--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/unicode/numberformatter.h	Tue Mar 18 17:55:14 2025 -0400
@@ -0,0 +1,2642 @@
+// © 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/fieldpos.h"
+#include "unicode/formattedvalue.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"
+
+/**
+ * \file
+ * \brief C++ API: Library for localized number formatting introduced in ICU 60.
+ *
+ * This library was introduced in ICU 60 to simplify the process of formatting localized number strings.
+ * Basic usage examples:
+ *
+ * <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>.
+ *
+ * @author Shane Carr
+ */
+
+U_NAMESPACE_BEGIN
+
+// Forward declarations:
+class IFixedDecimal;
+class FieldPositionIteratorHandler;
+class FormattedStringBuilder;
+
+namespace numparse {
+namespace impl {
+
+// Forward declarations:
+class NumberParserImpl;
+class MultiplierParseHandler;
+
+}
+}
+
+namespace number {  // icu::number
+
+// Forward declarations:
+class UnlocalizedNumberFormatter;
+class LocalizedNumberFormatter;
+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;
+
+/**
+ * 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 */
+        struct ScientificSettings {
+            /** @internal */
+            int8_t fEngineeringInterval;
+            /** @internal */
+            bool fRequireMinInt;
+            /** @internal */
+            impl::digits_t fMinExponentDigits;
+            /** @internal */
+            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);
+
+    /**
+     * 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);
+
+  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 */
+        struct FractionSignificantSettings {
+            // For RND_FRACTION, RND_SIGNIFICANT, and RND_FRACTION_SIGNIFICANT
+            /** @internal */
+            impl::digits_t fMinFrac;
+            /** @internal */
+            impl::digits_t fMaxFrac;
+            /** @internal */
+            impl::digits_t fMinSig;
+            /** @internal */
+            impl::digits_t fMaxSig;
+        } fracSig;
+        /** @internal */
+        struct IncrementSettings {
+            // For RND_INCREMENT, RND_INCREMENT_ONE, and RND_INCREMENT_FIVE
+            /** @internal */
+            double fIncrement;
+            /** @internal */
+            impl::digits_t fMinFrac;
+            /** @internal */
+            impl::digits_t fMaxFrac;
+        } increment;
+        UCurrencyUsage currencyUsage; // For RND_CURRENCY
+        UErrorCode errorCode; // For RND_ERROR
+    } fUnion;
+
+    typedef PrecisionUnion::FractionSignificantSettings FractionSignificantSettings;
+    typedef PrecisionUnion::IncrementSettings IncrementSettings;
+
+    /** The Precision encapsulates the RoundingMode when used within the implementation. */
+    UNumberFormatRoundingMode fRoundingMode;
+
+    Precision(const PrecisionType& type, const PrecisionUnion& union_,
+              UNumberFormatRoundingMode roundingMode)
+            : fType(type), fUnion(union_), fRoundingMode(roundingMode) {}
+
+    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);
+
+    static IncrementPrecision constructIncrement(double increment, int32_t minFrac);
+
+    static CurrencyPrecision constructCurrency(UCurrencyUsage usage);
+
+    static Precision constructPassThrough();
+
+    // 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;
+};
+
+/**
+ * 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:
+    /**
+     * Ensure that no less than this number of significant digits are retained when rounding according to fraction
+     * rules.
+     *
+     * <p>
+     * For example, with integer rounding, the number 3.141 becomes "3". However, with minimum figures set to 2, 3.141
+     * becomes "3.1" instead.
+     *
+     * <p>
+     * This setting does not affect the number of trailing zeros. For example, 3.01 would print as "3", not "3.0".
+     *
+     * @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.
+     *
+     * <p>
+     * For example, with integer rounding, the number 123.4 becomes "123". However, with maximum figures set to 2, 123.4
+     * becomes "120" instead.
+     *
+     * <p>
+     * This setting does not affect the number of trailing zeros. For example, with fixed fraction of 2, 123.4 would
+     * become "120.00".
+     *
+     * @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) U_NOEXCEPT;
+
+    /** @stable ICU 62 */
+    Scale& operator=(Scale&& src) U_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 (fError != U_ZERO_ERROR) {
+            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 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) U_NOEXCEPT;
+
+    /** @internal */
+    SymbolsWrapper &operator=(SymbolsWrapper&& src) U_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) {}
+#endif  // U_HIDE_INTERNAL_API
+
+    /** @internal */
+    int16_t getPrimary() const;
+
+    /** @internal */
+    int16_t getSecondary() const;
+
+  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;
+
+    // To allow NumberFormatterImpl to access isBogus() and perform other operations:
+    friend class NumberFormatterImpl;
+
+    // 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);
+#endif  // U_HIDE_INTERNAL_API
+
+    /** @internal */
+    static Padder forProperties(const DecimalFormatProperties& properties);
+
+  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
+/** @internal */
+struct U_I18N_API MacroProps : public UMemory {
+    /** @internal */
+    Notation notation;
+
+    /** @internal */
+    MeasureUnit unit; // = NoUnit::base();
+
+    /** @internal */
+    MeasureUnit perUnit; // = NoUnit::base();
+
+    /** @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 */
+    UNumberDecimalSeparatorDisplay decimal = UNUM_DECIMAL_SEPARATOR_COUNT;
+
+    /** @internal */
+    Scale scale;  // = Scale();  (benign value)
+
+    /** @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
+     */
+    bool copyErrorTo(UErrorCode &status) const {
+        return notation.copyErrorTo(status) || precision.copyErrorTo(status) ||
+               padder.copyErrorTo(status) || integerWidth.copyErrorTo(status) ||
+               symbols.copyErrorTo(status) || scale.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.
+     *
+     * Pass this method any instance of {@link MeasureUnit}. For units of measure:
+     *
+     * <pre>
+     * NumberFormatter::with().unit(MeasureUnit::getMeter())
+     * </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:
+     *
+     * http://userguide.icu-project.org/formatparse/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) &&;
+
+#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.
+     *
+     * @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;
+};
+
+/**
+ * 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) U_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) U_NOEXCEPT;
+
+  private:
+    explicit UnlocalizedNumberFormatter(const NumberFormatterSettings<UnlocalizedNumberFormatter>& other);
+
+    explicit UnlocalizedNumberFormatter(
+            NumberFormatterSettings<UnlocalizedNumberFormatter>&& src) U_NOEXCEPT;
+
+    // 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;
+};
+
+/**
+ * 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 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;
+
+    /**
+     * 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) U_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) U_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
+
+    explicit LocalizedNumberFormatter(const NumberFormatterSettings<LocalizedNumberFormatter>& other);
+
+    explicit LocalizedNumberFormatter(NumberFormatterSettings<LocalizedNumberFormatter>&& src) U_NOEXCEPT;
+
+    LocalizedNumberFormatter(const impl::MacroProps &macros, const Locale &locale);
+
+    LocalizedNumberFormatter(impl::MacroProps &&macros, const Locale &locale);
+
+    void clear();
+
+    void lnfMoveHelper(LocalizedNumberFormatter&& src);
+
+    /**
+     * @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
+
+/**
+ * The result of a number formatting operation. This class allows the result to be exported in several data types,
+ * including a UnicodeString and a FieldPositionIterator.
+ *
+ * Instances of this class are immutable and thread-safe.
+ *
+ * @stable ICU 60
+ */
+class U_I18N_API FormattedNumber : public UMemory, public FormattedValue {
+  public:
+
+    /**
+     * Default constructor; makes an empty FormattedNumber.
+     * @stable ICU 64
+     */
+    FormattedNumber()
+        : fData(nullptr), fErrorCode(U_INVALID_STATE_ERROR) {}
+
+    /**
+     * Move constructor: Leaves the source FormattedNumber in an undefined state.
+     * @stable ICU 62
+     */
+    FormattedNumber(FormattedNumber&& src) U_NOEXCEPT;
+
+    /**
+     * Destruct an instance of FormattedNumber.
+     * @stable ICU 60
+     */
+    virtual ~FormattedNumber() U_OVERRIDE;
+
+    /** Copying not supported; use move constructor instead. */
+    FormattedNumber(const FormattedNumber&) = delete;
+
+    /** Copying not supported; use move assignment instead. */
+    FormattedNumber& operator=(const FormattedNumber&) = delete;
+
+    /**
+     * Move assignment: Leaves the source FormattedNumber in an undefined state.
+     * @stable ICU 62
+     */
+    FormattedNumber& operator=(FormattedNumber&& src) U_NOEXCEPT;
+
+    // Copybrief: this method is older than the parent method
+    /**
+     * @copybrief FormattedValue::toString()
+     *
+     * For more information, see FormattedValue::toString()
+     *
+     * @stable ICU 62
+     */
+    UnicodeString toString(UErrorCode& status) const U_OVERRIDE;
+
+    // Copydoc: this method is new in ICU 64
+    /** @copydoc FormattedValue::toTempString() */
+    UnicodeString toTempString(UErrorCode& status) const U_OVERRIDE;
+
+    // Copybrief: this method is older than the parent method
+    /**
+     * @copybrief FormattedValue::appendTo()
+     *
+     * For more information, see FormattedValue::appendTo()
+     *
+     * @stable ICU 62
+     */
+    Appendable &appendTo(Appendable& appendable, UErrorCode& status) const U_OVERRIDE;
+
+    // Copydoc: this method is new in ICU 64
+    /** @copydoc FormattedValue::nextPosition() */
+    UBool nextPosition(ConstrainedFieldPosition& cfpos, UErrorCode& status) const U_OVERRIDE;
+
+#ifndef U_HIDE_DRAFT_API
+    /**
+     * Export the formatted number as a "numeric string" conforming to the
+     * syntax defined in the Decimal Arithmetic Specification, available at
+     * http://speleotrove.com/decimal
+     *
+     * This endpoint is useful for obtaining the exact number being printed
+     * after scaling and rounding have been applied by the number formatter.
+     *
+     * Example call site:
+     *
+     *     auto decimalNumber = fn.toDecimalNumber<std::string>(status);
+     *
+     * @tparam StringClass A string class compatible with StringByteSink;
+     *         for example, std::string.
+     * @param status Set if an error occurs.
+     * @return A StringClass containing the numeric string.
+     * @draft ICU 65
+     */
+    template<typename StringClass>
+    inline StringClass toDecimalNumber(UErrorCode& status) const;
+#endif // U_HIDE_DRAFT_API
+
+#ifndef U_HIDE_INTERNAL_API
+
+    /**
+     *  Gets the raw DecimalQuantity for plural rule selection.
+     *  @internal
+     */
+    void getDecimalQuantity(impl::DecimalQuantity& output, UErrorCode& status) const;
+
+    /**
+     * Populates the mutable builder type FieldPositionIteratorHandler.
+     * @internal
+     */
+    void getAllFieldPositionsImpl(FieldPositionIteratorHandler& fpih, UErrorCode& status) const;
+
+#endif  /* U_HIDE_INTERNAL_API */
+
+  private:
+    // Can't use LocalPointer because UFormattedNumberData is forward-declared
+    const impl::UFormattedNumberData *fData;
+
+    // Error code for the terminal methods
+    UErrorCode fErrorCode;
+
+    /**
+     * Internal constructor from data type. Adopts the data pointer.
+     * @internal
+     */
+    explicit FormattedNumber(impl::UFormattedNumberData *results)
+        : fData(results), fErrorCode(U_ZERO_ERROR) {}
+
+    explicit FormattedNumber(UErrorCode errorCode)
+        : fData(nullptr), fErrorCode(errorCode) {}
+
+    // TODO(ICU-20775): Propose this as API.
+    void toDecimalNumber(ByteSink& sink, UErrorCode& status) const;
+
+    // To give LocalizedNumberFormatter format methods access to this class's constructor:
+    friend class LocalizedNumberFormatter;
+
+    // To give C API access to internals
+    friend struct impl::UFormattedNumberImpl;
+};
+
+#ifndef U_HIDE_DRAFT_API
+// Note: This is draft ICU 65
+template<typename StringClass>
+StringClass FormattedNumber::toDecimalNumber(UErrorCode& status) const {
+    StringClass result;
+    StringByteSink<StringClass> sink(&result);
+    toDecimalNumber(sink, status);
+    return result;
+}
+#endif // U_HIDE_DRAFT_API
+
+/**
+ * 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.
+     *
+     * @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.
+     *
+     * @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__
+