summaryrefslogtreecommitdiffstats
path: root/intl/icu/source/i18n/unicode/numberrangeformatter.h
blob: c6749b33c7ab529c395c2eeeb7f60cdcefe3c34d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
// © 2018 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html

#ifndef __NUMBERRANGEFORMATTER_H__
#define __NUMBERRANGEFORMATTER_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#if !UCONFIG_NO_FORMATTING

#include "unicode/appendable.h"
#include "unicode/fieldpos.h"
#include "unicode/formattedvalue.h"
#include "unicode/fpositer.h"
#include "unicode/numberformatter.h"
#include "unicode/unumberrangeformatter.h"

#ifndef __wasi__
#include <atomic>
#endif

/**
 * \file
 * \brief C++ API: Library for localized formatting of number, currency, and unit ranges.
 *
 * The main entrypoint to the formatting of ranges of numbers, including currencies and other units of measurement.
 * <p>
 * Usage example:
 * <p>
 * <pre>
 * NumberRangeFormatter::with()
 *     .identityFallback(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE)
 *     .numberFormatterFirst(NumberFormatter::with().adoptUnit(MeasureUnit::createMeter()))
 *     .numberFormatterSecond(NumberFormatter::with().adoptUnit(MeasureUnit::createKilometer()))
 *     .locale("en-GB")
 *     .formatFormattableRange(750, 1.2, status)
 *     .toString(status);
 * // => "750 m - 1.2 km"
 * </pre>
 * <p>
 * Like NumberFormatter, NumberRangeFormatter instances (i.e., LocalizedNumberRangeFormatter
 * and UnlocalizedNumberRangeFormatter) are immutable and thread-safe. This API is based on the
 * <em>fluent</em> design pattern popularized by libraries such as Google's Guava.
 *
 * @author Shane Carr
 */


U_NAMESPACE_BEGIN

// Forward declarations:
class PluralRules;

namespace number {  // icu::number

// Forward declarations:
class UnlocalizedNumberRangeFormatter;
class LocalizedNumberRangeFormatter;
class FormattedNumberRange;

namespace impl {

// Forward declarations:
struct RangeMacroProps;
class DecimalQuantity;
class UFormattedNumberRangeData;
class NumberRangeFormatterImpl;
struct UFormattedNumberRangeImpl;

} // namespace impl

/**
 * \cond
 * Export an explicit template instantiation. See datefmt.h
 * (When building DLLs for Windows this is required.)
 */
#if U_PLATFORM == U_PF_WINDOWS && !defined(U_IN_DOXYGEN) && !defined(U_STATIC_IMPLEMENTATION)
} // namespace icu::number
U_NAMESPACE_END

#ifndef __wasi__
template struct U_I18N_API std::atomic< U_NAMESPACE_QUALIFIER number::impl::NumberRangeFormatterImpl*>;
#endif

U_NAMESPACE_BEGIN
namespace number {  // icu::number
#endif
/** \endcond */

// Other helper classes would go here, but there are none.

namespace impl {  // icu::number::impl

// Do not enclose entire MacroProps with #ifndef U_HIDE_INTERNAL_API, needed for a protected field
/** @internal */
struct U_I18N_API RangeMacroProps : public UMemory {
    /** @internal */
    UnlocalizedNumberFormatter formatter1; // = NumberFormatter::with();

    /** @internal */
    UnlocalizedNumberFormatter formatter2; // = NumberFormatter::with();

    /** @internal */
    bool singleFormatter = true;

    /** @internal */
    UNumberRangeCollapse collapse = UNUM_RANGE_COLLAPSE_AUTO;

    /** @internal */
    UNumberRangeIdentityFallback identityFallback = UNUM_IDENTITY_FALLBACK_APPROXIMATELY;

    /** @internal */
    Locale locale;

    // NOTE: Uses default copy and move constructors.

    /**
     * Check all members for errors.
     * @internal
     */
    bool copyErrorTo(UErrorCode &status) const {
        return formatter1.copyErrorTo(status) || formatter2.copyErrorTo(status);
    }
};

} // namespace impl

/**
 * An abstract base class for specifying settings related to number formatting. This class is implemented by
 * {@link UnlocalizedNumberRangeFormatter} and {@link LocalizedNumberRangeFormatter}. This class is not intended for
 * public subclassing.
 */
template<typename Derived>
class U_I18N_API NumberRangeFormatterSettings {
  public:
    /**
     * Sets the NumberFormatter instance to use for the numbers in the range. The same formatter is applied to both
     * sides of the range.
     * <p>
     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
     * NumberRangeFormatter will be used.
     *
     * @param formatter
     *            The formatter to use for both numbers in the range.
     * @return The fluent chain.
     * @stable ICU 63
     */
    Derived numberFormatterBoth(const UnlocalizedNumberFormatter &formatter) const &;

    /**
     * Overload of numberFormatterBoth() for use on an rvalue reference.
     *
     * @param formatter
     *            The formatter to use for both numbers in the range.
     * @return The fluent chain.
     * @see #numberFormatterBoth
     * @stable ICU 63
     */
    Derived numberFormatterBoth(const UnlocalizedNumberFormatter &formatter) &&;

    /**
     * Overload of numberFormatterBoth() for use on an rvalue reference.
     *
     * @param formatter
     *            The formatter to use for both numbers in the range.
     * @return The fluent chain.
     * @see #numberFormatterBoth
     * @stable ICU 63
     */
    Derived numberFormatterBoth(UnlocalizedNumberFormatter &&formatter) const &;

    /**
     * Overload of numberFormatterBoth() for use on an rvalue reference.
     *
     * @param formatter
     *            The formatter to use for both numbers in the range.
     * @return The fluent chain.
     * @see #numberFormatterBoth
     * @stable ICU 63
     */
    Derived numberFormatterBoth(UnlocalizedNumberFormatter &&formatter) &&;

    /**
     * Sets the NumberFormatter instance to use for the first number in the range.
     * <p>
     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
     * NumberRangeFormatter will be used.
     *
     * @param formatterFirst
     *            The formatter to use for the first number in the range.
     * @return The fluent chain.
     * @stable ICU 63
     */
    Derived numberFormatterFirst(const UnlocalizedNumberFormatter &formatterFirst) const &;

    /**
     * Overload of numberFormatterFirst() for use on an rvalue reference.
     *
     * @param formatterFirst
     *            The formatter to use for the first number in the range.
     * @return The fluent chain.
     * @see #numberFormatterFirst
     * @stable ICU 63
     */
    Derived numberFormatterFirst(const UnlocalizedNumberFormatter &formatterFirst) &&;

    /**
     * Overload of numberFormatterFirst() for use on an rvalue reference.
     *
     * @param formatterFirst
     *            The formatter to use for the first number in the range.
     * @return The fluent chain.
     * @see #numberFormatterFirst
     * @stable ICU 63
     */
    Derived numberFormatterFirst(UnlocalizedNumberFormatter &&formatterFirst) const &;

    /**
     * Overload of numberFormatterFirst() for use on an rvalue reference.
     *
     * @param formatterFirst
     *            The formatter to use for the first number in the range.
     * @return The fluent chain.
     * @see #numberFormatterFirst
     * @stable ICU 63
     */
    Derived numberFormatterFirst(UnlocalizedNumberFormatter &&formatterFirst) &&;

    /**
     * Sets the NumberFormatter instance to use for the second number in the range.
     * <p>
     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
     * NumberRangeFormatter will be used.
     *
     * @param formatterSecond
     *            The formatter to use for the second number in the range.
     * @return The fluent chain.
     * @stable ICU 63
     */
    Derived numberFormatterSecond(const UnlocalizedNumberFormatter &formatterSecond) const &;

    /**
     * Overload of numberFormatterSecond() for use on an rvalue reference.
     *
     * @param formatterSecond
     *            The formatter to use for the second number in the range.
     * @return The fluent chain.
     * @see #numberFormatterSecond
     * @stable ICU 63
     */
    Derived numberFormatterSecond(const UnlocalizedNumberFormatter &formatterSecond) &&;

    /**
     * Overload of numberFormatterSecond() for use on an rvalue reference.
     *
     * @param formatterSecond
     *            The formatter to use for the second number in the range.
     * @return The fluent chain.
     * @see #numberFormatterSecond
     * @stable ICU 63
     */
    Derived numberFormatterSecond(UnlocalizedNumberFormatter &&formatterSecond) const &;

    /**
     * Overload of numberFormatterSecond() for use on an rvalue reference.
     *
     * @param formatterSecond
     *            The formatter to use for the second number in the range.
     * @return The fluent chain.
     * @see #numberFormatterSecond
     * @stable ICU 63
     */
    Derived numberFormatterSecond(UnlocalizedNumberFormatter &&formatterSecond) &&;

    /**
     * Sets the aggressiveness of "collapsing" fields across the range separator. Possible values:
     * <p>
     * <ul>
     * <li>ALL: "3-5K miles"</li>
     * <li>UNIT: "3K - 5K miles"</li>
     * <li>NONE: "3K miles - 5K miles"</li>
     * <li>AUTO: usually UNIT or NONE, depending on the locale and formatter settings</li>
     * </ul>
     * <p>
     * The default value is AUTO.
     *
     * @param collapse
     *            The collapsing strategy to use for this range.
     * @return The fluent chain.
     * @stable ICU 63
     */
    Derived collapse(UNumberRangeCollapse collapse) const &;

    /**
     * Overload of collapse() for use on an rvalue reference.
     *
     * @param collapse
     *            The collapsing strategy to use for this range.
     * @return The fluent chain.
     * @see #collapse
     * @stable ICU 63
     */
    Derived collapse(UNumberRangeCollapse collapse) &&;

    /**
     * Sets the behavior when the two sides of the range are the same. This could happen if the same two numbers are
     * passed to the formatFormattableRange function, or if different numbers are passed to the function but they
     * become the same after rounding rules are applied. Possible values:
     * <p>
     * <ul>
     * <li>SINGLE_VALUE: "5 miles"</li>
     * <li>APPROXIMATELY_OR_SINGLE_VALUE: "~5 miles" or "5 miles", depending on whether the number was the same before
     * rounding was applied</li>
     * <li>APPROXIMATELY: "~5 miles"</li>
     * <li>RANGE: "5-5 miles" (with collapse=UNIT)</li>
     * </ul>
     * <p>
     * The default value is APPROXIMATELY.
     *
     * @param identityFallback
     *            The strategy to use when formatting two numbers that end up being the same.
     * @return The fluent chain.
     * @stable ICU 63
     */
    Derived identityFallback(UNumberRangeIdentityFallback identityFallback) const &;

    /**
     * Overload of identityFallback() for use on an rvalue reference.
     *
     * @param identityFallback
     *            The strategy to use when formatting two numbers that end up being the same.
     * @return The fluent chain.
     * @see #identityFallback
     * @stable ICU 63
     */
    Derived identityFallback(UNumberRangeIdentityFallback identityFallback) &&;

    /**
     * Returns the current (Un)LocalizedNumberRangeFormatter 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)LocalizedNumberRangeFormatter 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)LocalizedNumberRangeFormatter 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 63
     */
    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::RangeMacroProps fMacros;

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

    friend class LocalizedNumberRangeFormatter;
    friend class UnlocalizedNumberRangeFormatter;
};

// Explicit instantiations in source/i18n/numrange_fluent.cpp.
// (MSVC treats imports/exports of explicit instantiations differently.)
#ifndef _MSC_VER
extern template class NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>;
extern template class NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>;
#endif

/**
 * A NumberRangeFormatter that does not yet have a locale. In order to format, a locale must be specified.
 *
 * Instances of this class are immutable and thread-safe.
 *
 * @see NumberRangeFormatter
 * @stable ICU 63
 */
class U_I18N_API UnlocalizedNumberRangeFormatter
        : public NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>, public UMemory {

  public:
    /**
     * Associate the given locale with the number range 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 63
     */
    LocalizedNumberRangeFormatter 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 63
     */
    LocalizedNumberRangeFormatter locale(const icu::Locale &locale) &&;

    /**
     * Default constructor: puts the formatter into a valid but undefined state.
     *
     * @stable ICU 63
     */
    UnlocalizedNumberRangeFormatter() = default;

    /**
     * Returns a copy of this UnlocalizedNumberRangeFormatter.
     * @stable ICU 63
     */
    UnlocalizedNumberRangeFormatter(const UnlocalizedNumberRangeFormatter &other);

    /**
     * Move constructor:
     * The source UnlocalizedNumberRangeFormatter will be left in a valid but undefined state.
     * @stable ICU 63
     */
    UnlocalizedNumberRangeFormatter(UnlocalizedNumberRangeFormatter&& src) noexcept;

    /**
     * Copy assignment operator.
     * @stable ICU 63
     */
    UnlocalizedNumberRangeFormatter& operator=(const UnlocalizedNumberRangeFormatter& other);

    /**
     * Move assignment operator:
     * The source UnlocalizedNumberRangeFormatter will be left in a valid but undefined state.
     * @stable ICU 63
     */
    UnlocalizedNumberRangeFormatter& operator=(UnlocalizedNumberRangeFormatter&& src) noexcept;

  private:
    explicit UnlocalizedNumberRangeFormatter(
            const NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>& other);

    explicit UnlocalizedNumberRangeFormatter(
            NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>&& src) noexcept;

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

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

/**
 * A NumberRangeFormatter that has a locale associated with it; this means .formatRange() methods are available.
 *
 * Instances of this class are immutable and thread-safe.
 *
 * @see NumberFormatter
 * @stable ICU 63
 */
class U_I18N_API LocalizedNumberRangeFormatter
        : public NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>, public UMemory {
  public:
    /**
     * Format the given Formattables to a string using the settings specified in the NumberRangeFormatter fluent setting
     * chain.
     *
     * @param first
     *            The first number in the range, usually to the left in LTR locales.
     * @param second
     *            The second number in the range, usually to the right in LTR locales.
     * @param status
     *            Set if an error occurs while formatting.
     * @return A FormattedNumberRange object; call .toString() to get the string.
     * @stable ICU 63
     */
    FormattedNumberRange formatFormattableRange(
        const Formattable& first, const Formattable& second, UErrorCode& status) const;

    /**
     * Default constructor: puts the formatter into a valid but undefined state.
     *
     * @stable ICU 63
     */
    LocalizedNumberRangeFormatter() = default;

    /**
     * Returns a copy of this LocalizedNumberRangeFormatter.
     * @stable ICU 63
     */
    LocalizedNumberRangeFormatter(const LocalizedNumberRangeFormatter &other);

    /**
     * Move constructor:
     * The source LocalizedNumberRangeFormatter will be left in a valid but undefined state.
     * @stable ICU 63
     */
    LocalizedNumberRangeFormatter(LocalizedNumberRangeFormatter&& src) noexcept;

    /**
     * Copy assignment operator.
     * @stable ICU 63
     */
    LocalizedNumberRangeFormatter& operator=(const LocalizedNumberRangeFormatter& other);

    /**
     * Move assignment operator:
     * The source LocalizedNumberRangeFormatter will be left in a valid but undefined state.
     * @stable ICU 63
     */
    LocalizedNumberRangeFormatter& operator=(LocalizedNumberRangeFormatter&& src) noexcept;

#ifndef U_HIDE_INTERNAL_API

    /**
     * @param results
     *            The results object. This method will mutate it to save the results.
     * @param equalBeforeRounding
     *            Whether the number was equal before copying it into a DecimalQuantity.
     *            Used for determining the identity fallback behavior.
     * @param status
     *            Set if an error occurs while formatting.
     * @internal
     */
    void formatImpl(impl::UFormattedNumberRangeData& results, bool equalBeforeRounding,
                    UErrorCode& status) const;

#endif  /* U_HIDE_INTERNAL_API */

    /**
     * Destruct this LocalizedNumberRangeFormatter, cleaning up any memory it might own.
     * @stable ICU 63
     */
    ~LocalizedNumberRangeFormatter();

  private:
#ifndef __wasi__
    std::atomic<impl::NumberRangeFormatterImpl*> fAtomicFormatter = {};
#else
    impl::NumberRangeFormatterImpl* fAtomicFormatter = nullptr;
#endif

    const impl::NumberRangeFormatterImpl* getFormatter(UErrorCode& stauts) const;

    explicit LocalizedNumberRangeFormatter(
        const NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>& other);

    explicit LocalizedNumberRangeFormatter(
        NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>&& src) noexcept;

    LocalizedNumberRangeFormatter(const impl::RangeMacroProps &macros, const Locale &locale);

    LocalizedNumberRangeFormatter(impl::RangeMacroProps &&macros, const Locale &locale);

    // To give the fluent setters access to this class's constructor:
    friend class NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>;
    friend class NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>;

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

/**
 * The result of a number range 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 63
 */
class U_I18N_API FormattedNumberRange : public UMemory, public FormattedValue {
  public:
    // Copybrief: this method is older than the parent method
    /**
     * @copybrief FormattedValue::toString()
     *
     * For more information, see FormattedValue::toString()
     *
     * @stable ICU 63
     */
    UnicodeString toString(UErrorCode& status) const override;

    // Copydoc: this method is new in ICU 64
    /** @copydoc FormattedValue::toTempString() */
    UnicodeString toTempString(UErrorCode& status) const override;

    // Copybrief: this method is older than the parent method
    /**
     * @copybrief FormattedValue::appendTo()
     *
     * For more information, see FormattedValue::appendTo()
     *
     * @stable ICU 63
     */
    Appendable &appendTo(Appendable &appendable, UErrorCode& status) const override;

    // Copydoc: this method is new in ICU 64
    /** @copydoc FormattedValue::nextPosition() */
    UBool nextPosition(ConstrainedFieldPosition& cfpos, UErrorCode& status) const override;

    /**
     * Extracts the formatted range as a pair of decimal numbers. This endpoint
     * is useful for obtaining the exact number being printed after scaling
     * and rounding have been applied by the number range formatting pipeline.
     * 
     * The syntax of the unformatted numbers is a "numeric string"
     * as defined in the Decimal Arithmetic Specification, available at
     * http://speleotrove.com/decimal
     *
     * Example C++17 call site:
     *
     *     auto [ first, second ] = range.getDecimalNumbers<std::string>(status);
     *
     * @tparam StringClass A string class compatible with StringByteSink;
     *         for example, std::string.
     * @param status Set if an error occurs.
     * @return A pair of StringClasses containing the numeric strings.
     * @stable ICU 68
     */
    template<typename StringClass>
    inline std::pair<StringClass, StringClass> getDecimalNumbers(UErrorCode& status) const;

    /**
     * Returns whether the pair of numbers was successfully formatted as a range or whether an identity fallback was
     * used. For example, if the first and second number were the same either before or after rounding occurred, an
     * identity fallback was used.
     *
     * @return An indication the resulting identity situation in the formatted number range.
     * @stable ICU 63
     * @see UNumberRangeIdentityFallback
     */
    UNumberRangeIdentityResult getIdentityResult(UErrorCode& status) const;

    /**
     * Default constructor; makes an empty FormattedNumberRange.
     * @stable ICU 70
     */
    FormattedNumberRange()
        : fData(nullptr), fErrorCode(U_INVALID_STATE_ERROR) {}

    /**
     * Copying not supported; use move constructor instead.
     */
    FormattedNumberRange(const FormattedNumberRange&) = delete;

    /**
     * Copying not supported; use move assignment instead.
     */
    FormattedNumberRange& operator=(const FormattedNumberRange&) = delete;

    /**
     * Move constructor:
     * Leaves the source FormattedNumberRange in an undefined state.
     * @stable ICU 63
     */
    FormattedNumberRange(FormattedNumberRange&& src) noexcept;

    /**
     * Move assignment:
     * Leaves the source FormattedNumberRange in an undefined state.
     * @stable ICU 63
     */
    FormattedNumberRange& operator=(FormattedNumberRange&& src) noexcept;

    /**
     * Destruct an instance of FormattedNumberRange, cleaning up any memory it might own.
     * @stable ICU 63
     */
    ~FormattedNumberRange();

  private:
    // Can't use LocalPointer because UFormattedNumberRangeData is forward-declared
    const impl::UFormattedNumberRangeData *fData;

    // Error code for the terminal methods
    UErrorCode fErrorCode;

    /**
     * Internal constructor from data type. Adopts the data pointer.
     */
    explicit FormattedNumberRange(impl::UFormattedNumberRangeData *results)
        : fData(results), fErrorCode(U_ZERO_ERROR) {}

    explicit FormattedNumberRange(UErrorCode errorCode)
        : fData(nullptr), fErrorCode(errorCode) {}

    void getDecimalNumbers(ByteSink& sink1, ByteSink& sink2, UErrorCode& status) const;

    const impl::UFormattedNumberRangeData* getData(UErrorCode& status) const;

    // To allow PluralRules to access the underlying data
    friend class ::icu::PluralRules;

    // To give LocalizedNumberRangeFormatter format methods access to this class's constructor:
    friend class LocalizedNumberRangeFormatter;

    // To give C API access to internals
    friend struct impl::UFormattedNumberRangeImpl;
};

// inline impl of @stable ICU 68 method
template<typename StringClass>
std::pair<StringClass, StringClass> FormattedNumberRange::getDecimalNumbers(UErrorCode& status) const {
    StringClass str1;
    StringClass str2;
    StringByteSink<StringClass> sink1(&str1);
    StringByteSink<StringClass> sink2(&str2);
    getDecimalNumbers(sink1, sink2, status);
    return std::make_pair(str1, str2);
}

/**
 * See the main description in numberrangeformatter.h for documentation and examples.
 *
 * @stable ICU 63
 */
class U_I18N_API NumberRangeFormatter final {
  public:
    /**
     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is not currently
     * known at the call site.
     *
     * @return An {@link UnlocalizedNumberRangeFormatter}, to be used for chaining.
     * @stable ICU 63
     */
    static UnlocalizedNumberRangeFormatter with();

    /**
     * Call this method at the beginning of a NumberRangeFormatter 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 range formatting.
     * @return A {@link LocalizedNumberRangeFormatter}, to be used for chaining.
     * @stable ICU 63
     */
    static LocalizedNumberRangeFormatter withLocale(const Locale &locale);

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

}  // namespace number
U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // __NUMBERRANGEFORMATTER_H__