ENH: coding cleanup for memory streams

- simplify structure.
- protect against nullptr when resetting memory streams
- make UIListStream swappable
- add uiliststream as an example of using a plain std::istream

applications/test/IListStream/Test-IListStream.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -56,6 +56,15 @@ void printInfo(const BufType& buf)
 }
 
 
+template<>
+void printInfo(const List<char>& buf)
+{
+    Info<< nl << "=========================" << endl;
+    toString(Info, buf);
+    Info<< nl << "=========================" << endl;
+}
+
+
 void printTokens(Istream& is)
 {
     label count = 0;
@@ -126,21 +135,22 @@ int main(int argc, char *argv[])
     Info<<nl << "directly written:";
     printInfo(ibuf);
 
-    // But cannot easily swap in/out an entirely new list storage:
+    // Swap in/out an entirely new list storage:
-    //
+    List<char> newvalues(52);
-    // List<char> newvalues(52);
+    {
-    // {
+        for (int i=0; i<26; ++i)
-    //     for (int i=0; i<26; ++i)
+        {
-    //     {
+            newvalues[2*i+0] = char('a' + i);
-    //         newvalues[2*i+0] = char('a' + i);
+            newvalues[2*i+1] = char('A' + i);
-    //         newvalues[2*i+1] = char('A' + i);
+        }
-    //     }
+    }
-    // }
+    ibuf.swap(newvalues);
-    // ibuf.swap(newvalues);
-    //
-    // Info<<nl << "after swap:";
-    // printInfo(ibuf);
 
+    Info<<nl << "after swap:";
+    printInfo(ibuf);
+
+    Info<<nl << "swapped out:";
+    printInfo(newvalues);
 
     Info<< "\nEnd\n" << endl;
 

applications/test/OCountStream/Test-OCountStream.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -40,17 +40,26 @@ int main(int argc, char *argv[])
     OCountStream cnt;
     OStringStream str;
 
+    ocountstream plain;
+
     for (label i = 0; i < 50; ++i)
     {
-        str << 1002 << " " << "abcd" << " "
+        str
+            << 1002 << " " << "abcd" << " "
             << "def" << " " << 3.14159 << ";\n";
 
-        cnt << 1002 << " " << "abcd" << " "
+        cnt
+            << 1002 << " " << "abcd" << " "
+            << "def" << " " << 3.14159 << ";\n";
+
+        plain
+            << 1002 << " " << "abcd" << " "
             << "def" << " " << 3.14159 << ";\n";
     }
 
     cnt.print(Info);
     Info<< "via string-stream: " << str.str().size() << " chars" << endl;
+    Info<< "via ocountstream: " << plain.size() << " chars" << endl;
 
     Info<< "\nEnd\n" << endl;
 

applications/test/UIListStream/Test-UIListStream.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -30,6 +30,9 @@ Description
 #include "IOstreams.H"
 #include "argList.H"
 
+#include <sstream>
+#include <vector>
+
 using namespace Foam;
 
 Ostream& toString(Ostream& os, const UList<char>& list)
@@ -45,6 +48,19 @@ Ostream& toString(Ostream& os, const UList<char>& list)
 }
 
 
+Ostream& toString(Ostream& os, const std::vector<char>& list)
+{
+    os << '"';
+    for (const char c : list)
+    {
+        os << c;
+    }
+    os << '"';
+
+    return os;
+}
+
+
 template<class BufType>
 void printInfo(const BufType& buf)
 {
@@ -55,6 +71,15 @@ void printInfo(const BufType& buf)
 }
 
 
+template<>
+void printInfo(const UList<char>& buf)
+{
+    Info<< nl << "=========================" << endl;
+    toString(Info, buf);
+    Info<< nl << "=========================" << endl;
+}
+
+
 void printTokens(Istream& is)
 {
     label count = 0;
@@ -82,7 +107,7 @@ int main(int argc, char *argv[])
     DynamicList<char> storage(1000);
 
     UOListStream obuf(storage);
-    obuf << 1002 << " " << "abcd" << " " << "def" << " " << 3.14159 << ";\n";
+    obuf << 1002 << "\n" << "abcd" << "\n" << "def" << "\n" << 3.14159 << ";\n";
 
     obuf.print(Info);
 
@@ -92,15 +117,73 @@ int main(int argc, char *argv[])
     Info<<"as string: " << string(storage.cdata(), storage.size()) << endl;
 
     // Attach input buffer - could also do without previous resize
+    {
+        UIListStream ibuf(storage);
 
-    UIListStream ibuf(storage);
+        printTokens(ibuf);
 
-    printTokens(ibuf);
+        Info<< nl << "Repeat..." << endl;
+        ibuf.rewind();
 
-    Info<< nl << "Repeat..." << endl;
+        printTokens(ibuf);
-    ibuf.rewind();
+    }
 
-    printTokens(ibuf);
+
+    // Attach input buffer - could also do without previous resize
+    {
+        Info<< "parse as std::istream\n";
+
+        uiliststream is(storage.cdata(), storage.size());
+
+        string tok;
+
+        while (std::getline(is, tok))
+        {
+            std::cerr << "tok: " << tok << nl;
+        }
+
+        Info<< nl << "Repeat..." << endl;
+
+        is.rewind();
+        while (std::getline(is, tok))
+        {
+            std::cerr << "tok: " << tok << nl;
+        }
+    }
+
+
+    // Simple test using stl items only
+    {
+        std::vector<char> chars;
+        chars.reserve(1024);
+
+        for (int i=0; i < 10; ++i)
+        {
+            chars.push_back('A' + i);
+            chars.push_back('0' + i);
+            chars.push_back('\n');
+        }
+
+        Info<< "parse std::vector of char: ";
+        toString(Info, chars);
+        Info<< "----" << nl;
+
+        uiliststream is(chars.data(), chars.size());
+        string tok;
+        std::cerr<< nl << "Parsed..." << nl;
+        while (std::getline(is, tok))
+        {
+            std::cerr << "tok: " << tok << nl;
+        }
+
+        Info<< nl << "Repeat..." << endl;
+
+        is.rewind();
+        while (std::getline(is, tok))
+        {
+            std::cerr << "tok: " << tok << nl;
+        }
+    }
 
     Info<< "\nEnd\n" << endl;
 

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -51,7 +51,7 @@ namespace Foam
                     Class IListStreamAllocator Declaration
 \*---------------------------------------------------------------------------*/
 
-//- An stream/stream-buffer input allocator for with List storage
+//- An stream/stream-buffer input allocator with List storage
 class IListStreamAllocator
 :
     private List<char>,
@@ -61,43 +61,46 @@ protected:
 
     // Constructors
 
-        //- Construct with an empty list
+        //- Construct empty
         IListStreamAllocator()
         :
             List<char>(),
-            UIListStreamAllocator(list_storage())
+            UIListStreamAllocator(List<char>::data(), List<char>::size())
         {}
 
-        //- Move construct from an existing List
+        //- Move construct from List
         IListStreamAllocator(List<char>&& buffer)
         :
             List<char>(std::move(buffer)),
-            UIListStreamAllocator(list_storage())
+            UIListStreamAllocator(List<char>::data(), List<char>::size())
         {}
 
-
+        //- Move construct from DynamicList
-        //- Move construct from an existing DynamicList
         template<int SizeMin>
         IListStreamAllocator(DynamicList<char,SizeMin>&& buffer)
         :
             List<char>(std::move(buffer)),
-            UIListStreamAllocator(list_storage())
+            UIListStreamAllocator(List<char>::data(), List<char>::size())
         {}
 
         //- Transfer (move) construct
         IListStreamAllocator(const Xfer<List<char>>& buffer)
         :
             List<char>(buffer),
-            UIListStreamAllocator(list_storage())
+            UIListStreamAllocator(List<char>::data(), List<char>::size())
         {}
 
 
     // Protected Member Functions
 
         //- Convenience method to address the underlying List storage
-        inline List<char>& list_storage()
+        inline void reset_gbuffer()
         {
-            return static_cast<List<char>&>(*this);
+            UIListStreamAllocator::reset
+            (
+                List<char>::data(),
+                List<char>::size()
+            );
         }
 
 public:
@@ -107,21 +110,24 @@ public:
         //- The current get position in the buffer
         using UIListStreamAllocator::size;
 
+        inline void swap(List<char>& list)
+        {
+            List<char>::swap(list);
+            reset_gbuffer();
+        }
+
         //- Clear storage
         inline void clearStorage()
         {
-            list_storage().clear();
+            List<char>::clear();
-            sync_gbuffer_to_list();
+            reset_gbuffer();
         }
 
         //- Transfer contents to the Xfer container as a plain List
         inline Xfer<List<char>> xfer()
         {
-            Xfer<List<char>> moved = list_storage().xfer();
+            Xfer<List<char>> moved = List<char>::xfer();
-
+            reset_gbuffer();
-            // Update buffer pointers for remaining (zero) size list
-            sync_gbuffer_to_list(); // or rewind
-
             return moved;
         }
 };
@@ -156,7 +162,7 @@ public:
         {}
 
 
-        //- Move construct from an existing List
+        //- Move construct from List
         IListStream
         (
             List<char>&& buffer,
@@ -170,7 +176,7 @@ public:
         {}
 
 
-        //- Move construct from an existing DynamicList
+        //- Move construct from DynamicList
         template<int SizeMin>
         IListStream
         (

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -49,14 +49,12 @@ class countstreambuf
 :
     public std::streambuf
 {
-    // Private data
+    //- The number of bytes counted
-
+    std::streamsize size_;
-        //- The number of bytes
-        std::streamsize size_;
 
 protected:
 
-    //- Simply handle output counting via overflow
+    //- Handle output counting via overflow
     virtual int overflow(int c = EOF)
     {
         if (c != EOF)
@@ -79,25 +77,25 @@ protected:
         return 0;
     }
 
-
 public:
 
-    // Constructors
+    //- Construct null, or with precount size
+    countstreambuf(std::streamsize precount=0)
+    :
+        size_(precount)
+    {}
 
-        //- Construct null, or with precount size
+    //- \return The number of bytes counted
-        countstreambuf(std::streamsize precount=0)
+    std::streamsize size() const
-        :
+    {
-            size_(precount)
+        return size_;
-        {}
+    }
 
-
+    //- Some information about the number of bytes counted
-    // Access
+    inline void printBufInfo(Ostream& os) const
-
+    {
-        //- Number of bytes counted
+        os << "count=" << size_;
-        std::streamsize size() const
+    }
-        {
-            return size_;
-        }
 };
 
 
@@ -105,53 +103,30 @@ public:
                         Class ocountstream Declaration
 \*---------------------------------------------------------------------------*/
 
-//- Trivial output stream for calculating byte counts
+//- Trivial output stream for calculating byte counts.
-//  Since all output values are discarded, it can also be used as a /dev/null
+//  Since all output values are discarded, it can be used as a /dev/null
-//  output buffer as well
+//  output buffer as well.
 class ocountstream
 :
     virtual public std::ios,
+    protected countstreambuf,
     public std::ostream
 {
-    // Private data
-
-    countstreambuf buf_;
-
 public:
 
-    // Constructors
+    //- Construct null
+    ocountstream()
+    :
+        countstreambuf(),
+        std::ostream(static_cast<countstreambuf*>(this))
+    {}
 
-        //- Construct null
+    //- Rewind the stream, reset the count
-        ocountstream()
+    void rewind()
-        :
+    {
-            std::ostream(&buf_)
+        this->pubseekpos(0, std::ios_base::out);
-        {}
+        clear(); // for safety, clear any old errors
-
+    }
-
-    // Member Functions
-
-      // Access
-
-        //- This hides both signatures of std::basic_ios::rdbuf()
-        countstreambuf* rdbuf()
-        {
-            return &buf_;
-        }
-
-
-        //- Get number of bytes counted
-        std::streamsize size() const
-        {
-            return buf_.size();
-        }
-
-
-        //- Rewind the stream, reset the count
-        void rewind()
-        {
-            buf_.pubseekpos(0);
-            clear();    // for safety, clear any old errors
-        }
 };
 
 
@@ -189,7 +164,7 @@ protected:
 
         void printBufInfo(Ostream& os) const
         {
-            os << "count=" << buf_.size();
+            buf_.printBufInfo(os);
         }
 
 public:

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -29,9 +29,9 @@ Description
     Similar to OStringStream but with a List for its storage instead of
     as string to allow reuse of List contents without copying.
 
-    The default list size is 512 with a 256 byte block increment.
+    The default list size is 512-bytes with a 256-byte block increment.
-    These values can be changed on construction of via the
+    These values can be changed after construction using the reserve() and
-    reserve() and setBlockSize() methods.
+    the setBlockSize() methods.
 
 See Also
     Foam::IListStream
@@ -45,6 +45,7 @@ See Also
 
 #include "DynamicList.H"
 #include "OSstream.H"
+#include "stdFoam.H"
 #include "memoryStreamBuffer.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -52,43 +53,39 @@ See Also
 namespace Foam
 {
 
-// Forward declaration
-class OListStreamAllocator;
-
 /*---------------------------------------------------------------------------*\
                     Class OListStreamAllocator Declaration
 \*---------------------------------------------------------------------------*/
 
-//- An stream/stream-buffer output allocator for lists
+//- An stream/stream-buffer output allocator with DynamicList-like storage
 class OListStreamAllocator
 {
-    //- A streambuf adapter to output to a List
+    //- A streambuf adapter with resizing similar to DynamicList
-    class listbuf
+    class dynbuf
     :
         public memorybuf::out
     {
-        friend OListStreamAllocator;
+        friend class OListStreamAllocator;
 
-        //- Helper for setting the block size.
+        //- Helper for block size - small list minimum of 64 bytes.
-        //  Small list minimum of 64 bytes.
+        constexpr static int min_size(int n)
-        static int min_size(int n)
         {
-            return max(64, n);
+            return stdFoam::max(64, n);
         }
 
         //- Block size when resizing the list
         int block_ = 256;
 
         //- Underlying list storage.
-        //  Internally manage like a DynamicList, but the addressable size
+        //  Internally manage like a DynamicList, with its capacity known
-        //  is known through the stream pointers.
+        //  from the list size and the addressable size known through the
+        //  stream pointers.
         List<char> storage_;
 
-
     protected:
 
-        //- Increment capacity directly and
+        //- Increment capacity directly and adjust buffer pointers to
-        //  adjust buffer pointers to agree with list dimensions
+        //- correspond with the storage size.
         inline void minCapacity
         (
             const std::streamsize n,
@@ -115,8 +112,8 @@ class OListStreamAllocator
                 //     << " pos:" << cur
                 //     << " incr:" << incr << endl;
 
-                storage_.setSize(newCapacity);
+                storage_.resize(newCapacity);
-                sync_pbuffer_to_list();
+                sync_pbuffer();
                 pbump(cur);
             }
         }
@@ -167,34 +164,34 @@ class OListStreamAllocator
         //- Initialize put buffer
         void init_pbuffer(const std::streamsize n)
         {
-            set_pbuffer(storage_);
+            sync_pbuffer();
             minCapacity(n);
         }
 
 
     public:
 
-      // Constructors
+    // Constructors
 
         //- Construct with an empty list, or specified number of reserved bytes
-        listbuf(size_t nbytes = 512)
+        dynbuf(size_t nbytes = 512)
         :
             storage_()
         {
             init_pbuffer(min_size(nbytes));
         }
 
-        //- Move construct content from an existing List
+        //- Move construct from List
-        listbuf(List<char>&& buffer)
+        dynbuf(List<char>&& buffer)
         :
             storage_(std::move(buffer))
         {
             init_pbuffer(block_);
         }
 
-        //- Move construct content from an existing DynamicList
+        //- Move construct from DynamicList
         template<int AnySize>
-        listbuf(DynamicList<char,AnySize>&& buffer)
+        dynbuf(DynamicList<char,AnySize>&& buffer)
         :
             storage_(std::move(buffer))
         {
@@ -202,7 +199,7 @@ class OListStreamAllocator
         }
 
         //- Transfer (move) construct
-        listbuf(const Xfer<List<char>>& buffer)
+        dynbuf(const Xfer<List<char>>& buffer)
         :
             storage_(buffer)
         {
@@ -210,7 +207,7 @@ class OListStreamAllocator
         }
 
 
-      // Member Functions
+    // Member Functions
 
         //- Return the current list output capacity
         inline label capacity() const
@@ -219,26 +216,36 @@ class OListStreamAllocator
         }
 
         //- Sync put buffer pointers to agree with list dimensions
-        inline void sync_pbuffer_to_list()
+        inline void sync_pbuffer()
         {
-            set_pbuffer(storage_);
+            resetp(storage_.data(), storage_.size());
         }
 
         //- Clear storage
         inline void clearStorage()
         {
             storage_.clear();
-            sync_pbuffer_to_list();
+            sync_pbuffer();
         }
 
         //- Shrink to addressed storage
         inline void shrink()
         {
             const auto cur = tellp();
-            storage_.setSize(cur);
+            storage_.resize(cur);
-            sync_pbuffer_to_list();
+            sync_pbuffer();
             pbump(cur);
         }
+
+        //- Transfer contents to the Xfer container as a plain List
+        inline Xfer<List<char>> xfer()
+        {
+            const auto cur = tellp();   // Addressed area
+            storage_.resize(cur);
+            auto lst = storage_.xfer();
+            sync_pbuffer();
+            return lst;
+        }
     };
 
 protected:
@@ -248,7 +255,7 @@ protected:
         typedef std::ostream stream_type;
 
         //- The stream buffer
-        listbuf buf_;
+        dynbuf buf_;
 
         //- The stream
         stream_type stream_;
@@ -263,14 +270,14 @@ protected:
             stream_(&buf_)
         {}
 
-        //- Move construct from an existing List
+        //- Move construct from List
         OListStreamAllocator(List<char>&& buffer)
         :
             buf_(std::move(buffer)),
             stream_(&buf_)
         {}
 
-        //- Move construct from an existing DynamicList
+        //- Move construct from DynamicList
         template<int SizeMin>
         OListStreamAllocator(DynamicList<char,SizeMin>&& buffer)
         :
@@ -290,8 +297,8 @@ protected:
 
         void printBufInfo(Ostream& os) const
         {
-            os  << "pos=" << buf_.tellp()
+            os  << "put=" << buf_.tellp()
-                << " capacity=" << buf_.capacity()
+                << "/" << buf_.capacity()
                 << " block=" << buf_.block_;
         }
 
@@ -299,12 +306,30 @@ public:
 
     // Member Functions
 
+        //- Const UList access to the characters written (shallow copy).
+        inline const UList<char> list() const
+        {
+            return buf_.list();
+        }
+
+        //- Non-const UList access to the characters written (shallow copy).
+        inline UList<char> list()
+        {
+            return buf_.list();
+        }
+
         //- The current list output capacity
         inline label capacity() const
         {
             return buf_.capacity();
         }
 
+        //- The current output position in the buffer,
+        //- which is also the addressed list size
+        inline label size() const
+        {
+            return buf_.tellp();
+        }
 
         //- Reserve output space for at least this amount.
         inline void reserve(const std::streamsize n)
@@ -317,55 +342,16 @@ public:
             }
         }
 
-
         //- Adjust block size for output
         inline void setBlockSize(int n)
         {
             return buf_.setBlockSize(n);
         }
 
-
-        //- The current output position in the buffer,
-        //  which is also the addressed list size
-        inline label size() const
-        {
-            return buf_.tellp();
-        }
-
-
-        //- Const access to written contents as a list of characters
-        inline const UList<char> list() const
-        {
-            return UList<char>
-            (
-                const_cast<char*>(buf_.storage_.cdata()),
-                buf_.tellp()
-            );
-        }
-
-
-        //- Non-const access to written contents as a list of characters
-        inline UList<char> list()
-        {
-            return UList<char>(buf_.storage_.data(), buf_.tellp());
-        }
-
-
         //- Transfer contents to the Xfer container as a plain List
         inline Xfer<List<char>> xfer()
         {
-            buf_.shrink();  // Shrink to addressed area
+            return buf_.xfer();
-            auto lst = buf_.storage_.xfer();
-            buf_.sync_pbuffer_to_list();
-            return lst;
-        }
-
-
-        //- Move to buffer start, clear errors
-        void rewind()
-        {
-            buf_.pubseekpos(0, std::ios_base::out);
-            stream_.clear(); // for safety, clear any old errors
         }
 
         //- Shrink to addressed space, should not affect stream.
@@ -381,6 +367,12 @@ public:
             stream_.clear(); // for safety, clear any old errors
         }
 
+        //- Move to buffer start, clear errors
+        void rewind()
+        {
+            buf_.pubseekpos(0, std::ios_base::out);
+            stream_.clear(); // for safety, clear any old errors
+        }
 };
 
 
@@ -464,7 +456,7 @@ public:
         {}
 
 
-    // Member functions
+    // Member Functions
 
         //- Rewind the stream, clearing any old errors
         virtual void rewind()

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -35,10 +35,10 @@ Description
 
     An example of possible use:
     \code
-        DynamicList<char> buffer(4096);   // allocate some large buffer
+        DynamicList<char> buffer(4096);     // allocate some large buffer
 
         nread = something.read(buffer.data(),1024); // fill with content
-        buffer.setSize(nread);            // content size
+        buffer.resize(nread);               // content size
 
         // construct dictionary, or something else
         UIListStream is(buffer)
@@ -46,7 +46,7 @@ Description
 
         // sometime later
         nread = something.read(buffer.data(),2048); // fill with content
-        buffer.setSize(nread);              // content size
+        buffer.resize(nread);               // content size
 
         // without intermediate variable
         dictionary dict2(UIListStream(buffer)());
@@ -73,47 +73,49 @@ namespace Foam
 {
 
 /*---------------------------------------------------------------------------*\
-                       Class UIListAllocator Declaration
+                        Class uiliststream Declaration
 \*---------------------------------------------------------------------------*/
 
-//- An stream/stream-buffer input allocator for a externally allocated lists
+//- Similar to std::istringstream, but with an externally managed input buffer.
+//  This allows the input buffer to be filled or refilled from various sources
+//  without copying.
+class uiliststream
+:
+    virtual public std::ios,
+    protected memorybuf::in,
+    public std::istream
+{
+public:
+
+    //- Construct for character array and number of bytes
+    uiliststream(const char* buffer, size_t nbytes)
+    :
+        memorybuf::in(const_cast<char*>(buffer), nbytes),
+        std::istream(static_cast<memorybuf::in*>(this))
+    {}
+
+    //- Reset buffer pointers
+    inline void reset(char *buffer, size_t nbytes)
+    {
+        resetg(buffer, nbytes);
+    }
+
+    //- Rewind the stream, clearing any old errors
+    void rewind()
+    {
+        this->pubseekpos(0, std::ios_base::in);
+        clear(); // for safety, clear any old errors
+    }
+};
+
+
+/*---------------------------------------------------------------------------*\
+                    Class UIListStreamAllocator Declaration
+\*---------------------------------------------------------------------------*/
+
+//- An stream/stream-buffer input allocator for a externally allocated list
 class UIListStreamAllocator
 {
-    //- A streambuf class for input from UList or equivalent
-    class ulistbuf
-    :
-        public memorybuf::in
-    {
-        friend UIListStreamAllocator;
-
-        //- Underlying list storage
-        UList<char> list_;
-
-    public:
-
-        //- Construct for specified buffer
-        ulistbuf(UList<char>& buffer)
-        :
-            list_(buffer)
-        {
-            set_gbuffer(list_);
-        }
-
-        //- Construct for specified buffer
-        ulistbuf(char* buffer, std::streamsize num)
-        :
-            list_(buffer, num)
-        {
-            set_gbuffer(list_);
-        }
-
-        //- Sync get buffer pointers to agree with list dimensions
-        inline void sync_gbuffer_to_list()
-        {
-            set_gbuffer(list_);
-        }
-    };
-
 protected:
 
     // Protected data
@@ -121,7 +123,7 @@ protected:
         typedef std::istream stream_type;
 
         //- The stream buffer
-        ulistbuf buf_;
+        memorybuf::in buf_;
 
         //- The stream
         stream_type stream_;
@@ -129,14 +131,7 @@ protected:
 
     // Constructors
 
-        //- Construct with list buffer
+        //- Construct for character array and number of bytes
-        UIListStreamAllocator(UList<char>& list)
-        :
-            buf_(list),
-            stream_(&buf_)
-        {}
-
-        //- Construct with buffer and number of bytes
         UIListStreamAllocator(char *buffer, size_t nbytes)
         :
             buf_(buffer, nbytes),
@@ -146,50 +141,45 @@ protected:
 
     // Protected Member Functions
 
-        //- Sync get buffer pointers to agree with list dimensions
+        //- Reset buffer pointers
-        inline void sync_gbuffer_to_list()
+        inline void reset(char *buffer, size_t nbytes)
         {
-            buf_.sync_gbuffer_to_list();
+            buf_.resetg(buffer, nbytes);
         }
 
         void printBufInfo(Ostream& os) const
         {
-            os  << "pos=" << buf_.tellg()
+            buf_.printBufInfo(os);
-                << " size=" << buf_.list_.size();
         }
 
 public:
 
     // Public Member Functions
 
-        //- Const access to available contents as a list of characters
+        //- Const UList access to the input characters (shallow copy).
-        inline const UList<char>& list() const
+        inline const UList<char> list() const
         {
-            return buf_.list_;
+            return buf_.list();
         }
 
-
+        //- Non-const UList access to the input characters (shallow copy).
-        //- Non-const access to available contents as a list of characters
         inline UList<char> list()
         {
-            return buf_.list_;
+            return buf_.list();
         }
 
-
         //- The list size
         inline label size() const
         {
-            return buf_.list_.size();
+            return buf_.capacity();
         }
 
-
         //- Position of the get buffer
         std::streampos tellg() const
         {
             return buf_.tellg();
         }
 
-
         //- Move to buffer start, clear errors
         void rewind()
         {
@@ -278,7 +268,6 @@ public:
             return allocator_type::tellg();
         }
 
-
         //- Rewind the stream, clearing any old errors
         virtual void rewind()
         {
@@ -286,7 +275,6 @@ public:
             setGood();  // resynchronize with internal state
         }
 
-
         //- Print description to Ostream
         virtual void print(Ostream& os) const;
 

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -40,7 +40,7 @@ Description
         {
             UOListStream os(buffer);
             os << "content1" << " and more content";
-            buffer.setSize(os.size());      // synchronize sizes
+            buffer.resize(os.size());       // synchronize sizes
         }
 
         something.write(buffer, buffer.size());
@@ -53,13 +53,13 @@ Description
 
         UOListStream os(buffer);
         os << "content1" << " and more content";
-        buffer.setSize(os.size());          // synchronize sizes
+        buffer.resize(os.size());           // synchronize sizes
 
         something.write(buffer, buffer.size());
 
         os.rewind();
         os << "content2";
-        buffer.setSize(os.size());      // synchronize sizes
+        buffer.resize(os.size());      // synchronize sizes
 
         something.write(buffer, buffer.size());
 
@@ -91,51 +91,12 @@ namespace Foam
 {
 
 /*---------------------------------------------------------------------------*\
-                    Class UOListAllocator Declaration
+                    Class UOListStreamAllocator Declaration
 \*---------------------------------------------------------------------------*/
 
 //- An stream/stream-buffer allocator for external buffers
-class UOListAllocator
+class UOListStreamAllocator
 {
-    //- A streambuf adapter for output to UList or equivalent
-    class ulistbuf
-    :
-        public memorybuf::out
-    {
-        friend UOListAllocator;
-
-        //- Underlying list storage
-        UList<char> list_;
-
-    public:
-
-      // Constructors
-
-        //- Construct for specified buffer
-        ulistbuf(char* buffer, std::streamsize num)
-        :
-            list_(buffer, num)
-        {
-            set_pbuffer(list_);
-        }
-
-
-      // Member Functions
-
-        //- Return the current list output capacity
-        inline label capacity() const
-        {
-            return list_.size();
-        }
-
-        //- Sync put buffer pointers to agree with list dimensions
-        inline void sync_pbuffer_to_list()
-        {
-            set_pbuffer(list_);
-        }
-    };
-
-
 protected:
 
     // Protected data
@@ -143,7 +104,7 @@ protected:
         typedef std::ostream stream_type;
 
         //- The stream buffer
-        ulistbuf buf_;
+        memorybuf::out buf_;
 
         //- The stream
         stream_type stream_;
@@ -151,63 +112,47 @@ protected:
 
     // Constructors
 
-        //- Construct with buffer and number of bytes
+        //- Construct for character array and number of bytes
-        UOListAllocator(char *buffer, size_t nbytes)
+        UOListStreamAllocator(char *buffer, size_t nbytes)
         :
             buf_(buffer, nbytes),
             stream_(&buf_)
         {}
 
-
-    // Protected Member Functions
-
         void printBufInfo(Ostream& os) const
         {
-            os  << "pos=" << buf_.tellp()
+            buf_.printBufInfo(os);
-                << " capacity=" << buf_.capacity();
         }
 
 public:
 
     // Public Member Functions
 
+        //- Const UList access to the characters written (shallow copy).
+        inline const UList<char> list() const
+        {
+            return buf_.list();
+        }
+
+        //- Non-const UList access to the characters written (shallow copy).
+        inline UList<char> list()
+        {
+            return buf_.list();
+        }
+
         //- The current list output capacity
         inline label capacity() const
         {
             return buf_.capacity();
         }
 
-
         //- The current output position in the buffer,
-        //  which is also the addressed list size
+        //- which is also the addressed list size
         inline label size() const
         {
             return buf_.tellp();
         }
 
-
-        //- Const access to written contents as a list of characters
-        inline const UList<char> list() const
-        {
-            return UList<char>
-            (
-                const_cast<char*>(buf_.list_.cdata()),
-                buf_.tellp()
-            );
-        }
-
-
-        //- Non-const access to written contents as a list of characters
-        inline UList<char> list()
-        {
-            return UList<char>
-            (
-                const_cast<char*>(buf_.list_.cdata()),
-                buf_.tellp()
-            );
-        }
-
-
         //- Move to buffer start, clear errors
         void rewind()
         {
@@ -224,10 +169,10 @@ public:
 //- An OSstream attached to an unallocated external buffer
 class UOListStream
 :
-    public UOListAllocator,
+    public UOListStreamAllocator,
     public OSstream
 {
-    typedef UOListAllocator allocator_type;
+    typedef UOListStreamAllocator allocator_type;
 
 public:
 

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

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -42,6 +42,9 @@ Description
 namespace Foam
 {
 
+// Forward declarations
+class Ostream;
+
 /*---------------------------------------------------------------------------*\
                           Class memorybuf Declaration
 \*---------------------------------------------------------------------------*/
@@ -126,6 +129,19 @@ protected:
     }
 
 
+    //- \return the current buffer get position
+    inline std::streamsize tellg() const
+    {
+        return (gptr() - eback());
+    }
+
+    //- \return the current buffer put position
+    inline std::streamsize tellp() const
+    {
+        return (pptr() - pbase());
+    }
+
+
 public:
 
     // Forward declarations
@@ -145,6 +161,9 @@ class memorybuf::in
 {
 protected:
 
+    //- Default construct null
+    in() = default;
+
     //- Get sequence of characters
     virtual std::streamsize xsgetn(char* s, std::streamsize n)
     {
@@ -159,17 +178,53 @@ protected:
         return count;
     }
 
+public:
 
-    //- The buffer get position
+    //- Construct for character array and number of bytes
-    inline std::streamsize tellg() const
+    in(char* s, std::streamsize n)
     {
-        return (gptr() - eback());
+        resetg(s, n);
     }
 
-    //- Sync get buffer pointers to agree with list dimensions
+    //- Reset for character array and number of bytes
-    inline void set_gbuffer(UList<char>& list)
+    inline void resetg(char* s, std::streamsize n)
     {
-        setg(list.begin(), list.begin(), list.end());
+        if (s)
+        {
+            setg(s, s, s + n);
+        }
+        else
+        {
+            setg(nullptr, nullptr, nullptr);
+        }
+    }
+
+    //- The buffer get position
+    using memorybuf::tellg;
+
+    //- The buffer capacity
+    inline std::streamsize capacity() const
+    {
+        return (egptr() - eback());
+    }
+
+    //- Const UList access to the input characters (shallow copy).
+    inline const UList<char> list() const
+    {
+        return UList<char>(eback(), (egptr() - eback()));
+    }
+
+    //- Non-const UList access to the input characters (shallow copy).
+    inline UList<char> list()
+    {
+        return UList<char>(eback(), (egptr() - eback()));
+    }
+
+    //- Some information about the input buffer position/capacity
+    inline void printBufInfo(Ostream& os) const
+    {
+        os  << "get=" << (gptr() - eback()) // tellp()
+            << "/" << (egptr() - eback());  // capacity
     }
 };
 
@@ -185,6 +240,9 @@ class memorybuf::out
 {
 protected:
 
+    //- Default construct null
+    out() = default;
+
     //- Put sequence of characters
     virtual std::streamsize xsputn(const char* s, std::streamsize n)
     {
@@ -198,18 +256,54 @@ protected:
         return count;
     }
 
+public:
+
+    //- Construct for character array and number of bytes
+    out(char* s, std::streamsize n)
+    {
+        resetp(s, n);
+    }
+
+    //- Reset for character array and number of bytes
+    inline void resetp(char* s, std::streamsize n)
+    {
+        if (s)
+        {
+            setp(s, s + n);
+        }
+        else
+        {
+            setp(nullptr, nullptr);
+        }
+    }
+
     //- The buffer put position
-    inline std::streamsize tellp() const
+    using memorybuf::tellp;
+
+    //- The buffer capacity
+    inline std::streamsize capacity() const
     {
-        return (pptr() - pbase());
+        return (epptr() - pbase());
     }
 
-    //- Sync put buffer pointers to agree with list dimensions
+    //- Const UList access to the characters written (shallow copy).
-    inline void set_pbuffer(UList<char>& list)
+    inline const UList<char> list() const
     {
-        setp(list.begin(), list.end());
+        return UList<char>(pbase(), (pptr() - pbase()));
     }
 
+    //- Non-const UList access to the characters written (shallow copy).
+    inline UList<char> list()
+    {
+        return UList<char>(pbase(), (pptr() - pbase()));
+    }
+
+    //- Some information about the output buffer position/capacity
+    inline void printBufInfo(Ostream& os) const
+    {
+        os  << "put=" << (pptr() - pbase()) // tellp()
+            << "/" << (epptr() - pbase());  // capacity
+    }
 };