rippled/include/xrpl/protocol/XRPAmount.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#ifndef RIPPLE_PROTOCOL_XRPAMOUNT_H_INCLUDED
#define RIPPLE_PROTOCOL_XRPAMOUNT_H_INCLUDED

#include <xrpl/basics/Number.h>
#include <xrpl/basics/contract.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/json/json_value.h>
#include <xrpl/protocol/FeeUnits.h>

#include <boost/multiprecision/cpp_int.hpp>
#include <boost/operators.hpp>

#include <cstdint>
#include <optional>
#include <string>
#include <type_traits>

namespace ripple {

class XRPAmount : private boost::totally_ordered<XRPAmount>,
                  private boost::additive<XRPAmount>,
                  private boost::equality_comparable<XRPAmount, std::int64_t>,
                  private boost::additive<XRPAmount, std::int64_t>
{
public:
    using unit_type = feeunit::dropTag;
    using value_type = std::int64_t;

private:
    value_type drops_;

public:
    XRPAmount() = default;
    constexpr XRPAmount(XRPAmount const& other) = default;
    constexpr XRPAmount&
    operator=(XRPAmount const& other) = default;

    // Round to nearest, even on tie.
    explicit XRPAmount(Number const& x) : XRPAmount(static_cast<value_type>(x))
    {
    }

    constexpr XRPAmount(beast::Zero) : drops_(0)
    {
    }

    constexpr XRPAmount&
    operator=(beast::Zero)
    {
        drops_ = 0;
        return *this;
    }

    constexpr explicit XRPAmount(value_type drops) : drops_(drops)
    {
    }

    XRPAmount&
    operator=(value_type drops)
    {
        drops_ = drops;
        return *this;
    }

    constexpr XRPAmount
    operator*(value_type const& rhs) const
    {
        return XRPAmount{drops_ * rhs};
    }

    friend constexpr XRPAmount
    operator*(value_type lhs, XRPAmount const& rhs)
    {
        // multiplication is commutative
        return rhs * lhs;
    }

    XRPAmount&
    operator+=(XRPAmount const& other)
    {
        drops_ += other.drops();
        return *this;
    }

    XRPAmount&
    operator-=(XRPAmount const& other)
    {
        drops_ -= other.drops();
        return *this;
    }

    XRPAmount&
    operator+=(value_type const& rhs)
    {
        drops_ += rhs;
        return *this;
    }

    XRPAmount&
    operator-=(value_type const& rhs)
    {
        drops_ -= rhs;
        return *this;
    }

    XRPAmount&
    operator*=(value_type const& rhs)
    {
        drops_ *= rhs;
        return *this;
    }

    XRPAmount
    operator-() const
    {
        return XRPAmount{-drops_};
    }

    bool
    operator==(XRPAmount const& other) const
    {
        return drops_ == other.drops_;
    }

    bool
    operator==(value_type other) const
    {
        return drops_ == other;
    }

    bool
    operator<(XRPAmount const& other) const
    {
        return drops_ < other.drops_;
    }

    /** Returns true if the amount is not zero */
    explicit constexpr
    operator bool() const noexcept
    {
        return drops_ != 0;
    }

    operator Number() const noexcept
    {
        return drops();
    }

    /** Return the sign of the amount */
    constexpr int
    signum() const noexcept
    {
        return (drops_ < 0) ? -1 : (drops_ ? 1 : 0);
    }

    /** Returns the number of drops */
    constexpr value_type
    drops() const
    {
        return drops_;
    }

    constexpr double
    decimalXRP() const;

    template <class Dest>
    std::optional<Dest>
    dropsAs() const
    {
        if ((drops_ > std::numeric_limits<Dest>::max()) ||
            (!std::numeric_limits<Dest>::is_signed && drops_ < 0) ||
            (std::numeric_limits<Dest>::is_signed &&
             drops_ < std::numeric_limits<Dest>::lowest()))
        {
            return std::nullopt;
        }
        return static_cast<Dest>(drops_);
    }

    template <class Dest>
    Dest
    dropsAs(Dest defaultValue) const
    {
        return dropsAs<Dest>().value_or(defaultValue);
    }

    template <class Dest>
    Dest
    dropsAs(XRPAmount defaultValue) const
    {
        return dropsAs<Dest>().value_or(defaultValue.drops());
    }

    /* Clips a 64-bit value to a 32-bit JSON number. It is only used
     * in contexts that don't expect the value to ever approach
     * the 32-bit limits (i.e. fees and reserves).
     */
    Json::Value
    jsonClipped() const
    {
        static_assert(
            std::is_signed_v<value_type> && std::is_integral_v<value_type>,
            "Expected XRPAmount to be a signed integral type");

        constexpr auto min = std::numeric_limits<Json::Int>::min();
        constexpr auto max = std::numeric_limits<Json::Int>::max();

        if (drops_ < min)
            return min;
        if (drops_ > max)
            return max;
        return static_cast<Json::Int>(drops_);
    }

    /** Returns the underlying value. Code SHOULD NOT call this
        function unless the type has been abstracted away,
        e.g. in a templated function.
    */
    constexpr value_type
    value() const
    {
        return drops_;
    }

    friend std::istream&
    operator>>(std::istream& s, XRPAmount& val)
    {
        s >> val.drops_;
        return s;
    }

    static XRPAmount
    minPositiveAmount()
    {
        return XRPAmount{1};
    }
};

/** Number of drops per 1 XRP */
constexpr XRPAmount DROPS_PER_XRP{1'000'000};

constexpr double
XRPAmount::decimalXRP() const
{
    return static_cast<double>(drops_) / DROPS_PER_XRP.drops();
}

// Output XRPAmount as just the drops value.
template <class Char, class Traits>
std::basic_ostream<Char, Traits>&
operator<<(std::basic_ostream<Char, Traits>& os, const XRPAmount& q)
{
    return os << q.drops();
}

inline std::string
to_string(XRPAmount const& amount)
{
    return std::to_string(amount.drops());
}

inline XRPAmount
mulRatio(
    XRPAmount const& amt,
    std::uint32_t num,
    std::uint32_t den,
    bool roundUp)
{
    using namespace boost::multiprecision;

    if (!den)
        Throw<std::runtime_error>("division by zero");

    int128_t const amt128(amt.drops());
    auto const neg = amt.drops() < 0;
    auto const m = amt128 * num;
    auto r = m / den;
    if (m % den)
    {
        if (!neg && roundUp)
            r += 1;
        if (neg && !roundUp)
            r -= 1;
    }
    if (r > std::numeric_limits<XRPAmount::value_type>::max())
        Throw<std::overflow_error>("XRP mulRatio overflow");
    return XRPAmount(r.convert_to<XRPAmount::value_type>());
}

}  // namespace ripple

#endif  // RIPPLE_BASICS_XRPAMOUNT_H_INCLUDED