boost/boost/format/alt_sstream.hpp

   1 // ----------------------------------------------------------------------------
   2 //  alt_sstream.hpp : alternative stringstream
   3 // ----------------------------------------------------------------------------
   4
   5 //  Copyright Samuel Krempp 2003. Use, modification, and distribution are
   6 //  subject to the Boost Software License, Version 1.0. (See accompanying
   7 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8
   9 //  See http://www.boost.org/libs/format for library home page
  10
  11 // ----------------------------------------------------------------------------
  12
  13
  14
  15 #ifndef BOOST_SK_ALT_SSTREAM_HPP
  16 #define BOOST_SK_ALT_SSTREAM_HPP
  17
  18 #include <string>
  19 #include <boost/format/detail/compat_workarounds.hpp>
  20 #include <boost/utility/base_from_member.hpp>
  21 #include <boost/shared_ptr.hpp>
  22 #include <boost/assert.hpp>
  23
  24 namespace boost {
  25     namespace io {
  26
  27         template<class Ch, class Tr=::std::char_traits<Ch>,
  28                  class Alloc=::std::allocator<Ch> >
  29         class basic_altstringbuf;
  30
  31         template<class Ch, class Tr =::std::char_traits<Ch>,
  32                  class Alloc=::std::allocator<Ch> >
  33         class basic_oaltstringstream;
  34
  35
  36         template<class Ch, class Tr, class Alloc>
  37         class basic_altstringbuf
  38             : public ::std::basic_streambuf<Ch, Tr>
  39         {
  40             typedef ::std::basic_streambuf<Ch, Tr>  streambuf_t;
  41             typedef typename CompatAlloc<Alloc>::compatible_type compat_allocator_type;
  42             typedef typename CompatTraits<Tr>::compatible_type   compat_traits_type;
  43         public:
  44             typedef Ch     char_type;
  45             typedef Tr     traits_type;
  46             typedef typename compat_traits_type::int_type     int_type;
  47             typedef typename compat_traits_type::pos_type     pos_type;
  48             typedef typename compat_traits_type::off_type     off_type;
  49             typedef Alloc                     allocator_type;
  50             typedef ::std::basic_string<Ch, Tr, Alloc> string_type;
  51
  52             typedef ::std::streamsize streamsize;
  53
  54
  55             explicit basic_altstringbuf(std::ios_base::openmode mode
  56                                         = std::ios_base::in | std::ios_base::out)
  57                 : putend_(NULL), is_allocated_(false), mode_(mode)
  58                 {}
  59             explicit basic_altstringbuf(const string_type& s,
  60                                         ::std::ios_base::openmode mode
  61                                         = ::std::ios_base::in | ::std::ios_base::out)
  62                 : putend_(NULL), is_allocated_(false), mode_(mode)
  63                 { dealloc(); str(s); }
  64             virtual ~basic_altstringbuf()
  65                 { dealloc(); }
  66             using streambuf_t::pbase;
  67             using streambuf_t::pptr;
  68             using streambuf_t::epptr;
  69             using streambuf_t::eback;
  70             using streambuf_t::gptr;
  71             using streambuf_t::egptr;
  72
  73             void clear_buffer();
  74             void str(const string_type& s);
  75
  76             // 0-copy access :
  77             Ch * begin() const;
  78             streamsize size() const;
  79             streamsize cur_size() const; // stop at current pointer
  80             Ch * pend() const // the highest position reached by pptr() since creation
  81                 { return ((putend_ < pptr()) ? pptr() : putend_); }
  82             streamsize pcount() const
  83                 { return static_cast<streamsize>( pptr() - pbase()) ;}
  84
  85             // copy buffer to string :
  86             string_type str() const
  87                 { return string_type(begin(), size()); }
  88             string_type cur_str() const
  89                 { return string_type(begin(), cur_size()); }
  90         protected:
  91             explicit basic_altstringbuf (basic_altstringbuf * s,
  92                                          ::std::ios_base::openmode mode
  93                                          = ::std::ios_base::in | ::std::ios_base::out)
  94                 : putend_(NULL), is_allocated_(false), mode_(mode)
  95                 { dealloc(); str(s); }
  96
  97             virtual pos_type seekoff(off_type off, ::std::ios_base::seekdir way,
  98                                      ::std::ios_base::openmode which
  99                                      = ::std::ios_base::in | ::std::ios_base::out);
 100             virtual pos_type seekpos (pos_type pos,
 101                                       ::std::ios_base::openmode which
 102                                       = ::std::ios_base::in | ::std::ios_base::out);
 103             virtual int_type underflow();
 104             virtual int_type pbackfail(int_type meta = compat_traits_type::eof());
 105             virtual int_type overflow(int_type meta = compat_traits_type::eof());
 106             void dealloc();
 107         private:
 108             enum { alloc_min = 256}; // minimum size of allocations
 109
 110             Ch *putend_;  // remembers (over seeks) the highest value of pptr()
 111             bool is_allocated_;
 112             ::std::ios_base::openmode mode_;
 113             compat_allocator_type alloc_;  // the allocator object
 114         };
 115
 116
 117 // ---   class basic_oaltstringstream ----------------------------------------
 118         template <class Ch, class Tr, class Alloc>
 119         class basic_oaltstringstream
 120             : private base_from_member< shared_ptr< basic_altstringbuf< Ch, Tr, Alloc> > >,
 121               public ::std::basic_ostream<Ch, Tr>
 122         {
 123             class No_Op {
 124                 // used as no-op deleter for (not-owner) shared_pointers
 125             public:
 126                 template<class T>
 127                 const T & operator()(const T & arg) { return arg; }
 128             };
 129             typedef ::std::basic_ostream<Ch, Tr> stream_t;
 130             typedef boost::base_from_member<boost::shared_ptr<
 131                 basic_altstringbuf<Ch,Tr, Alloc> > >
 132                 pbase_type;
 133             typedef ::std::basic_string<Ch, Tr, Alloc>  string_type;
 134             typedef basic_altstringbuf<Ch, Tr, Alloc>   stringbuf_t;
 135         public:
 136             typedef Alloc  allocator_type;
 137             basic_oaltstringstream()
 138                 : pbase_type(new stringbuf_t), stream_t(rdbuf())
 139                 { }
 140             basic_oaltstringstream(::boost::shared_ptr<stringbuf_t> buf)
 141                 : pbase_type(buf), stream_t(rdbuf())
 142                 { }
 143             basic_oaltstringstream(stringbuf_t * buf)
 144                 : pbase_type(buf, No_Op() ), stream_t(rdbuf())
 145                 { }
 146             stringbuf_t * rdbuf() const
 147                 { return pbase_type::member.get(); }
 148             void clear_buffer()
 149                 { rdbuf()->clear_buffer(); }
 150
 151             // 0-copy access :
 152             Ch * begin() const
 153                 { return rdbuf()->begin(); }
 154             ::std::streamsize size() const
 155                 { return rdbuf()->size(); }
 156             ::std::streamsize cur_size() const // stops at current position
 157                 { return rdbuf()->cur_size(); }
 158
 159             // copy buffer to string :
 160             string_type str()     const   // [pbase, epptr[
 161                 { return rdbuf()->str(); }
 162             string_type cur_str() const   // [pbase, pptr[
 163                 { return rdbuf()->cur_str(); }
 164         };
 165
 166     } // N.S. io
 167 } // N.S. boost
 168
 169 #include <boost/format/alt_sstream_impl.hpp>
 170
 171 #endif // include guard
 172