daw_fp_fallback.h

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// Copyright (c) Darrell Wright
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/beached/daw_json_link
//
 
#pragma once
 
#include "version.h"
 
#include "daw_json_assert.h"
 
#include <daw/daw_attributes.h>
#include <daw/daw_cpp_feature_check.h>
 
#include <cstdlib>
#include <limits>
#include <system_error>
#include <type_traits>
 
#if not defined( DAW_JSON_USE_STRTOD )
#include <charconv>
#endif
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace json_details {
      template<typename Real>
      DAW_ATTRIB_NOINLINE DAW_ATTRIB_NONNULL( ) [[nodiscard]] Real
        parse_with_strtod( char const *first, char const *last ) {
        static_assert( std::is_floating_point_v<Real>,
                       "Unexpected type passed to parse_with_strtod" );
#if defined( DAW_JSON_USE_STRTOD )
        (void)last;
        char **end = nullptr;
        if constexpr( std::is_same_v<Real, float> ) {
          return static_cast<Real>( std::strtof( first, end ) );
        } else if( std::is_same_v<Real, double> ) {
          return static_cast<Real>( std::strtod( first, end ) );
        } else {
          return static_cast<Real>( std::strtold( first, end ) );
        }
#else
        Real result;
        auto fc_res = std::from_chars( first, last, result );
        if( fc_res.ec == std::errc::result_out_of_range ) {
          if( *first == '-' ) {
            return -std::numeric_limits<Real>::infinity( );
          }
          return std::numeric_limits<Real>::infinity( );
        }
        daw_json_ensure( fc_res.ec == std::errc( ),
                         ErrorReason::InvalidNumber );
        return result;
#endif
      }
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json