ENH: add ITstream::toString() method

- creates a std::string with space-delimited tokens, which can be sent
  to another application or even re-parsed into tokens

src/OpenFOAM/db/IOstreams/Tstreams/ITstream.C

@@ -27,6 +27,7 @@ License
 
 #include "error.H"
 #include "ITstream.H"
+#include "StringStream.H"
 #include "UIListStream.H"
 
 // * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
@@ -187,6 +188,28 @@ void Foam::ITstream::print(Ostream& os) const
 }
 
 
+std::string Foam::ITstream::toString() const
+{
+    OStringStream buf;
+
+    const tokenList& tokens = *this;
+
+    label len = tokens.size();
+
+    for (const token& tok : tokens)
+    {
+        buf << tok;
+
+        if (--len)
+        {
+            buf << ' ';
+        }
+    }
+
+    return buf.str();
+}
+
+
 Foam::Istream& Foam::ITstream::read(token& tok)
 {
     // Return the put back token if it exists

src/OpenFOAM/db/IOstreams/Tstreams/ITstream.H

@@ -192,7 +192,7 @@ public:
         );
 
 
-    // Member functions
+    // Member Functions
 
         // Inquiry
 
@@ -233,7 +233,7 @@ public:
             }
 
 
-        // Read functions
+        // Read Functions
 
             //- Return next token from stream
             virtual Istream& read(token& tok);
@@ -289,10 +289,14 @@ public:
             }
 
 
-        // Print
+        // Output
 
             //- Print description of stream to Ostream
             void print(Ostream& os) const;
+
+            //- Concatenate tokens into a space-separated std::string.
+            //- The resulting string may contain quote characters.
+            std::string toString() const;
 };