STNumber.cpp

#include <xrpl/protocol/STNumber.h>
 
#include <xrpl/basics/Number.h>
#include <xrpl/basics/contract.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/json/json_value.h>
#include <xrpl/protocol/Asset.h>
#include <xrpl/protocol/Rules.h>  // IWYU pragma: keep
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STAmount.h>
#include <xrpl/protocol/STBase.h>
#include <xrpl/protocol/STTakesAsset.h>
#include <xrpl/protocol/Serializer.h>
 
#include <boost/lexical_cast.hpp>
#include <boost/regex/v5/regbase.hpp>
#include <boost/regex/v5/regex.hpp>
#include <boost/regex/v5/regex_match.hpp>
 
#include <cstddef>
#include <cstdint>
#include <format>
#include <limits>
#include <ostream>
#include <stdexcept>
#include <string>
#include <utility>
 
namespace xrpl {
 
STNumber::STNumber(SField const& field, Number const& value) : STTakesAsset(field), value_(value)
{
}
 
STNumber::STNumber(SerialIter& sit, SField const& field) : STTakesAsset(field)
{
    // We must call these methods in separate statements
    // to guarantee their order of execution.
    auto mantissa = sit.geti64();
    auto exponent = sit.geti32();
    value_ = Number{mantissa, exponent};
}
 
SerializedTypeID
STNumber::getSType() const
{
    return STI_NUMBER;
}
 
std::string
STNumber::getText() const
{
    return to_string(value_);
}
 
void
STNumber::associateAsset(Asset const& a)
{
    STTakesAsset::associateAsset(a);
 
    XRPL_ASSERT_PARTS(
        getFName().shouldMeta(SField::kSmdNeedsAsset),
        "STNumber::associateAsset",
        "field needs asset");
 
    roundToAsset(a, value_);
}
 
void
STNumber::add(Serializer& s) const
{
    XRPL_ASSERT(getFName().isBinary(), "xrpl::STNumber::add : field is binary");
    XRPL_ASSERT(getFName().fieldType == getSType(), "xrpl::STNumber::add : field type match");
 
    auto value = value_;
    auto const mantissa = value.mantissa();
    auto const exponent = value.exponent();
 
    SField const& field = getFName();
    if (field.shouldMeta(SField::kSmdNeedsAsset))
    {
        // asset is defined in the STTakesAsset base class
        if (asset_)
        {
            // The number should be rounded to the asset's precision, but round
            // it here if it has an asset assigned.
            roundToAsset(*asset_, value);
            XRPL_ASSERT_PARTS(value_ == value, "xrpl::STNumber::add", "value is already rounded");
        }
        else
        {
            // There are circumstances where an already-rounded Number is
            // serialized without being touched by a transactor, and thus
            // without an asset. We can't know if it's rounded, because it could
            // represent _anything_, particularly when serializing user-provided
            // Json. Regardless, the only time we should be serializing an
            // STNumber is when the scale is large.
            XRPL_ASSERT_PARTS(
                Number::getMantissaScale() != MantissaRange::MantissaScale::Small,
                "xrpl::STNumber::add",
                "STNumber only used with large mantissa scale");
        }
    }
 
    XRPL_ASSERT_PARTS(
        mantissa <= std::numeric_limits<std::int64_t>::max() &&
            mantissa >= std::numeric_limits<std::int64_t>::min(),
        "xrpl::STNumber::add",
        "mantissa in valid range");
    s.add64(mantissa);
    s.add32(exponent);
}
 
Number const&
STNumber::value() const
{
    return value_;
}
 
void
STNumber::setValue(Number const& v)
{
    value_ = v;
}
 
STBase*
STNumber::copy(std::size_t n, void* buf) const
{
    return emplace(n, buf, *this);
}
 
STBase*
STNumber::move(std::size_t n, void* buf)
{
    return emplace(n, buf, std::move(*this));
}
 
bool
STNumber::isEquivalent(STBase const& t) const
{
    XRPL_ASSERT(
        t.getSType() == this->getSType(), "xrpl::STNumber::isEquivalent : field type match");
    auto const& v = dynamic_cast<STNumber const&>(t);
    return value_ == v;
}
 
bool
STNumber::isDefault() const
{
    return value_ == Number();
}
 
std::ostream&
operator<<(std::ostream& out, STNumber const& rhs)
{
    return out << rhs.getText();
}
 
NumberParts
partsFromString(std::string const& number)
{
    static boost::regex const kReNumber(
        "^"                       // the beginning of the string
        "([-+]?)"                 // (optional) + or - character
        "(0|[1-9][0-9]*)"         // a number (no leading zeroes, unless 0)
        "(\\.([0-9]+))?"          // (optional) period followed by any number
        "([eE]([+-]?)([0-9]+))?"  // (optional) E, optional + or -, any number
        "$",
        boost::regex_constants::optimize);
 
    boost::smatch match;
 
    if (!boost::regex_match(number, match, kReNumber))
        Throw<std::runtime_error>(std::format("'{}' is not a number", number));
 
    // Match fields:
    //   0 = whole input
    //   1 = sign
    //   2 = integer portion
    //   3 = whole fraction (with '.')
    //   4 = fraction (without '.')
    //   5 = whole exponent (with 'e')
    //   6 = exponent sign
    //   7 = exponent number
 
    bool const negative = (match[1].matched && (match[1] == "-"));
 
    std::uint64_t mantissa = 0;
    int exponent = 0;
 
    if (!match[4].matched)  // integer only
    {
        mantissa = boost::lexical_cast<std::uint64_t>(std::string(match[2]));
        exponent = 0;
    }
    else
    {
        // integer and fraction
        mantissa = boost::lexical_cast<std::uint64_t>(match[2] + match[4]);
        exponent = -(match[4].length());
    }
 
    if (match[5].matched)
    {
        // we have an exponent
        if (match[6].matched && (match[6] == "-"))
        {
            exponent -= boost::lexical_cast<int>(std::string(match[7]));
        }
        else
        {
            exponent += boost::lexical_cast<int>(std::string(match[7]));
        }
    }
 
    return {.mantissa = mantissa, .exponent = exponent, .negative = negative};
}
 
STNumber
numberFromJson(SField const& field, json::Value const& value)
{
    NumberParts parts;
 
    if (value.isInt())
    {
        if (value.asInt() >= 0)
        {
            parts.mantissa = value.asInt();
        }
        else
        {
            parts.mantissa = value.asAbsUInt();
            parts.negative = true;
        }
    }
    else if (value.isUInt())
    {
        parts.mantissa = value.asUInt();
    }
    else if (value.isString())
    {
        parts = partsFromString(value.asString());
 
        XRPL_ASSERT_PARTS(
            !getCurrentTransactionRules(), "xrpld::numberFromJson", "Not in a Transactor context");
 
        // Number mantissas are much bigger than the allowable parsed values, so
        // it can't be out of range.
        static_assert(
            // NOLINTNEXTLINE(misc-redundant-expression)
            std::numeric_limits<std::uint64_t>::max() >=
            std::numeric_limits<decltype(parts.mantissa)>::max());
    }
    else
    {
        Throw<std::runtime_error>("not a number");
    }
 
    Number const num{parts.negative, parts.mantissa, parts.exponent, Number::Normalized{}};
 
    // Canonicalize "parts" and "num" with each other by getting rid of trailing 0s until either the
    // exponents match, or there are no more 0s. If the two results don't match exactly, then the
    // value has been rounded one way or another, and should not be used, because it may lead to an
    // unexpected result. canonicalizeParts is not to be confused with Number::canonicalize, because
    // they have completely different goals.
    auto canonicalizeParts = [](NumberParts p, int otherExponent) {
        if (p.mantissa == 0)
            return NumberParts{};
 
        while (p.exponent < otherExponent && p.mantissa % 10 == 0)
        {
            p.mantissa /= 10;
            ++p.exponent;
        }
 
        return p;
    };
 
    auto const numberMantissa = num.mantissa();
    auto const numberExponent = num.exponent();
 
    auto const canonicalParts = canonicalizeParts(parts, numberExponent);
 
    auto const canonicalNum = canonicalizeParts(
        NumberParts{
            .mantissa = Number::externalToInternal(numberMantissa),
            .exponent = numberExponent,
            .negative = numberMantissa < 0,
        },
        canonicalParts.exponent);
 
    if (canonicalParts.mantissa != canonicalNum.mantissa ||
        canonicalParts.exponent != canonicalNum.exponent ||
        canonicalParts.negative != canonicalNum.negative)
    {
        Throw<std::runtime_error>("number cannot be represented");
    }
 
    return STNumber{field, num};
}
 
}  // namespace xrpl