ClickHouse/base/base/wide_integer_to_string.h

#pragma once

#include <string>
#include <ostream>
#include <fmt/format.h>

#include "wide_integer.h"


namespace wide
{

template <size_t Bits, typename Signed>
inline std::string to_string(const integer<Bits, Signed> & n)
{
    std::string res;
    if (integer<Bits, Signed>::_impl::operator_eq(n, 0U))
        return "0";

    integer<Bits, unsigned> t;
    bool is_neg = integer<Bits, Signed>::_impl::is_negative(n);
    if (is_neg)
        t = integer<Bits, Signed>::_impl::operator_unary_minus(n);
    else
        t = n;

    while (!integer<Bits, unsigned>::_impl::operator_eq(t, 0U))
    {
        res.insert(res.begin(), '0' + char(integer<Bits, unsigned>::_impl::operator_percent(t, 10U)));
        t = integer<Bits, unsigned>::_impl::operator_slash(t, 10U);
    }

    if (is_neg)
        res.insert(res.begin(), '-');
    return res;
}

}


template <size_t Bits, typename Signed>
std::ostream & operator<<(std::ostream & out, const wide::integer<Bits, Signed> & value)
{
    return out << to_string(value);
}


/// See https://fmt.dev/latest/api.html#formatting-user-defined-types
template <size_t Bits, typename Signed>
struct fmt::formatter<wide::integer<Bits, Signed>>
{
    constexpr auto parse(format_parse_context & ctx)
    {
        auto it = ctx.begin();
        auto end = ctx.end();

        /// Only support {}.
        if (it != end && *it != '}')
            throw format_error("invalid format");

        return it;
    }

    template <typename FormatContext>
    auto format(const wide::integer<Bits, Signed> & value, FormatContext & ctx)
    {
        return format_to(ctx.out(), "{}", to_string(value));
    }
};