }
 
     return os;

src/OpenFOAM/expressions/value/exprValue.H

@@ -169,7 +169,7 @@ class exprValue
 
     // Private Member Functions
 
-        //- Assign zero, preserving the data type
+        //- Fill the data with zero, preserving the data type
         inline void fill_zero();
 
         //- Copy assignment
@@ -215,6 +215,12 @@ public:
             const expressions::valueTypeCode
         ) noexcept;
 
+        //- The vector-space rank associated with the valueTypeCode
+        inline static direction rank
+        (
+            const expressions::valueTypeCode
+        ) noexcept;
+
         //- True if the specified type is supported
         template<class Type>
         inline static bool supportedType();
@@ -250,6 +256,9 @@ public:
         //- The number of components associated with the value type
         inline direction nComponents() const noexcept;
 
+        //- The vector-space rank associated with the value type
+        inline direction rank() const noexcept;
+
         //- The name for the value type. Similar to pTraits typeName
         inline word valueTypeName() const;
 
@@ -260,9 +269,13 @@ public:
         //- Reset to 'none'
         void clear();
 
+        //- Read read tokens (if possible)
+        //  \return True on success
+        bool read(Istream& is);
+
         //- Guess type and read tokens (if possible)
         //  \return True on success
-        bool read(ITstream& is);
+        bool readTokens(ITstream& is);
 
 
     // Typed Access
@@ -346,11 +359,19 @@ public:
         //- Return info proxy for printing information to a stream
         InfoProxy<exprValue> info() const { return *this; }
 
-        //- The value as tokens. An empty list is returned for NONE.
+        //- The exprValue as tokens.
-        tokenList tokens() const;
+        //  For none : emits pair of brackets.
+        //  For invalid : emits "bad".
+        //
+        //  \param prune suppress the output for none/invalid
+        tokenList tokens(bool prune = false) const;
 
-        //- Print the (type-specific) content
+        //- Write the (type-specific) content.
-        void print(Ostream& os) const;
+        //  For none : emits pair of brackets.
+        //  For invalid : emits "bad".
+        //
+        //  \param prune suppress the output for none/invalid
+        void write(Ostream& os, bool prune = false) const;
 };
 
 
@@ -364,7 +385,11 @@ template<> struct is_contiguous<expressions::exprValue> : std::true_type {};
 
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
-//- Write value to output stream in ASCII format. No output for !good().
+//- Read/parse value from input stream (uses ASCII format).
+Istream& operator>>(Istream& is, expressions::exprValue& val);
+
+//- Write value to output stream (uses ASCII format).
+//- Writes 'none' or 'bad' for unknown/unsupported types.
 Ostream& operator<<(Ostream& os, const expressions::exprValue& val);
 
 template<>

src/OpenFOAM/expressions/value/exprValueI.H

@@ -64,6 +64,15 @@ inline Foam::direction Foam::expressions::exprValue::nComponents
 }
 
 
+inline Foam::direction Foam::expressions::exprValue::rank
+(
+    const expressions::valueTypeCode valTypeCode
+) noexcept
+{
+    return expressions::Detail::rank(valTypeCode);
+}
+
+
 template<class Type>
 inline bool Foam::expressions::exprValue::supportedType()
 {
@@ -110,7 +119,7 @@ inline Foam::expressions::exprValue::exprValue(const Type& val)
     {
         FatalErrorInFunction
             << "Cannot construct for unsupported type: "
-            << typeid(Type).name() << endl
+            << typeid(Type).name() << nl
             << abort(FatalError);
     }
 }
@@ -137,6 +146,13 @@ Foam::expressions::exprValue::nComponents() const noexcept
 }
 
 
+inline Foam::direction
+Foam::expressions::exprValue::rank() const noexcept
+{
+    return expressions::Detail::rank(typeCode_);
+}
+
+
 inline Foam::word
 Foam::expressions::exprValue::valueTypeName() const
 {