ENH: provide Istream::rewind() implementation

- base implementation drops any putback token

src/OpenFOAM/db/IOstreams/Fstreams/IFstream.C

@@ -275,9 +275,11 @@ const std::istream& Foam::IFstream::stdStream() const
 
 void Foam::IFstream::rewind()
 {
+    Istream::rewind();  // Drop any putback
+    lineNumber_ = 1;    // Reset line number
+
     if (IOstreamOption::COMPRESSED == ifstreamPointer::whichCompression())
     {
-        lineNumber_ = 1;  // Reset line number
         ifstreamPointer::reopen_gz(this->name());
         setState(ifstreamPointer::get()->rdstate());
     }

src/OpenFOAM/db/IOstreams/IOstreams/Istream.C

@@ -218,6 +218,12 @@ char Foam::Istream::readEndList(const char* funcName)
 }
 
 
+void Foam::Istream::rewind()
+{
+    putBackClear();  // Drop any putback
+}
+
+
 Foam::Istream& Foam::Istream::operator()() const
 {
     if (!good())

src/OpenFOAM/db/IOstreams/IOstreams/Istream.H

@@ -175,7 +175,8 @@ public:
             //- operation.
             virtual Istream& readRaw(char* data, std::streamsize count) = 0;
 
-            //- Rewind the stream so that it may be read again
+            //- Rewind the stream so that it may be read again.
+            //  The base implementation clears any putback.
             virtual void rewind() = 0;
 
 

src/OpenFOAM/db/IOstreams/Pstreams/UIPstreamBase.C

@@ -563,6 +563,8 @@ Foam::label Foam::UIPstreamBase::remaining() const noexcept
 
 void Foam::UIPstreamBase::rewind()
 {
+    Istream::rewind();  // Drop any putback
+
     recvBufPos_ = 0;  // Assume the entire buffer is for us to read from
     setOpened();
     setGood();

src/OpenFOAM/db/IOstreams/Sstreams/ISstream.C

@@ -1084,6 +1084,7 @@ bool Foam::ISstream::endRawRead()
 
 void Foam::ISstream::rewind()
 {
+    Istream::rewind();    // Drop any putback
     lineNumber_ = 1;      // Reset line number
 
     stdStream().clear();  // Clear the iostate error state flags

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

@@ -531,7 +531,11 @@ public:
         virtual bool endRawRead() override { return false; }
 
         //- Rewind the stream so that it may be read again. Same as seek(0)
-        virtual void rewind() override { ITstream::seek(0); }
+        virtual void rewind() override
+        {
+            Istream::rewind();
+            ITstream::seek(0);
+        }
 
 
     // Output

src/OpenFOAM/db/IOstreams/memory/ICharStream.H

@@ -357,6 +357,7 @@ public:
         //- Rewind the stream, clearing any old errors
         virtual void rewind() override
         {
+            Istream::rewind();
             stream_.rewind();
             syncState();
         }

src/OpenFOAM/db/IOstreams/memory/ISpanStream.H

@@ -419,6 +419,7 @@ public:
         //- Rewind the stream, clearing any old errors
         virtual void rewind() override
         {
+            Istream::rewind();
             stream_.rewind();
             syncState();
         }