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numberformatter.h (92898B)

---

// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html

#ifndef __NUMBERFORMATTER_H__
#define __NUMBERFORMATTER_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#if !UCONFIG_NO_FORMATTING

#include "unicode/appendable.h"
#include "unicode/bytestream.h"
#include "unicode/currunit.h"
#include "unicode/dcfmtsym.h"
#include "unicode/displayoptions.h"
#include "unicode/fieldpos.h"
#include "unicode/fpositer.h"
#include "unicode/measunit.h"
#include "unicode/nounit.h"
#include "unicode/parseerr.h"
#include "unicode/plurrule.h"
#include "unicode/ucurr.h"
#include "unicode/unum.h"
#include "unicode/unumberformatter.h"
#include "unicode/uobject.h"
#include "unicode/unumberoptions.h"
#include "unicode/formattednumber.h"

/**
* \file
* \brief C++ API: All-in-one formatter for localized numbers, currencies, and units.
* 
* For a full list of options, see icu::number::NumberFormatterSettings.
*
* <pre>
* // Most basic usage:
* NumberFormatter::withLocale(...).format(123).toString();  // 1,234 in en-US
*
* // Custom notation, unit, and rounding precision:
* NumberFormatter::with()
*     .notation(Notation::compactShort())
*     .unit(CurrencyUnit("EUR", status))
*     .precision(Precision::maxDigits(2))
*     .locale(...)
*     .format(1234)
*     .toString();  // €1.2K in en-US
*
* // Create a formatter in a singleton by value for use later:
* static const LocalizedNumberFormatter formatter = NumberFormatter::withLocale(...)
*     .unit(NoUnit::percent())
*     .precision(Precision::fixedFraction(3));
* formatter.format(5.9831).toString();  // 5.983% in en-US
*
* // Create a "template" in a singleton unique_ptr but without setting a locale until the call site:
* std::unique_ptr<UnlocalizedNumberFormatter> template = NumberFormatter::with()
*     .sign(UNumberSignDisplay::UNUM_SIGN_ALWAYS)
*     .unit(MeasureUnit::getMeter())
*     .unitWidth(UNumberUnitWidth::UNUM_UNIT_WIDTH_FULL_NAME)
*     .clone();
* template->locale(...).format(1234).toString();  // +1,234 meters in en-US
* </pre>
*
* <p>
* This API offers more features than DecimalFormat and is geared toward new users of ICU.
*
* <p>
* NumberFormatter instances (i.e., LocalizedNumberFormatter and UnlocalizedNumberFormatter)
* are immutable and thread safe. This means that invoking a configuration method has no
* effect on the receiving instance; you must store and use the new number formatter instance it returns instead.
*
* <pre>
* UnlocalizedNumberFormatter formatter = UnlocalizedNumberFormatter::with().notation(Notation::scientific());
* formatter.precision(Precision.maxFraction(2)); // does nothing!
* formatter.locale(Locale.getEnglish()).format(9.8765).toString(); // prints "9.8765E0", not "9.88E0"
* </pre>
*
* <p>
* This API is based on the <em>fluent</em> design pattern popularized by libraries such as Google's Guava. For
* extensive details on the design of this API, read <a href="https://goo.gl/szi5VB">the design doc</a>.
*
* <p>
* Note: To format monetary/currency values, specify the currency in the `.unit()` function.
*
* @author Shane Carr
*/

U_NAMESPACE_BEGIN

// Forward declarations:
class IFixedDecimal;
class FieldPositionIteratorHandler;
class FormattedStringBuilder;

namespace numparse::impl {

// Forward declarations:
class NumberParserImpl;
class MultiplierParseHandler;

} // namespace numparse::impl

namespace units {

// Forward declarations:
class UnitsRouter;

} // namespace units

namespace number {  // icu::number

// Forward declarations:
class UnlocalizedNumberFormatter;
class LocalizedNumberFormatter;
class SimpleNumberFormatter;
class FormattedNumber;
class Notation;
class ScientificNotation;
class Precision;
class FractionPrecision;
class CurrencyPrecision;
class IncrementPrecision;
class IntegerWidth;

namespace impl {

// can't be #ifndef U_HIDE_INTERNAL_API; referenced throughout this file in public classes
/**
* Datatype for minimum/maximum fraction digits. Must be able to hold kMaxIntFracSig.
*
* @internal
*/
typedef int16_t digits_t;

// can't be #ifndef U_HIDE_INTERNAL_API; needed for struct initialization
/**
* Use a default threshold of 3. This means that the third time .format() is called, the data structures get built
* using the "safe" code path. The first two calls to .format() will trigger the unsafe code path.
*
* @internal
*/
static constexpr int32_t kInternalDefaultThreshold = 3;

// Forward declarations:
class Padder;
struct MacroProps;
struct MicroProps;
class DecimalQuantity;
class UFormattedNumberData;
class NumberFormatterImpl;
struct ParsedPatternInfo;
class ScientificModifier;
class MultiplierProducer;
class RoundingImpl;
class ScientificHandler;
class Modifier;
class AffixPatternProvider;
class NumberPropertyMapper;
struct DecimalFormatProperties;
class MultiplierFormatHandler;
class CurrencySymbols;
class GeneratorHelpers;
class DecNum;
class NumberRangeFormatterImpl;
struct RangeMacroProps;
struct UFormattedNumberImpl;
class MutablePatternModifier;
class ImmutablePatternModifier;
struct DecimalFormatWarehouse;
struct SimpleMicroProps;
class AdoptingSignumModifierStore;

/**
* Used for NumberRangeFormatter and implemented in numrange_fluent.cpp.
* Declared here so it can be friended.
*
* @internal
*/
void touchRangeLocales(impl::RangeMacroProps& macros);

} // namespace impl

/**
* Extra name reserved in case it is needed in the future.
*
* @stable ICU 63
*/
typedef Notation CompactNotation;

/**
* Extra name reserved in case it is needed in the future.
*
* @stable ICU 63
*/
typedef Notation SimpleNotation;

/**
* A class that defines the notation style to be used when formatting numbers in NumberFormatter.
*
* @stable ICU 60
*/
class U_I18N_API Notation : public UMemory {
 public:
   /**
    * Print the number using scientific notation (also known as scientific form, standard index form, or standard form
    * in the UK). The format for scientific notation varies by locale; for example, many Western locales display the
    * number in the form "#E0", where the number is displayed with one digit before the decimal separator, zero or more
    * digits after the decimal separator, and the corresponding power of 10 displayed after the "E".
    *
    * <p>
    * Example outputs in <em>en-US</em> when printing 8.765E4 through 8.765E-3:
    *
    * <pre>
    * 8.765E4
    * 8.765E3
    * 8.765E2
    * 8.765E1
    * 8.765E0
    * 8.765E-1
    * 8.765E-2
    * 8.765E-3
    * 0E0
    * </pre>
    *
    * @return A ScientificNotation for chaining or passing to the NumberFormatter notation() setter.
    * @stable ICU 60
    */
   static ScientificNotation scientific();

   /**
    * Print the number using engineering notation, a variant of scientific notation in which the exponent must be
    * divisible by 3.
    *
    * <p>
    * Example outputs in <em>en-US</em> when printing 8.765E4 through 8.765E-3:
    *
    * <pre>
    * 87.65E3
    * 8.765E3
    * 876.5E0
    * 87.65E0
    * 8.765E0
    * 876.5E-3
    * 87.65E-3
    * 8.765E-3
    * 0E0
    * </pre>
    *
    * @return A ScientificNotation for chaining or passing to the NumberFormatter notation() setter.
    * @stable ICU 60
    */
   static ScientificNotation engineering();

   /**
    * Print the number using short-form compact notation.
    *
    * <p>
    * <em>Compact notation</em>, defined in Unicode Technical Standard #35 Part 3 Section 2.4.1, prints numbers with
    * localized prefixes or suffixes corresponding to different powers of ten. Compact notation is similar to
    * engineering notation in how it scales numbers.
    *
    * <p>
    * Compact notation is ideal for displaying large numbers (over ~1000) to humans while at the same time minimizing
    * screen real estate.
    *
    * <p>
    * In short form, the powers of ten are abbreviated. In <em>en-US</em>, the abbreviations are "K" for thousands, "M"
    * for millions, "B" for billions, and "T" for trillions. Example outputs in <em>en-US</em> when printing 8.765E7
    * through 8.765E0:
    *
    * <pre>
    * 88M
    * 8.8M
    * 876K
    * 88K
    * 8.8K
    * 876
    * 88
    * 8.8
    * </pre>
    *
    * <p>
    * When compact notation is specified without an explicit rounding precision, numbers are rounded off to the closest
    * integer after scaling the number by the corresponding power of 10, but with a digit shown after the decimal
    * separator if there is only one digit before the decimal separator. The default compact notation rounding precision
    * is equivalent to:
    *
    * <pre>
    * Precision::integer().withMinDigits(2)
    * </pre>
    *
    * @return A CompactNotation for passing to the NumberFormatter notation() setter.
    * @stable ICU 60
    */
   static CompactNotation compactShort();

   /**
    * Print the number using long-form compact notation. For more information on compact notation, see
    * {@link #compactShort}.
    *
    * <p>
    * In long form, the powers of ten are spelled out fully. Example outputs in <em>en-US</em> when printing 8.765E7
    * through 8.765E0:
    *
    * <pre>
    * 88 million
    * 8.8 million
    * 876 thousand
    * 88 thousand
    * 8.8 thousand
    * 876
    * 88
    * 8.8
    * </pre>
    *
    * @return A CompactNotation for passing to the NumberFormatter notation() setter.
    * @stable ICU 60
    */
   static CompactNotation compactLong();

   /**
    * Print the number using simple notation without any scaling by powers of ten. This is the default behavior.
    *
    * <p>
    * Since this is the default behavior, this method needs to be called only when it is necessary to override a
    * previous setting.
    *
    * <p>
    * Example outputs in <em>en-US</em> when printing 8.765E7 through 8.765E0:
    *
    * <pre>
    * 87,650,000
    * 8,765,000
    * 876,500
    * 87,650
    * 8,765
    * 876.5
    * 87.65
    * 8.765
    * </pre>
    *
    * @return A SimpleNotation for passing to the NumberFormatter notation() setter.
    * @stable ICU 60
    */
   static SimpleNotation simple();

 private:
   enum NotationType {
       NTN_SCIENTIFIC, NTN_COMPACT, NTN_SIMPLE, NTN_ERROR
   } fType;

   union NotationUnion {
       // For NTN_SCIENTIFIC
       /** @internal (private) */
       struct ScientificSettings {
           /** @internal (private) */
           int8_t fEngineeringInterval;
           /** @internal (private) */
           bool fRequireMinInt;
           /** @internal (private) */
           impl::digits_t fMinExponentDigits;
           /** @internal (private) */
           UNumberSignDisplay fExponentSignDisplay;
       } scientific;

       // For NTN_COMPACT
       UNumberCompactStyle compactStyle;

       // For NTN_ERROR
       UErrorCode errorCode;
   } fUnion;

   typedef NotationUnion::ScientificSettings ScientificSettings;

   Notation(const NotationType &type, const NotationUnion &union_) : fType(type), fUnion(union_) {}

   Notation(UErrorCode errorCode) : fType(NTN_ERROR) {
       fUnion.errorCode = errorCode;
   }

   Notation() : fType(NTN_SIMPLE), fUnion() {}

   UBool copyErrorTo(UErrorCode &status) const {
       if (fType == NTN_ERROR) {
           status = fUnion.errorCode;
           return true;
       }
       return false;
   }

   // To allow MacroProps to initialize empty instances:
   friend struct impl::MacroProps;
   friend class ScientificNotation;

   // To allow implementation to access internal types:
   friend class impl::NumberFormatterImpl;
   friend class impl::ScientificModifier;
   friend class impl::ScientificHandler;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;
};

/**
* A class that defines the scientific notation style to be used when formatting numbers in NumberFormatter.
*
* <p>
* To create a ScientificNotation, use one of the factory methods in {@link Notation}.
*
* @stable ICU 60
*/
class U_I18N_API ScientificNotation : public Notation {
 public:
   /**
    * Sets the minimum number of digits to show in the exponent of scientific notation, padding with zeros if
    * necessary. Useful for fixed-width display.
    *
    * <p>
    * For example, with minExponentDigits=2, the number 123 will be printed as "1.23E02" in <em>en-US</em> instead of
    * the default "1.23E2".
    *
    * @param minExponentDigits
    *            The minimum number of digits to show in the exponent.
    * @return A ScientificNotation, for chaining.
    * @stable ICU 60
    */
   ScientificNotation withMinExponentDigits(int32_t minExponentDigits) const;

   /**
    * Sets whether to show the sign on positive and negative exponents in scientific notation. The default is AUTO,
    * showing the minus sign but not the plus sign.
    *
    * <p>
    * For example, with exponentSignDisplay=ALWAYS, the number 123 will be printed as "1.23E+2" in <em>en-US</em>
    * instead of the default "1.23E2".
    *
    * @param exponentSignDisplay
    *            The strategy for displaying the sign in the exponent.
    * @return A ScientificNotation, for chaining.
    * @stable ICU 60
    */
   ScientificNotation withExponentSignDisplay(UNumberSignDisplay exponentSignDisplay) const;

 private:
   // Inherit constructor
   using Notation::Notation;

   // Raw constructor for NumberPropertyMapper
   ScientificNotation(int8_t fEngineeringInterval, bool fRequireMinInt, impl::digits_t fMinExponentDigits,
                      UNumberSignDisplay fExponentSignDisplay);

   friend class Notation;

   // So that NumberPropertyMapper can create instances
   friend class impl::NumberPropertyMapper;
};

/**
* Extra name reserved in case it is needed in the future.
*
* @stable ICU 63
*/
typedef Precision SignificantDigitsPrecision;

/**
* A class that defines the rounding precision to be used when formatting numbers in NumberFormatter.
*
* <p>
* To create a Precision, use one of the factory methods.
*
* @stable ICU 60
*/
class U_I18N_API Precision : public UMemory {

 public:
   /**
    * Show all available digits to full precision.
    *
    * <p>
    * <strong>NOTE:</strong> When formatting a <em>double</em>, this method, along with {@link #minFraction} and
    * {@link #minSignificantDigits}, will trigger complex algorithm similar to <em>Dragon4</em> to determine the
    * low-order digits and the number of digits to display based on the value of the double.
    * If the number of fraction places or significant digits can be bounded, consider using {@link #maxFraction}
    * or {@link #maxSignificantDigits} instead to maximize performance.
    * For more information, read the following blog post.
    *
    * <p>
    * http://www.serpentine.com/blog/2011/06/29/here-be-dragons-advances-in-problems-you-didnt-even-know-you-had/
    *
    * @return A Precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static Precision unlimited();

   /**
    * Show numbers rounded if necessary to the nearest integer.
    *
    * @return A FractionPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static FractionPrecision integer();

   /**
    * Show numbers rounded if necessary to a certain number of fraction places (numerals after the decimal separator).
    * Additionally, pad with zeros to ensure that this number of places are always shown.
    *
    * <p>
    * Example output with minMaxFractionPlaces = 3:
    *
    * <p>
    * 87,650.000<br>
    * 8,765.000<br>
    * 876.500<br>
    * 87.650<br>
    * 8.765<br>
    * 0.876<br>
    * 0.088<br>
    * 0.009<br>
    * 0.000 (zero)
    *
    * <p>
    * This method is equivalent to {@link #minMaxFraction} with both arguments equal.
    *
    * @param minMaxFractionPlaces
    *            The minimum and maximum number of numerals to display after the decimal separator (rounding if too
    *            long or padding with zeros if too short).
    * @return A FractionPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static FractionPrecision fixedFraction(int32_t minMaxFractionPlaces);

   /**
    * Always show at least a certain number of fraction places after the decimal separator, padding with zeros if
    * necessary. Do not perform rounding (display numbers to their full precision).
    *
    * <p>
    * <strong>NOTE:</strong> If you are formatting <em>doubles</em>, see the performance note in {@link #unlimited}.
    *
    * @param minFractionPlaces
    *            The minimum number of numerals to display after the decimal separator (padding with zeros if
    *            necessary).
    * @return A FractionPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static FractionPrecision minFraction(int32_t minFractionPlaces);

   /**
    * Show numbers rounded if necessary to a certain number of fraction places (numerals after the decimal separator).
    * Unlike the other fraction rounding strategies, this strategy does <em>not</em> pad zeros to the end of the
    * number.
    *
    * @param maxFractionPlaces
    *            The maximum number of numerals to display after the decimal mark (rounding if necessary).
    * @return A FractionPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static FractionPrecision maxFraction(int32_t maxFractionPlaces);

   /**
    * Show numbers rounded if necessary to a certain number of fraction places (numerals after the decimal separator);
    * in addition, always show at least a certain number of places after the decimal separator, padding with zeros if
    * necessary.
    *
    * @param minFractionPlaces
    *            The minimum number of numerals to display after the decimal separator (padding with zeros if
    *            necessary).
    * @param maxFractionPlaces
    *            The maximum number of numerals to display after the decimal separator (rounding if necessary).
    * @return A FractionPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static FractionPrecision minMaxFraction(int32_t minFractionPlaces, int32_t maxFractionPlaces);

   /**
    * Show numbers rounded if necessary to a certain number of significant digits or significant figures. Additionally,
    * pad with zeros to ensure that this number of significant digits/figures are always shown.
    *
    * <p>
    * This method is equivalent to {@link #minMaxSignificantDigits} with both arguments equal.
    *
    * @param minMaxSignificantDigits
    *            The minimum and maximum number of significant digits to display (rounding if too long or padding with
    *            zeros if too short).
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 62
    */
   static SignificantDigitsPrecision fixedSignificantDigits(int32_t minMaxSignificantDigits);

   /**
    * Always show at least a certain number of significant digits/figures, padding with zeros if necessary. Do not
    * perform rounding (display numbers to their full precision).
    *
    * <p>
    * <strong>NOTE:</strong> If you are formatting <em>doubles</em>, see the performance note in {@link #unlimited}.
    *
    * @param minSignificantDigits
    *            The minimum number of significant digits to display (padding with zeros if too short).
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 62
    */
   static SignificantDigitsPrecision minSignificantDigits(int32_t minSignificantDigits);

   /**
    * Show numbers rounded if necessary to a certain number of significant digits/figures.
    *
    * @param maxSignificantDigits
    *            The maximum number of significant digits to display (rounding if too long).
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 62
    */
   static SignificantDigitsPrecision maxSignificantDigits(int32_t maxSignificantDigits);

   /**
    * Show numbers rounded if necessary to a certain number of significant digits/figures; in addition, always show at
    * least a certain number of significant digits, padding with zeros if necessary.
    *
    * @param minSignificantDigits
    *            The minimum number of significant digits to display (padding with zeros if necessary).
    * @param maxSignificantDigits
    *            The maximum number of significant digits to display (rounding if necessary).
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 62
    */
   static SignificantDigitsPrecision minMaxSignificantDigits(int32_t minSignificantDigits,
                                                             int32_t maxSignificantDigits);

   /**
    * Show numbers rounded if necessary to the closest multiple of a certain rounding increment. For example, if the
    * rounding increment is 0.5, then round 1.2 to 1 and round 1.3 to 1.5.
    *
    * <p>
    * In order to ensure that numbers are padded to the appropriate number of fraction places, call
    * withMinFraction() on the return value of this method.
    * For example, to round to the nearest 0.5 and always display 2 numerals after the
    * decimal separator (to display 1.2 as "1.00" and 1.3 as "1.50"), you can run:
    *
    * <pre>
    * Precision::increment(0.5).withMinFraction(2)
    * </pre>
    *
    * @param roundingIncrement
    *            The increment to which to round numbers.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static IncrementPrecision increment(double roundingIncrement);

   /**
    * Version of `Precision::increment()` that takes an integer at a particular power of 10.
    *
    * To round to the nearest 0.5 and display 2 fraction digits, with this function, you should write one of the following:
    *
    * <pre>
    * Precision::incrementExact(5, -1).withMinFraction(2)
    * Precision::incrementExact(50, -2).withMinFraction(2)
    * Precision::incrementExact(50, -2)
    * </pre>
    *
    * This is analagous to ICU4J `Precision.increment(new BigDecimal("0.50"))`.
    *
    * This behavior is modeled after ECMA-402. For more information, see:
    * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat/NumberFormat#roundingincrement
    *
    * @param mantissa
    *            The increment to which to round numbers.
    * @param magnitude
    *            The power of 10 of the ones digit of the mantissa.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 71
    */
   static IncrementPrecision incrementExact(uint64_t mantissa, int16_t magnitude);

   /**
    * Show numbers rounded and padded according to the rules for the currency unit. The most common
    * rounding precision settings for currencies include <code>Precision::fixedFraction(2)</code>,
    * <code>Precision::integer()</code>, and <code>Precision::increment(0.05)</code> for cash transactions
    * ("nickel rounding").
    *
    * <p>
    * The exact rounding details will be resolved at runtime based on the currency unit specified in the
    * NumberFormatter chain. To round according to the rules for one currency while displaying the symbol for another
    * currency, the withCurrency() method can be called on the return value of this method.
    *
    * @param currencyUsage
    *            Either STANDARD (for digital transactions) or CASH (for transactions where the rounding increment may
    *            be limited by the available denominations of cash or coins).
    * @return A CurrencyPrecision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   static CurrencyPrecision currency(UCurrencyUsage currencyUsage);

   /**
    * Configure how trailing zeros are displayed on numbers. For example, to hide trailing zeros
    * when the number is an integer, use UNUM_TRAILING_ZERO_HIDE_IF_WHOLE.
    *
    * @param trailingZeroDisplay Option to configure the display of trailing zeros.
    * @stable ICU 69
    */
   Precision trailingZeroDisplay(UNumberTrailingZeroDisplay trailingZeroDisplay) const;

 private:
   enum PrecisionType {
       RND_BOGUS,
       RND_NONE,
       RND_FRACTION,
       RND_SIGNIFICANT,
       RND_FRACTION_SIGNIFICANT,

       // Used for strange increments like 3.14.
       RND_INCREMENT,

       // Used for increments with 1 as the only digit. This is different than fraction
       // rounding because it supports having additional trailing zeros. For example, this
       // class is used to round with the increment 0.010.
       RND_INCREMENT_ONE,

       // Used for increments with 5 as the only digit (nickel rounding).
       RND_INCREMENT_FIVE,

       RND_CURRENCY,
       RND_ERROR
   } fType;

   union PrecisionUnion {
       /** @internal (private) */
       struct FractionSignificantSettings {
           // For RND_FRACTION, RND_SIGNIFICANT, and RND_FRACTION_SIGNIFICANT
           /** @internal (private) */
           impl::digits_t fMinFrac;
           /** @internal (private) */
           impl::digits_t fMaxFrac;
           /** @internal (private) */
           impl::digits_t fMinSig;
           /** @internal (private) */
           impl::digits_t fMaxSig;
           /** @internal (private) */
           UNumberRoundingPriority fPriority;
           /**
            * Whether to retain trailing zeros based on the looser strategy.
            * @internal (private)
            */
           bool fRetain;
       } fracSig;
       /** @internal (private) */
       struct IncrementSettings {
           // For RND_INCREMENT, RND_INCREMENT_ONE, and RND_INCREMENT_FIVE
           // Note: This is a union, so we shouldn't own memory, since
           // the default destructor would leak it.
           /** @internal (private) */
           uint64_t fIncrement;
           /** @internal (private) */
           impl::digits_t fIncrementMagnitude;
           /** @internal (private) */
           impl::digits_t fMinFrac;
       } increment;
       UCurrencyUsage currencyUsage; // For RND_CURRENCY
       UErrorCode errorCode; // For RND_ERROR
   } fUnion;

   UNumberTrailingZeroDisplay fTrailingZeroDisplay = UNUM_TRAILING_ZERO_AUTO;

   typedef PrecisionUnion::FractionSignificantSettings FractionSignificantSettings;
   typedef PrecisionUnion::IncrementSettings IncrementSettings;

   Precision(const PrecisionType& type, const PrecisionUnion& union_)
           : fType(type), fUnion(union_) {}

   Precision(UErrorCode errorCode) : fType(RND_ERROR) {
       fUnion.errorCode = errorCode;
   }

   Precision() : fType(RND_BOGUS) {}

   bool isBogus() const {
       return fType == RND_BOGUS;
   }

   UBool copyErrorTo(UErrorCode &status) const {
       if (fType == RND_ERROR) {
           status = fUnion.errorCode;
           return true;
       }
       return false;
   }

   // On the parent type so that this method can be called internally on Precision instances.
   Precision withCurrency(const CurrencyUnit &currency, UErrorCode &status) const;

   static FractionPrecision constructFraction(int32_t minFrac, int32_t maxFrac);

   static Precision constructSignificant(int32_t minSig, int32_t maxSig);

   static Precision constructFractionSignificant(
       const FractionPrecision &base,
       int32_t minSig,
       int32_t maxSig,
       UNumberRoundingPriority priority,
       bool retain);

   static IncrementPrecision constructIncrement(uint64_t increment, impl::digits_t magnitude);

   static CurrencyPrecision constructCurrency(UCurrencyUsage usage);

   // To allow MacroProps/MicroProps to initialize bogus instances:
   friend struct impl::MacroProps;
   friend struct impl::MicroProps;

   // To allow NumberFormatterImpl to access isBogus() and other internal methods:
   friend class impl::NumberFormatterImpl;

   // To allow NumberPropertyMapper to create instances from DecimalFormatProperties:
   friend class impl::NumberPropertyMapper;

   // To allow access to the main implementation class:
   friend class impl::RoundingImpl;

   // To allow child classes to call private methods:
   friend class FractionPrecision;
   friend class CurrencyPrecision;
   friend class IncrementPrecision;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;

   // To allow access to isBogus and the default (bogus) constructor:
   friend class units::UnitsRouter;
};

/**
* A class that defines a rounding precision based on a number of fraction places and optionally significant digits to be
* used when formatting numbers in NumberFormatter.
*
* <p>
* To create a FractionPrecision, use one of the factory methods on Precision.
*
* @stable ICU 60
*/
class U_I18N_API FractionPrecision : public Precision {
 public:
   /**
    * Override maximum fraction digits with maximum significant digits depending on the magnitude
    * of the number. See UNumberRoundingPriority.
    *
    * @param minSignificantDigits
    *            Pad trailing zeros to achieve this minimum number of significant digits.
    * @param maxSignificantDigits
    *            Round the number to achieve this maximum number of significant digits.
    * @param priority
    *            How to disambiguate between fraction digits and significant digits.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    *
    * @stable ICU 69
    */
   Precision withSignificantDigits(
       int32_t minSignificantDigits,
       int32_t maxSignificantDigits,
       UNumberRoundingPriority priority) const;

   /**
    * Ensure that no less than this number of significant digits are retained when rounding
    * according to fraction rules.
    *
    * For example, with integer rounding, the number 3.141 becomes "3". However, with minimum
    * figures set to 2, 3.141 becomes "3.1" instead.
    *
    * This setting does not affect the number of trailing zeros. For example, 3.01 would print as
    * "3", not "3.0".
    *
    * This is equivalent to `withSignificantDigits(1, minSignificantDigits, RELAXED)`.
    *
    * @param minSignificantDigits
    *            The number of significant figures to guarantee.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   Precision withMinDigits(int32_t minSignificantDigits) const;

   /**
    * Ensure that no more than this number of significant digits are retained when rounding
    * according to fraction rules.
    *
    * For example, with integer rounding, the number 123.4 becomes "123". However, with maximum
    * figures set to 2, 123.4 becomes "120" instead.
    *
    * This setting does not affect the number of trailing zeros. For example, with fixed fraction
    * of 2, 123.4 would become "120.00".
    *
    * This is equivalent to `withSignificantDigits(1, maxSignificantDigits, STRICT)`.
    *
    * @param maxSignificantDigits
    *            Round the number to no more than this number of significant figures.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   Precision withMaxDigits(int32_t maxSignificantDigits) const;

 private:
   // Inherit constructor
   using Precision::Precision;

   // To allow parent class to call this class's constructor:
   friend class Precision;
};

/**
* A class that defines a rounding precision parameterized by a currency to be used when formatting numbers in
* NumberFormatter.
*
* <p>
* To create a CurrencyPrecision, use one of the factory methods on Precision.
*
* @stable ICU 60
*/
class U_I18N_API CurrencyPrecision : public Precision {
 public:
   /**
     * Associates a currency with this rounding precision.
     *
     * <p>
     * <strong>Calling this method is <em>not required</em></strong>, because the currency specified in unit()
     * is automatically applied to currency rounding precisions. However,
     * this method enables you to override that automatic association.
     *
     * <p>
     * This method also enables numbers to be formatted using currency rounding rules without explicitly using a
     * currency format.
     *
     * @param currency
     *            The currency to associate with this rounding precision.
     * @return A precision for chaining or passing to the NumberFormatter precision() setter.
     * @stable ICU 60
     */
   Precision withCurrency(const CurrencyUnit &currency) const;

 private:
   // Inherit constructor
   using Precision::Precision;

   // To allow parent class to call this class's constructor:
   friend class Precision;
};

/**
* A class that defines a rounding precision parameterized by a rounding increment to be used when formatting numbers in
* NumberFormatter.
*
* <p>
* To create an IncrementPrecision, use one of the factory methods on Precision.
*
* @stable ICU 60
*/
class U_I18N_API IncrementPrecision : public Precision {
 public:
   /**
    * Specifies the minimum number of fraction digits to render after the decimal separator, padding with zeros if
    * necessary.  By default, no trailing zeros are added.
    *
    * <p>
    * For example, if the rounding increment is 0.5 and minFrac is 2, then the resulting strings include "0.00",
    * "0.50", "1.00", and "1.50".
    *
    * <p>
    * Note: In ICU4J, this functionality is accomplished via the scale of the BigDecimal rounding increment.
    *
    * @param minFrac The minimum number of digits after the decimal separator.
    * @return A precision for chaining or passing to the NumberFormatter precision() setter.
    * @stable ICU 60
    */
   Precision withMinFraction(int32_t minFrac) const;

 private:
   // Inherit constructor
   using Precision::Precision;

   // To allow parent class to call this class's constructor:
   friend class Precision;
};

/**
* A class that defines the strategy for padding and truncating integers before the decimal separator.
*
* <p>
* To create an IntegerWidth, use one of the factory methods.
*
* @stable ICU 60
* @see NumberFormatter
*/
class U_I18N_API IntegerWidth : public UMemory {
 public:
   /**
    * Pad numbers at the beginning with zeros to guarantee a certain number of numerals before the decimal separator.
    *
    * <p>
    * For example, with minInt=3, the number 55 will get printed as "055".
    *
    * @param minInt
    *            The minimum number of places before the decimal separator.
    * @return An IntegerWidth for chaining or passing to the NumberFormatter integerWidth() setter.
    * @stable ICU 60
    */
   static IntegerWidth zeroFillTo(int32_t minInt);

   /**
    * Truncate numbers exceeding a certain number of numerals before the decimal separator.
    *
    * For example, with maxInt=3, the number 1234 will get printed as "234".
    *
    * @param maxInt
    *            The maximum number of places before the decimal separator. maxInt == -1 means no
    *            truncation.
    * @return An IntegerWidth for passing to the NumberFormatter integerWidth() setter.
    * @stable ICU 60
    */
   IntegerWidth truncateAt(int32_t maxInt);

 private:
   union {
       struct {
           impl::digits_t fMinInt;
           impl::digits_t fMaxInt;
           bool fFormatFailIfMoreThanMaxDigits;
       } minMaxInt;
       UErrorCode errorCode;
   } fUnion;
   bool fHasError = false;

   IntegerWidth(impl::digits_t minInt, impl::digits_t maxInt, bool formatFailIfMoreThanMaxDigits);

   IntegerWidth(UErrorCode errorCode) { // NOLINT
       fUnion.errorCode = errorCode;
       fHasError = true;
   }

   IntegerWidth() { // NOLINT
       fUnion.minMaxInt.fMinInt = -1;
   }

   /** Returns the default instance. */
   static IntegerWidth standard() {
       return IntegerWidth::zeroFillTo(1);
   }

   bool isBogus() const {
       return !fHasError && fUnion.minMaxInt.fMinInt == -1;
   }

   UBool copyErrorTo(UErrorCode &status) const {
       if (fHasError) {
           status = fUnion.errorCode;
           return true;
       }
       return false;
   }

   void apply(impl::DecimalQuantity &quantity, UErrorCode &status) const;

   bool operator==(const IntegerWidth& other) const;

   // To allow MacroProps/MicroProps to initialize empty instances:
   friend struct impl::MacroProps;
   friend struct impl::MicroProps;

   // To allow NumberFormatterImpl to access isBogus():
   friend class impl::NumberFormatterImpl;

   // To allow the use of this class when formatting:
   friend class impl::MutablePatternModifier;
   friend class impl::ImmutablePatternModifier;

   // So that NumberPropertyMapper can create instances
   friend class impl::NumberPropertyMapper;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;
};

/**
* A class that defines a quantity by which a number should be multiplied when formatting.
*
* <p>
* To create a Scale, use one of the factory methods.
*
* @stable ICU 62
*/
class U_I18N_API Scale : public UMemory {
 public:
   /**
    * Do not change the value of numbers when formatting or parsing.
    *
    * @return A Scale to prevent any multiplication.
    * @stable ICU 62
    */
   static Scale none();

   /**
    * Multiply numbers by a power of ten before formatting. Useful for combining with a percent unit:
    *
    * <pre>
    * NumberFormatter::with().unit(NoUnit::percent()).multiplier(Scale::powerOfTen(2))
    * </pre>
    *
    * @return A Scale for passing to the setter in NumberFormatter.
    * @stable ICU 62
    */
   static Scale powerOfTen(int32_t power);

   /**
    * Multiply numbers by an arbitrary value before formatting. Useful for unit conversions.
    *
    * This method takes a string in a decimal number format with syntax
    * as defined in the Decimal Arithmetic Specification, available at
    * http://speleotrove.com/decimal
    *
    * Also see the version of this method that takes a double.
    *
    * @return A Scale for passing to the setter in NumberFormatter.
    * @stable ICU 62
    */
   static Scale byDecimal(StringPiece multiplicand);

   /**
    * Multiply numbers by an arbitrary value before formatting. Useful for unit conversions.
    *
    * This method takes a double; also see the version of this method that takes an exact decimal.
    *
    * @return A Scale for passing to the setter in NumberFormatter.
    * @stable ICU 62
    */
   static Scale byDouble(double multiplicand);

   /**
    * Multiply a number by both a power of ten and by an arbitrary double value.
    *
    * @return A Scale for passing to the setter in NumberFormatter.
    * @stable ICU 62
    */
   static Scale byDoubleAndPowerOfTen(double multiplicand, int32_t power);

   // We need a custom destructor for the DecNum, which means we need to declare
   // the copy/move constructor/assignment quartet.

   /** @stable ICU 62 */
   Scale(const Scale& other);

   /** @stable ICU 62 */
   Scale& operator=(const Scale& other);

   /** @stable ICU 62 */
   Scale(Scale&& src) noexcept;

   /** @stable ICU 62 */
   Scale& operator=(Scale&& src) noexcept;

   /** @stable ICU 62 */
   ~Scale();

#ifndef U_HIDE_INTERNAL_API
   /** @internal */
   Scale(int32_t magnitude, impl::DecNum* arbitraryToAdopt);
#endif  /* U_HIDE_INTERNAL_API */

 private:
   int32_t fMagnitude;
   impl::DecNum* fArbitrary;
   UErrorCode fError;

   Scale(UErrorCode error) : fMagnitude(0), fArbitrary(nullptr), fError(error) {}

   Scale() : fMagnitude(0), fArbitrary(nullptr), fError(U_ZERO_ERROR) {}

   bool isValid() const {
       return fMagnitude != 0 || fArbitrary != nullptr;
   }

   UBool copyErrorTo(UErrorCode &status) const {
       if (U_FAILURE(fError)) {
           status = fError;
           return true;
       }
       return false;
   }

   void applyTo(impl::DecimalQuantity& quantity) const;

   void applyReciprocalTo(impl::DecimalQuantity& quantity) const;

   // To allow MacroProps/MicroProps to initialize empty instances:
   friend struct impl::MacroProps;
   friend struct impl::MicroProps;

   // To allow NumberFormatterImpl to access isBogus() and perform other operations:
   friend class impl::NumberFormatterImpl;

   // To allow the helper class MultiplierFormatHandler access to private fields:
   friend class impl::MultiplierFormatHandler;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;

   // To allow access to parsing code:
   friend class ::icu::numparse::impl::NumberParserImpl;
   friend class ::icu::numparse::impl::MultiplierParseHandler;
};

namespace impl {

// Do not enclose entire StringProp with #ifndef U_HIDE_INTERNAL_API, needed for a protected field.
// And do not enclose its class boilerplate within #ifndef U_HIDE_INTERNAL_API.
/**
* Manages NumberFormatterSettings::usage()'s char* instance on the heap.
* @internal
*/
class U_I18N_API StringProp : public UMemory {

 public:
   /** @internal */
   ~StringProp();

   /** @internal */
   StringProp(const StringProp &other);

   /** @internal */
   StringProp &operator=(const StringProp &other);

#ifndef U_HIDE_INTERNAL_API

   /** @internal */
   StringProp(StringProp &&src) noexcept;

   /** @internal */
   StringProp &operator=(StringProp &&src) noexcept;

   /** @internal */
   int16_t length() const {
       return fLength;
   }

   /** @internal
    * Makes a copy of value. Set to "" to unset.
    */
   void set(StringPiece value);

   /** @internal */
   bool isSet() const {
       return fLength > 0;
   }

#endif // U_HIDE_INTERNAL_API

 private:
   char *fValue;
   int16_t fLength;
   UErrorCode fError;

   StringProp() : fValue(nullptr), fLength(0), fError(U_ZERO_ERROR) {
   }

   UBool copyErrorTo(UErrorCode &status) const {
       if (U_FAILURE(fError)) {
           status = fError;
           return true;
       }
       return false;
   }

   // Allow NumberFormatterImpl to access fValue.
   friend class impl::NumberFormatterImpl;

   // Allow skeleton generation code to access private members.
   friend class impl::GeneratorHelpers;

   // Allow MacroProps/MicroProps to initialize empty instances and to call
   // copyErrorTo().
   friend struct impl::MacroProps;
};

// Do not enclose entire SymbolsWrapper with #ifndef U_HIDE_INTERNAL_API, needed for a protected field
/** @internal */
class U_I18N_API SymbolsWrapper : public UMemory {
 public:
   /** @internal */
   SymbolsWrapper() : fType(SYMPTR_NONE), fPtr{nullptr} {}

   /** @internal */
   SymbolsWrapper(const SymbolsWrapper &other);

   /** @internal */
   SymbolsWrapper &operator=(const SymbolsWrapper &other);

   /** @internal */
   SymbolsWrapper(SymbolsWrapper&& src) noexcept;

   /** @internal */
   SymbolsWrapper &operator=(SymbolsWrapper&& src) noexcept;

   /** @internal */
   ~SymbolsWrapper();

#ifndef U_HIDE_INTERNAL_API

   /**
    * The provided object is copied, but we do not adopt it.
    * @internal
    */
   void setTo(const DecimalFormatSymbols &dfs);

   /**
    * Adopt the provided object.
    * @internal
    */
   void setTo(const NumberingSystem *ns);

   /**
    * Whether the object is currently holding a DecimalFormatSymbols.
    * @internal
    */
   bool isDecimalFormatSymbols() const;

   /**
    * Whether the object is currently holding a NumberingSystem.
    * @internal
    */
   bool isNumberingSystem() const;

   /**
    * Get the DecimalFormatSymbols pointer. No ownership change.
    * @internal
    */
   const DecimalFormatSymbols *getDecimalFormatSymbols() const;

   /**
    * Get the NumberingSystem pointer. No ownership change.
    * @internal
    */
   const NumberingSystem *getNumberingSystem() const;

#endif  // U_HIDE_INTERNAL_API

   /** @internal */
   UBool copyErrorTo(UErrorCode &status) const {
       if (fType == SYMPTR_DFS && fPtr.dfs == nullptr) {
           status = U_MEMORY_ALLOCATION_ERROR;
           return true;
       } else if (fType == SYMPTR_NS && fPtr.ns == nullptr) {
           status = U_MEMORY_ALLOCATION_ERROR;
           return true;
       }
       return false;
   }

 private:
   enum SymbolsPointerType {
       SYMPTR_NONE, SYMPTR_DFS, SYMPTR_NS
   } fType;

   union {
       const DecimalFormatSymbols *dfs;
       const NumberingSystem *ns;
   } fPtr;

   void doCopyFrom(const SymbolsWrapper &other);

   void doMoveFrom(SymbolsWrapper&& src);

   void doCleanup();
};

// Do not enclose entire Grouper with #ifndef U_HIDE_INTERNAL_API, needed for a protected field
/** @internal */
class U_I18N_API Grouper : public UMemory {
 public:
#ifndef U_HIDE_INTERNAL_API
   /** @internal */
   static Grouper forStrategy(UNumberGroupingStrategy grouping);

   /**
    * Resolve the values in Properties to a Grouper object.
    * @internal
    */
   static Grouper forProperties(const DecimalFormatProperties& properties);

   // Future: static Grouper forProperties(DecimalFormatProperties& properties);

   /** @internal */
   Grouper(int16_t grouping1, int16_t grouping2, int16_t minGrouping, UNumberGroupingStrategy strategy)
           : fGrouping1(grouping1),
             fGrouping2(grouping2),
             fMinGrouping(minGrouping),
             fStrategy(strategy) {}

   /** @internal */
   int16_t getPrimary() const;

   /** @internal */
   int16_t getSecondary() const;
#endif  // U_HIDE_INTERNAL_API

 private:
   /**
    * The grouping sizes, with the following special values:
    * <ul>
    * <li>-1 = no grouping
    * <li>-2 = needs locale data
    * <li>-4 = fall back to Western grouping if not in locale
    * </ul>
    */
   int16_t fGrouping1;
   int16_t fGrouping2;

   /**
    * The minimum grouping size, with the following special values:
    * <ul>
    * <li>-2 = needs locale data
    * <li>-3 = no less than 2
    * </ul>
    */
   int16_t fMinGrouping;

   /**
    * The UNumberGroupingStrategy that was used to create this Grouper, or UNUM_GROUPING_COUNT if this
    * was not created from a UNumberGroupingStrategy.
    */
   UNumberGroupingStrategy fStrategy;

   Grouper() : fGrouping1(-3) {}

   bool isBogus() const {
       return fGrouping1 == -3;
   }

   /** NON-CONST: mutates the current instance. */
   void setLocaleData(const impl::ParsedPatternInfo &patternInfo, const Locale& locale);

   bool groupAtPosition(int32_t position, const impl::DecimalQuantity &value) const;

   // To allow MacroProps/MicroProps to initialize empty instances:
   friend struct MacroProps;
   friend struct MicroProps;
   friend struct SimpleMicroProps;

   // To allow NumberFormatterImpl to access isBogus() and perform other operations:
   friend class NumberFormatterImpl;
   friend class ::icu::number::SimpleNumberFormatter;

   // To allow NumberParserImpl to perform setLocaleData():
   friend class ::icu::numparse::impl::NumberParserImpl;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;
};

// Do not enclose entire Padder with #ifndef U_HIDE_INTERNAL_API, needed for a protected field
/** @internal */
class U_I18N_API Padder : public UMemory {
 public:
#ifndef U_HIDE_INTERNAL_API
   /** @internal */
   static Padder none();

   /** @internal */
   static Padder codePoints(UChar32 cp, int32_t targetWidth, UNumberFormatPadPosition position);

   /** @internal */
   static Padder forProperties(const DecimalFormatProperties& properties);
#endif  // U_HIDE_INTERNAL_API

 private:
   UChar32 fWidth;  // -3 = error; -2 = bogus; -1 = no padding
   union {
       struct {
           int32_t fCp;
           UNumberFormatPadPosition fPosition;
       } padding;
       UErrorCode errorCode;
   } fUnion;

   Padder(UChar32 cp, int32_t width, UNumberFormatPadPosition position);

   Padder(int32_t width);

   Padder(UErrorCode errorCode) : fWidth(-3) { // NOLINT
       fUnion.errorCode = errorCode;
   }

   Padder() : fWidth(-2) {} // NOLINT

   bool isBogus() const {
       return fWidth == -2;
   }

   UBool copyErrorTo(UErrorCode &status) const {
       if (fWidth == -3) {
           status = fUnion.errorCode;
           return true;
       }
       return false;
   }

   bool isValid() const {
       return fWidth > 0;
   }

   int32_t padAndApply(const impl::Modifier &mod1, const impl::Modifier &mod2,
                       FormattedStringBuilder &string, int32_t leftIndex, int32_t rightIndex,
                       UErrorCode &status) const;

   // To allow MacroProps/MicroProps to initialize empty instances:
   friend struct MacroProps;
   friend struct MicroProps;

   // To allow NumberFormatterImpl to access isBogus() and perform other operations:
   friend class impl::NumberFormatterImpl;

   // To allow access to the skeleton generation code:
   friend class impl::GeneratorHelpers;
};

// Do not enclose entire MacroProps with #ifndef U_HIDE_INTERNAL_API, needed for a protected field.
// U_I18N_API because intltest uses it.
/** @internal */
struct U_I18N_API_CLASS MacroProps : public UMemory {
   /** @internal */
   Notation notation;

   /** @internal */
   MeasureUnit unit;  // = MeasureUnit();  (the base dimensionless unit)

   /** @internal */
   MeasureUnit perUnit;  // = MeasureUnit();  (the base dimensionless unit)

   /** @internal */
   Precision precision;  // = Precision();  (bogus)

   /** @internal */
   UNumberFormatRoundingMode roundingMode = UNUM_ROUND_HALFEVEN;

   /** @internal */
   Grouper grouper;  // = Grouper();  (bogus)

   /** @internal */
   Padder padder;    // = Padder();   (bogus)

   /** @internal */
   IntegerWidth integerWidth; // = IntegerWidth(); (bogus)

   /** @internal */
   SymbolsWrapper symbols;

   // UNUM_XYZ_COUNT denotes null (bogus) values.

   /** @internal */
   UNumberUnitWidth unitWidth = UNUM_UNIT_WIDTH_COUNT;

   /** @internal */
   UNumberSignDisplay sign = UNUM_SIGN_COUNT;

   /** @internal */
   bool approximately = false;

   /** @internal */
   UNumberDecimalSeparatorDisplay decimal = UNUM_DECIMAL_SEPARATOR_COUNT;

   /** @internal */
   Scale scale;  // = Scale();  (benign value)

   /** @internal */
   StringProp usage;  // = StringProp();  (no usage)

   /** @internal */
   StringProp unitDisplayCase;  // = StringProp();  (nominative)

   /** @internal */
   const AffixPatternProvider* affixProvider = nullptr;  // no ownership

   /** @internal */
   const PluralRules* rules = nullptr;  // no ownership

   /** @internal */
   int32_t threshold = kInternalDefaultThreshold;

   /** @internal */
   Locale locale;

   // NOTE: Uses default copy and move constructors.

   /**
    * Check all members for errors.
    * @internal
    */
   U_I18N_API bool copyErrorTo(UErrorCode &status) const {
       return notation.copyErrorTo(status) || precision.copyErrorTo(status) ||
              padder.copyErrorTo(status) || integerWidth.copyErrorTo(status) ||
              symbols.copyErrorTo(status) || scale.copyErrorTo(status) || usage.copyErrorTo(status) ||
              unitDisplayCase.copyErrorTo(status);
   }
};

} // namespace impl

#if (U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN) && defined(_MSC_VER)
// Ignore MSVC warning 4661. This is generated for NumberFormatterSettings<>::toSkeleton() as this method
// is defined elsewhere (in number_skeletons.cpp). The compiler is warning that the explicit template instantiation
// inside this single translation unit (CPP file) is incomplete, and thus it isn't sure if the template class is
// fully defined. However, since each translation unit explicitly instantiates all the necessary template classes,
// they will all be passed to the linker, and the linker will still find and export all the class members.
#pragma warning(push)
#pragma warning(disable: 4661)
#endif

/**
* An abstract base class for specifying settings related to number formatting. This class is implemented by
* {@link UnlocalizedNumberFormatter} and {@link LocalizedNumberFormatter}. This class is not intended for
* public subclassing.
*/
template<typename Derived>
class U_I18N_API NumberFormatterSettings {
 public:
   /**
    * Specifies the notation style (simple, scientific, or compact) for rendering numbers.
    *
    * <ul>
    * <li>Simple notation: "12,300"
    * <li>Scientific notation: "1.23E4"
    * <li>Compact notation: "12K"
    * </ul>
    *
    * <p>
    * All notation styles will be properly localized with locale data, and all notation styles are compatible with
    * units, rounding precisions, and other number formatter settings.
    *
    * <p>
    * Pass this method the return value of a {@link Notation} factory method. For example:
    *
    * <pre>
    * NumberFormatter::with().notation(Notation::compactShort())
    * </pre>
    *
    * The default is to use simple notation.
    *
    * @param notation
    *            The notation strategy to use.
    * @return The fluent chain.
    * @see Notation
    * @stable ICU 60
    */
   Derived notation(const Notation &notation) const &;

   /**
    * Overload of notation() for use on an rvalue reference.
    *
    * @param notation
    *            The notation strategy to use.
    * @return The fluent chain.
    * @see #notation
    * @stable ICU 62
    */
   Derived notation(const Notation &notation) &&;

   /**
    * Specifies the unit (unit of measure, currency, or percent) to associate with rendered numbers.
    *
    * <ul>
    * <li>Unit of measure: "12.3 meters"
    * <li>Currency: "$12.30"
    * <li>Percent: "12.3%"
    * </ul>
    *
    * All units will be properly localized with locale data, and all units are compatible with notation styles,
    * rounding precisions, and other number formatter settings.
    *
    * \note If the usage() is set, the output unit **will be changed** to
    *       produce localised units, according to usage, locale and unit. See
    *       FormattedNumber::getOutputUnit().
    *
    * Pass this method any instance of {@link MeasureUnit}. For units of measure:
    *
    * <pre>
    * NumberFormatter::with().unit(MeasureUnit::getMeter())
    * NumberFormatter::with().unit(MeasureUnit::forIdentifier("foot-per-second", status))
    * </pre>
    *
    * Currency:
    *
    * <pre>
    * NumberFormatter::with().unit(CurrencyUnit(u"USD", status))
    * </pre>
    *
    * Percent:
    *
    * <pre>
    * NumberFormatter::with().unit(NoUnit.percent())
    * </pre>
    *
    * See {@link #perUnit} for information on how to format strings like "5 meters per second".
    *
    * The default is to render without units (equivalent to NoUnit.base()).
    *
    * @param unit
    *            The unit to render.
    * @return The fluent chain.
    * @see MeasureUnit
    * @see Currency
    * @see NoUnit
    * @see #perUnit
    * @stable ICU 60
    */
   Derived unit(const icu::MeasureUnit &unit) const &;

   /**
    * Overload of unit() for use on an rvalue reference.
    *
    * @param unit
    *            The unit to render.
    * @return The fluent chain.
    * @see #unit
    * @stable ICU 62
    */
   Derived unit(const icu::MeasureUnit &unit) &&;

   /**
    * Like unit(), but takes ownership of a pointer.  Convenient for use with the MeasureFormat factory
    * methods that return pointers that need ownership.
    *
    * Note: consider using the MeasureFormat factory methods that return by value.
    *
    * @param unit
    *            The unit to render.
    * @return The fluent chain.
    * @see #unit
    * @see MeasureUnit
    * @stable ICU 60
    */
   Derived adoptUnit(icu::MeasureUnit *unit) const &;

   /**
    * Overload of adoptUnit() for use on an rvalue reference.
    *
    * @param unit
    *            The unit to render.
    * @return The fluent chain.
    * @see #adoptUnit
    * @stable ICU 62
    */
   Derived adoptUnit(icu::MeasureUnit *unit) &&;

   /**
    * Sets a unit to be used in the denominator. For example, to format "3 m/s", pass METER to the unit and SECOND to
    * the perUnit.
    *
    * Pass this method any instance of {@link MeasureUnit}. Example:
    *
    * <pre>
    * NumberFormatter::with()
    *      .unit(MeasureUnit::getMeter())
    *      .perUnit(MeasureUnit::getSecond())
    * </pre>
    *
    * The default is not to display any unit in the denominator.
    *
    * If a per-unit is specified without a primary unit via {@link #unit}, the behavior is undefined.
    *
    * @param perUnit
    *            The unit to render in the denominator.
    * @return The fluent chain
    * @see #unit
    * @stable ICU 61
    */
   Derived perUnit(const icu::MeasureUnit &perUnit) const &;

   /**
    * Overload of perUnit() for use on an rvalue reference.
    *
    * @param perUnit
    *            The unit to render in the denominator.
    * @return The fluent chain.
    * @see #perUnit
    * @stable ICU 62
    */
   Derived perUnit(const icu::MeasureUnit &perUnit) &&;

   /**
    * Like perUnit(), but takes ownership of a pointer.  Convenient for use with the MeasureFormat factory
    * methods that return pointers that need ownership.
    *
    * Note: consider using the MeasureFormat factory methods that return by value.
    *
    * @param perUnit
    *            The unit to render in the denominator.
    * @return The fluent chain.
    * @see #perUnit
    * @see MeasureUnit
    * @stable ICU 61
    */
   Derived adoptPerUnit(icu::MeasureUnit *perUnit) const &;

   /**
    * Overload of adoptPerUnit() for use on an rvalue reference.
    *
    * @param perUnit
    *            The unit to render in the denominator.
    * @return The fluent chain.
    * @see #adoptPerUnit
    * @stable ICU 62
    */
   Derived adoptPerUnit(icu::MeasureUnit *perUnit) &&;

   /**
    * Specifies the rounding precision to use when formatting numbers.
    *
    * <ul>
    * <li>Round to 3 decimal places: "3.142"
    * <li>Round to 3 significant figures: "3.14"
    * <li>Round to the closest nickel: "3.15"
    * <li>Do not perform rounding: "3.1415926..."
    * </ul>
    *
    * <p>
    * Pass this method the return value of one of the factory methods on {@link Precision}. For example:
    *
    * <pre>
    * NumberFormatter::with().precision(Precision::fixedFraction(2))
    * </pre>
    *
    * <p>
    * In most cases, the default rounding strategy is to round to 6 fraction places; i.e.,
    * <code>Precision.maxFraction(6)</code>. The exceptions are if compact notation is being used, then the compact
    * notation rounding strategy is used (see {@link Notation#compactShort} for details), or if the unit is a currency,
    * then standard currency rounding is used, which varies from currency to currency (see {@link Precision#currency} for
    * details).
    *
    * @param precision
    *            The rounding precision to use.
    * @return The fluent chain.
    * @see Precision
    * @stable ICU 62
    */
   Derived precision(const Precision& precision) const &;

   /**
    * Overload of precision() for use on an rvalue reference.
    *
    * @param precision
    *            The rounding precision to use.
    * @return The fluent chain.
    * @see #precision
    * @stable ICU 62
    */
   Derived precision(const Precision& precision) &&;

   /**
    * Specifies how to determine the direction to round a number when it has more digits than fit in the
    * desired precision.  When formatting 1.235:
    *
    * <ul>
    * <li>Ceiling rounding mode with integer precision: "2"
    * <li>Half-down rounding mode with 2 fixed fraction digits: "1.23"
    * <li>Half-up rounding mode with 2 fixed fraction digits: "1.24"
    * </ul>
    *
    * The default is HALF_EVEN. For more information on rounding mode, see the ICU userguide here:
    *
    * https://unicode-org.github.io/icu/userguide/format_parse/numbers/rounding-modes
    *
    * @param roundingMode The rounding mode to use.
    * @return The fluent chain.
    * @stable ICU 62
    */
   Derived roundingMode(UNumberFormatRoundingMode roundingMode) const &;

   /**
    * Overload of roundingMode() for use on an rvalue reference.
    *
    * @param roundingMode The rounding mode to use.
    * @return The fluent chain.
    * @see #roundingMode
    * @stable ICU 62
    */
   Derived roundingMode(UNumberFormatRoundingMode roundingMode) &&;

   /**
    * Specifies the grouping strategy to use when formatting numbers.
    *
    * <ul>
    * <li>Default grouping: "12,300" and "1,230"
    * <li>Grouping with at least 2 digits: "12,300" and "1230"
    * <li>No grouping: "12300" and "1230"
    * </ul>
    *
    * <p>
    * The exact grouping widths will be chosen based on the locale.
    *
    * <p>
    * Pass this method an element from the {@link UNumberGroupingStrategy} enum. For example:
    *
    * <pre>
    * NumberFormatter::with().grouping(UNUM_GROUPING_MIN2)
    * </pre>
    *
    * The default is to perform grouping according to locale data; most locales, but not all locales,
    * enable it by default.
    *
    * @param strategy
    *            The grouping strategy to use.
    * @return The fluent chain.
    * @stable ICU 61
    */
   Derived grouping(UNumberGroupingStrategy strategy) const &;

   /**
    * Overload of grouping() for use on an rvalue reference.
    *
    * @param strategy
    *            The grouping strategy to use.
    * @return The fluent chain.
    * @see #grouping
    * @stable ICU 62
    */
   Derived grouping(UNumberGroupingStrategy strategy) &&;

   /**
    * Specifies the minimum and maximum number of digits to render before the decimal mark.
    *
    * <ul>
    * <li>Zero minimum integer digits: ".08"
    * <li>One minimum integer digit: "0.08"
    * <li>Two minimum integer digits: "00.08"
    * </ul>
    *
    * <p>
    * Pass this method the return value of {@link IntegerWidth#zeroFillTo}. For example:
    *
    * <pre>
    * NumberFormatter::with().integerWidth(IntegerWidth::zeroFillTo(2))
    * </pre>
    *
    * The default is to have one minimum integer digit.
    *
    * @param style
    *            The integer width to use.
    * @return The fluent chain.
    * @see IntegerWidth
    * @stable ICU 60
    */
   Derived integerWidth(const IntegerWidth &style) const &;

   /**
    * Overload of integerWidth() for use on an rvalue reference.
    *
    * @param style
    *            The integer width to use.
    * @return The fluent chain.
    * @see #integerWidth
    * @stable ICU 62
    */
   Derived integerWidth(const IntegerWidth &style) &&;

   /**
    * Specifies the symbols (decimal separator, grouping separator, percent sign, numerals, etc.) to use when rendering
    * numbers.
    *
    * <ul>
    * <li><em>en_US</em> symbols: "12,345.67"
    * <li><em>fr_FR</em> symbols: "12&nbsp;345,67"
    * <li><em>de_CH</em> symbols: "12’345.67"
    * <li><em>my_MY</em> symbols: "၁၂,၃၄၅.၆၇"
    * </ul>
    *
    * <p>
    * Pass this method an instance of {@link DecimalFormatSymbols}. For example:
    *
    * <pre>
    * NumberFormatter::with().symbols(DecimalFormatSymbols(Locale("de_CH"), status))
    * </pre>
    *
    * <p>
    * <strong>Note:</strong> DecimalFormatSymbols automatically chooses the best numbering system based on the locale.
    * In the examples above, the first three are using the Latin numbering system, and the fourth is using the Myanmar
    * numbering system.
    *
    * <p>
    * <strong>Note:</strong> The instance of DecimalFormatSymbols will be copied: changes made to the symbols object
    * after passing it into the fluent chain will not be seen.
    *
    * <p>
    * <strong>Note:</strong> Calling this method will override any previously specified DecimalFormatSymbols
    * or NumberingSystem.
    *
    * <p>
    * The default is to choose the symbols based on the locale specified in the fluent chain.
    *
    * @param symbols
    *            The DecimalFormatSymbols to use.
    * @return The fluent chain.
    * @see DecimalFormatSymbols
    * @stable ICU 60
    */
   Derived symbols(const DecimalFormatSymbols &symbols) const &;

   /**
    * Overload of symbols() for use on an rvalue reference.
    *
    * @param symbols
    *            The DecimalFormatSymbols to use.
    * @return The fluent chain.
    * @see #symbols
    * @stable ICU 62
    */
   Derived symbols(const DecimalFormatSymbols &symbols) &&;

   /**
    * Specifies that the given numbering system should be used when fetching symbols.
    *
    * <ul>
    * <li>Latin numbering system: "12,345"
    * <li>Myanmar numbering system: "၁၂,၃၄၅"
    * <li>Math Sans Bold numbering system: "𝟭𝟮,𝟯𝟰𝟱"
    * </ul>
    *
    * <p>
    * Pass this method an instance of {@link NumberingSystem}. For example, to force the locale to always use the Latin
    * alphabet numbering system (ASCII digits):
    *
    * <pre>
    * NumberFormatter::with().adoptSymbols(NumberingSystem::createInstanceByName("latn", status))
    * </pre>
    *
    * <p>
    * <strong>Note:</strong> Calling this method will override any previously specified DecimalFormatSymbols
    * or NumberingSystem.
    *
    * <p>
    * The default is to choose the best numbering system for the locale.
    *
    * <p>
    * This method takes ownership of a pointer in order to work nicely with the NumberingSystem factory methods.
    *
    * @param symbols
    *            The NumberingSystem to use.
    * @return The fluent chain.
    * @see NumberingSystem
    * @stable ICU 60
    */
   Derived adoptSymbols(NumberingSystem *symbols) const &;

   /**
    * Overload of adoptSymbols() for use on an rvalue reference.
    *
    * @param symbols
    *            The NumberingSystem to use.
    * @return The fluent chain.
    * @see #adoptSymbols
    * @stable ICU 62
    */
   Derived adoptSymbols(NumberingSystem *symbols) &&;

   /**
    * Sets the width of the unit (measure unit or currency).  Most common values:
    *
    * <ul>
    * <li>Short: "$12.00", "12 m"
    * <li>ISO Code: "USD 12.00"
    * <li>Full name: "12.00 US dollars", "12 meters"
    * </ul>
    *
    * <p>
    * Pass an element from the {@link UNumberUnitWidth} enum to this setter. For example:
    *
    * <pre>
    * NumberFormatter::with().unitWidth(UNumberUnitWidth::UNUM_UNIT_WIDTH_FULL_NAME)
    * </pre>
    *
    * <p>
    * The default is the SHORT width.
    *
    * @param width
    *            The width to use when rendering numbers.
    * @return The fluent chain
    * @see UNumberUnitWidth
    * @stable ICU 60
    */
   Derived unitWidth(UNumberUnitWidth width) const &;

   /**
    * Overload of unitWidth() for use on an rvalue reference.
    *
    * @param width
    *            The width to use when rendering numbers.
    * @return The fluent chain.
    * @see #unitWidth
    * @stable ICU 62
    */
   Derived unitWidth(UNumberUnitWidth width) &&;

   /**
    * Sets the plus/minus sign display strategy. Most common values:
    *
    * <ul>
    * <li>Auto: "123", "-123"
    * <li>Always: "+123", "-123"
    * <li>Accounting: "$123", "($123)"
    * </ul>
    *
    * <p>
    * Pass an element from the {@link UNumberSignDisplay} enum to this setter. For example:
    *
    * <pre>
    * NumberFormatter::with().sign(UNumberSignDisplay::UNUM_SIGN_ALWAYS)
    * </pre>
    *
    * <p>
    * The default is AUTO sign display.
    *
    * @param style
    *            The sign display strategy to use when rendering numbers.
    * @return The fluent chain
    * @see UNumberSignDisplay
    * @stable ICU 60
    */
   Derived sign(UNumberSignDisplay style) const &;

   /**
    * Overload of sign() for use on an rvalue reference.
    *
    * @param style
    *            The sign display strategy to use when rendering numbers.
    * @return The fluent chain.
    * @see #sign
    * @stable ICU 62
    */
   Derived sign(UNumberSignDisplay style) &&;

   /**
    * Sets the decimal separator display strategy. This affects integer numbers with no fraction part. Most common
    * values:
    *
    * <ul>
    * <li>Auto: "1"
    * <li>Always: "1."
    * </ul>
    *
    * <p>
    * Pass an element from the {@link UNumberDecimalSeparatorDisplay} enum to this setter. For example:
    *
    * <pre>
    * NumberFormatter::with().decimal(UNumberDecimalSeparatorDisplay::UNUM_DECIMAL_SEPARATOR_ALWAYS)
    * </pre>
    *
    * <p>
    * The default is AUTO decimal separator display.
    *
    * @param style
    *            The decimal separator display strategy to use when rendering numbers.
    * @return The fluent chain
    * @see UNumberDecimalSeparatorDisplay
    * @stable ICU 60
    */
   Derived decimal(UNumberDecimalSeparatorDisplay style) const &;

   /**
    * Overload of decimal() for use on an rvalue reference.
    *
    * @param style
    *            The decimal separator display strategy to use when rendering numbers.
    * @return The fluent chain.
    * @see #decimal
    * @stable ICU 62
    */
   Derived decimal(UNumberDecimalSeparatorDisplay style) &&;

   /**
    * Sets a scale (multiplier) to be used to scale the number by an arbitrary amount before formatting.
    * Most common values:
    *
    * <ul>
    * <li>Multiply by 100: useful for percentages.
    * <li>Multiply by an arbitrary value: useful for unit conversions.
    * </ul>
    *
    * <p>
    * Pass an element from a {@link Scale} factory method to this setter. For example:
    *
    * <pre>
    * NumberFormatter::with().scale(Scale::powerOfTen(2))
    * </pre>
    *
    * <p>
    * The default is to not apply any multiplier.
    *
    * @param scale
    *            The scale to apply when rendering numbers.
    * @return The fluent chain
    * @stable ICU 62
    */
   Derived scale(const Scale &scale) const &;

   /**
    * Overload of scale() for use on an rvalue reference.
    *
    * @param scale
    *            The scale to apply when rendering numbers.
    * @return The fluent chain.
    * @see #scale
    * @stable ICU 62
    */
   Derived scale(const Scale &scale) &&;

   /**
    * Specifies the usage for which numbers will be formatted ("person-height",
    * "road", "rainfall", etc.)
    *
    * When a `usage` is specified, the output unit will change depending on the
    * `Locale` and the unit quantity. For example, formatting length
    * measurements specified in meters:
    *
    * `NumberFormatter::with().usage("person").unit(MeasureUnit::getMeter()).locale("en-US")`
    *   * When formatting 0.25, the output will be "10 inches".
    *   * When formatting 1.50, the output will be "4 feet and 11 inches".
    *
    * The input unit specified via unit() determines the type of measurement
    * being formatted (e.g. "length" when the unit is "foot"). The usage
    * requested will be looked for only within this category of measurement
    * units.
    *
    * The output unit can be found via FormattedNumber::getOutputUnit().
    *
    * If the usage has multiple parts (e.g. "land-agriculture-grain") and does
    * not match a known usage preference, the last part will be dropped
    * repeatedly until a match is found (e.g. trying "land-agriculture", then
    * "land"). If a match is still not found, usage will fall back to
    * "default".
    *
    * Setting usage to an empty string clears the usage (disables usage-based
    * localized formatting).
    *
    * Setting a usage string but not a correct input unit will result in an
    * U_ILLEGAL_ARGUMENT_ERROR.
    *
    * When using usage, specifying rounding or precision is unnecessary.
    * Specifying a precision in some manner will override the default
    * formatting.
    *
    * @param usage A `usage` parameter from the units resource. See the
    * unitPreferenceData in *source/data/misc/units.txt*, generated from
    * `unitPreferenceData` in [CLDR's
    * supplemental/units.xml](https://github.com/unicode-org/cldr/blob/main/common/supplemental/units.xml).
    * @return The fluent chain.
    * @stable ICU 68
    */
   Derived usage(StringPiece usage) const &;

   /**
    * Overload of usage() for use on an rvalue reference.
    *
    * @param usage The unit `usage`.
    * @return The fluent chain.
    * @stable ICU 68
    */
   Derived usage(StringPiece usage) &&;

   /**
    * Specifies the DisplayOptions. For example, UDisplayOptionsGrammaticalCase specifies
    * the desired case for a unit formatter's output (e.g. accusative, dative, genitive).
    *
    * @param displayOptions
    * @return The fluent chain.
    * @stable ICU 72
    */
   Derived displayOptions(const DisplayOptions &displayOptions) const &;

   /**
    * Overload of displayOptions() for use on an rvalue reference.
    *
    * @param displayOptions
    * @return The fluent chain.
    * @stable ICU 72
    */
   Derived displayOptions(const DisplayOptions &displayOptions) &&;

#ifndef U_HIDE_INTERNAL_API
   /**
    * NOTE: Use `displayOptions` instead. This method was part of
    * an internal technology preview in ICU 69, but will be removed
    * in ICU 73, in favor of `displayOptions`
    *
    * Specifies the desired case for a unit formatter's output (e.g.
    * accusative, dative, genitive).
    *
    * @internal
    */
   Derived unitDisplayCase(StringPiece unitDisplayCase) const &;

   /**
    * NOTE: Use `displayOptions` instead. This method was part of
    * an internal technology preview in ICU 69, but will be removed
    * in ICU 73, in favor of `displayOptions`
    *
    * Overload of unitDisplayCase() for use on an rvalue reference.
    *
    * @internal
    */
   Derived unitDisplayCase(StringPiece unitDisplayCase) &&;
#endif // U_HIDE_INTERNAL_API

#ifndef U_HIDE_INTERNAL_API

   /**
    * Set the padding strategy. May be added in the future; see #13338.
    *
    * @internal ICU 60: This API is ICU internal only.
    */
   Derived padding(const impl::Padder &padder) const &;

   /** @internal */
   Derived padding(const impl::Padder &padder) &&;

   /**
    * Internal fluent setter to support a custom regulation threshold. A threshold of 1 causes the data structures to
    * be built right away. A threshold of 0 prevents the data structures from being built.
    *
    * @internal ICU 60: This API is ICU internal only.
    */
   Derived threshold(int32_t threshold) const &;

   /** @internal */
   Derived threshold(int32_t threshold) &&;

   /**
    * Internal fluent setter to overwrite the entire macros object.
    *
    * @internal ICU 60: This API is ICU internal only.
    */
   Derived macros(const impl::MacroProps& macros) const &;

   /** @internal */
   Derived macros(const impl::MacroProps& macros) &&;

   /** @internal */
   Derived macros(impl::MacroProps&& macros) const &;

   /** @internal */
   Derived macros(impl::MacroProps&& macros) &&;

#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Creates a skeleton string representation of this number formatter. A skeleton string is a
    * locale-agnostic serialized form of a number formatter.
    *
    * Not all options are capable of being represented in the skeleton string; for example, a
    * DecimalFormatSymbols object. If any such option is encountered, the error code is set to
    * U_UNSUPPORTED_ERROR.
    *
    * The returned skeleton is in normalized form, such that two number formatters with equivalent
    * behavior should produce the same skeleton.
    *
    * For more information on number skeleton strings, see:
    * https://unicode-org.github.io/icu/userguide/format_parse/numbers/skeletons.html
    *
    * @return A number skeleton string with behavior corresponding to this number formatter.
    * @stable ICU 62
    */
   UnicodeString toSkeleton(UErrorCode& status) const;

   /**
    * Returns the current (Un)LocalizedNumberFormatter as a LocalPointer
    * wrapping a heap-allocated copy of the current object.
    *
    * This is equivalent to new-ing the move constructor with a value object
    * as the argument.
    *
    * @return A wrapped (Un)LocalizedNumberFormatter pointer, or a wrapped
    *         nullptr on failure.
    * @stable ICU 64
    */
   LocalPointer<Derived> clone() const &;

   /**
    * Overload of clone for use on an rvalue reference.
    *
    * @return A wrapped (Un)LocalizedNumberFormatter pointer, or a wrapped
    *         nullptr on failure.
    * @stable ICU 64
    */
   LocalPointer<Derived> clone() &&;

   /**
    * Sets the UErrorCode if an error occurred in the fluent chain.
    * Preserves older error codes in the outErrorCode.
    * @return true if U_FAILURE(outErrorCode)
    * @stable ICU 60
    */
   UBool copyErrorTo(UErrorCode &outErrorCode) const {
       if (U_FAILURE(outErrorCode)) {
           // Do not overwrite the older error code
           return true;
       }
       fMacros.copyErrorTo(outErrorCode);
       return U_FAILURE(outErrorCode);
   }

   // NOTE: Uses default copy and move constructors.

 private:
   impl::MacroProps fMacros;

   // Don't construct me directly!  Use (Un)LocalizedNumberFormatter.
   NumberFormatterSettings() = default;

   friend class LocalizedNumberFormatter;
   friend class UnlocalizedNumberFormatter;

   // Give NumberRangeFormatter access to the MacroProps
   friend void impl::touchRangeLocales(impl::RangeMacroProps& macros);
   friend class impl::NumberRangeFormatterImpl;
};

// Explicit instantiations in source/i18n/number_fluent.cpp.
// (MSVC treats imports/exports of explicit instantiations differently.)
#ifndef _MSC_VER
extern template class NumberFormatterSettings<UnlocalizedNumberFormatter>;
extern template class NumberFormatterSettings<LocalizedNumberFormatter>;
#endif

/**
* A NumberFormatter that does not yet have a locale. In order to format numbers, a locale must be specified.
*
* Instances of this class are immutable and thread-safe.
*
* @see NumberFormatter
* @stable ICU 60
*/
class U_I18N_API UnlocalizedNumberFormatter
       : public NumberFormatterSettings<UnlocalizedNumberFormatter>, public UMemory {

 public:
   /**
    * Associate the given locale with the number formatter. The locale is used for picking the appropriate symbols,
    * formats, and other data for number display.
    *
    * @param locale
    *            The locale to use when loading data for number formatting.
    * @return The fluent chain.
    * @stable ICU 60
    */
   LocalizedNumberFormatter locale(const icu::Locale &locale) const &;

   /**
    * Overload of locale() for use on an rvalue reference.
    *
    * @param locale
    *            The locale to use when loading data for number formatting.
    * @return The fluent chain.
    * @see #locale
    * @stable ICU 62
    */
   LocalizedNumberFormatter locale(const icu::Locale &locale) &&;

   /**
    * Default constructor: puts the formatter into a valid but undefined state.
    *
    * @stable ICU 62
    */
   UnlocalizedNumberFormatter() = default;

   /**
    * Returns a copy of this UnlocalizedNumberFormatter.
    * @stable ICU 60
    */
   UnlocalizedNumberFormatter(const UnlocalizedNumberFormatter &other);

   /**
    * Move constructor:
    * The source UnlocalizedNumberFormatter will be left in a valid but undefined state.
    * @stable ICU 62
    */
   UnlocalizedNumberFormatter(UnlocalizedNumberFormatter&& src) noexcept;

   /**
    * Copy assignment operator.
    * @stable ICU 62
    */
   UnlocalizedNumberFormatter& operator=(const UnlocalizedNumberFormatter& other);

   /**
    * Move assignment operator:
    * The source UnlocalizedNumberFormatter will be left in a valid but undefined state.
    * @stable ICU 62
    */
   UnlocalizedNumberFormatter& operator=(UnlocalizedNumberFormatter&& src) noexcept;

 private:
   explicit UnlocalizedNumberFormatter(const NumberFormatterSettings<UnlocalizedNumberFormatter>& other);

   explicit UnlocalizedNumberFormatter(
           NumberFormatterSettings<UnlocalizedNumberFormatter>&& src) noexcept;

   explicit UnlocalizedNumberFormatter(const impl::MacroProps &macros);

   explicit UnlocalizedNumberFormatter(impl::MacroProps &&macros);

   // To give the fluent setters access to this class's constructor:
   friend class NumberFormatterSettings<UnlocalizedNumberFormatter>;

   // To give NumberFormatter::with() access to this class's constructor:
   friend class NumberFormatter;

   // To give LNF::withoutLocale() access to this class's constructor:
   friend class LocalizedNumberFormatter;
};

/**
* A NumberFormatter that has a locale associated with it; this means .format() methods are available.
*
* Instances of this class are immutable and thread-safe.
*
* @see NumberFormatter
* @stable ICU 60
*/
class U_I18N_API LocalizedNumberFormatter
       : public NumberFormatterSettings<LocalizedNumberFormatter>, public UMemory {
 public:
   /**
    * Format the given integer number to a string using the settings specified in the NumberFormatter fluent
    * setting chain.
    *
    * @param value
    *            The number to format.
    * @param status
    *            Set to an ErrorCode if one occurred in the setter chain or during formatting.
    * @return A FormattedNumber object; call .toString() to get the string.
    * @stable ICU 60
    */
   FormattedNumber formatInt(int64_t value, UErrorCode &status) const;

   /**
    * Format the given float or double to a string using the settings specified in the NumberFormatter fluent setting
    * chain.
    *
    * @param value
    *            The number to format.
    * @param status
    *            Set to an ErrorCode if one occurred in the setter chain or during formatting.
    * @return A FormattedNumber object; call .toString() to get the string.
    * @stable ICU 60
    */
   FormattedNumber formatDouble(double value, UErrorCode &status) const;

   /**
    * Format the given decimal number to a string using the settings
    * specified in the NumberFormatter fluent setting chain.
    * The syntax of the unformatted number is a "numeric string"
    * as defined in the Decimal Arithmetic Specification, available at
    * http://speleotrove.com/decimal
    *
    * @param value
    *            The number to format.
    * @param status
    *            Set to an ErrorCode if one occurred in the setter chain or during formatting.
    * @return A FormattedNumber object; call .toString() to get the string.
    * @stable ICU 60
    */
   FormattedNumber formatDecimal(StringPiece value, UErrorCode& status) const;

#ifndef U_HIDE_INTERNAL_API

           
   /**
    * @internal
    */
   const DecimalFormatSymbols* getDecimalFormatSymbols() const;
   
   /** Internal method.
    * @internal
    */
   FormattedNumber formatDecimalQuantity(const impl::DecimalQuantity& dq, UErrorCode& status) const;

   /** Internal method for DecimalFormat compatibility.
    * @internal
    */
   void getAffixImpl(bool isPrefix, bool isNegative, UnicodeString& result, UErrorCode& status) const;

   /**
    * Internal method for testing.
    * @internal
    */
   const impl::NumberFormatterImpl* getCompiled() const;

   /**
    * Internal method for testing.
    * @internal
    */
   int32_t getCallCount() const;

#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Creates a representation of this LocalizedNumberFormat as an icu::Format, enabling the use
    * of this number formatter with APIs that need an object of that type, such as MessageFormat.
    *
    * This API is not intended to be used other than for enabling API compatibility. The formatDouble,
    * formatInt, and formatDecimal methods should normally be used when formatting numbers, not the Format
    * object returned by this method.
    *
    * The caller owns the returned object and must delete it when finished.
    *
    * @return A Format wrapping this LocalizedNumberFormatter.
    * @stable ICU 62
    */
   Format* toFormat(UErrorCode& status) const;

   /**
    * Disassociate the locale from this formatter.
    *
    * @return The fluent chain.
    * @stable ICU 75
    */
   UnlocalizedNumberFormatter withoutLocale() const &;

   /**
    * Overload of withoutLocale() for use on an rvalue reference.
    *
    * @return The fluent chain.
    * @see #withoutLocale
    * @stable ICU 75
    */
   UnlocalizedNumberFormatter withoutLocale() &&;

   /**
    * Default constructor: puts the formatter into a valid but undefined state.
    *
    * @stable ICU 62
    */
   LocalizedNumberFormatter() = default;

   /**
    * Returns a copy of this LocalizedNumberFormatter.
    * @stable ICU 60
    */
   LocalizedNumberFormatter(const LocalizedNumberFormatter &other);

   /**
    * Move constructor:
    * The source LocalizedNumberFormatter will be left in a valid but undefined state.
    * @stable ICU 62
    */
   LocalizedNumberFormatter(LocalizedNumberFormatter&& src) noexcept;

   /**
    * Copy assignment operator.
    * @stable ICU 62
    */
   LocalizedNumberFormatter& operator=(const LocalizedNumberFormatter& other);

   /**
    * Move assignment operator:
    * The source LocalizedNumberFormatter will be left in a valid but undefined state.
    * @stable ICU 62
    */
   LocalizedNumberFormatter& operator=(LocalizedNumberFormatter&& src) noexcept;

#ifndef U_HIDE_INTERNAL_API

   /**
    * This is the core entrypoint to the number formatting pipeline. It performs self-regulation: a static code path
    * for the first few calls, and compiling a more efficient data structure if called repeatedly.
    *
    * <p>
    * This function is very hot, being called in every call to the number formatting pipeline.
    *
    * @param results
    *            The results object. This method will mutate it to save the results.
    * @param status
    * @internal
    */
   void formatImpl(impl::UFormattedNumberData *results, UErrorCode &status) const;

#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Destruct this LocalizedNumberFormatter, cleaning up any memory it might own.
    * @stable ICU 60
    */
   ~LocalizedNumberFormatter();

 private:
   // Note: fCompiled can't be a LocalPointer because impl::NumberFormatterImpl is defined in an internal
   // header, and LocalPointer needs the full class definition in order to delete the instance.
   const impl::NumberFormatterImpl* fCompiled {nullptr};
   char fUnsafeCallCount[8] {};  // internally cast to u_atomic_int32_t

   // Owned pointer to a DecimalFormatWarehouse, used when copying a LocalizedNumberFormatter
   // from a DecimalFormat.
   const impl::DecimalFormatWarehouse* fWarehouse {nullptr};

   explicit LocalizedNumberFormatter(const NumberFormatterSettings<LocalizedNumberFormatter>& other);

   explicit LocalizedNumberFormatter(NumberFormatterSettings<LocalizedNumberFormatter>&& src) noexcept;

   LocalizedNumberFormatter(const impl::MacroProps &macros, const Locale &locale);

   LocalizedNumberFormatter(impl::MacroProps &&macros, const Locale &locale);

   void resetCompiled();

   void lnfMoveHelper(LocalizedNumberFormatter&& src);

   void lnfCopyHelper(const LocalizedNumberFormatter& src, UErrorCode& status);

   /**
    * @return true if the compiled formatter is available.
    */
   bool computeCompiled(UErrorCode& status) const;

   // To give the fluent setters access to this class's constructor:
   friend class NumberFormatterSettings<UnlocalizedNumberFormatter>;
   friend class NumberFormatterSettings<LocalizedNumberFormatter>;

   // To give UnlocalizedNumberFormatter::locale() access to this class's constructor:
   friend class UnlocalizedNumberFormatter;
};

#if (U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN) && defined(_MSC_VER)
// Warning 4661.
#pragma warning(pop)
#endif

/**
* See the main description in numberformatter.h for documentation and examples.
*
* @stable ICU 60
*/
class U_I18N_API NumberFormatter final {
 public:
   /**
    * Call this method at the beginning of a NumberFormatter fluent chain in which the locale is not currently known at
    * the call site.
    *
    * @return An {@link UnlocalizedNumberFormatter}, to be used for chaining.
    * @stable ICU 60
    */
   static UnlocalizedNumberFormatter with();

   /**
    * Call this method at the beginning of a NumberFormatter fluent chain in which the locale is known at the call
    * site.
    *
    * @param locale
    *            The locale from which to load formats and symbols for number formatting.
    * @return A {@link LocalizedNumberFormatter}, to be used for chaining.
    * @stable ICU 60
    */
   static LocalizedNumberFormatter withLocale(const Locale &locale);

   /**
    * Call this method at the beginning of a NumberFormatter fluent chain to create an instance based
    * on a given number skeleton string.
    *
    * It is possible for an error to occur while parsing. See the overload of this method if you are
    * interested in the location of a possible parse error.
    *
    * For more information on number skeleton strings, see:
    * https://unicode-org.github.io/icu/userguide/format_parse/numbers/skeletons.html
    *
    * @param skeleton
    *            The skeleton string off of which to base this NumberFormatter.
    * @param status
    *            Set to U_NUMBER_SKELETON_SYNTAX_ERROR if the skeleton was invalid.
    * @return An UnlocalizedNumberFormatter, to be used for chaining.
    * @stable ICU 62
    */
   static UnlocalizedNumberFormatter forSkeleton(const UnicodeString& skeleton, UErrorCode& status);

   /**
    * Call this method at the beginning of a NumberFormatter fluent chain to create an instance based
    * on a given number skeleton string.
    *
    * If an error occurs while parsing the skeleton string, the offset into the skeleton string at
    * which the error occurred will be saved into the UParseError, if provided.
    *
    * For more information on number skeleton strings, see:
    * https://unicode-org.github.io/icu/userguide/format_parse/numbers/skeletons.html
    *
    * @param skeleton
    *            The skeleton string off of which to base this NumberFormatter.
    * @param perror
    *            A parse error struct populated if an error occurs when parsing.
*                If no error occurs, perror.offset will be set to -1.
    * @param status
    *            Set to U_NUMBER_SKELETON_SYNTAX_ERROR if the skeleton was invalid.
    * @return An UnlocalizedNumberFormatter, to be used for chaining.
    * @stable ICU 64
    */
   static UnlocalizedNumberFormatter forSkeleton(const UnicodeString& skeleton,
                                                 UParseError& perror, UErrorCode& status);

   /**
    * Use factory methods instead of the constructor to create a NumberFormatter.
    */
   NumberFormatter() = delete;
};

}  // namespace number
U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // __NUMBERFORMATTER_H__