numeric_utils.hpp

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        {
            return true;
        }

        template <typename Char, typename T>
        static bool
        call(Char ch, std::size_t count, T& n)
        {
            return call(ch, count, n
              , mpl::bool_<
                    (   (MaxDigits < 0)
                    ||  (MaxDigits > radix_traits<Radix>::template digits<T>::value)
                    )
                  && std::numeric_limits<T>::is_modulo
                >()
            );
        }
    };

    ///////////////////////////////////////////////////////////////////////////
    //  End of loop checking: check if the number of digits
    //  being parsed exceeds MaxDigits. Note: if MaxDigits == -1
    //  we don't do any checking.
    ///////////////////////////////////////////////////////////////////////////
    template <int MaxDigits>
    struct check_max_digits
    {
        static bool
        call(std::size_t count)
        {
            return count < MaxDigits; // bounded
        }
    };

    template <>
    struct check_max_digits<-1>
    {
        static bool
        call(std::size_t /*count*/)
        {
            return true; // unbounded
        }
    };

    ///////////////////////////////////////////////////////////////////////////
    //  extract_int: main code for extracting integers
    ///////////////////////////////////////////////////////////////////////////
#define SPIRIT_NUMERIC_INNER_LOOP(z, x, data)                                   \
        if (!check_max_digits<MaxDigits>::call(count + leading_zeros)           \
            || it == last)                                                      \
            break;                                                              \
        ch = *it;                                                               \
        if (!radix_check::is_valid(ch) || !extractor::call(ch, count, val))     \
            break;                                                              \
        ++it;                                                                   \
        ++count;                                                                \
    /**/

    template <
        typename T, unsigned Radix, unsigned MinDigits, int MaxDigits
      , typename Accumulator = positive_accumulator<Radix>
      , bool Accumulate = false
    >
    struct extract_int
    {
#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
# pragma warning(push)  
# pragma warning(disable: 4127)   // conditional expression is constant
#endif 
        template <typename Iterator, typename Attribute>
        static bool
        parse_main(
            Iterator& first
          , Iterator const& last
          , Attribute& attr)
        {
            typedef radix_traits<Radix> radix_check;
            typedef int_extractor<Radix, Accumulator, MaxDigits> extractor;
            typedef typename
                boost::detail::iterator_traits<Iterator>::value_type
            char_type;

            Iterator it = first;
            std::size_t leading_zeros = 0;
            if (!Accumulate)
            {
                // skip leading zeros
                while (it != last && *it == '0')
                {
                    ++it;
                    ++leading_zeros;
                }
            }

            Attribute val = Accumulate ? attr : 0;
            std::size_t count = 0;
            char_type ch;

            while (true)
            {
                BOOST_PP_REPEAT(
                    SPIRIT_NUMERICS_LOOP_UNROLL
                  , SPIRIT_NUMERIC_INNER_LOOP, _)
            }

            if (count + leading_zeros >= MinDigits)
            {
                attr = val;
                first = it;
                return true;
            }
            return false;
        }
#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
# pragma warning(pop)  
#endif 

        template <typename Iterator>
        static bool
        parse(
            Iterator& first
          , Iterator const& last
          , unused_type)
        {
            T n = 0; // must calculate value to detect over/underflow
            return parse_main(first, last, n);
        }

        template <typename Iterator, typename Attribute>
        static bool
        parse(
            Iterator& first
          , Iterator const& last
          , Attribute& attr)
        {
            return parse_main(first, last, attr);
        }
    };
#undef SPIRIT_NUMERIC_INNER_LOOP

    ///////////////////////////////////////////////////////////////////////////
    //  extract_int: main code for extracting integers
    //  common case where MinDigits == 1 and MaxDigits = -1
    ///////////////////////////////////////////////////////////////////////////
#define SPIRIT_NUMERIC_INNER_LOOP(z, x, data)                                   \
        if (it == last)                                                         \
            break;                                                              \
        ch = *it;                                                               \
        if (!radix_check::is_valid(ch) || !extractor::call(ch, count, val))     \
            break;                                                              \
        ++it;                                                                   \
        ++count;                                                                \
    /**/

    template <typename T, unsigned Radix, typename Accumulator, bool Accumulate>
    struct extract_int<T, Radix, 1, -1, Accumulator, Accumulate>
    {
#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
# pragma warning(push)  
# pragma warning(disable: 4127)   // conditional expression is constant
#endif 
        template <typename Iterator, typename Attribute>
        static bool
        parse_main(
            Iterator& first
          , Iterator const& last
          , Attribute& attr)
        {
            typedef radix_traits<Radix> radix_check;
            typedef int_extractor<Radix, Accumulator, -1> extractor;
            typedef typename
                boost::detail::iterator_traits<Iterator>::value_type
            char_type;

            Iterator it = first;
            std::size_t count = 0;
            if (!Accumulate)
            {
                // skip leading zeros
                while (it != last && *it == '0')
                {
                    ++it;
                    ++count;
                }

                if (it == last)
                {
                    if (count == 0) // must have at least one digit
                        return false;
                    attr = 0;
                    first = it;
                    return true;
                }
            }

            Attribute val = Accumulate ? attr : 0;
            char_type ch = *it;

            if (!radix_check::is_valid(ch) || !extractor::call(ch, 0, val))
            {
                if (count == 0) // must have at least one digit
                    return false;
                attr = val;
                first = it;
                return true;
            }

            count = 0;
            ++it;
            while (true)
            {
                BOOST_PP_REPEAT(
                    SPIRIT_NUMERICS_LOOP_UNROLL
                  , SPIRIT_NUMERIC_INNER_LOOP, _)
            }

            attr = val;
            first = it;
            return true;
        }
#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)  
# pragma warning(pop)  
#endif 

        template <typename Iterator>
        static bool
        parse(
            Iterator& first
          , Iterator const& last
          , unused_type)
        {
            T n = 0; // must calculate value to detect over/underflow
            return parse_main(first, last, n);
        }

        template <typename Iterator, typename Attribute>
        static bool
        parse(
            Iterator& first
          , Iterator const& last
          , Attribute& attr)
        {
            return parse_main(first, last, attr);
        }
    };

#undef SPIRIT_NUMERIC_INNER_LOOP

}}}}

#endif