/data/refman/pasoursint/CMSSW_5_3_0/src/PhysicsTools/MVAComputer/interface/memstream.h

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#ifndef PhysicsTools_MVAComputer_memstream_h
#define PhysicsTools_MVAComputer_memstream_h
// -*- C++ -*-
//
// Package:     MVAComputer
//

//
// Author:      Christophe Saout <christophe.saout@cern.ch>
// Created:     Sat Apr 24 15:18 CEST 2007
// $Id: memstream.h,v 1.4 2011/05/23 13:41:03 eulisse Exp $
//

#include <iostream>

namespace ext {

// provide STL stream to read/write into memory buffers
//
// constructors both take pointer to a buffer and buffer size

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_omemstream : private std::basic_streambuf<Item_t, Traits_t>,
                         public std::basic_ostream<Item_t, Traits_t> {
    public:
        typedef typename Traits_t::char_type    char_type;
        typedef typename Traits_t::int_type     int_type;
        typedef Traits_t                        traits_type;

        basic_omemstream(char_type *buf, size_t size) :
                        std::basic_ostream<Item_t, Traits_t>(this),
                        buffer(buf), cur(buf), last(buf + size)
        { this->exceptions(std::ios_base::badbit); }

        char_type* begin() const { return buffer; }
        char_type* end() const { return cur; }
        size_t size() const { return cur - buffer; }
        bool empty() const { return cur == buffer; }

    private:
        std::streamsize xsputn(char_type const *data, std::streamsize size) {
                size_t n = std::min<size_t>(last - cur, size);
                traits_type::copy(cur, data, n);
                cur += n;
                return n;
        }

        int_type overflow(int_type c)
        {
                if (!traits_type::eq_int_type(c, traits_type::eof())) {
                        char_type t = traits_type::to_char_type(c);
                        if (xsputn(&t, 1) < 1)
                                return traits_type::eof();
                }

                return c;
        }

        int sync() { return 0; }

        char_type       *buffer, *cur, *last;
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_imemstream : private std::basic_streambuf<Item_t, Traits_t>,
                         public std::basic_istream<Item_t, Traits_t> {
    public:
        typedef typename Traits_t::char_type    char_type;
        typedef typename Traits_t::int_type     int_type;
        typedef Traits_t                        traits_type;

        basic_imemstream(const char_type *buf, size_t size) :
                        std::basic_istream<Item_t, Traits_t>(this)
        {
                this->exceptions(std::ios_base::badbit);
                this->setg(const_cast<char_type*>(buf),
                     const_cast<char_type*>(buf),
                     const_cast<char_type*>(buf + size));
        }

    private:
        int_type underflow()
        {
                if (this->gptr() && this->gptr() < this->egptr())
                        return traits_type::to_int_type(*this->gptr());

                return traits_type::eof();
        }
};

typedef basic_omemstream<char>          omemstream;
typedef basic_omemstream<wchar_t>       womemstream;
typedef basic_imemstream<char>          imemstream;
typedef basic_imemstream<wchar_t>       wimemstream;

} // namespace ext

#endif // PhysicsTools_MVAComputer_memstream_h