// Copyright (c) 2016-2020 Dr. Colin Hirsch and Daniel Frey

// Please see LICENSE for license or visit https://github.com/taocpp/PEGTL/

#ifndef TAO_PEGTL_INTERNAL_ISTREAM_READER_HPP

#define TAO_PEGTL_INTERNAL_ISTREAM_READER_HPP

#include <istream>

#include "../config.hpp"

#include "../input_error.hpp"

namespace tao

{

   namespace TAO_PEGTL_NAMESPACE

   {

      namespace internal

      {

         struct istream_reader

         {

            explicit istream_reader( std::istream& s ) noexcept

               : m_istream( s )

            {

            }

            std::size_t operator()( char* buffer, const std::size_t length )

            {

               m_istream.read( buffer, std::streamsize( length ) );

               if( const auto r = m_istream.gcount() ) {

                  return std::size_t( r );

               }

               if( m_istream.eof() ) {

                  return 0;

               }

               TAO_PEGTL_THROW_INPUT_ERROR( "error in istream.read()" );

            }

            std::istream& m_istream;

         };

      }  // namespace internal

   }  // namespace TAO_PEGTL_NAMESPACE

}  // namespace tao

#endif