// 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_CSTREAM_READER_HPP

#define TAO_PEGTL_INTERNAL_CSTREAM_READER_HPP

#include <cassert>

#include <cstddef>

#include <cstdio>

#include "../config.hpp"

#include "../input_error.hpp"

namespace tao

{

   namespace TAO_PEGTL_NAMESPACE

   {

      namespace internal

      {

         struct cstream_reader

         {

            explicit cstream_reader( std::FILE* s ) noexcept

               : m_cstream( s )

            {

               assert( m_cstream != nullptr );

            }

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

            {

               if( const auto r = std::fread( buffer, 1, length, m_cstream ) ) {

                  return r;

               }

               if( std::feof( m_cstream ) != 0 ) {

                  return 0;

               }

               // Please contact us if you know how to provoke the following exception.

               // The example on cppreference.com doesn't work, at least not on macOS.

               TAO_PEGTL_THROW_INPUT_ERROR( "error in fread() from cstream" );  // LCOV_EXCL_LINE

            }

            std::FILE* m_cstream;

         };

      }  // namespace internal

   }  // namespace TAO_PEGTL_NAMESPACE

}  // namespace tao

#endif