getuntil.hpp

c++ の getline は、なんとなく改行コードまでを取得するという仕様で、ネットのプロトコル等で利用するには、不満が残ります。そこで、汎用的な以下のようなものが有用ではないか？と思い、以前に作成したものを貼っときます。

>>> getuntil.hpp

//
// Distributed under 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)
//
// Copyright (c) 2007 OKI Miyuki (oki.miyuki at gmail dot com)
//
#include <iostream>
#include <string>

template<typename CharT, typename CharTraits, typename Allocator>
std::basic_istream<CharT, CharTraits>& getuntil(
std::basic_istream<CharT, CharTraits>&  istrm,
std::basic_string<CharT, CharTraits, Allocator>& str,
const std::basic_string<CharT, CharTraits, Allocator>& delm
) {
typedef std::basic_istream<CharT, CharTraits> istrm_type;
std::ios_base::iostate cur_state  =  std::ios_base::goodbit;
bool read_once = false;
const typename istrm_type::sentry sync( istrm, true );
if( sync ) {
  try {
    str.clear();
    typename CharTraits::int_type row_xor  =  0;
    typename CharTraits::int_type ins_xor  =  0;
    size_t delm_len  =  delm.size();
    typename CharTraits::int_type val = istrm.rdbuf()->sgetc();
    for( size_t i = 0; i < delm_len - 1; ++i, val = istrm.rdbuf()->snextc() ) {
        if( CharTraits::eq_int_type( CharTraits::eof(), val ) )  break;
        read_once  =  true;
        ins_xor   ^=  val;
        row_xor   ^=  CharTraits::to_int_type( delm[ i ] );
        str       +=  CharTraits::to_char_type( val );
    }
    row_xor  ^=  CharTraits::to_int_type( *delm.rbegin() );
    for( size_t ipos = 0; ; val = istrm.rdbuf()->snextc(), ++ipos ) {
      if( CharTraits::eq_int_type( CharTraits::eof(), val ) ) {
        cur_state  |=  std::ios_base::eofbit;
        break;
      }
      read_once =  true;
      ins_xor  ^=  val;
      str      +=  CharTraits::to_char_type( val );
      if(
        ins_xor == row_xor
        && val == CharTraits::to_int_type( *delm.rbegin() )
        && str.substr( ipos ) == delm
      ) {
        istrm.rdbuf()->sbumpc();
        break;
      }
      if( str.max_size() <= str.size() ) {
        cur_state  |=  std::ios_base::failbit;
        break;
      }
      ins_xor  ^=  CharTraits::to_int_type( str[ipos] );
    }
  } catch(...) {
    istrm.setstate( std::ios_base::badbit, true );
  }
}
if( !read_once ) {
  cur_state  |=  std::ios_base::failbit;
}
istrm.setstate( cur_state );

return istrm;
}

template<typename CharT, typename CharTraits, typename Allocator>
std::basic_istream<CharT, CharTraits>& getuntil(
std::basic_istream<CharT, CharTraits>&  istrm,
std::basic_string<CharT, CharTraits, Allocator>& str,
const CharT* delm
) {
std::basic_string<CharT,CharTraits,Allocator> delimiter( delm );
return getuntil( istrm, str, delimiter );
}

　使い方は、こんな感じです。

>>> getuntil.cpp

#include "getuntil.hpp"
#include <fstream>
#include <sstream>
#include <iomanip>

#include <boost/asio.hpp>

int main() {
std::ifstream ifs( "getuntil.cpp", std::ios::binary );

int i  =  0;
std::string delm( "\r\n" );
std::string line;
while( ifs.good() ) {
  getuntil( ifs, line, delm );
  std::cout << std::setw(3) << ++i << ": " << line;
}

std::cout << std::endl;
std::cout << "Enter stringstream test" << std::endl;

std::stringstream  ss;
ss << "high-ho, high-ho!";
ss << "It's home from work we go! high-ho, high-ho!...";

while( ss.good() ) {
  getuntil( ss, line, "ho!" );
  std::cout << line << std::endl;
}

std::cout << std::endl;
std::cout << "Enter boost::asio::streambuf test" << std::endl;

boost::asio::streambuf  sb;

std::ostream  ostrm( &sb );
ostrm << "This is data from client\r\n";
ostrm << "And flying send\r\n";

std::istream  istrm( &sb );

while( istrm.good() ) {
  getuntil( istrm, line, "\r\n" );
  std::cout << line;
}
}