From b2d4f25fff71d5d79e96791e90467ac85bfcbabf Mon Sep 17 00:00:00 2001
From: Will Bainbridge <http://cfd.direct>
Date: Wed, 21 Jun 2023 16:01:38 +0100
Subject: [PATCH] codeStream: Typed substitutions

Dictionary entries constructed with #calc and #codeStream can now
conveniently access and use typed variables. This means calculations
involving vectors and tensors and list and field types are now possible.

To access a variable and construct it as a given type within a #calc
or #codeStream entry, put the type immediately after the $ symbol inside
angled brackets <>. So, $<vector>var or $<vector>{var} substitutes a
variable named var as a vector.

Examples:

- Reflect a point in a plane defined by a normal

    p       (1 2 3);
    n       (1 1 0);
    pStar   #calc "$<vector>p - (2*sqr($<vector>n)/magSqr($<vector>n)&$<vector>p)";

- Rotate a list of points around an axis by a given angle

    points  ((3 0 0) (2 1 1) (1 2 2) (0 3 3));
    rotation
    {
        axis    (0 1 1);
        angle   45;
    }

    #codeStream
    {
        codeInclude
        #{
            #include "pointField.H"
            #include "transform.H"
        #};

        code
        #{
            const pointField points($<List<point>>points);
            const vector axis = $<vector>!rotation/axis;
            const scalar angle = degToRad($!rotation/angle);
            os << "pointsRotated" << nl << (Ra(axis, angle) & points)() << ";";
        #};
    };

- Compute the centre and trianglation of a polygon

   polygon  ((0 0 0) (1 0 0) (2 1 0) (0 2 0) (-1 1 0));

   #codeStream
   {
       codeInclude
       #{
           #include "polygonTriangulate.H"
       #};

       code
       #{
           const List<point> polygon($<List<point>>polygon);
           writeEntry(os, "polygonCentre", face::centre(polygon));

           polygonTriangulate triEngine;
           triEngine.triangulate(polygon);
           os << "polygonTris" << ' ' << triEngine.triPoints() << ";";
       #};
    };

- Generate a single block blockMeshDict for use with snappyHexMesh with no redundant information

    min         (-2.5 -1.2 -3.0);   // Minimum coordinates of the block
    max         (2.5 1.2 3.0);      // Maximum coordinates of the block
    nCellsByL   33.3333;            // Number of cells per unit length

    // Calculate the number of cells in each block direction
    nCells      #calc "Vector<label>($nCellsByL*($<vector>max - $<vector>min) + vector::one/2)";

    // Generate the vertices using a boundBox
    vertices    #codeStream
    {
        codeInclude
        #{
            #include "boundBox.H"
        #};

        code
        #{
            os << boundBox($<vector>min, $<vector>max).points();
        #};
    };

    blocks
    (
        hex (0 1 2 3 4 5 6 7) $nCells simpleGrading (1 1 1)
    );

    defaultPatch
    {
        type patch;
    }

    boundary
    ();
---
 .../dynamicCode/codeStreamTemplate.C          |  2 +
 src/OpenFOAM/db/dictionary/dictionary.H       | 21 ++++-
 .../db/dictionary/dictionaryTemplates.C       | 25 ++++++
 .../primitives/strings/string/string.C        | 22 +++++
 .../primitives/strings/string/string.H        | 18 +++++
 .../primitives/strings/stringOps/stringOps.C  | 80 ++++++++++++++-----
 .../primitives/strings/stringOps/stringOps.H  |  1 +
 7 files changed, 147 insertions(+), 22 deletions(-)

diff --git a/etc/codeTemplates/dynamicCode/codeStreamTemplate.C b/etc/codeTemplates/dynamicCode/codeStreamTemplate.C
index f90b42dd1e..4d7582bb02 100644
--- a/etc/codeTemplates/dynamicCode/codeStreamTemplate.C
+++ b/etc/codeTemplates/dynamicCode/codeStreamTemplate.C
@@ -27,8 +27,10 @@ Description
 \*---------------------------------------------------------------------------*/
 
 #include "dictionary.H"
+#include "fieldTypes.H"
 #include "Ostream.H"
 #include "Pstream.H"
+#include "read.H"
 #include "unitConversion.H"
 
 //{{{ begin codeInclude
diff --git a/src/OpenFOAM/db/dictionary/dictionary.H b/src/OpenFOAM/db/dictionary/dictionary.H
index da905ba2df..4174ff7d2b 100644
--- a/src/OpenFOAM/db/dictionary/dictionary.H
+++ b/src/OpenFOAM/db/dictionary/dictionary.H
@@ -513,9 +513,11 @@ public:
                 bool patternMatch=true
             ) const;
 
-            //- Find and return an entry data stream pointer if present
-            //  otherwise return nullptr. Allows scoping using '/' with
-            //  special handling for '!' and '..'.
+            //- Find and return an entry data stream pointer if present,
+            //  otherwise return nullptr.
+            //  If recursive, search parent dictionaries.
+            //  If patternMatch, use regular expressions.
+            //  Allows scoping using '/' with special handling for '!' and '..'.
             const entry* lookupScopedEntryPtr
             (
                 const word&,
@@ -523,6 +525,19 @@ public:
                 bool patternMatch
             ) const;
 
+            //- Find and return a T,
+            //  if not found throw a fatal error.
+            //  If recursive, search parent dictionaries.
+            //  If patternMatch, use regular expressions.
+            //  Allows scoping using '/' with special handling for '!' and '..'.
+            template<class T>
+            T lookupScoped
+            (
+                const word&,
+                bool recursive=false,
+                bool patternMatch=true
+            ) const;
+
             //- Check if entry is a sub-dictionary
             bool isDict(const word&) const;
 
diff --git a/src/OpenFOAM/db/dictionary/dictionaryTemplates.C b/src/OpenFOAM/db/dictionary/dictionaryTemplates.C
index 8cb82d2408..ead0342f04 100644
--- a/src/OpenFOAM/db/dictionary/dictionaryTemplates.C
+++ b/src/OpenFOAM/db/dictionary/dictionaryTemplates.C
@@ -223,6 +223,31 @@ bool Foam::dictionary::readIfPresent
 }
 
 
+template<class T>
+T Foam::dictionary::lookupScoped
+(
+    const word& keyword,
+    bool recursive,
+    bool patternMatch
+) const
+{
+    const entry* entryPtr =
+        lookupScopedEntryPtr(keyword, recursive, patternMatch);
+
+    if (entryPtr == nullptr)
+    {
+        FatalIOErrorInFunction
+        (
+            *this
+        )   << "keyword " << keyword << " is undefined in dictionary "
+            << name()
+            << exit(FatalIOError);
+    }
+
+    return pTraits<T>(entryPtr->stream());
+}
+
+
 template<class T>
 void Foam::dictionary::add(const keyType& k, const T& t, bool overwrite)
 {
diff --git a/src/OpenFOAM/primitives/strings/string/string.C b/src/OpenFOAM/primitives/strings/string/string.C
index b2f338c83c..a092aaa402 100644
--- a/src/OpenFOAM/primitives/strings/string/string.C
+++ b/src/OpenFOAM/primitives/strings/string/string.C
@@ -295,4 +295,26 @@ void Foam::string::strip(const string& str)
 }
 
 
+Foam::string::size_type Foam::string::findClosing
+(
+    const char c,
+    string::size_type i0 = 0
+) const
+{
+    size_t level = 1;
+
+    string::size_type i = i0 + 1;
+
+    while (level > 0 && i < size())
+    {
+        if (operator[](i) == operator[](i0)) ++level;
+        if (operator[](i) == c) --level;
+
+        ++i;
+    }
+
+    return level == 0 ? i - 1 : string::npos;
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/strings/string/string.H b/src/OpenFOAM/primitives/strings/string/string.H
index b8c299ad06..6ea0485d9d 100644
--- a/src/OpenFOAM/primitives/strings/string/string.H
+++ b/src/OpenFOAM/primitives/strings/string/string.H
@@ -244,6 +244,24 @@ public:
         //- Strip characters from the start and end of the string
         void strip(const string&);
 
+        //- Find the closing character. Brackets counting algorithm. The
+        //  opening bracket character is taken to be the one at the starting
+        //  position. The closing character is provided by argument.
+        //
+        //  Examples:
+        //
+        //          [char #1]       [char #15]
+        //               |             |
+        //               V             V
+        //      string("0(2(4,6)8,a(c)e)g").findClosing(')',1) == 15
+        //
+        //          [char #3] [char #7]
+        //                 |   |
+        //                 V   V
+        //      string("0(2(4,6)8,a(c)e)g").findClosing(')',3) == 7
+        //
+        size_type findClosing(const char, const size_type) const;
+
 
     // Member Operators
 
diff --git a/src/OpenFOAM/primitives/strings/stringOps/stringOps.C b/src/OpenFOAM/primitives/strings/stringOps/stringOps.C
index e2e9b0aebc..ff57c15eea 100644
--- a/src/OpenFOAM/primitives/strings/stringOps/stringOps.C
+++ b/src/OpenFOAM/primitives/strings/stringOps/stringOps.C
@@ -410,6 +410,7 @@ Foam::string& Foam::stringOps::inplaceExpandCodeString
 (
     string& s,
     const dictionary& dict,
+    const word& dictVar,
     const char sigil
 )
 {
@@ -427,16 +428,28 @@ Foam::string& Foam::stringOps::inplaceExpandCodeString
         {
             // Find end of first occurrence
             string::size_type endVar = begVar;
-            string::size_type delim = 0;
+            string::size_type begDelim = 0, endDelim = 0;
 
-            if (s[begVar+1] == '{')
+            // Get the type, if any
+            word varType;
+            if (s[begVar+1] == '<')
             {
-                endVar = s.find('}', begVar);
-                delim = 1;
+                begDelim += s.findClosing('>', begVar+1) - begVar;
+                varType = s.substr(begVar+2, begDelim-2);
+            }
+
+            // Parse any braces and find the end of the variable
+            if (s[begVar+begDelim+1] == '{')
+            {
+                endVar = s.find('}', begVar+begDelim);
+                begDelim += 1;
+                endDelim += 1;
             }
             else
             {
-                string::iterator iter = s.begin() + begVar + 1;
+                endVar = begVar + begDelim;
+
+                string::iterator iter = s.begin() + begVar + begDelim + 1;
 
                 // Accept all dictionary and environment variable characters
                 while
@@ -474,8 +487,8 @@ Foam::string& Foam::stringOps::inplaceExpandCodeString
                 (
                     s.substr
                     (
-                        begVar + 1 + delim,
-                        endVar - begVar - 2*delim
+                        begVar + begDelim + 1,
+                        (endVar - endDelim) - (begVar + begDelim)
                     ),
                     false
                 );
@@ -491,25 +504,54 @@ Foam::string& Foam::stringOps::inplaceExpandCodeString
                 // Substitute if found
                 if (ePtr)
                 {
-                    // Write to string buffer. Force floating point numbers to
-                    // be printed with at least some decimal digits.
                     OStringStream buf;
-                    buf << scientific;
-                    buf.precision(IOstream::defaultPrecision());
 
-                    if (ePtr->isDict())
+                    if (!dictVar.empty() && !varType.empty())
                     {
-                        ePtr->dict().write(buf, false);
+                        // If the dictionary is accessible and the type is
+                        // known, then lookup the variable in the code, rather
+                        // than substituting its value. That way we don't need
+                        // to recompile this string if the value changes.
+                        buf << dictVar
+                            << ".lookupScoped<" << varType << ">"
+                            << "(\"" << varName << "\", true, false)";
                     }
-                    else if (isA<primitiveEntry>(*ePtr))
+
+                    if (dictVar.empty() && !varType.empty())
                     {
-                        dynamicCast<const primitiveEntry>(*ePtr)
-                           .write(buf, true);
+                        // If the dictionary is not accessible but the type is
+                        // known, then read the substituted value from a string
+                        buf << "read<" << varType << ">(\"";
                     }
-                    else
+
+                    if (dictVar.empty() || varType.empty())
                     {
-                        // Can't do any other types. Fail.
-                        dynamicCast<const primitiveEntry>(*ePtr);
+                        // If the dictionary is not accessible and/or the type
+                        // is not known, then we need to substitute the
+                        // variable's value
+
+                        // Make sure floating point values print with at least
+                        // some decimal points
+                        buf << scientific;
+                        buf.precision(IOstream::defaultPrecision());
+
+                        // Write the dictionary or primitive entry. Fail if
+                        // anything else.
+                        if (ePtr->isDict())
+                        {
+                            ePtr->dict().write(buf, false);
+                        }
+                        else
+                        {
+                            dynamicCast<const primitiveEntry>(*ePtr)
+                                .write(buf, true);
+                        }
+                    }
+
+                    if (dictVar.empty() && !varType.empty())
+                    {
+                        // Close the string and read function as necessary
+                        buf << "\")";
                     }
 
                     s.std::string::replace
diff --git a/src/OpenFOAM/primitives/strings/stringOps/stringOps.H b/src/OpenFOAM/primitives/strings/stringOps/stringOps.H
index f6ab369fe1..23167fcc2a 100644
--- a/src/OpenFOAM/primitives/strings/stringOps/stringOps.H
+++ b/src/OpenFOAM/primitives/strings/stringOps/stringOps.H
@@ -110,6 +110,7 @@ namespace stringOps
     (
         string&,
         const dictionary& dict,
+        const word& dictVar = "dict",
         const char sigil = '$'
     );