alt_sstream_impl.hpp

CGAL is a collaborative effort of several sites in Europe and Israel. The goal is to make the most i

// ----------------------------------------------------------------------------
//  alt_sstream_impl.hpp : alternative stringstream, templates implementation 
// ----------------------------------------------------------------------------

//  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_IMPL_HPP
#define BOOST_SK_ALT_SSTREAM_IMPL_HPP

namespace boost {
    namespace io {
// --- Implementation  ------------------------------------------------------//

        template<class Ch, class Tr, class Alloc>
        void basic_altstringbuf<Ch, Tr, Alloc>:: 
        clear_buffer () {
            const Ch * p = pptr();
            const Ch * b = pbase();
            if(p != NULL && p != b) {
                seekpos(0, ::std::ios_base::out); 
            }
            p = gptr();
            b = eback();
            if(p != NULL && p != b) {
                seekpos(0, ::std::ios_base::in); 
            }
        }

        template<class Ch, class Tr, class Alloc>
        void basic_altstringbuf<Ch, Tr, Alloc>:: 
        str (const string_type& s) {
            std::size_t sz=s.size();
            if(sz != 0 && mode_ & (::std::ios_base::in | ::std::ios_base::out) ) {
                Ch *new_ptr = alloc_.allocate(sz, is_allocated_? eback() : 0);
                // if this didnt throw, we're safe, update the buffer
                dealloc();
                sz = s.copy(new_ptr);
                putend_ = new_ptr + sz;
                if(mode_ & ::std::ios_base::in)
                    streambuf_t::setg(new_ptr, new_ptr, new_ptr + sz);
                if(mode_ & ::std::ios_base::out) {
                    streambuf_t::setp(new_ptr, new_ptr + sz);
                    if(mode_ & (::std::ios_base::app | ::std::ios_base::ate))
                        streambuf_t::pbump(sz);
                    if(gptr() == NULL)
                        streambuf_t::setg(new_ptr, NULL, new_ptr);
                }
                is_allocated_ = true;
            }
            else 
                dealloc();
        }
        template<class Ch, class Tr, class Alloc>
        Ch*   basic_altstringbuf<Ch, Tr, Alloc>:: 
        begin () const {
            if(mode_ & ::std::ios_base::out && pptr() != NULL)
                return pbase();
            else if(mode_ & ::std::ios_base::in && gptr() != NULL)
                return eback();
            return NULL;
        }

        template<class Ch, class Tr, class Alloc>
        std::streamsize  basic_altstringbuf<Ch, Tr, Alloc>:: 
        size () const { 
            if(mode_ & ::std::ios_base::out && pptr())
                return static_cast<streamsize>( pend() - pbase());
            else if(mode_ & ::std::ios_base::in && gptr())
                return static_cast<streamsize>( egptr() - eback());
            else 
                return 0;
        }

        template<class Ch, class Tr, class Alloc>
        std::streamsize  basic_altstringbuf<Ch, Tr, Alloc>:: 
        cur_size () const { 
            if(mode_ & ::std::ios_base::out && pptr())
                return static_cast<streamsize>( pptr() - pbase());
            else if(mode_ & ::std::ios_base::in && gptr())
                return static_cast<streamsize>( gptr() - eback());
            else 
                return 0;
        }

        template<class Ch, class Tr, class Alloc>
        typename basic_altstringbuf<Ch, Tr, Alloc>::pos_type  
        basic_altstringbuf<Ch, Tr, Alloc>:: 
        seekoff (off_type off, ::std::ios_base::seekdir way, ::std::ios_base::openmode which) {
            if(pptr() != NULL && putend_ < pptr())
                putend_ = pptr();
            if(which & ::std::ios_base::in && gptr() != NULL) {
                // get area
                if(way == ::std::ios_base::end)
                    off += putend_ - eback();
                else if(way == ::std::ios_base::cur && (which & ::std::ios_base::out) == 0)
                    off += gptr() - eback();
                else if(way != ::std::ios_base::beg)
                    off = off_type(-1);
                if(0 <= off && off <= putend_ - eback()) {
                    // set gptr
                    streambuf_t::gbump(off + (eback() - gptr()));
                    if(which & ::std::ios_base::out && pptr() != NULL)
                        // update pptr to match gptr
                        streambuf_t::pbump(gptr()-pptr());
                }
                else
                    off = off_type(-1);
            }
            else if(which & ::std::ios_base::out && pptr() != NULL) {
                // put area
                if(way == ::std::ios_base::end)
                    off += putend_ - eback();
                else if(way == ::std::ios_base::cur)
                    off += pptr() - eback();
                else if(way != ::std::ios_base::beg)
                    off = off_type(-1);

                if(0 <= off && off <= putend_ - eback())
                    // set pptr
                    streambuf_t::pbump((int)(eback() - pptr() + off)); 
                else
                    off = off_type(-1);
            }
            else // neither in nor out
                off = off_type(-1);
            return (pos_type(off));
        }
        //- end seekoff(..)

        
        template<class Ch, class Tr, class Alloc>
        typename basic_altstringbuf<Ch, Tr, Alloc>::pos_type 
        basic_altstringbuf<Ch, Tr, Alloc>:: 
        seekpos (pos_type pos, ::std::ios_base::openmode which) {
            off_type off = off_type(pos); // operation guaranteed by