io_string.h

/*
Copyright (c) 2016 Alexei Novakov
https://github.com/novalexei

Distributed under the Boost Software License, Version 1.0.
http://boost.org/LICENSE_1_0.txt
*/
#ifndef MOD_SERVLET_IO_STRING_H
#define MOD_SERVLET_IO_STRING_H

#include <servlet/lib/io.h>

namespace servlet
{

template<typename CharT, typename Traits = std::char_traits<CharT>>
class string_sink
{
public:
    typedef std::basic_string<CharT, Traits>                    string_type;
    typedef std::experimental::basic_string_view<CharT, Traits> string_view_type;

    string_sink(std::size_t max_size = std::string::npos) : _max_size{max_size} {}

    std::streamsize write(const CharT* s, std::streamsize n)
    {
        if (_max_size <= _chars_written) return 0;
        if (_chars_written + n > _max_size)
        {
            std::streamsize ln = _max_size - _chars_written;
            _buffer.append(s, ln);
            _chars_written = _max_size;
            return ln;
        }
        _buffer.append(s, n);
        _chars_written += n;
        return n;
    }
    void flush() { _flushed = true; }

    void reset() { _buffer.clear(); _flushed = false; _chars_written = 0; }
    string_view_type view() const { return string_view_type{_buffer}; }
    string_type& str() { return _buffer; }
    bool was_flushed() const { return _flushed; }
    std::size_t characters_written() const { return _chars_written; }

private:
    string_type _buffer;
    std::size_t _max_size;
    std::size_t _chars_written = 0;
    bool _flushed = false;
};

template<typename CharT, typename Traits = std::char_traits<CharT>>
using basic_inplace_ostream = basic_outstream<string_sink<CharT, Traits>, non_buffered, CharT, Traits>;
typedef basic_inplace_ostream<char> inplace_ostream;

} // end of servlet namespace

#endif //MOD_SERVLET_IO_STRING_H