// ----------------------------------------------------------------------------

//  alt_sstream.hpp : alternative stringstream 

// ----------------------------------------------------------------------------



//  Copyright Samuel Krempp 2003. Use, modification, and distribution are

//  subject to the Boost Software License, Version 1.0. (See accompanying

//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)



//  See http://www.boost.org/libs/format for library home page



// ----------------------------------------------------------------------------







#ifndef BOOST_SK_ALT_SSTREAM_HPP

#define BOOST_SK_ALT_SSTREAM_HPP



#include <string>

#include <boost/format/detail/compat_workarounds.hpp>

#include <boost/utility/base_from_member.hpp>

#include <boost/shared_ptr.hpp>

#include <boost/assert.hpp>



namespace boost {

    namespace io {



        template<class Ch, class Tr=::std::char_traits<Ch>, 

                 class Alloc=::std::allocator<Ch> >

        class basic_altstringbuf;



        template<class Ch, class Tr =::std::char_traits<Ch>, 

                 class Alloc=::std::allocator<Ch> >

        class basic_oaltstringstream;





        template<class Ch, class Tr, class Alloc>

        class basic_altstringbuf 

            : public ::std::basic_streambuf<Ch, Tr>

        {

            typedef ::std::basic_streambuf<Ch, Tr>  streambuf_t;

            typedef typename CompatAlloc<Alloc>::compatible_type compat_allocator_type;

            typedef typename CompatTraits<Tr>::compatible_type   compat_traits_type;

        public:

            typedef Ch     char_type;

            typedef Tr     traits_type;

            typedef typename compat_traits_type::int_type     int_type;

            typedef typename compat_traits_type::pos_type     pos_type;

            typedef typename compat_traits_type::off_type     off_type;

            typedef Alloc                     allocator_type;

            typedef ::std::basic_string<Ch, Tr, Alloc> string_type;

            typedef typename string_type::size_type    size_type;



            typedef ::std::streamsize streamsize;





            explicit basic_altstringbuf(std::ios_base::openmode mode

                                        = std::ios_base::in | std::ios_base::out)

                : putend_(NULL), is_allocated_(false), mode_(mode) 

                {}

            explicit basic_altstringbuf(const string_type& s,

                                        ::std::ios_base::openmode mode

                                        = ::std::ios_base::in | ::std::ios_base::out)

                : putend_(NULL), is_allocated_(false), mode_(mode) 

                { dealloc(); str(s); }

            virtual ~basic_altstringbuf() 

                { dealloc(); }

            using streambuf_t::pbase;

            using streambuf_t::pptr;

            using streambuf_t::epptr;

            using streambuf_t::eback;

            using streambuf_t::gptr;

            using streambuf_t::egptr;

    

            void clear_buffer();

            void str(const string_type& s);



            // 0-copy access :

            Ch * begin() const; 

            size_type size() const;

            size_type cur_size() const; // stop at current pointer

            Ch * pend() const // the highest position reached by pptr() since creation

                { return ((putend_ < pptr()) ? pptr() : putend_); }

            size_type pcount() const 

                { return static_cast<size_type>( pptr() - pbase()) ;}



            // copy buffer to string :

            string_type str() const 

                { return string_type(begin(), size()); }

            string_type cur_str() const 

                { return string_type(begin(), cur_size()); }

        protected:

            explicit basic_altstringbuf (basic_altstringbuf * s,

                                         ::std::ios_base::openmode mode 

                                         = ::std::ios_base::in | ::std::ios_base::out)

                : putend_(NULL), is_allocated_(false), mode_(mode) 

                { dealloc(); str(s); }



            virtual pos_type seekoff(off_type off, ::std::ios_base::seekdir way, 

                                     ::std::ios_base::openmode which 

                                     = ::std::ios_base::in | ::std::ios_base::out);

            virtual pos_type seekpos (pos_type pos, 

                                      ::std::ios_base::openmode which 

                                      = ::std::ios_base::in | ::std::ios_base::out);

            virtual int_type underflow();

            virtual int_type pbackfail(int_type meta = compat_traits_type::eof());

            virtual int_type overflow(int_type meta = compat_traits_type::eof());

            void dealloc();

        private:

            enum { alloc_min = 256}; // minimum size of allocations



            Ch *putend_;  // remembers (over seeks) the highest value of pptr()

            bool is_allocated_;

            ::std::ios_base::openmode mode_;

            compat_allocator_type alloc_;  // the allocator object

        };





// ---   class basic_oaltstringstream ----------------------------------------

        template <class Ch, class Tr, class Alloc>

        class basic_oaltstringstream 

            : private base_from_member< shared_ptr< basic_altstringbuf< Ch, Tr, Alloc> > >,

              public ::std::basic_ostream<Ch, Tr>

        {

            class No_Op { 

                // used as no-op deleter for (not-owner) shared_pointers

            public: 

                template<class T>

                const T & operator()(const T & arg) { return arg; }

            };

            typedef ::std::basic_ostream<Ch, Tr> stream_t;

            typedef boost::base_from_member<boost::shared_ptr<

                basic_altstringbuf<Ch,Tr, Alloc> > > 

                pbase_type;

            typedef ::std::basic_string<Ch, Tr, Alloc>  string_type;

            typedef typename string_type::size_type     size_type;

            typedef basic_altstringbuf<Ch, Tr, Alloc>   stringbuf_t;

        public:

            typedef Alloc  allocator_type;

            basic_oaltstringstream() 

                : pbase_type(new stringbuf_t), stream_t(rdbuf()) 

                { }

            basic_oaltstringstream(::boost::shared_ptr<stringbuf_t> buf) 

                : pbase_type(buf), stream_t(rdbuf()) 

                { }

            basic_oaltstringstream(stringbuf_t * buf) 

                : pbase_type(buf, No_Op() ), stream_t(rdbuf()) 

                { }

            stringbuf_t * rdbuf() const 

                { return pbase_type::member.get(); }

            void clear_buffer() 

                { rdbuf()->clear_buffer(); }



            // 0-copy access :

            Ch * begin() const 

                { return rdbuf()->begin(); }

            size_type size() const 

                { return rdbuf()->size(); }

            size_type cur_size() const // stops at current position

                { return rdbuf()->cur_size(); }



            // copy buffer to string :

            string_type str()     const   // [pbase, epptr[

                { return rdbuf()->str(); } 

            string_type cur_str() const   // [pbase, pptr[

                { return rdbuf()->cur_str(); }

            void str(const string_type& s) 

                { rdbuf()->str(s); }

        };



    } // N.S. io

} // N.S. boost



#include <boost/format/alt_sstream_impl.hpp>



#endif // include guard



