From 21720bea1249a9d2b75b8f65ef4e73ff13c831c8 Mon Sep 17 00:00:00 2001
From: Mark Olesen <Mark.Olesen@esi-group.com>
Date: Mon, 29 Mar 2021 14:03:10 +0200
Subject: [PATCH] ENH: support field width for `#eval` expressions

For example,
```
entry #eval 10 { vector(rand(), 0, 0) };
```

ENH: be more generous and ignore trailing ';' in expressions

STYLE: adjust parse token name for tensor::I
---
 applications/test/dictionary/testDictEval3    |  4 +
 applications/tools/foamCalc/foamCalc.C        |  6 +-
 .../functionEntries/evalEntry/evalEntry.C     | 76 ++++++++++++-------
 .../functionEntries/evalEntry/evalEntry.H     | 16 ++--
 .../expressions/fields/fieldExprLemonParser.h |  2 +-
 .../fields/fieldExprLemonParser.lyy-m4        |  4 +-
 .../expressions/fields/fieldExprScanner.cc    |  4 +-
 .../expressions/fields/fieldExprScanner.rl    |  4 +-
 .../strings/stringOps/stringOpsEvaluate.C     | 34 +++++++--
 .../strings/stringOps/stringOpsEvaluate.H     | 12 ++-
 .../expressions/patch/patchExprLemonParser.h  |  2 +-
 .../patch/patchExprLemonParser.lyy-m4         |  4 +-
 .../expressions/patch/patchExprScanner.cc     |  4 +-
 .../expressions/patch/patchExprScanner.rl     |  4 +-
 .../volume/volumeExprLemonParser.h            |  2 +-
 .../volume/volumeExprLemonParser.lyy-m4       |  4 +-
 .../expressions/volume/volumeExprScanner.cc   |  4 +-
 .../expressions/volume/volumeExprScanner.rl   |  4 +-
 18 files changed, 128 insertions(+), 62 deletions(-)

diff --git a/applications/test/dictionary/testDictEval3 b/applications/test/dictionary/testDictEval3
index 560b59d34e..79bebc9c20 100644
--- a/applications/test/dictionary/testDictEval3
+++ b/applications/test/dictionary/testDictEval3
@@ -68,4 +68,8 @@ apiMonth   #eval{ ($FOAM_API % 100) };
 empty  #eval "";
 
 
+// Field of specified length
+random  #eval 4  { vector(rand(), 0, 0) ; /* trailing rubbish */ ; };
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/applications/tools/foamCalc/foamCalc.C b/applications/tools/foamCalc/foamCalc.C
index d96df259de..3ac3c86059 100644
--- a/applications/tools/foamCalc/foamCalc.C
+++ b/applications/tools/foamCalc/foamCalc.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -97,6 +97,7 @@ int main(int argc, char *argv[])
     argList::addBoolOption("rules", "Print parser rules and exit");
     argList::addBoolOption("tokens", "Print token names and exit");
     argList::addOption("precision", "int", "Output with specified precision");
+    argList::addOption("size", "int", "Field output width (default: 1)");
 
     // Flag arguments as optional so that -rules and -tokens works
     argList::noMandatoryArgs();
@@ -110,6 +111,7 @@ int main(int argc, char *argv[])
 
     const bool printRules = args.found("rules");
     const bool printNames = args.found("tokens");
+    const label fieldWidth = args.getOrDefault<label>("size", 1);
 
     if (printNames || printRules)
     {
@@ -155,7 +157,7 @@ int main(int argc, char *argv[])
         return 1;
     }
 
-    Info<< stringOps::evaluate(expr).c_str() << nl;
+    Info<< stringOps::evaluate(fieldWidth, expr).c_str() << nl;
 
     return 0;
 }
diff --git a/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.C b/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.C
index b1a40df9a6..6673631339 100644
--- a/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.C
+++ b/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,6 +31,7 @@ License
 #include "stringOps.H"
 #include "fieldExprDriver.H"
 #include "addToMemberFunctionSelectionTable.H"
+#include <cctype>
 
 #undef  DetailInfo
 #define DetailInfo  if (::Foam::infoDetailLevel > 0) InfoErr
@@ -69,34 +70,35 @@ Foam::tokenList Foam::functionEntries::evalEntry::evaluate
         << is.lineNumber() << " in file " <<  parentDict.name() << nl;
     #endif
 
-    // String to evaluate
-    string s;
-
     token tok(is);
-
-    if (!tok.good())
+    label fieldWidth(1);  // Field width for the result
+    if (tok.isLabel())
     {
-        FatalIOErrorInFunction(is)
-            << "Bad token - could not get string to evaluate"
-            << exit(FatalIOError);
-
-        return tokenList();
+        // - #eval INT "expr"
+        // - #eval INT { expr }
+        // - #eval INT #{ expr #}
+        fieldWidth = max(1, tok.labelToken());
+        is >> tok;
     }
 
+    string s;  // String to evaluate
     if (tok.isString())
     {
+        // - #eval "expr"
+        // - #eval #{ expr #}
         s = tok.stringToken();
     }
-    else if (tok == token::BEGIN_BLOCK)
+    else if (tok.isPunctuation(token::BEGIN_BLOCK))
     {
+        // - #eval { expr }
         dynamic_cast<ISstream&>(is).getLine(s, token::END_BLOCK);
     }
     else
     {
-        is.putBack(tok);
-
         FatalIOErrorInFunction(is)
-            << "Invalid input for #eval" << nl
+            << "Invalid input for #eval."
+               " Expecting a string or block to evaluate, but found" << nl
+            << tok.info() << endl
             << exit(FatalIOError);
     }
 
@@ -111,15 +113,31 @@ Foam::tokenList Foam::functionEntries::evalEntry::evaluate
     expressions::exprString::inplaceExpand(s, parentDict, true);
     stringOps::inplaceTrim(s);
 
-    // An extraneous trailing ';' is a common input error, catch it now.
-    // May need to relax in the future, trim or something else
+    // An extraneous trailing ';' is a common input error.
+    // - trim if it does not influence the result
 
-    if (std::string::npos != s.find(';'))
+    const auto trailing = s.find(';');
+    if (std::string::npos != trailing)
     {
-        FatalIOErrorInFunction(is)
-            << "Invalid input for #eval" << nl
-            << s << endl
-            << exit(FatalIOError);
+        bool ignore = true;
+        for (size_t other = trailing; ignore && other < s.length(); ++other)
+        {
+            ignore = s[other] == ';' || std::isspace(s[other]);
+        }
+
+        if (ignore)
+        {
+            // Can trim trailing without semantical change
+            s.erase(trailing);
+            stringOps::inplaceTrim(s);
+        }
+        else
+        {
+            FatalIOErrorInFunction(is)
+                << "Invalid input (after trailing ';') for #eval" << nl
+                << s << endl
+                << exit(FatalIOError);
+        }
     }
 
     #ifdef FULLDEBUG
@@ -138,7 +156,7 @@ Foam::tokenList Foam::functionEntries::evalEntry::evaluate
 
     expressions::exprResult result;
     {
-        expressions::fieldExprDriver driver(1);
+        expressions::fieldExprDriver driver(fieldWidth);
         driver.parse(s);
         result = std::move(driver.result());
     }
@@ -152,11 +170,15 @@ Foam::tokenList Foam::functionEntries::evalEntry::evaluate
         return tokenList();
     }
 
-    // Could average/reduce to a single value, but probably not needed
-    //// result.testIfSingleValue(false);  // No parallel check
-
     OTstream toks;
-    result.writeValue(toks);
+    if (result.size() <= 1)
+    {
+        result.writeValue(toks);
+    }
+    else
+    {
+        result.writeField(toks);
+    }
 
     return std::move(toks);
 }
diff --git a/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.H b/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.H
index c400bda9a1..c4e482b624 100644
--- a/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.H
+++ b/src/OpenFOAM/db/dictionary/functionEntries/evalEntry/evalEntry.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,11 +31,12 @@ Description
     with scalars, vectors etc.
 
     The input can any form of string or, for convenience,
-    a '{}' delimited string literal.  In all cases, C/C++ comment stripping
-    is also performed.
-
-    For example,
+    a '{}' delimited string literal.
+    In all cases, C/C++ comment stripping is performed.
+    The default size of the evaluated field is one,
+    which can be overridden by providing an initial integer value.
 
+    Some examples,
     \verbatim
     a 1;
     b 3;
@@ -45,12 +46,15 @@ Description
         // ignore: sin(pi()*$a/$b)
         sin(degToRad(45))
     };
+
+    // With different field length:
+    points #eval 4 #{ vector(rand(), 0, 0) #};
     \endverbatim
 
 Note
     The string expansions support use of environment variables.
     Unknown variables will expand to an empty string, so it can be advisable
-    to an expansion with an alternative. For example,
+    to expand with an alternative. For example,
 
     \verbatim
     d #eval{ sin(degToRad( ${angle:-0} )) };
diff --git a/src/OpenFOAM/expressions/fields/fieldExprLemonParser.h b/src/OpenFOAM/expressions/fields/fieldExprLemonParser.h
index 57702c282f..e27e88ba5a 100644
--- a/src/OpenFOAM/expressions/fields/fieldExprLemonParser.h
+++ b/src/OpenFOAM/expressions/fields/fieldExprLemonParser.h
@@ -62,7 +62,7 @@
 #define TOK_VECTOR_ID                       62
 #define TOK_SPH_TENSOR_ID                   63
 #define TOK_SYM_TENSOR_ID                   64
-#define TOK_UNIT_TENSOR                     65
+#define TOK_IDENTITY_TENSOR                 65
 #define TOK_TENSOR_ID                       66
 #define TOK_LTRUE                           67
 #define TOK_LFALSE                          68
diff --git a/src/OpenFOAM/expressions/fields/fieldExprLemonParser.lyy-m4 b/src/OpenFOAM/expressions/fields/fieldExprLemonParser.lyy-m4
index 13b8f76470..2c5784cc04 100644
--- a/src/OpenFOAM/expressions/fields/fieldExprLemonParser.lyy-m4
+++ b/src/OpenFOAM/expressions/fields/fieldExprLemonParser.lyy-m4
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -283,7 +283,7 @@ dnl
 \*---------------------------------------------------------------------------*/
 
 evaluate ::= _target_ (a) . { driver->setResult(a); }
-tfield (lhs) ::= UNIT_TENSOR .  { lhs = _new_tfield(Foam::tensor::I); }
+tfield (lhs) ::= IDENTITY_TENSOR . { lhs = _new_tfield(Foam::tensor::I); }
 
 rule_get_field(_target_, TENSOR_ID)
 
diff --git a/src/OpenFOAM/expressions/fields/fieldExprScanner.cc b/src/OpenFOAM/expressions/fields/fieldExprScanner.cc
index 7a0587338e..caf34d2e11 100644
--- a/src/OpenFOAM/expressions/fields/fieldExprScanner.cc
+++ b/src/OpenFOAM/expressions/fields/fieldExprScanner.cc
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -471,7 +471,7 @@ tr9:
 	goto st11;
 tr11:
 #line 292 "fieldExprScanner.rl"
-	{te = p+1;{ EMIT_TOKEN(UNIT_TENSOR); }}
+	{te = p+1;{ EMIT_TOKEN(IDENTITY_TENSOR); }}
 	goto st11;
 tr12:
 #line 235 "fieldExprScanner.rl"
diff --git a/src/OpenFOAM/expressions/fields/fieldExprScanner.rl b/src/OpenFOAM/expressions/fields/fieldExprScanner.rl
index b4425210df..2a0b5bbee1 100644
--- a/src/OpenFOAM/expressions/fields/fieldExprScanner.rl
+++ b/src/OpenFOAM/expressions/fields/fieldExprScanner.rl
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -289,7 +289,7 @@ static int driverTokenType
     "Zero"      =>{ EMIT_TOKEN(ZERO); };
     "true"      =>{ EMIT_TOKEN(LTRUE); };
     "false"     =>{ EMIT_TOKEN(LFALSE); };
-    "tensor::I" =>{ EMIT_TOKEN(UNIT_TENSOR); };
+    "tensor::I" =>{ EMIT_TOKEN(IDENTITY_TENSOR); };
     "arg"       =>{ EMIT_TOKEN(ARG); };
 ##    "time"      =>{ EMIT_TOKEN(TIME); };
 
diff --git a/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.C b/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.C
index 3520c62e3c..9c62fdba2f 100644
--- a/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.C
+++ b/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -35,11 +35,17 @@ License
 
 Foam::string Foam::stringOps::evaluate
 (
+    label fieldWidth,
     const std::string& str,
     size_t pos,
     size_t len
 )
 {
+    if (fieldWidth < 1)
+    {
+        fieldWidth = 1;
+    }
+
     /// InfoErr<< "Evaluate " << str.substr(pos, len) << nl;
 
     const auto trimPoints = stringOps::findTrim(str, pos, len);
@@ -49,14 +55,14 @@ Foam::string Foam::stringOps::evaluate
 
     if (!len)
     {
-        return "";
+        return string();
     }
 
     /// InfoErr<< "Evaluate " << str.substr(pos, len) << nl;
 
     expressions::exprResult result;
     {
-        expressions::fieldExprDriver driver(1);
+        expressions::fieldExprDriver driver(fieldWidth);
         driver.parse(str, pos, len);
         result = std::move(driver.result());
     }
@@ -67,14 +73,32 @@ Foam::string Foam::stringOps::evaluate
             << "Failed evaluation: "
             << str.substr(pos, len) << nl;
 
-        return "";
+        return string();
     }
 
     OStringStream os;
-    result.writeValue(os);
+    if (result.size() <= 1)
+    {
+        result.writeValue(os);
+    }
+    else
+    {
+        result.writeField(os);
+    }
 
     return os.str();
 }
 
 
+Foam::string Foam::stringOps::evaluate
+(
+    const std::string& str,
+    size_t pos,
+    size_t len
+)
+{
+    return stringOps::evaluate(1, str, pos, len);
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.H b/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.H
index 90a8f497f2..2f87bae83a 100644
--- a/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.H
+++ b/src/OpenFOAM/primitives/strings/stringOps/stringOpsEvaluate.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -34,6 +34,7 @@ Description
 #ifndef stringOpsEvaluate_H
 #define stringOpsEvaluate_H
 
+#include "labelFwd.H"
 #include "string.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -42,6 +43,15 @@ namespace Foam
 {
 namespace stringOps
 {
+    //- String evaluation with specified (positive, non-zero) field width
+    string evaluate
+    (
+        label fieldWidth,
+        const std::string& s,
+        size_t pos = 0,
+        size_t len = std::string::npos
+    );
+
     //- A simple string evaluation that handles various basic
     //- expressions. For trivial input, use readScalar instead (faster).
     //
diff --git a/src/finiteVolume/expressions/patch/patchExprLemonParser.h b/src/finiteVolume/expressions/patch/patchExprLemonParser.h
index f10e76fcb8..d67aea0065 100644
--- a/src/finiteVolume/expressions/patch/patchExprLemonParser.h
+++ b/src/finiteVolume/expressions/patch/patchExprLemonParser.h
@@ -67,7 +67,7 @@
 #define TOK_SSPH_TENSOR_ID                  67
 #define TOK_SYM_TENSOR_ID                   68
 #define TOK_SSYM_TENSOR_ID                  69
-#define TOK_UNIT_TENSOR                     70
+#define TOK_IDENTITY_TENSOR                 70
 #define TOK_TENSOR_ID                       71
 #define TOK_STENSOR_ID                      72
 #define TOK_LTRUE                           73
diff --git a/src/finiteVolume/expressions/patch/patchExprLemonParser.lyy-m4 b/src/finiteVolume/expressions/patch/patchExprLemonParser.lyy-m4
index 8c5c613cc5..d2e7684e9b 100644
--- a/src/finiteVolume/expressions/patch/patchExprLemonParser.lyy-m4
+++ b/src/finiteVolume/expressions/patch/patchExprLemonParser.lyy-m4
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -242,7 +242,7 @@ dnl
 \*---------------------------------------------------------------------------*/
 
 evaluate ::= _target_ (a) . { driver->setResult(a); }
-tfield (lhs) ::= UNIT_TENSOR .  { lhs = _new_tfield(Foam::tensor::I); }
+tfield (lhs) ::= IDENTITY_TENSOR . { lhs = _new_tfield(Foam::tensor::I); }
 
 rule_get_field(_target_, TENSOR_ID)
 rule_get_field(_target_, STENSOR_ID)
diff --git a/src/finiteVolume/expressions/patch/patchExprScanner.cc b/src/finiteVolume/expressions/patch/patchExprScanner.cc
index a66fc3ede3..41a5ccb4f8 100644
--- a/src/finiteVolume/expressions/patch/patchExprScanner.cc
+++ b/src/finiteVolume/expressions/patch/patchExprScanner.cc
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -595,7 +595,7 @@ tr9:
 	goto st11;
 tr11:
 #line 418 "patchExprScanner.rl"
-	{te = p+1;{ EMIT_TOKEN(UNIT_TENSOR); }}
+	{te = p+1;{ EMIT_TOKEN(IDENTITY_TENSOR); }}
 	goto st11;
 tr12:
 #line 359 "patchExprScanner.rl"
diff --git a/src/finiteVolume/expressions/patch/patchExprScanner.rl b/src/finiteVolume/expressions/patch/patchExprScanner.rl
index 4748732d05..209fd02d4b 100644
--- a/src/finiteVolume/expressions/patch/patchExprScanner.rl
+++ b/src/finiteVolume/expressions/patch/patchExprScanner.rl
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -415,7 +415,7 @@ static int driverTokenType
     "Zero"      =>{ EMIT_TOKEN(ZERO); };
     "true"      =>{ EMIT_TOKEN(LTRUE); };
     "false"     =>{ EMIT_TOKEN(LFALSE); };
-    "tensor::I" =>{ EMIT_TOKEN(UNIT_TENSOR); };
+    "tensor::I" =>{ EMIT_TOKEN(IDENTITY_TENSOR); };
     "arg"       =>{ EMIT_TOKEN(ARG); };
     "time"      =>{ EMIT_TOKEN(TIME); };
 
diff --git a/src/finiteVolume/expressions/volume/volumeExprLemonParser.h b/src/finiteVolume/expressions/volume/volumeExprLemonParser.h
index 2e2ec7653f..f658b6fe3c 100644
--- a/src/finiteVolume/expressions/volume/volumeExprLemonParser.h
+++ b/src/finiteVolume/expressions/volume/volumeExprLemonParser.h
@@ -63,7 +63,7 @@
 #define TOK_VECTOR_ID                       63
 #define TOK_SPH_TENSOR_ID                   64
 #define TOK_SYM_TENSOR_ID                   65
-#define TOK_UNIT_TENSOR                     66
+#define TOK_IDENTITY_TENSOR                 66
 #define TOK_TENSOR_ID                       67
 #define TOK_LTRUE                           68
 #define TOK_LFALSE                          69
diff --git a/src/finiteVolume/expressions/volume/volumeExprLemonParser.lyy-m4 b/src/finiteVolume/expressions/volume/volumeExprLemonParser.lyy-m4
index 67c71a82d4..23cda84009 100644
--- a/src/finiteVolume/expressions/volume/volumeExprLemonParser.lyy-m4
+++ b/src/finiteVolume/expressions/volume/volumeExprLemonParser.lyy-m4
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -274,7 +274,7 @@ dnl
 \*---------------------------------------------------------------------------*/
 
 evaluate ::= _target_ (a) . { driver->setResult(a); }
-tfield (lhs) ::= UNIT_TENSOR .  { lhs = _new_tfield(Foam::tensor::I); }
+tfield (lhs) ::= IDENTITY_TENSOR . { lhs = _new_tfield(Foam::tensor::I); }
 
 rule_get_field(_target_, TENSOR_ID)
 
diff --git a/src/finiteVolume/expressions/volume/volumeExprScanner.cc b/src/finiteVolume/expressions/volume/volumeExprScanner.cc
index 5d0c84e293..14922aa88d 100644
--- a/src/finiteVolume/expressions/volume/volumeExprScanner.cc
+++ b/src/finiteVolume/expressions/volume/volumeExprScanner.cc
@@ -7,7 +7,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -624,7 +624,7 @@ tr9:
 	goto st11;
 tr11:
 #line 447 "volumeExprScanner.rl"
-	{te = p+1;{ EMIT_TOKEN(UNIT_TENSOR); }}
+	{te = p+1;{ EMIT_TOKEN(IDENTITY_TENSOR); }}
 	goto st11;
 tr12:
 #line 388 "volumeExprScanner.rl"
diff --git a/src/finiteVolume/expressions/volume/volumeExprScanner.rl b/src/finiteVolume/expressions/volume/volumeExprScanner.rl
index ea957317fb..8c552a9331 100644
--- a/src/finiteVolume/expressions/volume/volumeExprScanner.rl
+++ b/src/finiteVolume/expressions/volume/volumeExprScanner.rl
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -444,7 +444,7 @@ static int driverTokenType
     "Zero"      =>{ EMIT_TOKEN(ZERO); };
     "true"      =>{ EMIT_TOKEN(LTRUE); };
     "false"     =>{ EMIT_TOKEN(LFALSE); };
-    "tensor::I" =>{ EMIT_TOKEN(UNIT_TENSOR); };
+    "tensor::I" =>{ EMIT_TOKEN(IDENTITY_TENSOR); };
     "arg"       =>{ EMIT_TOKEN(ARG); };
     "time"      =>{ EMIT_TOKEN(TIME); };