1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 **********************************************************************
5 *   Copyright (C) 1998-2016, International Business Machines
6 *   Corporation and others.  All Rights Reserved.
7 **********************************************************************
8 *
9 * File unistr.h
10 *
11 * Modification History:
12 *
13 *   Date        Name        Description
14 *   09/25/98    stephen     Creation.
15 *   11/11/98    stephen     Changed per 11/9 code review.
16 *   04/20/99    stephen     Overhauled per 4/16 code review.
17 *   11/18/99    aliu        Made to inherit from Replaceable.  Added method
18 *                           handleReplaceBetween(); other methods unchanged.
19 *   06/25/01    grhoten     Remove dependency on iostream.
20 ******************************************************************************
21 */
22 
23 #ifndef UNISTR_H
24 #define UNISTR_H
25 
26 /**
27  * \file
28  * \brief C++ API: Unicode String
29  */
30 
31 #include "unicode/utypes.h"
32 
33 #if U_SHOW_CPLUSPLUS_API
34 
35 #include <cstddef>
36 #include "unicode/char16ptr.h"
37 #include "unicode/rep.h"
38 #include "unicode/std_string.h"
39 #include "unicode/stringpiece.h"
40 #include "unicode/bytestream.h"
41 
42 struct UConverter;          // unicode/ucnv.h
43 
44 #ifndef USTRING_H
45 /**
46  * \ingroup ustring_ustrlen
47  */
48 U_STABLE int32_t U_EXPORT2
49 u_strlen(const UChar *s);
50 #endif
51 
52 U_NAMESPACE_BEGIN
53 
54 #if !UCONFIG_NO_BREAK_ITERATION
55 class BreakIterator;        // unicode/brkiter.h
56 #endif
57 class Edits;
58 
59 U_NAMESPACE_END
60 
61 // Not #ifndef U_HIDE_INTERNAL_API because UnicodeString needs the UStringCaseMapper.
62 /**
63  * Internal string case mapping function type.
64  * All error checking must be done.
65  * src and dest must not overlap.
66  * @internal
67  */
68 typedef int32_t U_CALLCONV
69 UStringCaseMapper(int32_t caseLocale, uint32_t options,
70 #if !UCONFIG_NO_BREAK_ITERATION
71                   icu::BreakIterator *iter,
72 #endif
73                   char16_t *dest, int32_t destCapacity,
74                   const char16_t *src, int32_t srcLength,
75                   icu::Edits *edits,
76                   UErrorCode &errorCode);
77 
78 U_NAMESPACE_BEGIN
79 
80 class Locale;               // unicode/locid.h
81 class StringCharacterIterator;
82 class UnicodeStringAppendable;  // unicode/appendable.h
83 
84 /* The <iostream> include has been moved to unicode/ustream.h */
85 
86 /**
87  * Constant to be used in the UnicodeString(char *, int32_t, EInvariant) constructor
88  * which constructs a Unicode string from an invariant-character char * string.
89  * About invariant characters see utypes.h.
90  * This constructor has no runtime dependency on conversion code and is
91  * therefore recommended over ones taking a charset name string
92  * (where the empty string "" indicates invariant-character conversion).
93  *
94  * @stable ICU 3.2
95  */
96 #define US_INV icu::UnicodeString::kInvariant
97 
98 /**
99  * Unicode String literals in C++.
100  *
101  * Note: these macros are not recommended for new code.
102  * Prior to the availability of C++11 and u"unicode string literals",
103  * these macros were provided for portability and efficiency when
104  * initializing UnicodeStrings from literals.
105  *
106  * They work only for strings that contain "invariant characters", i.e.,
107  * only latin letters, digits, and some punctuation.
108  * See utypes.h for details.
109  *
110  * The string parameter must be a C string literal.
111  * The length of the string, not including the terminating
112  * `NUL`, must be specified as a constant.
113  * @stable ICU 2.0
114  */
115 #if !U_CHAR16_IS_TYPEDEF
116 # define UNICODE_STRING(cs, _length) icu::UnicodeString(TRUE, u ## cs, _length)
117 #else
118 # define UNICODE_STRING(cs, _length) icu::UnicodeString(TRUE, (const char16_t*)u ## cs, _length)
119 #endif
120 
121 /**
122  * Unicode String literals in C++.
123  * Dependent on the platform properties, different UnicodeString
124  * constructors should be used to create a UnicodeString object from
125  * a string literal.
126  * The macros are defined for improved performance.
127  * They work only for strings that contain "invariant characters", i.e.,
128  * only latin letters, digits, and some punctuation.
129  * See utypes.h for details.
130  *
131  * The string parameter must be a C string literal.
132  * @stable ICU 2.0
133  */
134 #define UNICODE_STRING_SIMPLE(cs) UNICODE_STRING(cs, -1)
135 
136 /**
137  * \def UNISTR_FROM_CHAR_EXPLICIT
138  * This can be defined to be empty or "explicit".
139  * If explicit, then the UnicodeString(char16_t) and UnicodeString(UChar32)
140  * constructors are marked as explicit, preventing their inadvertent use.
141  * @stable ICU 49
142  */
143 #ifndef UNISTR_FROM_CHAR_EXPLICIT
144 # if defined(U_COMBINED_IMPLEMENTATION) || defined(U_COMMON_IMPLEMENTATION) || defined(U_I18N_IMPLEMENTATION) || defined(U_IO_IMPLEMENTATION)
145     // Auto-"explicit" in ICU library code.
146 #   define UNISTR_FROM_CHAR_EXPLICIT explicit
147 # else
148     // Empty by default for source code compatibility.
149 #   define UNISTR_FROM_CHAR_EXPLICIT
150 # endif
151 #endif
152 
153 /**
154  * \def UNISTR_FROM_STRING_EXPLICIT
155  * This can be defined to be empty or "explicit".
156  * If explicit, then the UnicodeString(const char *) and UnicodeString(const char16_t *)
157  * constructors are marked as explicit, preventing their inadvertent use.
158  *
159  * In particular, this helps prevent accidentally depending on ICU conversion code
160  * by passing a string literal into an API with a const UnicodeString & parameter.
161  * @stable ICU 49
162  */
163 #ifndef UNISTR_FROM_STRING_EXPLICIT
164 # if defined(U_COMBINED_IMPLEMENTATION) || defined(U_COMMON_IMPLEMENTATION) || defined(U_I18N_IMPLEMENTATION) || defined(U_IO_IMPLEMENTATION)
165     // Auto-"explicit" in ICU library code.
166 #   define UNISTR_FROM_STRING_EXPLICIT explicit
167 # else
168     // Empty by default for source code compatibility.
169 #   define UNISTR_FROM_STRING_EXPLICIT
170 # endif
171 #endif
172 
173 /**
174  * \def UNISTR_OBJECT_SIZE
175  * Desired sizeof(UnicodeString) in bytes.
176  * It should be a multiple of sizeof(pointer) to avoid unusable space for padding.
177  * The object size may want to be a multiple of 16 bytes,
178  * which is a common granularity for heap allocation.
179  *
180  * Any space inside the object beyond sizeof(vtable pointer) + 2
181  * is available for storing short strings inside the object.
182  * The bigger the object, the longer a string that can be stored inside the object,
183  * without additional heap allocation.
184  *
185  * Depending on a platform's pointer size, pointer alignment requirements,
186  * and struct padding, the compiler will usually round up sizeof(UnicodeString)
187  * to 4 * sizeof(pointer) (or 3 * sizeof(pointer) for P128 data models),
188  * to hold the fields for heap-allocated strings.
189  * Such a minimum size also ensures that the object is easily large enough
190  * to hold at least 2 char16_ts, for one supplementary code point (U16_MAX_LENGTH).
191  *
192  * sizeof(UnicodeString) >= 48 should work for all known platforms.
193  *
194  * For example, on a 64-bit machine where sizeof(vtable pointer) is 8,
195  * sizeof(UnicodeString) = 64 would leave space for
196  * (64 - sizeof(vtable pointer) - 2) / U_SIZEOF_UCHAR = (64 - 8 - 2) / 2 = 27
197  * char16_ts stored inside the object.
198  *
199  * The minimum object size on a 64-bit machine would be
200  * 4 * sizeof(pointer) = 4 * 8 = 32 bytes,
201  * and the internal buffer would hold up to 11 char16_ts in that case.
202  *
203  * @see U16_MAX_LENGTH
204  * @stable ICU 56
205  */
206 #ifndef UNISTR_OBJECT_SIZE
207 # define UNISTR_OBJECT_SIZE 64
208 #endif
209 
210 /**
211  * UnicodeString is a string class that stores Unicode characters directly and provides
212  * similar functionality as the Java String and StringBuffer/StringBuilder classes.
213  * It is a concrete implementation of the abstract class Replaceable (for transliteration).
214  *
215  * The UnicodeString equivalent of std::string’s clear() is remove().
216  *
217  * A UnicodeString may "alias" an external array of characters
218  * (that is, point to it, rather than own the array)
219  * whose lifetime must then at least match the lifetime of the aliasing object.
220  * This aliasing may be preserved when returning a UnicodeString by value,
221  * depending on the compiler and the function implementation,
222  * via Return Value Optimization (RVO) or the move assignment operator.
223  * (However, the copy assignment operator does not preserve aliasing.)
224  * For details see the description of storage models at the end of the class API docs
225  * and in the User Guide chapter linked from there.
226  *
227  * The UnicodeString class is not suitable for subclassing.
228  *
229  * For an overview of Unicode strings in C and C++ see the
230  * [User Guide Strings chapter](http://userguide.icu-project.org/strings#TOC-Strings-in-C-C-).
231  *
232  * In ICU, a Unicode string consists of 16-bit Unicode *code units*.
233  * A Unicode character may be stored with either one code unit
234  * (the most common case) or with a matched pair of special code units
235  * ("surrogates"). The data type for code units is char16_t.
236  * For single-character handling, a Unicode character code *point* is a value
237  * in the range 0..0x10ffff. ICU uses the UChar32 type for code points.
238  *
239  * Indexes and offsets into and lengths of strings always count code units, not code points.
240  * This is the same as with multi-byte char* strings in traditional string handling.
241  * Operations on partial strings typically do not test for code point boundaries.
242  * If necessary, the user needs to take care of such boundaries by testing for the code unit
243  * values or by using functions like
244  * UnicodeString::getChar32Start() and UnicodeString::getChar32Limit()
245  * (or, in C, the equivalent macros U16_SET_CP_START() and U16_SET_CP_LIMIT(), see utf.h).
246  *
247  * UnicodeString methods are more lenient with regard to input parameter values
248  * than other ICU APIs. In particular:
249  * - If indexes are out of bounds for a UnicodeString object
250  *   (< 0 or > length()) then they are "pinned" to the nearest boundary.
251  * - If the buffer passed to an insert/append/replace operation is owned by the
252  *   target object, e.g., calling str.append(str), an extra copy may take place
253  *   to ensure safety.
254  * - If primitive string pointer values (e.g., const char16_t * or char *)
255  *   for input strings are NULL, then those input string parameters are treated
256  *   as if they pointed to an empty string.
257  *   However, this is *not* the case for char * parameters for charset names
258  *   or other IDs.
259  * - Most UnicodeString methods do not take a UErrorCode parameter because
260  *   there are usually very few opportunities for failure other than a shortage
261  *   of memory, error codes in low-level C++ string methods would be inconvenient,
262  *   and the error code as the last parameter (ICU convention) would prevent
263  *   the use of default parameter values.
264  *   Instead, such methods set the UnicodeString into a "bogus" state
265  *   (see isBogus()) if an error occurs.
266  *
267  * In string comparisons, two UnicodeString objects that are both "bogus"
268  * compare equal (to be transitive and prevent endless loops in sorting),
269  * and a "bogus" string compares less than any non-"bogus" one.
270  *
271  * Const UnicodeString methods are thread-safe. Multiple threads can use
272  * const methods on the same UnicodeString object simultaneously,
273  * but non-const methods must not be called concurrently (in multiple threads)
274  * with any other (const or non-const) methods.
275  *
276  * Similarly, const UnicodeString & parameters are thread-safe.
277  * One object may be passed in as such a parameter concurrently in multiple threads.
278  * This includes the const UnicodeString & parameters for
279  * copy construction, assignment, and cloning.
280  *
281  * UnicodeString uses several storage methods.
282  * String contents can be stored inside the UnicodeString object itself,
283  * in an allocated and shared buffer, or in an outside buffer that is "aliased".
284  * Most of this is done transparently, but careful aliasing in particular provides
285  * significant performance improvements.
286  * Also, the internal buffer is accessible via special functions.
287  * For details see the
288  * [User Guide Strings chapter](http://userguide.icu-project.org/strings#TOC-Maximizing-Performance-with-the-UnicodeString-Storage-Model).
289  *
290  * @see utf.h
291  * @see CharacterIterator
292  * @stable ICU 2.0
293  */
294 class U_COMMON_API UnicodeString : public Replaceable
295 {
296 public:
297 
298   /**
299    * Constant to be used in the UnicodeString(char *, int32_t, EInvariant) constructor
300    * which constructs a Unicode string from an invariant-character char * string.
301    * Use the macro US_INV instead of the full qualification for this value.
302    *
303    * @see US_INV
304    * @stable ICU 3.2
305    */
306   enum EInvariant {
307     /**
308      * @see EInvariant
309      * @stable ICU 3.2
310      */
311     kInvariant
312   };
313 
314   //========================================
315   // Read-only operations
316   //========================================
317 
318   /* Comparison - bitwise only - for international comparison use collation */
319 
320   /**
321    * Equality operator. Performs only bitwise comparison.
322    * @param text The UnicodeString to compare to this one.
323    * @return TRUE if `text` contains the same characters as this one,
324    * FALSE otherwise.
325    * @stable ICU 2.0
326    */
327   inline UBool operator== (const UnicodeString& text) const;
328 
329   /**
330    * Inequality operator. Performs only bitwise comparison.
331    * @param text The UnicodeString to compare to this one.
332    * @return FALSE if `text` contains the same characters as this one,
333    * TRUE otherwise.
334    * @stable ICU 2.0
335    */
336   inline UBool operator!= (const UnicodeString& text) const;
337 
338   /**
339    * Greater than operator. Performs only bitwise comparison.
340    * @param text The UnicodeString to compare to this one.
341    * @return TRUE if the characters in this are bitwise
342    * greater than the characters in `text`, FALSE otherwise
343    * @stable ICU 2.0
344    */
345   inline UBool operator> (const UnicodeString& text) const;
346 
347   /**
348    * Less than operator. Performs only bitwise comparison.
349    * @param text The UnicodeString to compare to this one.
350    * @return TRUE if the characters in this are bitwise
351    * less than the characters in `text`, FALSE otherwise
352    * @stable ICU 2.0
353    */
354   inline UBool operator< (const UnicodeString& text) const;
355 
356   /**
357    * Greater than or equal operator. Performs only bitwise comparison.
358    * @param text The UnicodeString to compare to this one.
359    * @return TRUE if the characters in this are bitwise
360    * greater than or equal to the characters in `text`, FALSE otherwise
361    * @stable ICU 2.0
362    */
363   inline UBool operator>= (const UnicodeString& text) const;
364 
365   /**
366    * Less than or equal operator. Performs only bitwise comparison.
367    * @param text The UnicodeString to compare to this one.
368    * @return TRUE if the characters in this are bitwise
369    * less than or equal to the characters in `text`, FALSE otherwise
370    * @stable ICU 2.0
371    */
372   inline UBool operator<= (const UnicodeString& text) const;
373 
374   /**
375    * Compare the characters bitwise in this UnicodeString to
376    * the characters in `text`.
377    * @param text The UnicodeString to compare to this one.
378    * @return The result of bitwise character comparison: 0 if this
379    * contains the same characters as `text`, -1 if the characters in
380    * this are bitwise less than the characters in `text`, +1 if the
381    * characters in this are bitwise greater than the characters
382    * in `text`.
383    * @stable ICU 2.0
384    */
385   inline int8_t compare(const UnicodeString& text) const;
386 
387   /**
388    * Compare the characters bitwise in the range
389    * [`start`, `start + length`) with the characters
390    * in the **entire string** `text`.
391    * (The parameters "start" and "length" are not applied to the other text "text".)
392    * @param start the offset at which the compare operation begins
393    * @param length the number of characters of text to compare.
394    * @param text the other text to be compared against this string.
395    * @return The result of bitwise character comparison: 0 if this
396    * contains the same characters as `text`, -1 if the characters in
397    * this are bitwise less than the characters in `text`, +1 if the
398    * characters in this are bitwise greater than the characters
399    * in `text`.
400    * @stable ICU 2.0
401    */
402   inline int8_t compare(int32_t start,
403          int32_t length,
404          const UnicodeString& text) const;
405 
406   /**
407    * Compare the characters bitwise in the range
408    * [`start`, `start + length`) with the characters
409    * in `srcText` in the range
410    * [`srcStart`, `srcStart + srcLength`).
411    * @param start the offset at which the compare operation begins
412    * @param length the number of characters in this to compare.
413    * @param srcText the text to be compared
414    * @param srcStart the offset into `srcText` to start comparison
415    * @param srcLength the number of characters in `src` to compare
416    * @return The result of bitwise character comparison: 0 if this
417    * contains the same characters as `srcText`, -1 if the characters in
418    * this are bitwise less than the characters in `srcText`, +1 if the
419    * characters in this are bitwise greater than the characters
420    * in `srcText`.
421    * @stable ICU 2.0
422    */
423    inline int8_t compare(int32_t start,
424          int32_t length,
425          const UnicodeString& srcText,
426          int32_t srcStart,
427          int32_t srcLength) const;
428 
429   /**
430    * Compare the characters bitwise in this UnicodeString with the first
431    * `srcLength` characters in `srcChars`.
432    * @param srcChars The characters to compare to this UnicodeString.
433    * @param srcLength the number of characters in `srcChars` to compare
434    * @return The result of bitwise character comparison: 0 if this
435    * contains the same characters as `srcChars`, -1 if the characters in
436    * this are bitwise less than the characters in `srcChars`, +1 if the
437    * characters in this are bitwise greater than the characters
438    * in `srcChars`.
439    * @stable ICU 2.0
440    */
441   inline int8_t compare(ConstChar16Ptr srcChars,
442          int32_t srcLength) const;
443 
444   /**
445    * Compare the characters bitwise in the range
446    * [`start`, `start + length`) with the first
447    * `length` characters in `srcChars`
448    * @param start the offset at which the compare operation begins
449    * @param length the number of characters to compare.
450    * @param srcChars the characters to be compared
451    * @return The result of bitwise character comparison: 0 if this
452    * contains the same characters as `srcChars`, -1 if the characters in
453    * this are bitwise less than the characters in `srcChars`, +1 if the
454    * characters in this are bitwise greater than the characters
455    * in `srcChars`.
456    * @stable ICU 2.0
457    */
458   inline int8_t compare(int32_t start,
459          int32_t length,
460          const char16_t *srcChars) const;
461 
462   /**
463    * Compare the characters bitwise in the range
464    * [`start`, `start + length`) with the characters
465    * in `srcChars` in the range
466    * [`srcStart`, `srcStart + srcLength`).
467    * @param start the offset at which the compare operation begins
468    * @param length the number of characters in this to compare
469    * @param srcChars the characters to be compared
470    * @param srcStart the offset into `srcChars` to start comparison
471    * @param srcLength the number of characters in `srcChars` to compare
472    * @return The result of bitwise character comparison: 0 if this
473    * contains the same characters as `srcChars`, -1 if the characters in
474    * this are bitwise less than the characters in `srcChars`, +1 if the
475    * characters in this are bitwise greater than the characters
476    * in `srcChars`.
477    * @stable ICU 2.0
478    */
479   inline int8_t compare(int32_t start,
480          int32_t length,
481          const char16_t *srcChars,
482          int32_t srcStart,
483          int32_t srcLength) const;
484 
485   /**
486    * Compare the characters bitwise in the range
487    * [`start`, `limit`) with the characters
488    * in `srcText` in the range
489    * [`srcStart`, `srcLimit`).
490    * @param start the offset at which the compare operation begins
491    * @param limit the offset immediately following the compare operation
492    * @param srcText the text to be compared
493    * @param srcStart the offset into `srcText` to start comparison
494    * @param srcLimit the offset into `srcText` to limit comparison
495    * @return The result of bitwise character comparison: 0 if this
496    * contains the same characters as `srcText`, -1 if the characters in
497    * this are bitwise less than the characters in `srcText`, +1 if the
498    * characters in this are bitwise greater than the characters
499    * in `srcText`.
500    * @stable ICU 2.0
501    */
502   inline int8_t compareBetween(int32_t start,
503             int32_t limit,
504             const UnicodeString& srcText,
505             int32_t srcStart,
506             int32_t srcLimit) const;
507 
508   /**
509    * Compare two Unicode strings in code point order.
510    * The result may be different from the results of compare(), operator<, etc.
511    * if supplementary characters are present:
512    *
513    * In UTF-16, supplementary characters (with code points U+10000 and above) are
514    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
515    * which means that they compare as less than some other BMP characters like U+feff.
516    * This function compares Unicode strings in code point order.
517    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
518    *
519    * @param text Another string to compare this one to.
520    * @return a negative/zero/positive integer corresponding to whether
521    * this string is less than/equal to/greater than the second one
522    * in code point order
523    * @stable ICU 2.0
524    */
525   inline int8_t compareCodePointOrder(const UnicodeString& text) const;
526 
527   /**
528    * Compare two Unicode strings in code point order.
529    * The result may be different from the results of compare(), operator<, etc.
530    * if supplementary characters are present:
531    *
532    * In UTF-16, supplementary characters (with code points U+10000 and above) are
533    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
534    * which means that they compare as less than some other BMP characters like U+feff.
535    * This function compares Unicode strings in code point order.
536    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
537    *
538    * @param start The start offset in this string at which the compare operation begins.
539    * @param length The number of code units from this string to compare.
540    * @param srcText Another string to compare this one to.
541    * @return a negative/zero/positive integer corresponding to whether
542    * this string is less than/equal to/greater than the second one
543    * in code point order
544    * @stable ICU 2.0
545    */
546   inline int8_t compareCodePointOrder(int32_t start,
547                                       int32_t length,
548                                       const UnicodeString& srcText) const;
549 
550   /**
551    * Compare two Unicode strings in code point order.
552    * The result may be different from the results of compare(), operator<, etc.
553    * if supplementary characters are present:
554    *
555    * In UTF-16, supplementary characters (with code points U+10000 and above) are
556    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
557    * which means that they compare as less than some other BMP characters like U+feff.
558    * This function compares Unicode strings in code point order.
559    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
560    *
561    * @param start The start offset in this string at which the compare operation begins.
562    * @param length The number of code units from this string to compare.
563    * @param srcText Another string to compare this one to.
564    * @param srcStart The start offset in that string at which the compare operation begins.
565    * @param srcLength The number of code units from that string to compare.
566    * @return a negative/zero/positive integer corresponding to whether
567    * this string is less than/equal to/greater than the second one
568    * in code point order
569    * @stable ICU 2.0
570    */
571    inline int8_t compareCodePointOrder(int32_t start,
572                                        int32_t length,
573                                        const UnicodeString& srcText,
574                                        int32_t srcStart,
575                                        int32_t srcLength) const;
576 
577   /**
578    * Compare two Unicode strings in code point order.
579    * The result may be different from the results of compare(), operator<, etc.
580    * if supplementary characters are present:
581    *
582    * In UTF-16, supplementary characters (with code points U+10000 and above) are
583    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
584    * which means that they compare as less than some other BMP characters like U+feff.
585    * This function compares Unicode strings in code point order.
586    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
587    *
588    * @param srcChars A pointer to another string to compare this one to.
589    * @param srcLength The number of code units from that string to compare.
590    * @return a negative/zero/positive integer corresponding to whether
591    * this string is less than/equal to/greater than the second one
592    * in code point order
593    * @stable ICU 2.0
594    */
595   inline int8_t compareCodePointOrder(ConstChar16Ptr srcChars,
596                                       int32_t srcLength) const;
597 
598   /**
599    * Compare two Unicode strings in code point order.
600    * The result may be different from the results of compare(), operator<, etc.
601    * if supplementary characters are present:
602    *
603    * In UTF-16, supplementary characters (with code points U+10000 and above) are
604    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
605    * which means that they compare as less than some other BMP characters like U+feff.
606    * This function compares Unicode strings in code point order.
607    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
608    *
609    * @param start The start offset in this string at which the compare operation begins.
610    * @param length The number of code units from this string to compare.
611    * @param srcChars A pointer to another string to compare this one to.
612    * @return a negative/zero/positive integer corresponding to whether
613    * this string is less than/equal to/greater than the second one
614    * in code point order
615    * @stable ICU 2.0
616    */
617   inline int8_t compareCodePointOrder(int32_t start,
618                                       int32_t length,
619                                       const char16_t *srcChars) const;
620 
621   /**
622    * Compare two Unicode strings in code point order.
623    * The result may be different from the results of compare(), operator<, etc.
624    * if supplementary characters are present:
625    *
626    * In UTF-16, supplementary characters (with code points U+10000 and above) are
627    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
628    * which means that they compare as less than some other BMP characters like U+feff.
629    * This function compares Unicode strings in code point order.
630    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
631    *
632    * @param start The start offset in this string at which the compare operation begins.
633    * @param length The number of code units from this string to compare.
634    * @param srcChars A pointer to another string to compare this one to.
635    * @param srcStart The start offset in that string at which the compare operation begins.
636    * @param srcLength The number of code units from that string to compare.
637    * @return a negative/zero/positive integer corresponding to whether
638    * this string is less than/equal to/greater than the second one
639    * in code point order
640    * @stable ICU 2.0
641    */
642   inline int8_t compareCodePointOrder(int32_t start,
643                                       int32_t length,
644                                       const char16_t *srcChars,
645                                       int32_t srcStart,
646                                       int32_t srcLength) const;
647 
648   /**
649    * Compare two Unicode strings in code point order.
650    * The result may be different from the results of compare(), operator<, etc.
651    * if supplementary characters are present:
652    *
653    * In UTF-16, supplementary characters (with code points U+10000 and above) are
654    * stored with pairs of surrogate code units. These have values from 0xd800 to 0xdfff,
655    * which means that they compare as less than some other BMP characters like U+feff.
656    * This function compares Unicode strings in code point order.
657    * If either of the UTF-16 strings is malformed (i.e., it contains unpaired surrogates), then the result is not defined.
658    *
659    * @param start The start offset in this string at which the compare operation begins.
660    * @param limit The offset after the last code unit from this string to compare.
661    * @param srcText Another string to compare this one to.
662    * @param srcStart The start offset in that string at which the compare operation begins.
663    * @param srcLimit The offset after the last code unit from that string to compare.
664    * @return a negative/zero/positive integer corresponding to whether
665    * this string is less than/equal to/greater than the second one
666    * in code point order
667    * @stable ICU 2.0
668    */
669   inline int8_t compareCodePointOrderBetween(int32_t start,
670                                              int32_t limit,
671                                              const UnicodeString& srcText,
672                                              int32_t srcStart,
673                                              int32_t srcLimit) const;
674 
675   /**
676    * Compare two strings case-insensitively using full case folding.
677    * This is equivalent to this->foldCase(options).compare(text.foldCase(options)).
678    *
679    * @param text Another string to compare this one to.
680    * @param options A bit set of options:
681    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
682    *     Comparison in code unit order with default case folding.
683    *
684    *   - U_COMPARE_CODE_POINT_ORDER
685    *     Set to choose code point order instead of code unit order
686    *     (see u_strCompare for details).
687    *
688    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
689    *
690    * @return A negative, zero, or positive integer indicating the comparison result.
691    * @stable ICU 2.0
692    */
693   inline int8_t caseCompare(const UnicodeString& text, uint32_t options) const;
694 
695   /**
696    * Compare two strings case-insensitively using full case folding.
697    * This is equivalent to this->foldCase(options).compare(srcText.foldCase(options)).
698    *
699    * @param start The start offset in this string at which the compare operation begins.
700    * @param length The number of code units from this string to compare.
701    * @param srcText Another string to compare this one to.
702    * @param options A bit set of options:
703    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
704    *     Comparison in code unit order with default case folding.
705    *
706    *   - U_COMPARE_CODE_POINT_ORDER
707    *     Set to choose code point order instead of code unit order
708    *     (see u_strCompare for details).
709    *
710    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
711    *
712    * @return A negative, zero, or positive integer indicating the comparison result.
713    * @stable ICU 2.0
714    */
715   inline int8_t caseCompare(int32_t start,
716          int32_t length,
717          const UnicodeString& srcText,
718          uint32_t options) const;
719 
720   /**
721    * Compare two strings case-insensitively using full case folding.
722    * This is equivalent to this->foldCase(options).compare(srcText.foldCase(options)).
723    *
724    * @param start The start offset in this string at which the compare operation begins.
725    * @param length The number of code units from this string to compare.
726    * @param srcText Another string to compare this one to.
727    * @param srcStart The start offset in that string at which the compare operation begins.
728    * @param srcLength The number of code units from that string to compare.
729    * @param options A bit set of options:
730    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
731    *     Comparison in code unit order with default case folding.
732    *
733    *   - U_COMPARE_CODE_POINT_ORDER
734    *     Set to choose code point order instead of code unit order
735    *     (see u_strCompare for details).
736    *
737    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
738    *
739    * @return A negative, zero, or positive integer indicating the comparison result.
740    * @stable ICU 2.0
741    */
742   inline int8_t caseCompare(int32_t start,
743          int32_t length,
744          const UnicodeString& srcText,
745          int32_t srcStart,
746          int32_t srcLength,
747          uint32_t options) const;
748 
749   /**
750    * Compare two strings case-insensitively using full case folding.
751    * This is equivalent to this->foldCase(options).compare(srcChars.foldCase(options)).
752    *
753    * @param srcChars A pointer to another string to compare this one to.
754    * @param srcLength The number of code units from that string to compare.
755    * @param options A bit set of options:
756    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
757    *     Comparison in code unit order with default case folding.
758    *
759    *   - U_COMPARE_CODE_POINT_ORDER
760    *     Set to choose code point order instead of code unit order
761    *     (see u_strCompare for details).
762    *
763    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
764    *
765    * @return A negative, zero, or positive integer indicating the comparison result.
766    * @stable ICU 2.0
767    */
768   inline int8_t caseCompare(ConstChar16Ptr srcChars,
769          int32_t srcLength,
770          uint32_t options) const;
771 
772   /**
773    * Compare two strings case-insensitively using full case folding.
774    * This is equivalent to this->foldCase(options).compare(srcChars.foldCase(options)).
775    *
776    * @param start The start offset in this string at which the compare operation begins.
777    * @param length The number of code units from this string to compare.
778    * @param srcChars A pointer to another string to compare this one to.
779    * @param options A bit set of options:
780    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
781    *     Comparison in code unit order with default case folding.
782    *
783    *   - U_COMPARE_CODE_POINT_ORDER
784    *     Set to choose code point order instead of code unit order
785    *     (see u_strCompare for details).
786    *
787    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
788    *
789    * @return A negative, zero, or positive integer indicating the comparison result.
790    * @stable ICU 2.0
791    */
792   inline int8_t caseCompare(int32_t start,
793          int32_t length,
794          const char16_t *srcChars,
795          uint32_t options) const;
796 
797   /**
798    * Compare two strings case-insensitively using full case folding.
799    * This is equivalent to this->foldCase(options).compare(srcChars.foldCase(options)).
800    *
801    * @param start The start offset in this string at which the compare operation begins.
802    * @param length The number of code units from this string to compare.
803    * @param srcChars A pointer to another string to compare this one to.
804    * @param srcStart The start offset in that string at which the compare operation begins.
805    * @param srcLength The number of code units from that string to compare.
806    * @param options A bit set of options:
807    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
808    *     Comparison in code unit order with default case folding.
809    *
810    *   - U_COMPARE_CODE_POINT_ORDER
811    *     Set to choose code point order instead of code unit order
812    *     (see u_strCompare for details).
813    *
814    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
815    *
816    * @return A negative, zero, or positive integer indicating the comparison result.
817    * @stable ICU 2.0
818    */
819   inline int8_t caseCompare(int32_t start,
820          int32_t length,
821          const char16_t *srcChars,
822          int32_t srcStart,
823          int32_t srcLength,
824          uint32_t options) const;
825 
826   /**
827    * Compare two strings case-insensitively using full case folding.
828    * This is equivalent to this->foldCase(options).compareBetween(text.foldCase(options)).
829    *
830    * @param start The start offset in this string at which the compare operation begins.
831    * @param limit The offset after the last code unit from this string to compare.
832    * @param srcText Another string to compare this one to.
833    * @param srcStart The start offset in that string at which the compare operation begins.
834    * @param srcLimit The offset after the last code unit from that string to compare.
835    * @param options A bit set of options:
836    *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
837    *     Comparison in code unit order with default case folding.
838    *
839    *   - U_COMPARE_CODE_POINT_ORDER
840    *     Set to choose code point order instead of code unit order
841    *     (see u_strCompare for details).
842    *
843    *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
844    *
845    * @return A negative, zero, or positive integer indicating the comparison result.
846    * @stable ICU 2.0
847    */
848   inline int8_t caseCompareBetween(int32_t start,
849             int32_t limit,
850             const UnicodeString& srcText,
851             int32_t srcStart,
852             int32_t srcLimit,
853             uint32_t options) const;
854 
855   /**
856    * Determine if this starts with the characters in `text`
857    * @param text The text to match.
858    * @return TRUE if this starts with the characters in `text`,
859    * FALSE otherwise
860    * @stable ICU 2.0
861    */
862   inline UBool startsWith(const UnicodeString& text) const;
863 
864   /**
865    * Determine if this starts with the characters in `srcText`
866    * in the range [`srcStart`, `srcStart + srcLength`).
867    * @param srcText The text to match.
868    * @param srcStart the offset into `srcText` to start matching
869    * @param srcLength the number of characters in `srcText` to match
870    * @return TRUE if this starts with the characters in `text`,
871    * FALSE otherwise
872    * @stable ICU 2.0
873    */
874   inline UBool startsWith(const UnicodeString& srcText,
875             int32_t srcStart,
876             int32_t srcLength) const;
877 
878   /**
879    * Determine if this starts with the characters in `srcChars`
880    * @param srcChars The characters to match.
881    * @param srcLength the number of characters in `srcChars`
882    * @return TRUE if this starts with the characters in `srcChars`,
883    * FALSE otherwise
884    * @stable ICU 2.0
885    */
886   inline UBool startsWith(ConstChar16Ptr srcChars,
887             int32_t srcLength) const;
888 
889   /**
890    * Determine if this ends with the characters in `srcChars`
891    * in the range  [`srcStart`, `srcStart + srcLength`).
892    * @param srcChars The characters to match.
893    * @param srcStart the offset into `srcText` to start matching
894    * @param srcLength the number of characters in `srcChars` to match
895    * @return TRUE if this ends with the characters in `srcChars`, FALSE otherwise
896    * @stable ICU 2.0
897    */
898   inline UBool startsWith(const char16_t *srcChars,
899             int32_t srcStart,
900             int32_t srcLength) const;
901 
902   /**
903    * Determine if this ends with the characters in `text`
904    * @param text The text to match.
905    * @return TRUE if this ends with the characters in `text`,
906    * FALSE otherwise
907    * @stable ICU 2.0
908    */
909   inline UBool endsWith(const UnicodeString& text) const;
910 
911   /**
912    * Determine if this ends with the characters in `srcText`
913    * in the range [`srcStart`, `srcStart + srcLength`).
914    * @param srcText The text to match.
915    * @param srcStart the offset into `srcText` to start matching
916    * @param srcLength the number of characters in `srcText` to match
917    * @return TRUE if this ends with the characters in `text`,
918    * FALSE otherwise
919    * @stable ICU 2.0
920    */
921   inline UBool endsWith(const UnicodeString& srcText,
922           int32_t srcStart,
923           int32_t srcLength) const;
924 
925   /**
926    * Determine if this ends with the characters in `srcChars`
927    * @param srcChars The characters to match.
928    * @param srcLength the number of characters in `srcChars`
929    * @return TRUE if this ends with the characters in `srcChars`,
930    * FALSE otherwise
931    * @stable ICU 2.0
932    */
933   inline UBool endsWith(ConstChar16Ptr srcChars,
934           int32_t srcLength) const;
935 
936   /**
937    * Determine if this ends with the characters in `srcChars`
938    * in the range  [`srcStart`, `srcStart + srcLength`).
939    * @param srcChars The characters to match.
940    * @param srcStart the offset into `srcText` to start matching
941    * @param srcLength the number of characters in `srcChars` to match
942    * @return TRUE if this ends with the characters in `srcChars`,
943    * FALSE otherwise
944    * @stable ICU 2.0
945    */
946   inline UBool endsWith(const char16_t *srcChars,
947           int32_t srcStart,
948           int32_t srcLength) const;
949 
950 
951   /* Searching - bitwise only */
952 
953   /**
954    * Locate in this the first occurrence of the characters in `text`,
955    * using bitwise comparison.
956    * @param text The text to search for.
957    * @return The offset into this of the start of `text`,
958    * or -1 if not found.
959    * @stable ICU 2.0
960    */
961   inline int32_t indexOf(const UnicodeString& text) const;
962 
963   /**
964    * Locate in this the first occurrence of the characters in `text`
965    * starting at offset `start`, using bitwise comparison.
966    * @param text The text to search for.
967    * @param start The offset at which searching will start.
968    * @return The offset into this of the start of `text`,
969    * or -1 if not found.
970    * @stable ICU 2.0
971    */
972   inline int32_t indexOf(const UnicodeString& text,
973               int32_t start) const;
974 
975   /**
976    * Locate in this the first occurrence in the range
977    * [`start`, `start + length`) of the characters
978    * in `text`, using bitwise comparison.
979    * @param text The text to search for.
980    * @param start The offset at which searching will start.
981    * @param length The number of characters to search
982    * @return The offset into this of the start of `text`,
983    * or -1 if not found.
984    * @stable ICU 2.0
985    */
986   inline int32_t indexOf(const UnicodeString& text,
987               int32_t start,
988               int32_t length) const;
989 
990   /**
991    * Locate in this the first occurrence in the range
992    * [`start`, `start + length`) of the characters
993    *  in `srcText` in the range
994    * [`srcStart`, `srcStart + srcLength`),
995    * using bitwise comparison.
996    * @param srcText The text to search for.
997    * @param srcStart the offset into `srcText` at which
998    * to start matching
999    * @param srcLength the number of characters in `srcText` to match
1000    * @param start the offset into this at which to start matching
1001    * @param length the number of characters in this to search
1002    * @return The offset into this of the start of `text`,
1003    * or -1 if not found.
1004    * @stable ICU 2.0
1005    */
1006   inline int32_t indexOf(const UnicodeString& srcText,
1007               int32_t srcStart,
1008               int32_t srcLength,
1009               int32_t start,
1010               int32_t length) const;
1011 
1012   /**
1013    * Locate in this the first occurrence of the characters in
1014    * `srcChars`
1015    * starting at offset `start`, using bitwise comparison.
1016    * @param srcChars The text to search for.
1017    * @param srcLength the number of characters in `srcChars` to match
1018    * @param start the offset into this at which to start matching
1019    * @return The offset into this of the start of `text`,
1020    * or -1 if not found.
1021    * @stable ICU 2.0
1022    */
1023   inline int32_t indexOf(const char16_t *srcChars,
1024               int32_t srcLength,
1025               int32_t start) const;
1026 
1027   /**
1028    * Locate in this the first occurrence in the range
1029    * [`start`, `start + length`) of the characters
1030    * in `srcChars`, using bitwise comparison.
1031    * @param srcChars The text to search for.
1032    * @param srcLength the number of characters in `srcChars`
1033    * @param start The offset at which searching will start.
1034    * @param length The number of characters to search
1035    * @return The offset into this of the start of `srcChars`,
1036    * or -1 if not found.
1037    * @stable ICU 2.0
1038    */
1039   inline int32_t indexOf(ConstChar16Ptr srcChars,
1040               int32_t srcLength,
1041               int32_t start,
1042               int32_t length) const;
1043 
1044   /**
1045    * Locate in this the first occurrence in the range
1046    * [`start`, `start + length`) of the characters
1047    * in `srcChars` in the range
1048    * [`srcStart`, `srcStart + srcLength`),
1049    * using bitwise comparison.
1050    * @param srcChars The text to search for.
1051    * @param srcStart the offset into `srcChars` at which
1052    * to start matching
1053    * @param srcLength the number of characters in `srcChars` to match
1054    * @param start the offset into this at which to start matching
1055    * @param length the number of characters in this to search
1056    * @return The offset into this of the start of `text`,
1057    * or -1 if not found.
1058    * @stable ICU 2.0
1059    */
1060   int32_t indexOf(const char16_t *srcChars,
1061               int32_t srcStart,
1062               int32_t srcLength,
1063               int32_t start,
1064               int32_t length) const;
1065 
1066   /**
1067    * Locate in this the first occurrence of the BMP code point `c`,
1068    * using bitwise comparison.
1069    * @param c The code unit to search for.
1070    * @return The offset into this of `c`, or -1 if not found.
1071    * @stable ICU 2.0
1072    */
1073   inline int32_t indexOf(char16_t c) const;
1074 
1075   /**
1076    * Locate in this the first occurrence of the code point `c`,
1077    * using bitwise comparison.
1078    *
1079    * @param c The code point to search for.
1080    * @return The offset into this of `c`, or -1 if not found.
1081    * @stable ICU 2.0
1082    */
1083   inline int32_t indexOf(UChar32 c) const;
1084 
1085   /**
1086    * Locate in this the first occurrence of the BMP code point `c`,
1087    * starting at offset `start`, using bitwise comparison.
1088    * @param c The code unit to search for.
1089    * @param start The offset at which searching will start.
1090    * @return The offset into this of `c`, or -1 if not found.
1091    * @stable ICU 2.0
1092    */
1093   inline int32_t indexOf(char16_t c,
1094               int32_t start) const;
1095 
1096   /**
1097    * Locate in this the first occurrence of the code point `c`
1098    * starting at offset `start`, using bitwise comparison.
1099    *
1100    * @param c The code point to search for.
1101    * @param start The offset at which searching will start.
1102    * @return The offset into this of `c`, or -1 if not found.
1103    * @stable ICU 2.0
1104    */
1105   inline int32_t indexOf(UChar32 c,
1106               int32_t start) const;
1107 
1108   /**
1109    * Locate in this the first occurrence of the BMP code point `c`
1110    * in the range [`start`, `start + length`),
1111    * using bitwise comparison.
1112    * @param c The code unit to search for.
1113    * @param start the offset into this at which to start matching
1114    * @param length the number of characters in this to search
1115    * @return The offset into this of `c`, or -1 if not found.
1116    * @stable ICU 2.0
1117    */
1118   inline int32_t indexOf(char16_t c,
1119               int32_t start,
1120               int32_t length) const;
1121 
1122   /**
1123    * Locate in this the first occurrence of the code point `c`
1124    * in the range [`start`, `start + length`),
1125    * using bitwise comparison.
1126    *
1127    * @param c The code point to search for.
1128    * @param start the offset into this at which to start matching
1129    * @param length the number of characters in this to search
1130    * @return The offset into this of `c`, or -1 if not found.
1131    * @stable ICU 2.0
1132    */
1133   inline int32_t indexOf(UChar32 c,
1134               int32_t start,
1135               int32_t length) const;
1136 
1137   /**
1138    * Locate in this the last occurrence of the characters in `text`,
1139    * using bitwise comparison.
1140    * @param text The text to search for.
1141    * @return The offset into this of the start of `text`,
1142    * or -1 if not found.
1143    * @stable ICU 2.0
1144    */
1145   inline int32_t lastIndexOf(const UnicodeString& text) const;
1146 
1147   /**
1148    * Locate in this the last occurrence of the characters in `text`
1149    * starting at offset `start`, using bitwise comparison.
1150    * @param text The text to search for.
1151    * @param start The offset at which searching will start.
1152    * @return The offset into this of the start of `text`,
1153    * or -1 if not found.
1154    * @stable ICU 2.0
1155    */
1156   inline int32_t lastIndexOf(const UnicodeString& text,
1157               int32_t start) const;
1158 
1159   /**
1160    * Locate in this the last occurrence in the range
1161    * [`start`, `start + length`) of the characters
1162    * in `text`, using bitwise comparison.
1163    * @param text The text to search for.
1164    * @param start The offset at which searching will start.
1165    * @param length The number of characters to search
1166    * @return The offset into this of the start of `text`,
1167    * or -1 if not found.
1168    * @stable ICU 2.0
1169    */
1170   inline int32_t lastIndexOf(const UnicodeString& text,
1171               int32_t start,
1172               int32_t length) const;
1173 
1174   /**
1175    * Locate in this the last occurrence in the range
1176    * [`start`, `start + length`) of the characters
1177    * in `srcText` in the range
1178    * [`srcStart`, `srcStart + srcLength`),
1179    * using bitwise comparison.
1180    * @param srcText The text to search for.
1181    * @param srcStart the offset into `srcText` at which
1182    * to start matching
1183    * @param srcLength the number of characters in `srcText` to match
1184    * @param start the offset into this at which to start matching
1185    * @param length the number of characters in this to search
1186    * @return The offset into this of the start of `text`,
1187    * or -1 if not found.
1188    * @stable ICU 2.0
1189    */
1190   inline int32_t lastIndexOf(const UnicodeString& srcText,
1191               int32_t srcStart,
1192               int32_t srcLength,
1193               int32_t start,
1194               int32_t length) const;
1195 
1196   /**
1197    * Locate in this the last occurrence of the characters in `srcChars`
1198    * starting at offset `start`, using bitwise comparison.
1199    * @param srcChars The text to search for.
1200    * @param srcLength the number of characters in `srcChars` to match
1201    * @param start the offset into this at which to start matching
1202    * @return The offset into this of the start of `text`,
1203    * or -1 if not found.
1204    * @stable ICU 2.0
1205    */
1206   inline int32_t lastIndexOf(const char16_t *srcChars,
1207               int32_t srcLength,
1208               int32_t start) const;
1209 
1210   /**
1211    * Locate in this the last occurrence in the range
1212    * [`start`, `start + length`) of the characters
1213    * in `srcChars`, using bitwise comparison.
1214    * @param srcChars The text to search for.
1215    * @param srcLength the number of characters in `srcChars`
1216    * @param start The offset at which searching will start.
1217    * @param length The number of characters to search
1218    * @return The offset into this of the start of `srcChars`,
1219    * or -1 if not found.
1220    * @stable ICU 2.0
1221    */
1222   inline int32_t lastIndexOf(ConstChar16Ptr srcChars,
1223               int32_t srcLength,
1224               int32_t start,
1225               int32_t length) const;
1226 
1227   /**
1228    * Locate in this the last occurrence in the range
1229    * [`start`, `start + length`) of the characters
1230    * in `srcChars` in the range
1231    * [`srcStart`, `srcStart + srcLength`),
1232    * using bitwise comparison.
1233    * @param srcChars The text to search for.
1234    * @param srcStart the offset into `srcChars` at which
1235    * to start matching
1236    * @param srcLength the number of characters in `srcChars` to match
1237    * @param start the offset into this at which to start matching
1238    * @param length the number of characters in this to search
1239    * @return The offset into this of the start of `text`,
1240    * or -1 if not found.
1241    * @stable ICU 2.0
1242    */
1243   int32_t lastIndexOf(const char16_t *srcChars,
1244               int32_t srcStart,
1245               int32_t srcLength,
1246               int32_t start,
1247               int32_t length) const;
1248 
1249   /**
1250    * Locate in this the last occurrence of the BMP code point `c`,
1251    * using bitwise comparison.
1252    * @param c The code unit to search for.
1253    * @return The offset into this of `c`, or -1 if not found.
1254    * @stable ICU 2.0
1255    */
1256   inline int32_t lastIndexOf(char16_t c) const;
1257 
1258   /**
1259    * Locate in this the last occurrence of the code point `c`,
1260    * using bitwise comparison.
1261    *
1262    * @param c The code point to search for.
1263    * @return The offset into this of `c`, or -1 if not found.
1264    * @stable ICU 2.0
1265    */
1266   inline int32_t lastIndexOf(UChar32 c) const;
1267 
1268   /**
1269    * Locate in this the last occurrence of the BMP code point `c`
1270    * starting at offset `start`, using bitwise comparison.
1271    * @param c The code unit to search for.
1272    * @param start The offset at which searching will start.
1273    * @return The offset into this of `c`, or -1 if not found.
1274    * @stable ICU 2.0
1275    */
1276   inline int32_t lastIndexOf(char16_t c,
1277               int32_t start) const;
1278 
1279   /**
1280    * Locate in this the last occurrence of the code point `c`
1281    * starting at offset `start`, using bitwise comparison.
1282    *
1283    * @param c The code point to search for.
1284    * @param start The offset at which searching will start.
1285    * @return The offset into this of `c`, or -1 if not found.
1286    * @stable ICU 2.0
1287    */
1288   inline int32_t lastIndexOf(UChar32 c,
1289               int32_t start) const;
1290 
1291   /**
1292    * Locate in this the last occurrence of the BMP code point `c`
1293    * in the range [`start`, `start + length`),
1294    * using bitwise comparison.
1295    * @param c The code unit to search for.
1296    * @param start the offset into this at which to start matching
1297    * @param length the number of characters in this to search
1298    * @return The offset into this of `c`, or -1 if not found.
1299    * @stable ICU 2.0
1300    */
1301   inline int32_t lastIndexOf(char16_t c,
1302               int32_t start,
1303               int32_t length) const;
1304 
1305   /**
1306    * Locate in this the last occurrence of the code point `c`
1307    * in the range [`start`, `start + length`),
1308    * using bitwise comparison.
1309    *
1310    * @param c The code point to search for.
1311    * @param start the offset into this at which to start matching
1312    * @param length the number of characters in this to search
1313    * @return The offset into this of `c`, or -1 if not found.
1314    * @stable ICU 2.0
1315    */
1316   inline int32_t lastIndexOf(UChar32 c,
1317               int32_t start,
1318               int32_t length) const;
1319 
1320 
1321   /* Character access */
1322 
1323   /**
1324    * Return the code unit at offset `offset`.
1325    * If the offset is not valid (0..length()-1) then U+ffff is returned.
1326    * @param offset a valid offset into the text
1327    * @return the code unit at offset `offset`
1328    *         or 0xffff if the offset is not valid for this string
1329    * @stable ICU 2.0
1330    */
1331   inline char16_t charAt(int32_t offset) const;
1332 
1333   /**
1334    * Return the code unit at offset `offset`.
1335    * If the offset is not valid (0..length()-1) then U+ffff is returned.
1336    * @param offset a valid offset into the text
1337    * @return the code unit at offset `offset`
1338    * @stable ICU 2.0
1339    */
1340   inline char16_t operator[] (int32_t offset) const;
1341 
1342   /**
1343    * Return the code point that contains the code unit
1344    * at offset `offset`.
1345    * If the offset is not valid (0..length()-1) then U+ffff is returned.
1346    * @param offset a valid offset into the text
1347    * that indicates the text offset of any of the code units
1348    * that will be assembled into a code point (21-bit value) and returned
1349    * @return the code point of text at `offset`
1350    *         or 0xffff if the offset is not valid for this string
1351    * @stable ICU 2.0
1352    */
1353   UChar32 char32At(int32_t offset) const;
1354 
1355   /**
1356    * Adjust a random-access offset so that
1357    * it points to the beginning of a Unicode character.
1358    * The offset that is passed in points to
1359    * any code unit of a code point,
1360    * while the returned offset will point to the first code unit
1361    * of the same code point.
1362    * In UTF-16, if the input offset points to a second surrogate
1363    * of a surrogate pair, then the returned offset will point
1364    * to the first surrogate.
1365    * @param offset a valid offset into one code point of the text
1366    * @return offset of the first code unit of the same code point
1367    * @see U16_SET_CP_START
1368    * @stable ICU 2.0
1369    */
1370   int32_t getChar32Start(int32_t offset) const;
1371 
1372   /**
1373    * Adjust a random-access offset so that
1374    * it points behind a Unicode character.
1375    * The offset that is passed in points behind
1376    * any code unit of a code point,
1377    * while the returned offset will point behind the last code unit
1378    * of the same code point.
1379    * In UTF-16, if the input offset points behind the first surrogate
1380    * (i.e., to the second surrogate)
1381    * of a surrogate pair, then the returned offset will point
1382    * behind the second surrogate (i.e., to the first surrogate).
1383    * @param offset a valid offset after any code unit of a code point of the text
1384    * @return offset of the first code unit after the same code point
1385    * @see U16_SET_CP_LIMIT
1386    * @stable ICU 2.0
1387    */
1388   int32_t getChar32Limit(int32_t offset) const;
1389 
1390   /**
1391    * Move the code unit index along the string by delta code points.
1392    * Interpret the input index as a code unit-based offset into the string,
1393    * move the index forward or backward by delta code points, and
1394    * return the resulting index.
1395    * The input index should point to the first code unit of a code point,
1396    * if there is more than one.
1397    *
1398    * Both input and output indexes are code unit-based as for all
1399    * string indexes/offsets in ICU (and other libraries, like MBCS char*).
1400    * If delta<0 then the index is moved backward (toward the start of the string).
1401    * If delta>0 then the index is moved forward (toward the end of the string).
1402    *
1403    * This behaves like CharacterIterator::move32(delta, kCurrent).
1404    *
1405    * Behavior for out-of-bounds indexes:
1406    * `moveIndex32` pins the input index to 0..length(), i.e.,
1407    * if the input index<0 then it is pinned to 0;
1408    * if it is index>length() then it is pinned to length().
1409    * Afterwards, the index is moved by `delta` code points
1410    * forward or backward,
1411    * but no further backward than to 0 and no further forward than to length().
1412    * The resulting index return value will be in between 0 and length(), inclusively.
1413    *
1414    * Examples:
1415    * \code
1416    *     // s has code points 'a' U+10000 'b' U+10ffff U+2029
1417    *     UnicodeString s(u"a\U00010000b\U0010ffff\u2029");
1418    *
1419    *     // initial index: position of U+10000
1420    *     int32_t index=1;
1421    *
1422    *     // the following examples will all result in index==4, position of U+10ffff
1423    *
1424    *     // skip 2 code points from some position in the string
1425    *     index=s.moveIndex32(index, 2); // skips U+10000 and 'b'
1426    *
1427    *     // go to the 3rd code point from the start of s (0-based)
1428    *     index=s.moveIndex32(0, 3); // skips 'a', U+10000, and 'b'
1429    *
1430    *     // go to the next-to-last code point of s
1431    *     index=s.moveIndex32(s.length(), -2); // backward-skips U+2029 and U+10ffff
1432    * \endcode
1433    *
1434    * @param index input code unit index
1435    * @param delta (signed) code point count to move the index forward or backward
1436    *        in the string
1437    * @return the resulting code unit index
1438    * @stable ICU 2.0
1439    */
1440   int32_t moveIndex32(int32_t index, int32_t delta) const;
1441 
1442   /* Substring extraction */
1443 
1444   /**
1445    * Copy the characters in the range
1446    * [`start`, `start + length`) into the array `dst`,
1447    * beginning at `dstStart`.
1448    * If the string aliases to `dst` itself as an external buffer,
1449    * then extract() will not copy the contents.
1450    *
1451    * @param start offset of first character which will be copied into the array
1452    * @param length the number of characters to extract
1453    * @param dst array in which to copy characters.  The length of `dst`
1454    * must be at least (`dstStart + length`).
1455    * @param dstStart the offset in `dst` where the first character
1456    * will be extracted
1457    * @stable ICU 2.0
1458    */
1459   inline void extract(int32_t start,
1460            int32_t length,
1461            Char16Ptr dst,
1462            int32_t dstStart = 0) const;
1463 
1464   /**
1465    * Copy the contents of the string into dest.
1466    * This is a convenience function that
1467    * checks if there is enough space in dest,
1468    * extracts the entire string if possible,
1469    * and NUL-terminates dest if possible.
1470    *
1471    * If the string fits into dest but cannot be NUL-terminated
1472    * (length()==destCapacity) then the error code is set to U_STRING_NOT_TERMINATED_WARNING.
1473    * If the string itself does not fit into dest
1474    * (length()>destCapacity) then the error code is set to U_BUFFER_OVERFLOW_ERROR.
1475    *
1476    * If the string aliases to `dest` itself as an external buffer,
1477    * then extract() will not copy the contents.
1478    *
1479    * @param dest Destination string buffer.
1480    * @param destCapacity Number of char16_ts available at dest.
1481    * @param errorCode ICU error code.
1482    * @return length()
1483    * @stable ICU 2.0
1484    */
1485   int32_t
1486   extract(Char16Ptr dest, int32_t destCapacity,
1487           UErrorCode &errorCode) const;
1488 
1489   /**
1490    * Copy the characters in the range
1491    * [`start`, `start + length`) into the  UnicodeString
1492    * `target`.
1493    * @param start offset of first character which will be copied
1494    * @param length the number of characters to extract
1495    * @param target UnicodeString into which to copy characters.
1496    * @stable ICU 2.0
1497    */
1498   inline void extract(int32_t start,
1499            int32_t length,
1500            UnicodeString& target) const;
1501 
1502   /**
1503    * Copy the characters in the range [`start`, `limit`)
1504    * into the array `dst`, beginning at `dstStart`.
1505    * @param start offset of first character which will be copied into the array
1506    * @param limit offset immediately following the last character to be copied
1507    * @param dst array in which to copy characters.  The length of `dst`
1508    * must be at least (`dstStart + (limit - start)`).
1509    * @param dstStart the offset in `dst` where the first character
1510    * will be extracted
1511    * @stable ICU 2.0
1512    */
1513   inline void extractBetween(int32_t start,
1514               int32_t limit,
1515               char16_t *dst,
1516               int32_t dstStart = 0) const;
1517 
1518   /**
1519    * Copy the characters in the range [`start`, `limit`)
1520    * into the UnicodeString `target`.  Replaceable API.
1521    * @param start offset of first character which will be copied
1522    * @param limit offset immediately following the last character to be copied
1523    * @param target UnicodeString into which to copy characters.
1524    * @stable ICU 2.0
1525    */
1526   virtual void extractBetween(int32_t start,
1527               int32_t limit,
1528               UnicodeString& target) const;
1529 
1530   /**
1531    * Copy the characters in the range
1532    * [`start`, `start + startLength`) into an array of characters.
1533    * All characters must be invariant (see utypes.h).
1534    * Use US_INV as the last, signature-distinguishing parameter.
1535    *
1536    * This function does not write any more than `targetCapacity`
1537    * characters but returns the length of the entire output string
1538    * so that one can allocate a larger buffer and call the function again
1539    * if necessary.
1540    * The output string is NUL-terminated if possible.
1541    *
1542    * @param start offset of first character which will be copied
1543    * @param startLength the number of characters to extract
1544    * @param target the target buffer for extraction, can be NULL
1545    *               if targetLength is 0
1546    * @param targetCapacity the length of the target buffer
1547    * @param inv Signature-distinguishing paramater, use US_INV.
1548    * @return the output string length, not including the terminating NUL
1549    * @stable ICU 3.2
1550    */
1551   int32_t extract(int32_t start,
1552            int32_t startLength,
1553            char *target,
1554            int32_t targetCapacity,
1555            enum EInvariant inv) const;
1556 
1557 #if U_CHARSET_IS_UTF8 || !UCONFIG_NO_CONVERSION
1558 
1559   /**
1560    * Copy the characters in the range
1561    * [`start`, `start + length`) into an array of characters
1562    * in the platform's default codepage.
1563    * This function does not write any more than `targetLength`
1564    * characters but returns the length of the entire output string
1565    * so that one can allocate a larger buffer and call the function again
1566    * if necessary.
1567    * The output string is NUL-terminated if possible.
1568    *
1569    * @param start offset of first character which will be copied
1570    * @param startLength the number of characters to extract
1571    * @param target the target buffer for extraction
1572    * @param targetLength the length of the target buffer
1573    * If `target` is NULL, then the number of bytes required for
1574    * `target` is returned.
1575    * @return the output string length, not including the terminating NUL
1576    * @stable ICU 2.0
1577    */
1578   int32_t extract(int32_t start,
1579            int32_t startLength,
1580            char *target,
1581            uint32_t targetLength) const;
1582 
1583 #endif
1584 
1585 #if !UCONFIG_NO_CONVERSION
1586 
1587   /**
1588    * Copy the characters in the range
1589    * [`start`, `start + length`) into an array of characters
1590    * in a specified codepage.
1591    * The output string is NUL-terminated.
1592    *
1593    * Recommendation: For invariant-character strings use
1594    * extract(int32_t start, int32_t length, char *target, int32_t targetCapacity, enum EInvariant inv) const
1595    * because it avoids object code dependencies of UnicodeString on
1596    * the conversion code.
1597    *
1598    * @param start offset of first character which will be copied
1599    * @param startLength the number of characters to extract
1600    * @param target the target buffer for extraction
1601    * @param codepage the desired codepage for the characters.  0 has
1602    * the special meaning of the default codepage
1603    * If `codepage` is an empty string (`""`),
1604    * then a simple conversion is performed on the codepage-invariant
1605    * subset ("invariant characters") of the platform encoding. See utypes.h.
1606    * If `target` is NULL, then the number of bytes required for
1607    * `target` is returned. It is assumed that the target is big enough
1608    * to fit all of the characters.
1609    * @return the output string length, not including the terminating NUL
1610    * @stable ICU 2.0
1611    */
1612   inline int32_t extract(int32_t start,
1613                  int32_t startLength,
1614                  char *target,
1615                  const char *codepage = 0) const;
1616 
1617   /**
1618    * Copy the characters in the range
1619    * [`start`, `start + length`) into an array of characters
1620    * in a specified codepage.
1621    * This function does not write any more than `targetLength`
1622    * characters but returns the length of the entire output string
1623    * so that one can allocate a larger buffer and call the function again
1624    * if necessary.
1625    * The output string is NUL-terminated if possible.
1626    *
1627    * Recommendation: For invariant-character strings use
1628    * extract(int32_t start, int32_t length, char *target, int32_t targetCapacity, enum EInvariant inv) const
1629    * because it avoids object code dependencies of UnicodeString on
1630    * the conversion code.
1631    *
1632    * @param start offset of first character which will be copied
1633    * @param startLength the number of characters to extract
1634    * @param target the target buffer for extraction
1635    * @param targetLength the length of the target buffer
1636    * @param codepage the desired codepage for the characters.  0 has
1637    * the special meaning of the default codepage
1638    * If `codepage` is an empty string (`""`),
1639    * then a simple conversion is performed on the codepage-invariant
1640    * subset ("invariant characters") of the platform encoding. See utypes.h.
1641    * If `target` is NULL, then the number of bytes required for
1642    * `target` is returned.
1643    * @return the output string length, not including the terminating NUL
1644    * @stable ICU 2.0
1645    */
1646   int32_t extract(int32_t start,
1647            int32_t startLength,
1648            char *target,
1649            uint32_t targetLength,
1650            const char *codepage) const;
1651 
1652   /**
1653    * Convert the UnicodeString into a codepage string using an existing UConverter.
1654    * The output string is NUL-terminated if possible.
1655    *
1656    * This function avoids the overhead of opening and closing a converter if
1657    * multiple strings are extracted.
1658    *
1659    * @param dest destination string buffer, can be NULL if destCapacity==0
1660    * @param destCapacity the number of chars available at dest
1661    * @param cnv the converter object to be used (ucnv_resetFromUnicode() will be called),
1662    *        or NULL for the default converter
1663    * @param errorCode normal ICU error code
1664    * @return the length of the output string, not counting the terminating NUL;
1665    *         if the length is greater than destCapacity, then the string will not fit
1666    *         and a buffer of the indicated length would need to be passed in
1667    * @stable ICU 2.0
1668    */
1669   int32_t extract(char *dest, int32_t destCapacity,
1670                   UConverter *cnv,
1671                   UErrorCode &errorCode) const;
1672 
1673 #endif
1674 
1675   /**
1676    * Create a temporary substring for the specified range.
1677    * Unlike the substring constructor and setTo() functions,
1678    * the object returned here will be a read-only alias (using getBuffer())
1679    * rather than copying the text.
1680    * As a result, this substring operation is much faster but requires
1681    * that the original string not be modified or deleted during the lifetime
1682    * of the returned substring object.
1683    * @param start offset of the first character visible in the substring
1684    * @param length length of the substring
1685    * @return a read-only alias UnicodeString object for the substring
1686    * @stable ICU 4.4
1687    */
1688   UnicodeString tempSubString(int32_t start=0, int32_t length=INT32_MAX) const;
1689 
1690   /**
1691    * Create a temporary substring for the specified range.
1692    * Same as tempSubString(start, length) except that the substring range
1693    * is specified as a (start, limit) pair (with an exclusive limit index)
1694    * rather than a (start, length) pair.
1695    * @param start offset of the first character visible in the substring
1696    * @param limit offset immediately following the last character visible in the substring
1697    * @return a read-only alias UnicodeString object for the substring
1698    * @stable ICU 4.4
1699    */
1700   inline UnicodeString tempSubStringBetween(int32_t start, int32_t limit=INT32_MAX) const;
1701 
1702   /**
1703    * Convert the UnicodeString to UTF-8 and write the result
1704    * to a ByteSink. This is called by toUTF8String().
1705    * Unpaired surrogates are replaced with U+FFFD.
1706    * Calls u_strToUTF8WithSub().
1707    *
1708    * @param sink A ByteSink to which the UTF-8 version of the string is written.
1709    *             sink.Flush() is called at the end.
1710    * @stable ICU 4.2
1711    * @see toUTF8String
1712    */
1713   void toUTF8(ByteSink &sink) const;
1714 
1715   /**
1716    * Convert the UnicodeString to UTF-8 and append the result
1717    * to a standard string.
1718    * Unpaired surrogates are replaced with U+FFFD.
1719    * Calls toUTF8().
1720    *
1721    * @param result A standard string (or a compatible object)
1722    *        to which the UTF-8 version of the string is appended.
1723    * @return The string object.
1724    * @stable ICU 4.2
1725    * @see toUTF8
1726    */
1727   template<typename StringClass>
toUTF8String(StringClass & result)1728   StringClass &toUTF8String(StringClass &result) const {
1729     StringByteSink<StringClass> sbs(&result, length());
1730     toUTF8(sbs);
1731     return result;
1732   }
1733 
1734   /**
1735    * Convert the UnicodeString to UTF-32.
1736    * Unpaired surrogates are replaced with U+FFFD.
1737    * Calls u_strToUTF32WithSub().
1738    *
1739    * @param utf32 destination string buffer, can be NULL if capacity==0
1740    * @param capacity the number of UChar32s available at utf32
1741    * @param errorCode Standard ICU error code. Its input value must
1742    *                  pass the U_SUCCESS() test, or else the function returns
1743    *                  immediately. Check for U_FAILURE() on output or use with
1744    *                  function chaining. (See User Guide for details.)
1745    * @return The length of the UTF-32 string.
1746    * @see fromUTF32
1747    * @stable ICU 4.2
1748    */
1749   int32_t toUTF32(UChar32 *utf32, int32_t capacity, UErrorCode &errorCode) const;
1750 
1751   /* Length operations */
1752 
1753   /**
1754    * Return the length of the UnicodeString object.
1755    * The length is the number of char16_t code units are in the UnicodeString.
1756    * If you want the number of code points, please use countChar32().
1757    * @return the length of the UnicodeString object
1758    * @see countChar32
1759    * @stable ICU 2.0
1760    */
1761   inline int32_t length(void) const;
1762 
1763   /**
1764    * Count Unicode code points in the length char16_t code units of the string.
1765    * A code point may occupy either one or two char16_t code units.
1766    * Counting code points involves reading all code units.
1767    *
1768    * This functions is basically the inverse of moveIndex32().
1769    *
1770    * @param start the index of the first code unit to check
1771    * @param length the number of char16_t code units to check
1772    * @return the number of code points in the specified code units
1773    * @see length
1774    * @stable ICU 2.0
1775    */
1776   int32_t
1777   countChar32(int32_t start=0, int32_t length=INT32_MAX) const;
1778 
1779   /**
1780    * Check if the length char16_t code units of the string
1781    * contain more Unicode code points than a certain number.
1782    * This is more efficient than counting all code points in this part of the string
1783    * and comparing that number with a threshold.
1784    * This function may not need to scan the string at all if the length
1785    * falls within a certain range, and
1786    * never needs to count more than 'number+1' code points.
1787    * Logically equivalent to (countChar32(start, length)>number).
1788    * A Unicode code point may occupy either one or two char16_t code units.
1789    *
1790    * @param start the index of the first code unit to check (0 for the entire string)
1791    * @param length the number of char16_t code units to check
1792    *               (use INT32_MAX for the entire string; remember that start/length
1793    *                values are pinned)
1794    * @param number The number of code points in the (sub)string is compared against
1795    *               the 'number' parameter.
1796    * @return Boolean value for whether the string contains more Unicode code points
1797    *         than 'number'. Same as (u_countChar32(s, length)>number).
1798    * @see countChar32
1799    * @see u_strHasMoreChar32Than
1800    * @stable ICU 2.4
1801    */
1802   UBool
1803   hasMoreChar32Than(int32_t start, int32_t length, int32_t number) const;
1804 
1805   /**
1806    * Determine if this string is empty.
1807    * @return TRUE if this string contains 0 characters, FALSE otherwise.
1808    * @stable ICU 2.0
1809    */
1810   inline UBool isEmpty(void) const;
1811 
1812   /**
1813    * Return the capacity of the internal buffer of the UnicodeString object.
1814    * This is useful together with the getBuffer functions.
1815    * See there for details.
1816    *
1817    * @return the number of char16_ts available in the internal buffer
1818    * @see getBuffer
1819    * @stable ICU 2.0
1820    */
1821   inline int32_t getCapacity(void) const;
1822 
1823   /* Other operations */
1824 
1825   /**
1826    * Generate a hash code for this object.
1827    * @return The hash code of this UnicodeString.
1828    * @stable ICU 2.0
1829    */
1830   inline int32_t hashCode(void) const;
1831 
1832   /**
1833    * Determine if this object contains a valid string.
1834    * A bogus string has no value. It is different from an empty string,
1835    * although in both cases isEmpty() returns TRUE and length() returns 0.
1836    * setToBogus() and isBogus() can be used to indicate that no string value is available.
1837    * For a bogus string, getBuffer() and getTerminatedBuffer() return NULL, and
1838    * length() returns 0.
1839    *
1840    * @return TRUE if the string is bogus/invalid, FALSE otherwise
1841    * @see setToBogus()
1842    * @stable ICU 2.0
1843    */
1844   inline UBool isBogus(void) const;
1845 
1846 
1847   //========================================
1848   // Write operations
1849   //========================================
1850 
1851   /* Assignment operations */
1852 
1853   /**
1854    * Assignment operator.  Replace the characters in this UnicodeString
1855    * with the characters from `srcText`.
1856    *
1857    * Starting with ICU 2.4, the assignment operator and the copy constructor
1858    * allocate a new buffer and copy the buffer contents even for readonly aliases.
1859    * By contrast, the fastCopyFrom() function implements the old,
1860    * more efficient but less safe behavior
1861    * of making this string also a readonly alias to the same buffer.
1862    *
1863    * If the source object has an "open" buffer from getBuffer(minCapacity),
1864    * then the copy is an empty string.
1865    *
1866    * @param srcText The text containing the characters to replace
1867    * @return a reference to this
1868    * @stable ICU 2.0
1869    * @see fastCopyFrom
1870    */
1871   UnicodeString &operator=(const UnicodeString &srcText);
1872 
1873   /**
1874    * Almost the same as the assignment operator.
1875    * Replace the characters in this UnicodeString
1876    * with the characters from `srcText`.
1877    *
1878    * This function works the same as the assignment operator
1879    * for all strings except for ones that are readonly aliases.
1880    *
1881    * Starting with ICU 2.4, the assignment operator and the copy constructor
1882    * allocate a new buffer and copy the buffer contents even for readonly aliases.
1883    * This function implements the old, more efficient but less safe behavior
1884    * of making this string also a readonly alias to the same buffer.
1885    *
1886    * The fastCopyFrom function must be used only if it is known that the lifetime of
1887    * this UnicodeString does not exceed the lifetime of the aliased buffer
1888    * including its contents, for example for strings from resource bundles
1889    * or aliases to string constants.
1890    *
1891    * If the source object has an "open" buffer from getBuffer(minCapacity),
1892    * then the copy is an empty string.
1893    *
1894    * @param src The text containing the characters to replace.
1895    * @return a reference to this
1896    * @stable ICU 2.4
1897    */
1898   UnicodeString &fastCopyFrom(const UnicodeString &src);
1899 
1900   /**
1901    * Move assignment operator; might leave src in bogus state.
1902    * This string will have the same contents and state that the source string had.
1903    * The behavior is undefined if *this and src are the same object.
1904    * @param src source string
1905    * @return *this
1906    * @stable ICU 56
1907    */
1908   UnicodeString &operator=(UnicodeString &&src) U_NOEXCEPT;
1909 
1910   /**
1911    * Swap strings.
1912    * @param other other string
1913    * @stable ICU 56
1914    */
1915   void swap(UnicodeString &other) U_NOEXCEPT;
1916 
1917   /**
1918    * Non-member UnicodeString swap function.
1919    * @param s1 will get s2's contents and state
1920    * @param s2 will get s1's contents and state
1921    * @stable ICU 56
1922    */
1923   friend inline void U_EXPORT2
swap(UnicodeString & s1,UnicodeString & s2)1924   swap(UnicodeString &s1, UnicodeString &s2) U_NOEXCEPT {
1925     s1.swap(s2);
1926   }
1927 
1928   /**
1929    * Assignment operator.  Replace the characters in this UnicodeString
1930    * with the code unit `ch`.
1931    * @param ch the code unit to replace
1932    * @return a reference to this
1933    * @stable ICU 2.0
1934    */
1935   inline UnicodeString& operator= (char16_t ch);
1936 
1937   /**
1938    * Assignment operator.  Replace the characters in this UnicodeString
1939    * with the code point `ch`.
1940    * @param ch the code point to replace
1941    * @return a reference to this
1942    * @stable ICU 2.0
1943    */
1944   inline UnicodeString& operator= (UChar32 ch);
1945 
1946   /**
1947    * Set the text in the UnicodeString object to the characters
1948    * in `srcText` in the range
1949    * [`srcStart`, `srcText.length()`).
1950    * `srcText` is not modified.
1951    * @param srcText the source for the new characters
1952    * @param srcStart the offset into `srcText` where new characters
1953    * will be obtained
1954    * @return a reference to this
1955    * @stable ICU 2.2
1956    */
1957   inline UnicodeString& setTo(const UnicodeString& srcText,
1958                int32_t srcStart);
1959 
1960   /**
1961    * Set the text in the UnicodeString object to the characters
1962    * in `srcText` in the range
1963    * [`srcStart`, `srcStart + srcLength`).
1964    * `srcText` is not modified.
1965    * @param srcText the source for the new characters
1966    * @param srcStart the offset into `srcText` where new characters
1967    * will be obtained
1968    * @param srcLength the number of characters in `srcText` in the
1969    * replace string.
1970    * @return a reference to this
1971    * @stable ICU 2.0
1972    */
1973   inline UnicodeString& setTo(const UnicodeString& srcText,
1974                int32_t srcStart,
1975                int32_t srcLength);
1976 
1977   /**
1978    * Set the text in the UnicodeString object to the characters in
1979    * `srcText`.
1980    * `srcText` is not modified.
1981    * @param srcText the source for the new characters
1982    * @return a reference to this
1983    * @stable ICU 2.0
1984    */
1985   inline UnicodeString& setTo(const UnicodeString& srcText);
1986 
1987   /**
1988    * Set the characters in the UnicodeString object to the characters
1989    * in `srcChars`. `srcChars` is not modified.
1990    * @param srcChars the source for the new characters
1991    * @param srcLength the number of Unicode characters in srcChars.
1992    * @return a reference to this
1993    * @stable ICU 2.0
1994    */
1995   inline UnicodeString& setTo(const char16_t *srcChars,
1996                int32_t srcLength);
1997 
1998   /**
1999    * Set the characters in the UnicodeString object to the code unit
2000    * `srcChar`.
2001    * @param srcChar the code unit which becomes the UnicodeString's character
2002    * content
2003    * @return a reference to this
2004    * @stable ICU 2.0
2005    */
2006   inline UnicodeString& setTo(char16_t srcChar);
2007 
2008   /**
2009    * Set the characters in the UnicodeString object to the code point
2010    * `srcChar`.
2011    * @param srcChar the code point which becomes the UnicodeString's character
2012    * content
2013    * @return a reference to this
2014    * @stable ICU 2.0
2015    */
2016   inline UnicodeString& setTo(UChar32 srcChar);
2017 
2018   /**
2019    * Aliasing setTo() function, analogous to the readonly-aliasing char16_t* constructor.
2020    * The text will be used for the UnicodeString object, but
2021    * it will not be released when the UnicodeString is destroyed.
2022    * This has copy-on-write semantics:
2023    * When the string is modified, then the buffer is first copied into
2024    * newly allocated memory.
2025    * The aliased buffer is never modified.
2026    *
2027    * In an assignment to another UnicodeString, when using the copy constructor
2028    * or the assignment operator, the text will be copied.
2029    * When using fastCopyFrom(), the text will be aliased again,
2030    * so that both strings then alias the same readonly-text.
2031    *
2032    * @param isTerminated specifies if `text` is `NUL`-terminated.
2033    *                     This must be true if `textLength==-1`.
2034    * @param text The characters to alias for the UnicodeString.
2035    * @param textLength The number of Unicode characters in `text` to alias.
2036    *                   If -1, then this constructor will determine the length
2037    *                   by calling `u_strlen()`.
2038    * @return a reference to this
2039    * @stable ICU 2.0
2040    */
2041   UnicodeString &setTo(UBool isTerminated,
2042                        ConstChar16Ptr text,
2043                        int32_t textLength);
2044 
2045   /**
2046    * Aliasing setTo() function, analogous to the writable-aliasing char16_t* constructor.
2047    * The text will be used for the UnicodeString object, but
2048    * it will not be released when the UnicodeString is destroyed.
2049    * This has write-through semantics:
2050    * For as long as the capacity of the buffer is sufficient, write operations
2051    * will directly affect the buffer. When more capacity is necessary, then
2052    * a new buffer will be allocated and the contents copied as with regularly
2053    * constructed strings.
2054    * In an assignment to another UnicodeString, the buffer will be copied.
2055    * The extract(Char16Ptr dst) function detects whether the dst pointer is the same
2056    * as the string buffer itself and will in this case not copy the contents.
2057    *
2058    * @param buffer The characters to alias for the UnicodeString.
2059    * @param buffLength The number of Unicode characters in `buffer` to alias.
2060    * @param buffCapacity The size of `buffer` in char16_ts.
2061    * @return a reference to this
2062    * @stable ICU 2.0
2063    */
2064   UnicodeString &setTo(char16_t *buffer,
2065                        int32_t buffLength,
2066                        int32_t buffCapacity);
2067 
2068   /**
2069    * Make this UnicodeString object invalid.
2070    * The string will test TRUE with isBogus().
2071    *
2072    * A bogus string has no value. It is different from an empty string.
2073    * It can be used to indicate that no string value is available.
2074    * getBuffer() and getTerminatedBuffer() return NULL, and
2075    * length() returns 0.
2076    *
2077    * This utility function is used throughout the UnicodeString
2078    * implementation to indicate that a UnicodeString operation failed,
2079    * and may be used in other functions,
2080    * especially but not exclusively when such functions do not
2081    * take a UErrorCode for simplicity.
2082    *
2083    * The following methods, and no others, will clear a string object's bogus flag:
2084    * - remove()
2085    * - remove(0, INT32_MAX)
2086    * - truncate(0)
2087    * - operator=() (assignment operator)
2088    * - setTo(...)
2089    *
2090    * The simplest ways to turn a bogus string into an empty one
2091    * is to use the remove() function.
2092    * Examples for other functions that are equivalent to "set to empty string":
2093    * \code
2094    * if(s.isBogus()) {
2095    *   s.remove();           // set to an empty string (remove all), or
2096    *   s.remove(0, INT32_MAX); // set to an empty string (remove all), or
2097    *   s.truncate(0);        // set to an empty string (complete truncation), or
2098    *   s=UnicodeString();    // assign an empty string, or
2099    *   s.setTo((UChar32)-1); // set to a pseudo code point that is out of range, or
2100    *   s.setTo(u"", 0);      // set to an empty C Unicode string
2101    * }
2102    * \endcode
2103    *
2104    * @see isBogus()
2105    * @stable ICU 2.0
2106    */
2107   void setToBogus();
2108 
2109   /**
2110    * Set the character at the specified offset to the specified character.
2111    * @param offset A valid offset into the text of the character to set
2112    * @param ch The new character
2113    * @return A reference to this
2114    * @stable ICU 2.0
2115    */
2116   UnicodeString& setCharAt(int32_t offset,
2117                char16_t ch);
2118 
2119 
2120   /* Append operations */
2121 
2122   /**
2123    * Append operator. Append the code unit `ch` to the UnicodeString
2124    * object.
2125    * @param ch the code unit to be appended
2126    * @return a reference to this
2127    * @stable ICU 2.0
2128    */
2129  inline  UnicodeString& operator+= (char16_t ch);
2130 
2131   /**
2132    * Append operator. Append the code point `ch` to the UnicodeString
2133    * object.
2134    * @param ch the code point to be appended
2135    * @return a reference to this
2136    * @stable ICU 2.0
2137    */
2138  inline  UnicodeString& operator+= (UChar32 ch);
2139 
2140   /**
2141    * Append operator. Append the characters in `srcText` to the
2142    * UnicodeString object. `srcText` is not modified.
2143    * @param srcText the source for the new characters
2144    * @return a reference to this
2145    * @stable ICU 2.0
2146    */
2147   inline UnicodeString& operator+= (const UnicodeString& srcText);
2148 
2149   /**
2150    * Append the characters
2151    * in `srcText` in the range
2152    * [`srcStart`, `srcStart + srcLength`) to the
2153    * UnicodeString object at offset `start`. `srcText`
2154    * is not modified.
2155    * @param srcText the source for the new characters
2156    * @param srcStart the offset into `srcText` where new characters
2157    * will be obtained
2158    * @param srcLength the number of characters in `srcText` in
2159    * the append string
2160    * @return a reference to this
2161    * @stable ICU 2.0
2162    */
2163   inline UnicodeString& append(const UnicodeString& srcText,
2164             int32_t srcStart,
2165             int32_t srcLength);
2166 
2167   /**
2168    * Append the characters in `srcText` to the UnicodeString object.
2169    * `srcText` is not modified.
2170    * @param srcText the source for the new characters
2171    * @return a reference to this
2172    * @stable ICU 2.0
2173    */
2174   inline UnicodeString& append(const UnicodeString& srcText);
2175 
2176   /**
2177    * Append the characters in `srcChars` in the range
2178    * [`srcStart`, `srcStart + srcLength`) to the UnicodeString
2179    * object at offset
2180    * `start`. `srcChars` is not modified.
2181    * @param srcChars the source for the new characters
2182    * @param srcStart the offset into `srcChars` where new characters
2183    * will be obtained
2184    * @param srcLength the number of characters in `srcChars` in
2185    *                  the append string; can be -1 if `srcChars` is NUL-terminated
2186    * @return a reference to this
2187    * @stable ICU 2.0
2188    */
2189   inline UnicodeString& append(const char16_t *srcChars,
2190             int32_t srcStart,
2191             int32_t srcLength);
2192 
2193   /**
2194    * Append the characters in `srcChars` to the UnicodeString object
2195    * at offset `start`. `srcChars` is not modified.
2196    * @param srcChars the source for the new characters
2197    * @param srcLength the number of Unicode characters in `srcChars`;
2198    *                  can be -1 if `srcChars` is NUL-terminated
2199    * @return a reference to this
2200    * @stable ICU 2.0
2201    */
2202   inline UnicodeString& append(ConstChar16Ptr srcChars,
2203             int32_t srcLength);
2204 
2205   /**
2206    * Append the code unit `srcChar` to the UnicodeString object.
2207    * @param srcChar the code unit to append
2208    * @return a reference to this
2209    * @stable ICU 2.0
2210    */
2211   inline UnicodeString& append(char16_t srcChar);
2212 
2213   /**
2214    * Append the code point `srcChar` to the UnicodeString object.
2215    * @param srcChar the code point to append
2216    * @return a reference to this
2217    * @stable ICU 2.0
2218    */
2219   UnicodeString& append(UChar32 srcChar);
2220 
2221 
2222   /* Insert operations */
2223 
2224   /**
2225    * Insert the characters in `srcText` in the range
2226    * [`srcStart`, `srcStart + srcLength`) into the UnicodeString
2227    * object at offset `start`. `srcText` is not modified.
2228    * @param start the offset where the insertion begins
2229    * @param srcText the source for the new characters
2230    * @param srcStart the offset into `srcText` where new characters
2231    * will be obtained
2232    * @param srcLength the number of characters in `srcText` in
2233    * the insert string
2234    * @return a reference to this
2235    * @stable ICU 2.0
2236    */
2237   inline UnicodeString& insert(int32_t start,
2238             const UnicodeString& srcText,
2239             int32_t srcStart,
2240             int32_t srcLength);
2241 
2242   /**
2243    * Insert the characters in `srcText` into the UnicodeString object
2244    * at offset `start`. `srcText` is not modified.
2245    * @param start the offset where the insertion begins
2246    * @param srcText the source for the new characters
2247    * @return a reference to this
2248    * @stable ICU 2.0
2249    */
2250   inline UnicodeString& insert(int32_t start,
2251             const UnicodeString& srcText);
2252 
2253   /**
2254    * Insert the characters in `srcChars` in the range
2255    * [`srcStart`, `srcStart + srcLength`) into the UnicodeString
2256    *  object at offset `start`. `srcChars` is not modified.
2257    * @param start the offset at which the insertion begins
2258    * @param srcChars the source for the new characters
2259    * @param srcStart the offset into `srcChars` where new characters
2260    * will be obtained
2261    * @param srcLength the number of characters in `srcChars`
2262    * in the insert string
2263    * @return a reference to this
2264    * @stable ICU 2.0
2265    */
2266   inline UnicodeString& insert(int32_t start,
2267             const char16_t *srcChars,
2268             int32_t srcStart,
2269             int32_t srcLength);
2270 
2271   /**
2272    * Insert the characters in `srcChars` into the UnicodeString object
2273    * at offset `start`. `srcChars` is not modified.
2274    * @param start the offset where the insertion begins
2275    * @param srcChars the source for the new characters
2276    * @param srcLength the number of Unicode characters in srcChars.
2277    * @return a reference to this
2278    * @stable ICU 2.0
2279    */
2280   inline UnicodeString& insert(int32_t start,
2281             ConstChar16Ptr srcChars,
2282             int32_t srcLength);
2283 
2284   /**
2285    * Insert the code unit `srcChar` into the UnicodeString object at
2286    * offset `start`.
2287    * @param start the offset at which the insertion occurs
2288    * @param srcChar the code unit to insert
2289    * @return a reference to this
2290    * @stable ICU 2.0
2291    */
2292   inline UnicodeString& insert(int32_t start,
2293             char16_t srcChar);
2294 
2295   /**
2296    * Insert the code point `srcChar` into the UnicodeString object at
2297    * offset `start`.
2298    * @param start the offset at which the insertion occurs
2299    * @param srcChar the code point to insert
2300    * @return a reference to this
2301    * @stable ICU 2.0
2302    */
2303   inline UnicodeString& insert(int32_t start,
2304             UChar32 srcChar);
2305 
2306 
2307   /* Replace operations */
2308 
2309   /**
2310    * Replace the characters in the range
2311    * [`start`, `start + length`) with the characters in
2312    * `srcText` in the range
2313    * [`srcStart`, `srcStart + srcLength`).
2314    * `srcText` is not modified.
2315    * @param start the offset at which the replace operation begins
2316    * @param length the number of characters to replace. The character at
2317    * `start + length` is not modified.
2318    * @param srcText the source for the new characters
2319    * @param srcStart the offset into `srcText` where new characters
2320    * will be obtained
2321    * @param srcLength the number of characters in `srcText` in
2322    * the replace string
2323    * @return a reference to this
2324    * @stable ICU 2.0
2325    */
2326   inline UnicodeString& replace(int32_t start,
2327              int32_t length,
2328              const UnicodeString& srcText,
2329              int32_t srcStart,
2330              int32_t srcLength);
2331 
2332   /**
2333    * Replace the characters in the range
2334    * [`start`, `start + length`)
2335    * with the characters in `srcText`.  `srcText` is
2336    *  not modified.
2337    * @param start the offset at which the replace operation begins
2338    * @param length the number of characters to replace. The character at
2339    * `start + length` is not modified.
2340    * @param srcText the source for the new characters
2341    * @return a reference to this
2342    * @stable ICU 2.0
2343    */
2344   inline UnicodeString& replace(int32_t start,
2345              int32_t length,
2346              const UnicodeString& srcText);
2347 
2348   /**
2349    * Replace the characters in the range
2350    * [`start`, `start + length`) with the characters in
2351    * `srcChars` in the range
2352    * [`srcStart`, `srcStart + srcLength`). `srcChars`
2353    * is not modified.
2354    * @param start the offset at which the replace operation begins
2355    * @param length the number of characters to replace.  The character at
2356    * `start + length` is not modified.
2357    * @param srcChars the source for the new characters
2358    * @param srcStart the offset into `srcChars` where new characters
2359    * will be obtained
2360    * @param srcLength the number of characters in `srcChars`
2361    * in the replace string
2362    * @return a reference to this
2363    * @stable ICU 2.0
2364    */
2365   inline UnicodeString& replace(int32_t start,
2366              int32_t length,
2367              const char16_t *srcChars,
2368              int32_t srcStart,
2369              int32_t srcLength);
2370 
2371   /**
2372    * Replace the characters in the range
2373    * [`start`, `start + length`) with the characters in
2374    * `srcChars`.  `srcChars` is not modified.
2375    * @param start the offset at which the replace operation begins
2376    * @param length number of characters to replace.  The character at
2377    * `start + length` is not modified.
2378    * @param srcChars the source for the new characters
2379    * @param srcLength the number of Unicode characters in srcChars
2380    * @return a reference to this
2381    * @stable ICU 2.0
2382    */
2383   inline UnicodeString& replace(int32_t start,
2384              int32_t length,
2385              ConstChar16Ptr srcChars,
2386              int32_t srcLength);
2387 
2388   /**
2389    * Replace the characters in the range
2390    * [`start`, `start + length`) with the code unit
2391    * `srcChar`.
2392    * @param start the offset at which the replace operation begins
2393    * @param length the number of characters to replace.  The character at
2394    * `start + length` is not modified.
2395    * @param srcChar the new code unit
2396    * @return a reference to this
2397    * @stable ICU 2.0
2398    */
2399   inline UnicodeString& replace(int32_t start,
2400              int32_t length,
2401              char16_t srcChar);
2402 
2403   /**
2404    * Replace the characters in the range
2405    * [`start`, `start + length`) with the code point
2406    * `srcChar`.
2407    * @param start the offset at which the replace operation begins
2408    * @param length the number of characters to replace.  The character at
2409    * `start + length` is not modified.
2410    * @param srcChar the new code point
2411    * @return a reference to this
2412    * @stable ICU 2.0
2413    */
2414   UnicodeString& replace(int32_t start, int32_t length, UChar32 srcChar);
2415 
2416   /**
2417    * Replace the characters in the range [`start`, `limit`)
2418    * with the characters in `srcText`. `srcText` is not modified.
2419    * @param start the offset at which the replace operation begins
2420    * @param limit the offset immediately following the replace range
2421    * @param srcText the source for the new characters
2422    * @return a reference to this
2423    * @stable ICU 2.0
2424    */
2425   inline UnicodeString& replaceBetween(int32_t start,
2426                 int32_t limit,
2427                 const UnicodeString& srcText);
2428 
2429   /**
2430    * Replace the characters in the range [`start`, `limit`)
2431    * with the characters in `srcText` in the range
2432    * [`srcStart`, `srcLimit`). `srcText` is not modified.
2433    * @param start the offset at which the replace operation begins
2434    * @param limit the offset immediately following the replace range
2435    * @param srcText the source for the new characters
2436    * @param srcStart the offset into `srcChars` where new characters
2437    * will be obtained
2438    * @param srcLimit the offset immediately following the range to copy
2439    * in `srcText`
2440    * @return a reference to this
2441    * @stable ICU 2.0
2442    */
2443   inline UnicodeString& replaceBetween(int32_t start,
2444                 int32_t limit,
2445                 const UnicodeString& srcText,
2446                 int32_t srcStart,
2447                 int32_t srcLimit);
2448 
2449   /**
2450    * Replace a substring of this object with the given text.
2451    * @param start the beginning index, inclusive; `0 <= start <= limit`.
2452    * @param limit the ending index, exclusive; `start <= limit <= length()`.
2453    * @param text the text to replace characters `start` to `limit - 1`
2454    * @stable ICU 2.0
2455    */
2456   virtual void handleReplaceBetween(int32_t start,
2457                                     int32_t limit,
2458                                     const UnicodeString& text);
2459 
2460   /**
2461    * Replaceable API
2462    * @return TRUE if it has MetaData
2463    * @stable ICU 2.4
2464    */
2465   virtual UBool hasMetaData() const;
2466 
2467   /**
2468    * Copy a substring of this object, retaining attribute (out-of-band)
2469    * information.  This method is used to duplicate or reorder substrings.
2470    * The destination index must not overlap the source range.
2471    *
2472    * @param start the beginning index, inclusive; `0 <= start <= limit`.
2473    * @param limit the ending index, exclusive; `start <= limit <= length()`.
2474    * @param dest the destination index.  The characters from
2475    *             `start..limit-1` will be copied to `dest`.
2476    * Implementations of this method may assume that `dest <= start ||
2477    * dest >= limit`.
2478    * @stable ICU 2.0
2479    */
2480   virtual void copy(int32_t start, int32_t limit, int32_t dest);
2481 
2482   /* Search and replace operations */
2483 
2484   /**
2485    * Replace all occurrences of characters in oldText with the characters
2486    * in newText
2487    * @param oldText the text containing the search text
2488    * @param newText the text containing the replacement text
2489    * @return a reference to this
2490    * @stable ICU 2.0
2491    */
2492   inline UnicodeString& findAndReplace(const UnicodeString& oldText,
2493                 const UnicodeString& newText);
2494 
2495   /**
2496    * Replace all occurrences of characters in oldText with characters
2497    * in newText
2498    * in the range [`start`, `start + length`).
2499    * @param start the start of the range in which replace will performed
2500    * @param length the length of the range in which replace will be performed
2501    * @param oldText the text containing the search text
2502    * @param newText the text containing the replacement text
2503    * @return a reference to this
2504    * @stable ICU 2.0
2505    */
2506   inline UnicodeString& findAndReplace(int32_t start,
2507                 int32_t length,
2508                 const UnicodeString& oldText,
2509                 const UnicodeString& newText);
2510 
2511   /**
2512    * Replace all occurrences of characters in oldText in the range
2513    * [`oldStart`, `oldStart + oldLength`) with the characters
2514    * in newText in the range
2515    * [`newStart`, `newStart + newLength`)
2516    * in the range [`start`, `start + length`).
2517    * @param start the start of the range in which replace will performed
2518    * @param length the length of the range in which replace will be performed
2519    * @param oldText the text containing the search text
2520    * @param oldStart the start of the search range in `oldText`
2521    * @param oldLength the length of the search range in `oldText`
2522    * @param newText the text containing the replacement text
2523    * @param newStart the start of the replacement range in `newText`
2524    * @param newLength the length of the replacement range in `newText`
2525    * @return a reference to this
2526    * @stable ICU 2.0
2527    */
2528   UnicodeString& findAndReplace(int32_t start,
2529                 int32_t length,
2530                 const UnicodeString& oldText,
2531                 int32_t oldStart,
2532                 int32_t oldLength,
2533                 const UnicodeString& newText,
2534                 int32_t newStart,
2535                 int32_t newLength);
2536 
2537 
2538   /* Remove operations */
2539 
2540   /**
2541    * Removes all characters from the UnicodeString object and clears the bogus flag.
2542    * This is the UnicodeString equivalent of std::string’s clear().
2543    *
2544    * @return a reference to this
2545    * @see setToBogus
2546    * @stable ICU 2.0
2547    */
2548   inline UnicodeString& remove();
2549 
2550   /**
2551    * Remove the characters in the range
2552    * [`start`, `start + length`) from the UnicodeString object.
2553    * @param start the offset of the first character to remove
2554    * @param length the number of characters to remove
2555    * @return a reference to this
2556    * @stable ICU 2.0
2557    */
2558   inline UnicodeString& remove(int32_t start,
2559                                int32_t length = (int32_t)INT32_MAX);
2560 
2561   /**
2562    * Remove the characters in the range
2563    * [`start`, `limit`) from the UnicodeString object.
2564    * @param start the offset of the first character to remove
2565    * @param limit the offset immediately following the range to remove
2566    * @return a reference to this
2567    * @stable ICU 2.0
2568    */
2569   inline UnicodeString& removeBetween(int32_t start,
2570                                       int32_t limit = (int32_t)INT32_MAX);
2571 
2572   /**
2573    * Retain only the characters in the range
2574    * [`start`, `limit`) from the UnicodeString object.
2575    * Removes characters before `start` and at and after `limit`.
2576    * @param start the offset of the first character to retain
2577    * @param limit the offset immediately following the range to retain
2578    * @return a reference to this
2579    * @stable ICU 4.4
2580    */
2581   inline UnicodeString &retainBetween(int32_t start, int32_t limit = INT32_MAX);
2582 
2583   /* Length operations */
2584 
2585   /**
2586    * Pad the start of this UnicodeString with the character `padChar`.
2587    * If the length of this UnicodeString is less than targetLength,
2588    * length() - targetLength copies of padChar will be added to the
2589    * beginning of this UnicodeString.
2590    * @param targetLength the desired length of the string
2591    * @param padChar the character to use for padding. Defaults to
2592    * space (U+0020)
2593    * @return TRUE if the text was padded, FALSE otherwise.
2594    * @stable ICU 2.0
2595    */
2596   UBool padLeading(int32_t targetLength,
2597                     char16_t padChar = 0x0020);
2598 
2599   /**
2600    * Pad the end of this UnicodeString with the character `padChar`.
2601    * If the length of this UnicodeString is less than targetLength,
2602    * length() - targetLength copies of padChar will be added to the
2603    * end of this UnicodeString.
2604    * @param targetLength the desired length of the string
2605    * @param padChar the character to use for padding. Defaults to
2606    * space (U+0020)
2607    * @return TRUE if the text was padded, FALSE otherwise.
2608    * @stable ICU 2.0
2609    */
2610   UBool padTrailing(int32_t targetLength,
2611                      char16_t padChar = 0x0020);
2612 
2613   /**
2614    * Truncate this UnicodeString to the `targetLength`.
2615    * @param targetLength the desired length of this UnicodeString.
2616    * @return TRUE if the text was truncated, FALSE otherwise
2617    * @stable ICU 2.0
2618    */
2619   inline UBool truncate(int32_t targetLength);
2620 
2621   /**
2622    * Trims leading and trailing whitespace from this UnicodeString.
2623    * @return a reference to this
2624    * @stable ICU 2.0
2625    */
2626   UnicodeString& trim(void);
2627 
2628 
2629   /* Miscellaneous operations */
2630 
2631   /**
2632    * Reverse this UnicodeString in place.
2633    * @return a reference to this
2634    * @stable ICU 2.0
2635    */
2636   inline UnicodeString& reverse(void);
2637 
2638   /**
2639    * Reverse the range [`start`, `start + length`) in
2640    * this UnicodeString.
2641    * @param start the start of the range to reverse
2642    * @param length the number of characters to to reverse
2643    * @return a reference to this
2644    * @stable ICU 2.0
2645    */
2646   inline UnicodeString& reverse(int32_t start,
2647              int32_t length);
2648 
2649   /**
2650    * Convert the characters in this to UPPER CASE following the conventions of
2651    * the default locale.
2652    * @return A reference to this.
2653    * @stable ICU 2.0
2654    */
2655   UnicodeString& toUpper(void);
2656 
2657   /**
2658    * Convert the characters in this to UPPER CASE following the conventions of
2659    * a specific locale.
2660    * @param locale The locale containing the conventions to use.
2661    * @return A reference to this.
2662    * @stable ICU 2.0
2663    */
2664   UnicodeString& toUpper(const Locale& locale);
2665 
2666   /**
2667    * Convert the characters in this to lower case following the conventions of
2668    * the default locale.
2669    * @return A reference to this.
2670    * @stable ICU 2.0
2671    */
2672   UnicodeString& toLower(void);
2673 
2674   /**
2675    * Convert the characters in this to lower case following the conventions of
2676    * a specific locale.
2677    * @param locale The locale containing the conventions to use.
2678    * @return A reference to this.
2679    * @stable ICU 2.0
2680    */
2681   UnicodeString& toLower(const Locale& locale);
2682 
2683 #if !UCONFIG_NO_BREAK_ITERATION
2684 
2685   /**
2686    * Titlecase this string, convenience function using the default locale.
2687    *
2688    * Casing is locale-dependent and context-sensitive.
2689    * Titlecasing uses a break iterator to find the first characters of words
2690    * that are to be titlecased. It titlecases those characters and lowercases
2691    * all others.
2692    *
2693    * The titlecase break iterator can be provided to customize for arbitrary
2694    * styles, using rules and dictionaries beyond the standard iterators.
2695    * It may be more efficient to always provide an iterator to avoid
2696    * opening and closing one for each string.
2697    * The standard titlecase iterator for the root locale implements the
2698    * algorithm of Unicode TR 21.
2699    *
2700    * This function uses only the setText(), first() and next() methods of the
2701    * provided break iterator.
2702    *
2703    * @param titleIter A break iterator to find the first characters of words
2704    *                  that are to be titlecased.
2705    *                  If none is provided (0), then a standard titlecase
2706    *                  break iterator is opened.
2707    *                  Otherwise the provided iterator is set to the string's text.
2708    * @return A reference to this.
2709    * @stable ICU 2.1
2710    */
2711   UnicodeString &toTitle(BreakIterator *titleIter);
2712 
2713   /**
2714    * Titlecase this string.
2715    *
2716    * Casing is locale-dependent and context-sensitive.
2717    * Titlecasing uses a break iterator to find the first characters of words
2718    * that are to be titlecased. It titlecases those characters and lowercases
2719    * all others.
2720    *
2721    * The titlecase break iterator can be provided to customize for arbitrary
2722    * styles, using rules and dictionaries beyond the standard iterators.
2723    * It may be more efficient to always provide an iterator to avoid
2724    * opening and closing one for each string.
2725    * The standard titlecase iterator for the root locale implements the
2726    * algorithm of Unicode TR 21.
2727    *
2728    * This function uses only the setText(), first() and next() methods of the
2729    * provided break iterator.
2730    *
2731    * @param titleIter A break iterator to find the first characters of words
2732    *                  that are to be titlecased.
2733    *                  If none is provided (0), then a standard titlecase
2734    *                  break iterator is opened.
2735    *                  Otherwise the provided iterator is set to the string's text.
2736    * @param locale    The locale to consider.
2737    * @return A reference to this.
2738    * @stable ICU 2.1
2739    */
2740   UnicodeString &toTitle(BreakIterator *titleIter, const Locale &locale);
2741 
2742   /**
2743    * Titlecase this string, with options.
2744    *
2745    * Casing is locale-dependent and context-sensitive.
2746    * Titlecasing uses a break iterator to find the first characters of words
2747    * that are to be titlecased. It titlecases those characters and lowercases
2748    * all others. (This can be modified with options.)
2749    *
2750    * The titlecase break iterator can be provided to customize for arbitrary
2751    * styles, using rules and dictionaries beyond the standard iterators.
2752    * It may be more efficient to always provide an iterator to avoid
2753    * opening and closing one for each string.
2754    * The standard titlecase iterator for the root locale implements the
2755    * algorithm of Unicode TR 21.
2756    *
2757    * This function uses only the setText(), first() and next() methods of the
2758    * provided break iterator.
2759    *
2760    * @param titleIter A break iterator to find the first characters of words
2761    *                  that are to be titlecased.
2762    *                  If none is provided (0), then a standard titlecase
2763    *                  break iterator is opened.
2764    *                  Otherwise the provided iterator is set to the string's text.
2765    * @param locale    The locale to consider.
2766    * @param options   Options bit set, usually 0. See U_TITLECASE_NO_LOWERCASE,
2767    *                  U_TITLECASE_NO_BREAK_ADJUSTMENT, U_TITLECASE_ADJUST_TO_CASED,
2768    *                  U_TITLECASE_WHOLE_STRING, U_TITLECASE_SENTENCES.
2769    * @param options Options bit set, see ucasemap_open().
2770    * @return A reference to this.
2771    * @stable ICU 3.8
2772    */
2773   UnicodeString &toTitle(BreakIterator *titleIter, const Locale &locale, uint32_t options);
2774 
2775 #endif
2776 
2777   /**
2778    * Case-folds the characters in this string.
2779    *
2780    * Case-folding is locale-independent and not context-sensitive,
2781    * but there is an option for whether to include or exclude mappings for dotted I
2782    * and dotless i that are marked with 'T' in CaseFolding.txt.
2783    *
2784    * The result may be longer or shorter than the original.
2785    *
2786    * @param options Either U_FOLD_CASE_DEFAULT or U_FOLD_CASE_EXCLUDE_SPECIAL_I
2787    * @return A reference to this.
2788    * @stable ICU 2.0
2789    */
2790   UnicodeString &foldCase(uint32_t options=0 /*U_FOLD_CASE_DEFAULT*/);
2791 
2792   //========================================
2793   // Access to the internal buffer
2794   //========================================
2795 
2796   /**
2797    * Get a read/write pointer to the internal buffer.
2798    * The buffer is guaranteed to be large enough for at least minCapacity char16_ts,
2799    * writable, and is still owned by the UnicodeString object.
2800    * Calls to getBuffer(minCapacity) must not be nested, and
2801    * must be matched with calls to releaseBuffer(newLength).
2802    * If the string buffer was read-only or shared,
2803    * then it will be reallocated and copied.
2804    *
2805    * An attempted nested call will return 0, and will not further modify the
2806    * state of the UnicodeString object.
2807    * It also returns 0 if the string is bogus.
2808    *
2809    * The actual capacity of the string buffer may be larger than minCapacity.
2810    * getCapacity() returns the actual capacity.
2811    * For many operations, the full capacity should be used to avoid reallocations.
2812    *
2813    * While the buffer is "open" between getBuffer(minCapacity)
2814    * and releaseBuffer(newLength), the following applies:
2815    * - The string length is set to 0.
2816    * - Any read API call on the UnicodeString object will behave like on a 0-length string.
2817    * - Any write API call on the UnicodeString object is disallowed and will have no effect.
2818    * - You can read from and write to the returned buffer.
2819    * - The previous string contents will still be in the buffer;
2820    *   if you want to use it, then you need to call length() before getBuffer(minCapacity).
2821    *   If the length() was greater than minCapacity, then any contents after minCapacity
2822    *   may be lost.
2823    *   The buffer contents is not NUL-terminated by getBuffer().
2824    *   If length() < getCapacity() then you can terminate it by writing a NUL
2825    *   at index length().
2826    * - You must call releaseBuffer(newLength) before and in order to
2827    *   return to normal UnicodeString operation.
2828    *
2829    * @param minCapacity the minimum number of char16_ts that are to be available
2830    *        in the buffer, starting at the returned pointer;
2831    *        default to the current string capacity if minCapacity==-1
2832    * @return a writable pointer to the internal string buffer,
2833    *         or nullptr if an error occurs (nested calls, out of memory)
2834    *
2835    * @see releaseBuffer
2836    * @see getTerminatedBuffer()
2837    * @stable ICU 2.0
2838    */
2839   char16_t *getBuffer(int32_t minCapacity);
2840 
2841   /**
2842    * Release a read/write buffer on a UnicodeString object with an
2843    * "open" getBuffer(minCapacity).
2844    * This function must be called in a matched pair with getBuffer(minCapacity).
2845    * releaseBuffer(newLength) must be called if and only if a getBuffer(minCapacity) is "open".
2846    *
2847    * It will set the string length to newLength, at most to the current capacity.
2848    * If newLength==-1 then it will set the length according to the
2849    * first NUL in the buffer, or to the capacity if there is no NUL.
2850    *
2851    * After calling releaseBuffer(newLength) the UnicodeString is back to normal operation.
2852    *
2853    * @param newLength the new length of the UnicodeString object;
2854    *        defaults to the current capacity if newLength is greater than that;
2855    *        if newLength==-1, it defaults to u_strlen(buffer) but not more than
2856    *        the current capacity of the string
2857    *
2858    * @see getBuffer(int32_t minCapacity)
2859    * @stable ICU 2.0
2860    */
2861   void releaseBuffer(int32_t newLength=-1);
2862 
2863   /**
2864    * Get a read-only pointer to the internal buffer.
2865    * This can be called at any time on a valid UnicodeString.
2866    *
2867    * It returns 0 if the string is bogus, or
2868    * during an "open" getBuffer(minCapacity).
2869    *
2870    * It can be called as many times as desired.
2871    * The pointer that it returns will remain valid until the UnicodeString object is modified,
2872    * at which time the pointer is semantically invalidated and must not be used any more.
2873    *
2874    * The capacity of the buffer can be determined with getCapacity().
2875    * The part after length() may or may not be initialized and valid,
2876    * depending on the history of the UnicodeString object.
2877    *
2878    * The buffer contents is (probably) not NUL-terminated.
2879    * You can check if it is with
2880    * `(s.length() < s.getCapacity() && buffer[s.length()]==0)`.
2881    * (See getTerminatedBuffer().)
2882    *
2883    * The buffer may reside in read-only memory. Its contents must not
2884    * be modified.
2885    *
2886    * @return a read-only pointer to the internal string buffer,
2887    *         or nullptr if the string is empty or bogus
2888    *
2889    * @see getBuffer(int32_t minCapacity)
2890    * @see getTerminatedBuffer()
2891    * @stable ICU 2.0
2892    */
2893   inline const char16_t *getBuffer() const;
2894 
2895   /**
2896    * Get a read-only pointer to the internal buffer,
2897    * making sure that it is NUL-terminated.
2898    * This can be called at any time on a valid UnicodeString.
2899    *
2900    * It returns 0 if the string is bogus, or
2901    * during an "open" getBuffer(minCapacity), or if the buffer cannot
2902    * be NUL-terminated (because memory allocation failed).
2903    *
2904    * It can be called as many times as desired.
2905    * The pointer that it returns will remain valid until the UnicodeString object is modified,
2906    * at which time the pointer is semantically invalidated and must not be used any more.
2907    *
2908    * The capacity of the buffer can be determined with getCapacity().
2909    * The part after length()+1 may or may not be initialized and valid,
2910    * depending on the history of the UnicodeString object.
2911    *
2912    * The buffer contents is guaranteed to be NUL-terminated.
2913    * getTerminatedBuffer() may reallocate the buffer if a terminating NUL
2914    * is written.
2915    * For this reason, this function is not const, unlike getBuffer().
2916    * Note that a UnicodeString may also contain NUL characters as part of its contents.
2917    *
2918    * The buffer may reside in read-only memory. Its contents must not
2919    * be modified.
2920    *
2921    * @return a read-only pointer to the internal string buffer,
2922    *         or 0 if the string is empty or bogus
2923    *
2924    * @see getBuffer(int32_t minCapacity)
2925    * @see getBuffer()
2926    * @stable ICU 2.2
2927    */
2928   const char16_t *getTerminatedBuffer();
2929 
2930   //========================================
2931   // Constructors
2932   //========================================
2933 
2934   /** Construct an empty UnicodeString.
2935    * @stable ICU 2.0
2936    */
2937   inline UnicodeString();
2938 
2939   /**
2940    * Construct a UnicodeString with capacity to hold `capacity` char16_ts
2941    * @param capacity the number of char16_ts this UnicodeString should hold
2942    * before a resize is necessary; if count is greater than 0 and count
2943    * code points c take up more space than capacity, then capacity is adjusted
2944    * accordingly.
2945    * @param c is used to initially fill the string
2946    * @param count specifies how many code points c are to be written in the
2947    *              string
2948    * @stable ICU 2.0
2949    */
2950   UnicodeString(int32_t capacity, UChar32 c, int32_t count);
2951 
2952   /**
2953    * Single char16_t (code unit) constructor.
2954    *
2955    * It is recommended to mark this constructor "explicit" by
2956    * `-DUNISTR_FROM_CHAR_EXPLICIT=explicit`
2957    * on the compiler command line or similar.
2958    * @param ch the character to place in the UnicodeString
2959    * @stable ICU 2.0
2960    */
2961   UNISTR_FROM_CHAR_EXPLICIT UnicodeString(char16_t ch);
2962 
2963   /**
2964    * Single UChar32 (code point) constructor.
2965    *
2966    * It is recommended to mark this constructor "explicit" by
2967    * `-DUNISTR_FROM_CHAR_EXPLICIT=explicit`
2968    * on the compiler command line or similar.
2969    * @param ch the character to place in the UnicodeString
2970    * @stable ICU 2.0
2971    */
2972   UNISTR_FROM_CHAR_EXPLICIT UnicodeString(UChar32 ch);
2973 
2974   /**
2975    * char16_t* constructor.
2976    *
2977    * It is recommended to mark this constructor "explicit" by
2978    * `-DUNISTR_FROM_STRING_EXPLICIT=explicit`
2979    * on the compiler command line or similar.
2980    * @param text The characters to place in the UnicodeString.  `text`
2981    * must be NULL (U+0000) terminated.
2982    * @stable ICU 2.0
2983    */
2984   UNISTR_FROM_STRING_EXPLICIT UnicodeString(const char16_t *text);
2985 
2986 #if !U_CHAR16_IS_TYPEDEF
2987   /**
2988    * uint16_t * constructor.
2989    * Delegates to UnicodeString(const char16_t *).
2990    *
2991    * It is recommended to mark this constructor "explicit" by
2992    * `-DUNISTR_FROM_STRING_EXPLICIT=explicit`
2993    * on the compiler command line or similar.
2994    * @param text NUL-terminated UTF-16 string
2995    * @stable ICU 59
2996    */
UnicodeString(const uint16_t * text)2997   UNISTR_FROM_STRING_EXPLICIT UnicodeString(const uint16_t *text) :
2998       UnicodeString(ConstChar16Ptr(text)) {}
2999 #endif
3000 
3001 #if U_SIZEOF_WCHAR_T==2 || defined(U_IN_DOXYGEN)
3002   /**
3003    * wchar_t * constructor.
3004    * (Only defined if U_SIZEOF_WCHAR_T==2.)
3005    * Delegates to UnicodeString(const char16_t *).
3006    *
3007    * It is recommended to mark this constructor "explicit" by
3008    * `-DUNISTR_FROM_STRING_EXPLICIT=explicit`
3009    * on the compiler command line or similar.
3010    * @param text NUL-terminated UTF-16 string
3011    * @stable ICU 59
3012    */
UnicodeString(const wchar_t * text)3013   UNISTR_FROM_STRING_EXPLICIT UnicodeString(const wchar_t *text) :
3014       UnicodeString(ConstChar16Ptr(text)) {}
3015 #endif
3016 
3017   /**
3018    * nullptr_t constructor.
3019    * Effectively the same as the default constructor, makes an empty string object.
3020    *
3021    * It is recommended to mark this constructor "explicit" by
3022    * `-DUNISTR_FROM_STRING_EXPLICIT=explicit`
3023    * on the compiler command line or similar.
3024    * @param text nullptr
3025    * @stable ICU 59
3026    */
3027   UNISTR_FROM_STRING_EXPLICIT inline UnicodeString(const std::nullptr_t text);
3028 
3029   /**
3030    * char16_t* constructor.
3031    * @param text The characters to place in the UnicodeString.
3032    * @param textLength The number of Unicode characters in `text`
3033    * to copy.
3034    * @stable ICU 2.0
3035    */
3036   UnicodeString(const char16_t *text,
3037         int32_t textLength);
3038 
3039 #if !U_CHAR16_IS_TYPEDEF
3040   /**
3041    * uint16_t * constructor.
3042    * Delegates to UnicodeString(const char16_t *, int32_t).
3043    * @param text UTF-16 string
3044    * @param textLength string length
3045    * @stable ICU 59
3046    */
UnicodeString(const uint16_t * text,int32_t textLength)3047   UnicodeString(const uint16_t *text, int32_t textLength) :
3048       UnicodeString(ConstChar16Ptr(text), textLength) {}
3049 #endif
3050 
3051 #if U_SIZEOF_WCHAR_T==2 || defined(U_IN_DOXYGEN)
3052   /**
3053    * wchar_t * constructor.
3054    * (Only defined if U_SIZEOF_WCHAR_T==2.)
3055    * Delegates to UnicodeString(const char16_t *, int32_t).
3056    * @param text NUL-terminated UTF-16 string
3057    * @param textLength string length
3058    * @stable ICU 59
3059    */
UnicodeString(const wchar_t * text,int32_t textLength)3060   UnicodeString(const wchar_t *text, int32_t textLength) :
3061       UnicodeString(ConstChar16Ptr(text), textLength) {}
3062 #endif
3063 
3064   /**
3065    * nullptr_t constructor.
3066    * Effectively the same as the default constructor, makes an empty string object.
3067    * @param text nullptr
3068    * @param textLength ignored
3069    * @stable ICU 59
3070    */
3071   inline UnicodeString(const std::nullptr_t text, int32_t textLength);
3072 
3073   /**
3074    * Readonly-aliasing char16_t* constructor.
3075    * The text will be used for the UnicodeString object, but
3076    * it will not be released when the UnicodeString is destroyed.
3077    * This has copy-on-write semantics:
3078    * When the string is modified, then the buffer is first copied into
3079    * newly allocated memory.
3080    * The aliased buffer is never modified.
3081    *
3082    * In an assignment to another UnicodeString, when using the copy constructor
3083    * or the assignment operator, the text will be copied.
3084    * When using fastCopyFrom(), the text will be aliased again,
3085    * so that both strings then alias the same readonly-text.
3086    *
3087    * @param isTerminated specifies if `text` is `NUL`-terminated.
3088    *                     This must be true if `textLength==-1`.
3089    * @param text The characters to alias for the UnicodeString.
3090    * @param textLength The number of Unicode characters in `text` to alias.
3091    *                   If -1, then this constructor will determine the length
3092    *                   by calling `u_strlen()`.
3093    * @stable ICU 2.0
3094    */
3095   UnicodeString(UBool isTerminated,
3096                 ConstChar16Ptr text,
3097                 int32_t textLength);
3098 
3099   /**
3100    * Writable-aliasing char16_t* constructor.
3101    * The text will be used for the UnicodeString object, but
3102    * it will not be released when the UnicodeString is destroyed.
3103    * This has write-through semantics:
3104    * For as long as the capacity of the buffer is sufficient, write operations
3105    * will directly affect the buffer. When more capacity is necessary, then
3106    * a new buffer will be allocated and the contents copied as with regularly
3107    * constructed strings.
3108    * In an assignment to another UnicodeString, the buffer will be copied.
3109    * The extract(Char16Ptr dst) function detects whether the dst pointer is the same
3110    * as the string buffer itself and will in this case not copy the contents.
3111    *
3112    * @param buffer The characters to alias for the UnicodeString.
3113    * @param buffLength The number of Unicode characters in `buffer` to alias.
3114    * @param buffCapacity The size of `buffer` in char16_ts.
3115    * @stable ICU 2.0
3116    */
3117   UnicodeString(char16_t *buffer, int32_t buffLength, int32_t buffCapacity);
3118 
3119 #if !U_CHAR16_IS_TYPEDEF
3120   /**
3121    * Writable-aliasing uint16_t * constructor.
3122    * Delegates to UnicodeString(const char16_t *, int32_t, int32_t).
3123    * @param buffer writable buffer of/for UTF-16 text
3124    * @param buffLength length of the current buffer contents
3125    * @param buffCapacity buffer capacity
3126    * @stable ICU 59
3127    */
UnicodeString(uint16_t * buffer,int32_t buffLength,int32_t buffCapacity)3128   UnicodeString(uint16_t *buffer, int32_t buffLength, int32_t buffCapacity) :
3129       UnicodeString(Char16Ptr(buffer), buffLength, buffCapacity) {}
3130 #endif
3131 
3132 #if U_SIZEOF_WCHAR_T==2 || defined(U_IN_DOXYGEN)
3133   /**
3134    * Writable-aliasing wchar_t * constructor.
3135    * (Only defined if U_SIZEOF_WCHAR_T==2.)
3136    * Delegates to UnicodeString(const char16_t *, int32_t, int32_t).
3137    * @param buffer writable buffer of/for UTF-16 text
3138    * @param buffLength length of the current buffer contents
3139    * @param buffCapacity buffer capacity
3140    * @stable ICU 59
3141    */
UnicodeString(wchar_t * buffer,int32_t buffLength,int32_t buffCapacity)3142   UnicodeString(wchar_t *buffer, int32_t buffLength, int32_t buffCapacity) :
3143       UnicodeString(Char16Ptr(buffer), buffLength, buffCapacity) {}
3144 #endif
3145 
3146   /**
3147    * Writable-aliasing nullptr_t constructor.
3148    * Effectively the same as the default constructor, makes an empty string object.
3149    * @param buffer nullptr
3150    * @param buffLength ignored
3151    * @param buffCapacity ignored
3152    * @stable ICU 59
3153    */
3154   inline UnicodeString(std::nullptr_t buffer, int32_t buffLength, int32_t buffCapacity);
3155 
3156 #if U_CHARSET_IS_UTF8 || !UCONFIG_NO_CONVERSION
3157 
3158   /**
3159    * char* constructor.
3160    * Uses the default converter (and thus depends on the ICU conversion code)
3161    * unless U_CHARSET_IS_UTF8 is set to 1.
3162    *
3163    * For ASCII (really "invariant character") strings it is more efficient to use
3164    * the constructor that takes a US_INV (for its enum EInvariant).
3165    * For ASCII (invariant-character) string literals, see UNICODE_STRING and
3166    * UNICODE_STRING_SIMPLE.
3167    *
3168    * It is recommended to mark this constructor "explicit" by
3169    * `-DUNISTR_FROM_STRING_EXPLICIT=explicit`
3170    * on the compiler command line or similar.
3171    * @param codepageData an array of bytes, null-terminated,
3172    *                     in the platform's default codepage.
3173    * @stable ICU 2.0
3174    * @see UNICODE_STRING
3175    * @see UNICODE_STRING_SIMPLE
3176    */
3177   UNISTR_FROM_STRING_EXPLICIT UnicodeString(const char *codepageData);
3178 
3179   /**
3180    * char* constructor.
3181    * Uses the default converter (and thus depends on the ICU conversion code)
3182    * unless U_CHARSET_IS_UTF8 is set to 1.
3183    * @param codepageData an array of bytes in the platform's default codepage.
3184    * @param dataLength The number of bytes in `codepageData`.
3185    * @stable ICU 2.0
3186    */
3187   UnicodeString(const char *codepageData, int32_t dataLength);
3188 
3189 #endif
3190 
3191 #if !UCONFIG_NO_CONVERSION
3192 
3193   /**
3194    * char* constructor.
3195    * @param codepageData an array of bytes, null-terminated
3196    * @param codepage the encoding of `codepageData`.  The special
3197    * value 0 for `codepage` indicates that the text is in the
3198    * platform's default codepage.
3199    *
3200    * If `codepage` is an empty string (`""`),
3201    * then a simple conversion is performed on the codepage-invariant
3202    * subset ("invariant characters") of the platform encoding. See utypes.h.
3203    * Recommendation: For invariant-character strings use the constructor
3204    * UnicodeString(const char *src, int32_t length, enum EInvariant inv)
3205    * because it avoids object code dependencies of UnicodeString on
3206    * the conversion code.
3207    *
3208    * @stable ICU 2.0
3209    */
3210   UnicodeString(const char *codepageData, const char *codepage);
3211 
3212   /**
3213    * char* constructor.
3214    * @param codepageData an array of bytes.
3215    * @param dataLength The number of bytes in `codepageData`.
3216    * @param codepage the encoding of `codepageData`.  The special
3217    * value 0 for `codepage` indicates that the text is in the
3218    * platform's default codepage.
3219    * If `codepage` is an empty string (`""`),
3220    * then a simple conversion is performed on the codepage-invariant
3221    * subset ("invariant characters") of the platform encoding. See utypes.h.
3222    * Recommendation: For invariant-character strings use the constructor
3223    * UnicodeString(const char *src, int32_t length, enum EInvariant inv)
3224    * because it avoids object code dependencies of UnicodeString on
3225    * the conversion code.
3226    *
3227    * @stable ICU 2.0
3228    */
3229   UnicodeString(const char *codepageData, int32_t dataLength, const char *codepage);
3230 
3231   /**
3232    * char * / UConverter constructor.
3233    * This constructor uses an existing UConverter object to
3234    * convert the codepage string to Unicode and construct a UnicodeString
3235    * from that.
3236    *
3237    * The converter is reset at first.
3238    * If the error code indicates a failure before this constructor is called,
3239    * or if an error occurs during conversion or construction,
3240    * then the string will be bogus.
3241    *
3242    * This function avoids the overhead of opening and closing a converter if
3243    * multiple strings are constructed.
3244    *
3245    * @param src input codepage string
3246    * @param srcLength length of the input string, can be -1 for NUL-terminated strings
3247    * @param cnv converter object (ucnv_resetToUnicode() will be called),
3248    *        can be NULL for the default converter
3249    * @param errorCode normal ICU error code
3250    * @stable ICU 2.0
3251    */
3252   UnicodeString(
3253         const char *src, int32_t srcLength,
3254         UConverter *cnv,
3255         UErrorCode &errorCode);
3256 
3257 #endif
3258 
3259   /**
3260    * Constructs a Unicode string from an invariant-character char * string.
3261    * About invariant characters see utypes.h.
3262    * This constructor has no runtime dependency on conversion code and is
3263    * therefore recommended over ones taking a charset name string
3264    * (where the empty string "" indicates invariant-character conversion).
3265    *
3266    * Use the macro US_INV as the third, signature-distinguishing parameter.
3267    *
3268    * For example:
3269    * \code
3270    *     void fn(const char *s) {
3271    *       UnicodeString ustr(s, -1, US_INV);
3272    *       // use ustr ...
3273    *     }
3274    * \endcode
3275    * @param src String using only invariant characters.
3276    * @param textLength Length of src, or -1 if NUL-terminated.
3277    * @param inv Signature-distinguishing paramater, use US_INV.
3278    *
3279    * @see US_INV
3280    * @stable ICU 3.2
3281    */
3282   UnicodeString(const char *src, int32_t textLength, enum EInvariant inv);
3283 
3284 
3285   /**
3286    * Copy constructor.
3287    *
3288    * Starting with ICU 2.4, the assignment operator and the copy constructor
3289    * allocate a new buffer and copy the buffer contents even for readonly aliases.
3290    * By contrast, the fastCopyFrom() function implements the old,
3291    * more efficient but less safe behavior
3292    * of making this string also a readonly alias to the same buffer.
3293    *
3294    * If the source object has an "open" buffer from getBuffer(minCapacity),
3295    * then the copy is an empty string.
3296    *
3297    * @param that The UnicodeString object to copy.
3298    * @stable ICU 2.0
3299    * @see fastCopyFrom
3300    */
3301   UnicodeString(const UnicodeString& that);
3302 
3303   /**
3304    * Move constructor; might leave src in bogus state.
3305    * This string will have the same contents and state that the source string had.
3306    * @param src source string
3307    * @stable ICU 56
3308    */
3309   UnicodeString(UnicodeString &&src) U_NOEXCEPT;
3310 
3311   /**
3312    * 'Substring' constructor from tail of source string.
3313    * @param src The UnicodeString object to copy.
3314    * @param srcStart The offset into `src` at which to start copying.
3315    * @stable ICU 2.2
3316    */
3317   UnicodeString(const UnicodeString& src, int32_t srcStart);
3318 
3319   /**
3320    * 'Substring' constructor from subrange of source string.
3321    * @param src The UnicodeString object to copy.
3322    * @param srcStart The offset into `src` at which to start copying.
3323    * @param srcLength The number of characters from `src` to copy.
3324    * @stable ICU 2.2
3325    */
3326   UnicodeString(const UnicodeString& src, int32_t srcStart, int32_t srcLength);
3327 
3328   /**
3329    * Clone this object, an instance of a subclass of Replaceable.
3330    * Clones can be used concurrently in multiple threads.
3331    * If a subclass does not implement clone(), or if an error occurs,
3332    * then NULL is returned.
3333    * The caller must delete the clone.
3334    *
3335    * @return a clone of this object
3336    *
3337    * @see Replaceable::clone
3338    * @see getDynamicClassID
3339    * @stable ICU 2.6
3340    */
3341   virtual UnicodeString *clone() const;
3342 
3343   /** Destructor.
3344    * @stable ICU 2.0
3345    */
3346   virtual ~UnicodeString();
3347 
3348   /**
3349    * Create a UnicodeString from a UTF-8 string.
3350    * Illegal input is replaced with U+FFFD. Otherwise, errors result in a bogus string.
3351    * Calls u_strFromUTF8WithSub().
3352    *
3353    * @param utf8 UTF-8 input string.
3354    *             Note that a StringPiece can be implicitly constructed
3355    *             from a std::string or a NUL-terminated const char * string.
3356    * @return A UnicodeString with equivalent UTF-16 contents.
3357    * @see toUTF8
3358    * @see toUTF8String
3359    * @stable ICU 4.2
3360    */
3361   static UnicodeString fromUTF8(StringPiece utf8);
3362 
3363   /**
3364    * Create a UnicodeString from a UTF-32 string.
3365    * Illegal input is replaced with U+FFFD. Otherwise, errors result in a bogus string.
3366    * Calls u_strFromUTF32WithSub().
3367    *
3368    * @param utf32 UTF-32 input string. Must not be NULL.
3369    * @param length Length of the input string, or -1 if NUL-terminated.
3370    * @return A UnicodeString with equivalent UTF-16 contents.
3371    * @see toUTF32
3372    * @stable ICU 4.2
3373    */
3374   static UnicodeString fromUTF32(const UChar32 *utf32, int32_t length);
3375 
3376   /* Miscellaneous operations */
3377 
3378   /**
3379    * Unescape a string of characters and return a string containing
3380    * the result.  The following escape sequences are recognized:
3381    *
3382    * \\uhhhh       4 hex digits; h in [0-9A-Fa-f]
3383    * \\Uhhhhhhhh   8 hex digits
3384    * \\xhh         1-2 hex digits
3385    * \\ooo         1-3 octal digits; o in [0-7]
3386    * \\cX          control-X; X is masked with 0x1F
3387    *
3388    * as well as the standard ANSI C escapes:
3389    *
3390    * \\a => U+0007, \\b => U+0008, \\t => U+0009, \\n => U+000A,
3391    * \\v => U+000B, \\f => U+000C, \\r => U+000D, \\e => U+001B,
3392    * \\" => U+0022, \\' => U+0027, \\? => U+003F, \\\\ => U+005C
3393    *
3394    * Anything else following a backslash is generically escaped.  For
3395    * example, "[a\\-z]" returns "[a-z]".
3396    *
3397    * If an escape sequence is ill-formed, this method returns an empty
3398    * string.  An example of an ill-formed sequence is "\\u" followed by
3399    * fewer than 4 hex digits.
3400    *
3401    * This function is similar to u_unescape() but not identical to it.
3402    * The latter takes a source char*, so it does escape recognition
3403    * and also invariant conversion.
3404    *
3405    * @return a string with backslash escapes interpreted, or an
3406    * empty string on error.
3407    * @see UnicodeString#unescapeAt()
3408    * @see u_unescape()
3409    * @see u_unescapeAt()
3410    * @stable ICU 2.0
3411    */
3412   UnicodeString unescape() const;
3413 
3414   /**
3415    * Unescape a single escape sequence and return the represented
3416    * character.  See unescape() for a listing of the recognized escape
3417    * sequences.  The character at offset-1 is assumed (without
3418    * checking) to be a backslash.  If the escape sequence is
3419    * ill-formed, or the offset is out of range, U_SENTINEL=-1 is
3420    * returned.
3421    *
3422    * @param offset an input output parameter.  On input, it is the
3423    * offset into this string where the escape sequence is located,
3424    * after the initial backslash.  On output, it is advanced after the
3425    * last character parsed.  On error, it is not advanced at all.
3426    * @return the character represented by the escape sequence at
3427    * offset, or U_SENTINEL=-1 on error.
3428    * @see UnicodeString#unescape()
3429    * @see u_unescape()
3430    * @see u_unescapeAt()
3431    * @stable ICU 2.0
3432    */
3433   UChar32 unescapeAt(int32_t &offset) const;
3434 
3435   /**
3436    * ICU "poor man's RTTI", returns a UClassID for this class.
3437    *
3438    * @stable ICU 2.2
3439    */
3440   static UClassID U_EXPORT2 getStaticClassID();
3441 
3442   /**
3443    * ICU "poor man's RTTI", returns a UClassID for the actual class.
3444    *
3445    * @stable ICU 2.2
3446    */
3447   virtual UClassID getDynamicClassID() const;
3448 
3449   //========================================
3450   // Implementation methods
3451   //========================================
3452 
3453 protected:
3454   /**
3455    * Implement Replaceable::getLength() (see jitterbug 1027).
3456    * @stable ICU 2.4
3457    */
3458   virtual int32_t getLength() const;
3459 
3460   /**
3461    * The change in Replaceable to use virtual getCharAt() allows
3462    * UnicodeString::charAt() to be inline again (see jitterbug 709).
3463    * @stable ICU 2.4
3464    */
3465   virtual char16_t getCharAt(int32_t offset) const;
3466 
3467   /**
3468    * The change in Replaceable to use virtual getChar32At() allows
3469    * UnicodeString::char32At() to be inline again (see jitterbug 709).
3470    * @stable ICU 2.4
3471    */
3472   virtual UChar32 getChar32At(int32_t offset) const;
3473 
3474 private:
3475   // For char* constructors. Could be made public.
3476   UnicodeString &setToUTF8(StringPiece utf8);
3477   // For extract(char*).
3478   // We could make a toUTF8(target, capacity, errorCode) public but not
3479   // this version: New API will be cleaner if we make callers create substrings
3480   // rather than having start+length on every method,
3481   // and it should take a UErrorCode&.
3482   int32_t
3483   toUTF8(int32_t start, int32_t len,
3484          char *target, int32_t capacity) const;
3485 
3486   /**
3487    * Internal string contents comparison, called by operator==.
3488    * Requires: this & text not bogus and have same lengths.
3489    */
3490   UBool doEquals(const UnicodeString &text, int32_t len) const;
3491 
3492   inline int8_t
3493   doCompare(int32_t start,
3494            int32_t length,
3495            const UnicodeString& srcText,
3496            int32_t srcStart,
3497            int32_t srcLength) const;
3498 
3499   int8_t doCompare(int32_t start,
3500            int32_t length,
3501            const char16_t *srcChars,
3502            int32_t srcStart,
3503            int32_t srcLength) const;
3504 
3505   inline int8_t
3506   doCompareCodePointOrder(int32_t start,
3507                           int32_t length,
3508                           const UnicodeString& srcText,
3509                           int32_t srcStart,
3510                           int32_t srcLength) const;
3511 
3512   int8_t doCompareCodePointOrder(int32_t start,
3513                                  int32_t length,
3514                                  const char16_t *srcChars,
3515                                  int32_t srcStart,
3516                                  int32_t srcLength) const;
3517 
3518   inline int8_t
3519   doCaseCompare(int32_t start,
3520                 int32_t length,
3521                 const UnicodeString &srcText,
3522                 int32_t srcStart,
3523                 int32_t srcLength,
3524                 uint32_t options) const;
3525 
3526   int8_t
3527   doCaseCompare(int32_t start,
3528                 int32_t length,
3529                 const char16_t *srcChars,
3530                 int32_t srcStart,
3531                 int32_t srcLength,
3532                 uint32_t options) const;
3533 
3534   int32_t doIndexOf(char16_t c,
3535             int32_t start,
3536             int32_t length) const;
3537 
3538   int32_t doIndexOf(UChar32 c,
3539                         int32_t start,
3540                         int32_t length) const;
3541 
3542   int32_t doLastIndexOf(char16_t c,
3543                 int32_t start,
3544                 int32_t length) const;
3545 
3546   int32_t doLastIndexOf(UChar32 c,
3547                             int32_t start,
3548                             int32_t length) const;
3549 
3550   void doExtract(int32_t start,
3551          int32_t length,
3552          char16_t *dst,
3553          int32_t dstStart) const;
3554 
3555   inline void doExtract(int32_t start,
3556          int32_t length,
3557          UnicodeString& target) const;
3558 
3559   inline char16_t doCharAt(int32_t offset)  const;
3560 
3561   UnicodeString& doReplace(int32_t start,
3562                int32_t length,
3563                const UnicodeString& srcText,
3564                int32_t srcStart,
3565                int32_t srcLength);
3566 
3567   UnicodeString& doReplace(int32_t start,
3568                int32_t length,
3569                const char16_t *srcChars,
3570                int32_t srcStart,
3571                int32_t srcLength);
3572 
3573   UnicodeString& doAppend(const UnicodeString& src, int32_t srcStart, int32_t srcLength);
3574   UnicodeString& doAppend(const char16_t *srcChars, int32_t srcStart, int32_t srcLength);
3575 
3576   UnicodeString& doReverse(int32_t start,
3577                int32_t length);
3578 
3579   // calculate hash code
3580   int32_t doHashCode(void) const;
3581 
3582   // get pointer to start of array
3583   // these do not check for kOpenGetBuffer, unlike the public getBuffer() function
3584   inline char16_t* getArrayStart(void);
3585   inline const char16_t* getArrayStart(void) const;
3586 
3587   inline UBool hasShortLength() const;
3588   inline int32_t getShortLength() const;
3589 
3590   // A UnicodeString object (not necessarily its current buffer)
3591   // is writable unless it isBogus() or it has an "open" getBuffer(minCapacity).
3592   inline UBool isWritable() const;
3593 
3594   // Is the current buffer writable?
3595   inline UBool isBufferWritable() const;
3596 
3597   // None of the following does releaseArray().
3598   inline void setZeroLength();
3599   inline void setShortLength(int32_t len);
3600   inline void setLength(int32_t len);
3601   inline void setToEmpty();
3602   inline void setArray(char16_t *array, int32_t len, int32_t capacity); // sets length but not flags
3603 
3604   // allocate the array; result may be the stack buffer
3605   // sets refCount to 1 if appropriate
3606   // sets fArray, fCapacity, and flags
3607   // sets length to 0
3608   // returns boolean for success or failure
3609   UBool allocate(int32_t capacity);
3610 
3611   // release the array if owned
3612   void releaseArray(void);
3613 
3614   // turn a bogus string into an empty one
3615   void unBogus();
3616 
3617   // implements assigment operator, copy constructor, and fastCopyFrom()
3618   UnicodeString &copyFrom(const UnicodeString &src, UBool fastCopy=FALSE);
3619 
3620   // Copies just the fields without memory management.
3621   void copyFieldsFrom(UnicodeString &src, UBool setSrcToBogus) U_NOEXCEPT;
3622 
3623   // Pin start and limit to acceptable values.
3624   inline void pinIndex(int32_t& start) const;
3625   inline void pinIndices(int32_t& start,
3626                          int32_t& length) const;
3627 
3628 #if !UCONFIG_NO_CONVERSION
3629 
3630   /* Internal extract() using UConverter. */
3631   int32_t doExtract(int32_t start, int32_t length,
3632                     char *dest, int32_t destCapacity,
3633                     UConverter *cnv,
3634                     UErrorCode &errorCode) const;
3635 
3636   /*
3637    * Real constructor for converting from codepage data.
3638    * It assumes that it is called with !fRefCounted.
3639    *
3640    * If `codepage==0`, then the default converter
3641    * is used for the platform encoding.
3642    * If `codepage` is an empty string (`""`),
3643    * then a simple conversion is performed on the codepage-invariant
3644    * subset ("invariant characters") of the platform encoding. See utypes.h.
3645    */
3646   void doCodepageCreate(const char *codepageData,
3647                         int32_t dataLength,
3648                         const char *codepage);
3649 
3650   /*
3651    * Worker function for creating a UnicodeString from
3652    * a codepage string using a UConverter.
3653    */
3654   void
3655   doCodepageCreate(const char *codepageData,
3656                    int32_t dataLength,
3657                    UConverter *converter,
3658                    UErrorCode &status);
3659 
3660 #endif
3661 
3662   /*
3663    * This function is called when write access to the array
3664    * is necessary.
3665    *
3666    * We need to make a copy of the array if
3667    * the buffer is read-only, or
3668    * the buffer is refCounted (shared), and refCount>1, or
3669    * the buffer is too small.
3670    *
3671    * Return FALSE if memory could not be allocated.
3672    */
3673   UBool cloneArrayIfNeeded(int32_t newCapacity = -1,
3674                             int32_t growCapacity = -1,
3675                             UBool doCopyArray = TRUE,
3676                             int32_t **pBufferToDelete = 0,
3677                             UBool forceClone = FALSE);
3678 
3679   /**
3680    * Common function for UnicodeString case mappings.
3681    * The stringCaseMapper has the same type UStringCaseMapper
3682    * as in ustr_imp.h for ustrcase_map().
3683    */
3684   UnicodeString &
3685   caseMap(int32_t caseLocale, uint32_t options,
3686 #if !UCONFIG_NO_BREAK_ITERATION
3687           BreakIterator *iter,
3688 #endif
3689           UStringCaseMapper *stringCaseMapper);
3690 
3691   // ref counting
3692   void addRef(void);
3693   int32_t removeRef(void);
3694   int32_t refCount(void) const;
3695 
3696   // constants
3697   enum {
3698     /**
3699      * Size of stack buffer for short strings.
3700      * Must be at least U16_MAX_LENGTH for the single-code point constructor to work.
3701      * @see UNISTR_OBJECT_SIZE
3702      */
3703     US_STACKBUF_SIZE=(int32_t)(UNISTR_OBJECT_SIZE-sizeof(void *)-2)/U_SIZEOF_UCHAR,
3704     kInvalidUChar=0xffff, // U+FFFF returned by charAt(invalid index)
3705     kInvalidHashCode=0, // invalid hash code
3706     kEmptyHashCode=1, // hash code for empty string
3707 
3708     // bit flag values for fLengthAndFlags
3709     kIsBogus=1,         // this string is bogus, i.e., not valid or NULL
3710     kUsingStackBuffer=2,// using fUnion.fStackFields instead of fUnion.fFields
3711     kRefCounted=4,      // there is a refCount field before the characters in fArray
3712     kBufferIsReadonly=8,// do not write to this buffer
3713     kOpenGetBuffer=16,  // getBuffer(minCapacity) was called (is "open"),
3714                         // and releaseBuffer(newLength) must be called
3715     kAllStorageFlags=0x1f,
3716 
3717     kLengthShift=5,     // remaining 11 bits for non-negative short length, or negative if long
3718     kLength1=1<<kLengthShift,
3719     kMaxShortLength=0x3ff,  // max non-negative short length (leaves top bit 0)
3720     kLengthIsLarge=0xffe0,  // short length < 0, real length is in fUnion.fFields.fLength
3721 
3722     // combined values for convenience
3723     kShortString=kUsingStackBuffer,
3724     kLongString=kRefCounted,
3725     kReadonlyAlias=kBufferIsReadonly,
3726     kWritableAlias=0
3727   };
3728 
3729   friend class UnicodeStringAppendable;
3730 
3731   union StackBufferOrFields;        // forward declaration necessary before friend declaration
3732   friend union StackBufferOrFields; // make US_STACKBUF_SIZE visible inside fUnion
3733 
3734   /*
3735    * The following are all the class fields that are stored
3736    * in each UnicodeString object.
3737    * Note that UnicodeString has virtual functions,
3738    * therefore there is an implicit vtable pointer
3739    * as the first real field.
3740    * The fields should be aligned such that no padding is necessary.
3741    * On 32-bit machines, the size should be 32 bytes,
3742    * on 64-bit machines (8-byte pointers), it should be 40 bytes.
3743    *
3744    * We use a hack to achieve this.
3745    *
3746    * With at least some compilers, each of the following is forced to
3747    * a multiple of sizeof(pointer) [the largest field base unit here is a data pointer],
3748    * rounded up with additional padding if the fields do not already fit that requirement:
3749    * - sizeof(class UnicodeString)
3750    * - offsetof(UnicodeString, fUnion)
3751    * - sizeof(fUnion)
3752    * - sizeof(fStackFields)
3753    *
3754    * We optimize for the longest possible internal buffer for short strings.
3755    * fUnion.fStackFields begins with 2 bytes for storage flags
3756    * and the length of relatively short strings,
3757    * followed by the buffer for short string contents.
3758    * There is no padding inside fStackFields.
3759    *
3760    * Heap-allocated and aliased strings use fUnion.fFields.
3761    * Both fStackFields and fFields must begin with the same fields for flags and short length,
3762    * that is, those must have the same memory offsets inside the object,
3763    * because the flags must be inspected in order to decide which half of fUnion is being used.
3764    * We assume that the compiler does not reorder the fields.
3765    *
3766    * (Padding at the end of fFields is ok:
3767    * As long as it is no larger than fStackFields, it is not wasted space.)
3768    *
3769    * For some of the history of the UnicodeString class fields layout, see
3770    * - ICU ticket #11551 "longer UnicodeString contents in stack buffer"
3771    * - ICU ticket #11336 "UnicodeString: recombine stack buffer arrays"
3772    * - ICU ticket #8322 "why is sizeof(UnicodeString)==48?"
3773    */
3774   // (implicit) *vtable;
3775   union StackBufferOrFields {
3776     // fStackFields is used iff (fLengthAndFlags&kUsingStackBuffer) else fFields is used.
3777     // Each struct of the union must begin with fLengthAndFlags.
3778     struct {
3779       int16_t fLengthAndFlags;          // bit fields: see constants above
3780       char16_t fBuffer[US_STACKBUF_SIZE];  // buffer for short strings
3781     } fStackFields;
3782     struct {
3783       int16_t fLengthAndFlags;          // bit fields: see constants above
3784       int32_t fLength;    // number of characters in fArray if >127; else undefined
3785       int32_t fCapacity;  // capacity of fArray (in char16_ts)
3786       // array pointer last to minimize padding for machines with P128 data model
3787       // or pointer sizes that are not a power of 2
3788       char16_t   *fArray;    // the Unicode data
3789     } fFields;
3790   } fUnion;
3791 };
3792 
3793 /**
3794  * Create a new UnicodeString with the concatenation of two others.
3795  *
3796  * @param s1 The first string to be copied to the new one.
3797  * @param s2 The second string to be copied to the new one, after s1.
3798  * @return UnicodeString(s1).append(s2)
3799  * @stable ICU 2.8
3800  */
3801 U_COMMON_API UnicodeString U_EXPORT2
3802 operator+ (const UnicodeString &s1, const UnicodeString &s2);
3803 
3804 //========================================
3805 // Inline members
3806 //========================================
3807 
3808 //========================================
3809 // Privates
3810 //========================================
3811 
3812 inline void
pinIndex(int32_t & start)3813 UnicodeString::pinIndex(int32_t& start) const
3814 {
3815   // pin index
3816   if(start < 0) {
3817     start = 0;
3818   } else if(start > length()) {
3819     start = length();
3820   }
3821 }
3822 
3823 inline void
pinIndices(int32_t & start,int32_t & _length)3824 UnicodeString::pinIndices(int32_t& start,
3825                           int32_t& _length) const
3826 {
3827   // pin indices
3828   int32_t len = length();
3829   if(start < 0) {
3830     start = 0;
3831   } else if(start > len) {
3832     start = len;
3833   }
3834   if(_length < 0) {
3835     _length = 0;
3836   } else if(_length > (len - start)) {
3837     _length = (len - start);
3838   }
3839 }
3840 
3841 inline char16_t*
getArrayStart()3842 UnicodeString::getArrayStart() {
3843   return (fUnion.fFields.fLengthAndFlags&kUsingStackBuffer) ?
3844     fUnion.fStackFields.fBuffer : fUnion.fFields.fArray;
3845 }
3846 
3847 inline const char16_t*
getArrayStart()3848 UnicodeString::getArrayStart() const {
3849   return (fUnion.fFields.fLengthAndFlags&kUsingStackBuffer) ?
3850     fUnion.fStackFields.fBuffer : fUnion.fFields.fArray;
3851 }
3852 
3853 //========================================
3854 // Default constructor
3855 //========================================
3856 
3857 inline
UnicodeString()3858 UnicodeString::UnicodeString() {
3859   fUnion.fStackFields.fLengthAndFlags=kShortString;
3860 }
3861 
UnicodeString(const std::nullptr_t)3862 inline UnicodeString::UnicodeString(const std::nullptr_t /*text*/) {
3863   fUnion.fStackFields.fLengthAndFlags=kShortString;
3864 }
3865 
UnicodeString(const std::nullptr_t,int32_t)3866 inline UnicodeString::UnicodeString(const std::nullptr_t /*text*/, int32_t /*length*/) {
3867   fUnion.fStackFields.fLengthAndFlags=kShortString;
3868 }
3869 
UnicodeString(std::nullptr_t,int32_t,int32_t)3870 inline UnicodeString::UnicodeString(std::nullptr_t /*buffer*/, int32_t /*buffLength*/, int32_t /*buffCapacity*/) {
3871   fUnion.fStackFields.fLengthAndFlags=kShortString;
3872 }
3873 
3874 //========================================
3875 // Read-only implementation methods
3876 //========================================
3877 inline UBool
hasShortLength()3878 UnicodeString::hasShortLength() const {
3879   return fUnion.fFields.fLengthAndFlags>=0;
3880 }
3881 
3882 inline int32_t
getShortLength()3883 UnicodeString::getShortLength() const {
3884   // fLengthAndFlags must be non-negative -> short length >= 0
3885   // and arithmetic or logical shift does not matter.
3886   return fUnion.fFields.fLengthAndFlags>>kLengthShift;
3887 }
3888 
3889 inline int32_t
length()3890 UnicodeString::length() const {
3891   return hasShortLength() ? getShortLength() : fUnion.fFields.fLength;
3892 }
3893 
3894 inline int32_t
getCapacity()3895 UnicodeString::getCapacity() const {
3896   return (fUnion.fFields.fLengthAndFlags&kUsingStackBuffer) ?
3897     US_STACKBUF_SIZE : fUnion.fFields.fCapacity;
3898 }
3899 
3900 inline int32_t
hashCode()3901 UnicodeString::hashCode() const
3902 { return doHashCode(); }
3903 
3904 inline UBool
isBogus()3905 UnicodeString::isBogus() const
3906 { return (UBool)(fUnion.fFields.fLengthAndFlags & kIsBogus); }
3907 
3908 inline UBool
isWritable()3909 UnicodeString::isWritable() const
3910 { return (UBool)!(fUnion.fFields.fLengthAndFlags&(kOpenGetBuffer|kIsBogus)); }
3911 
3912 inline UBool
isBufferWritable()3913 UnicodeString::isBufferWritable() const
3914 {
3915   return (UBool)(
3916       !(fUnion.fFields.fLengthAndFlags&(kOpenGetBuffer|kIsBogus|kBufferIsReadonly)) &&
3917       (!(fUnion.fFields.fLengthAndFlags&kRefCounted) || refCount()==1));
3918 }
3919 
3920 inline const char16_t *
getBuffer()3921 UnicodeString::getBuffer() const {
3922   if(fUnion.fFields.fLengthAndFlags&(kIsBogus|kOpenGetBuffer)) {
3923     return nullptr;
3924   } else if(fUnion.fFields.fLengthAndFlags&kUsingStackBuffer) {
3925     return fUnion.fStackFields.fBuffer;
3926   } else {
3927     return fUnion.fFields.fArray;
3928   }
3929 }
3930 
3931 //========================================
3932 // Read-only alias methods
3933 //========================================
3934 inline int8_t
doCompare(int32_t start,int32_t thisLength,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)3935 UnicodeString::doCompare(int32_t start,
3936               int32_t thisLength,
3937               const UnicodeString& srcText,
3938               int32_t srcStart,
3939               int32_t srcLength) const
3940 {
3941   if(srcText.isBogus()) {
3942     return (int8_t)!isBogus(); // 0 if both are bogus, 1 otherwise
3943   } else {
3944     srcText.pinIndices(srcStart, srcLength);
3945     return doCompare(start, thisLength, srcText.getArrayStart(), srcStart, srcLength);
3946   }
3947 }
3948 
3949 inline UBool
3950 UnicodeString::operator== (const UnicodeString& text) const
3951 {
3952   if(isBogus()) {
3953     return text.isBogus();
3954   } else {
3955     int32_t len = length(), textLength = text.length();
3956     return !text.isBogus() && len == textLength && doEquals(text, len);
3957   }
3958 }
3959 
3960 inline UBool
3961 UnicodeString::operator!= (const UnicodeString& text) const
3962 { return (! operator==(text)); }
3963 
3964 inline UBool
3965 UnicodeString::operator> (const UnicodeString& text) const
3966 { return doCompare(0, length(), text, 0, text.length()) == 1; }
3967 
3968 inline UBool
3969 UnicodeString::operator< (const UnicodeString& text) const
3970 { return doCompare(0, length(), text, 0, text.length()) == -1; }
3971 
3972 inline UBool
3973 UnicodeString::operator>= (const UnicodeString& text) const
3974 { return doCompare(0, length(), text, 0, text.length()) != -1; }
3975 
3976 inline UBool
3977 UnicodeString::operator<= (const UnicodeString& text) const
3978 { return doCompare(0, length(), text, 0, text.length()) != 1; }
3979 
3980 inline int8_t
compare(const UnicodeString & text)3981 UnicodeString::compare(const UnicodeString& text) const
3982 { return doCompare(0, length(), text, 0, text.length()); }
3983 
3984 inline int8_t
compare(int32_t start,int32_t _length,const UnicodeString & srcText)3985 UnicodeString::compare(int32_t start,
3986                int32_t _length,
3987                const UnicodeString& srcText) const
3988 { return doCompare(start, _length, srcText, 0, srcText.length()); }
3989 
3990 inline int8_t
compare(ConstChar16Ptr srcChars,int32_t srcLength)3991 UnicodeString::compare(ConstChar16Ptr srcChars,
3992                int32_t srcLength) const
3993 { return doCompare(0, length(), srcChars, 0, srcLength); }
3994 
3995 inline int8_t
compare(int32_t start,int32_t _length,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)3996 UnicodeString::compare(int32_t start,
3997                int32_t _length,
3998                const UnicodeString& srcText,
3999                int32_t srcStart,
4000                int32_t srcLength) const
4001 { return doCompare(start, _length, srcText, srcStart, srcLength); }
4002 
4003 inline int8_t
compare(int32_t start,int32_t _length,const char16_t * srcChars)4004 UnicodeString::compare(int32_t start,
4005                int32_t _length,
4006                const char16_t *srcChars) const
4007 { return doCompare(start, _length, srcChars, 0, _length); }
4008 
4009 inline int8_t
compare(int32_t start,int32_t _length,const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4010 UnicodeString::compare(int32_t start,
4011                int32_t _length,
4012                const char16_t *srcChars,
4013                int32_t srcStart,
4014                int32_t srcLength) const
4015 { return doCompare(start, _length, srcChars, srcStart, srcLength); }
4016 
4017 inline int8_t
compareBetween(int32_t start,int32_t limit,const UnicodeString & srcText,int32_t srcStart,int32_t srcLimit)4018 UnicodeString::compareBetween(int32_t start,
4019                   int32_t limit,
4020                   const UnicodeString& srcText,
4021                   int32_t srcStart,
4022                   int32_t srcLimit) const
4023 { return doCompare(start, limit - start,
4024            srcText, srcStart, srcLimit - srcStart); }
4025 
4026 inline int8_t
doCompareCodePointOrder(int32_t start,int32_t thisLength,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4027 UnicodeString::doCompareCodePointOrder(int32_t start,
4028                                        int32_t thisLength,
4029                                        const UnicodeString& srcText,
4030                                        int32_t srcStart,
4031                                        int32_t srcLength) const
4032 {
4033   if(srcText.isBogus()) {
4034     return (int8_t)!isBogus(); // 0 if both are bogus, 1 otherwise
4035   } else {
4036     srcText.pinIndices(srcStart, srcLength);
4037     return doCompareCodePointOrder(start, thisLength, srcText.getArrayStart(), srcStart, srcLength);
4038   }
4039 }
4040 
4041 inline int8_t
compareCodePointOrder(const UnicodeString & text)4042 UnicodeString::compareCodePointOrder(const UnicodeString& text) const
4043 { return doCompareCodePointOrder(0, length(), text, 0, text.length()); }
4044 
4045 inline int8_t
compareCodePointOrder(int32_t start,int32_t _length,const UnicodeString & srcText)4046 UnicodeString::compareCodePointOrder(int32_t start,
4047                                      int32_t _length,
4048                                      const UnicodeString& srcText) const
4049 { return doCompareCodePointOrder(start, _length, srcText, 0, srcText.length()); }
4050 
4051 inline int8_t
compareCodePointOrder(ConstChar16Ptr srcChars,int32_t srcLength)4052 UnicodeString::compareCodePointOrder(ConstChar16Ptr srcChars,
4053                                      int32_t srcLength) const
4054 { return doCompareCodePointOrder(0, length(), srcChars, 0, srcLength); }
4055 
4056 inline int8_t
compareCodePointOrder(int32_t start,int32_t _length,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4057 UnicodeString::compareCodePointOrder(int32_t start,
4058                                      int32_t _length,
4059                                      const UnicodeString& srcText,
4060                                      int32_t srcStart,
4061                                      int32_t srcLength) const
4062 { return doCompareCodePointOrder(start, _length, srcText, srcStart, srcLength); }
4063 
4064 inline int8_t
compareCodePointOrder(int32_t start,int32_t _length,const char16_t * srcChars)4065 UnicodeString::compareCodePointOrder(int32_t start,
4066                                      int32_t _length,
4067                                      const char16_t *srcChars) const
4068 { return doCompareCodePointOrder(start, _length, srcChars, 0, _length); }
4069 
4070 inline int8_t
compareCodePointOrder(int32_t start,int32_t _length,const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4071 UnicodeString::compareCodePointOrder(int32_t start,
4072                                      int32_t _length,
4073                                      const char16_t *srcChars,
4074                                      int32_t srcStart,
4075                                      int32_t srcLength) const
4076 { return doCompareCodePointOrder(start, _length, srcChars, srcStart, srcLength); }
4077 
4078 inline int8_t
compareCodePointOrderBetween(int32_t start,int32_t limit,const UnicodeString & srcText,int32_t srcStart,int32_t srcLimit)4079 UnicodeString::compareCodePointOrderBetween(int32_t start,
4080                                             int32_t limit,
4081                                             const UnicodeString& srcText,
4082                                             int32_t srcStart,
4083                                             int32_t srcLimit) const
4084 { return doCompareCodePointOrder(start, limit - start,
4085            srcText, srcStart, srcLimit - srcStart); }
4086 
4087 inline int8_t
doCaseCompare(int32_t start,int32_t thisLength,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength,uint32_t options)4088 UnicodeString::doCaseCompare(int32_t start,
4089                              int32_t thisLength,
4090                              const UnicodeString &srcText,
4091                              int32_t srcStart,
4092                              int32_t srcLength,
4093                              uint32_t options) const
4094 {
4095   if(srcText.isBogus()) {
4096     return (int8_t)!isBogus(); // 0 if both are bogus, 1 otherwise
4097   } else {
4098     srcText.pinIndices(srcStart, srcLength);
4099     return doCaseCompare(start, thisLength, srcText.getArrayStart(), srcStart, srcLength, options);
4100   }
4101 }
4102 
4103 inline int8_t
caseCompare(const UnicodeString & text,uint32_t options)4104 UnicodeString::caseCompare(const UnicodeString &text, uint32_t options) const {
4105   return doCaseCompare(0, length(), text, 0, text.length(), options);
4106 }
4107 
4108 inline int8_t
caseCompare(int32_t start,int32_t _length,const UnicodeString & srcText,uint32_t options)4109 UnicodeString::caseCompare(int32_t start,
4110                            int32_t _length,
4111                            const UnicodeString &srcText,
4112                            uint32_t options) const {
4113   return doCaseCompare(start, _length, srcText, 0, srcText.length(), options);
4114 }
4115 
4116 inline int8_t
caseCompare(ConstChar16Ptr srcChars,int32_t srcLength,uint32_t options)4117 UnicodeString::caseCompare(ConstChar16Ptr srcChars,
4118                            int32_t srcLength,
4119                            uint32_t options) const {
4120   return doCaseCompare(0, length(), srcChars, 0, srcLength, options);
4121 }
4122 
4123 inline int8_t
caseCompare(int32_t start,int32_t _length,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength,uint32_t options)4124 UnicodeString::caseCompare(int32_t start,
4125                            int32_t _length,
4126                            const UnicodeString &srcText,
4127                            int32_t srcStart,
4128                            int32_t srcLength,
4129                            uint32_t options) const {
4130   return doCaseCompare(start, _length, srcText, srcStart, srcLength, options);
4131 }
4132 
4133 inline int8_t
caseCompare(int32_t start,int32_t _length,const char16_t * srcChars,uint32_t options)4134 UnicodeString::caseCompare(int32_t start,
4135                            int32_t _length,
4136                            const char16_t *srcChars,
4137                            uint32_t options) const {
4138   return doCaseCompare(start, _length, srcChars, 0, _length, options);
4139 }
4140 
4141 inline int8_t
caseCompare(int32_t start,int32_t _length,const char16_t * srcChars,int32_t srcStart,int32_t srcLength,uint32_t options)4142 UnicodeString::caseCompare(int32_t start,
4143                            int32_t _length,
4144                            const char16_t *srcChars,
4145                            int32_t srcStart,
4146                            int32_t srcLength,
4147                            uint32_t options) const {
4148   return doCaseCompare(start, _length, srcChars, srcStart, srcLength, options);
4149 }
4150 
4151 inline int8_t
caseCompareBetween(int32_t start,int32_t limit,const UnicodeString & srcText,int32_t srcStart,int32_t srcLimit,uint32_t options)4152 UnicodeString::caseCompareBetween(int32_t start,
4153                                   int32_t limit,
4154                                   const UnicodeString &srcText,
4155                                   int32_t srcStart,
4156                                   int32_t srcLimit,
4157                                   uint32_t options) const {
4158   return doCaseCompare(start, limit - start, srcText, srcStart, srcLimit - srcStart, options);
4159 }
4160 
4161 inline int32_t
indexOf(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength,int32_t start,int32_t _length)4162 UnicodeString::indexOf(const UnicodeString& srcText,
4163                int32_t srcStart,
4164                int32_t srcLength,
4165                int32_t start,
4166                int32_t _length) const
4167 {
4168   if(!srcText.isBogus()) {
4169     srcText.pinIndices(srcStart, srcLength);
4170     if(srcLength > 0) {
4171       return indexOf(srcText.getArrayStart(), srcStart, srcLength, start, _length);
4172     }
4173   }
4174   return -1;
4175 }
4176 
4177 inline int32_t
indexOf(const UnicodeString & text)4178 UnicodeString::indexOf(const UnicodeString& text) const
4179 { return indexOf(text, 0, text.length(), 0, length()); }
4180 
4181 inline int32_t
indexOf(const UnicodeString & text,int32_t start)4182 UnicodeString::indexOf(const UnicodeString& text,
4183                int32_t start) const {
4184   pinIndex(start);
4185   return indexOf(text, 0, text.length(), start, length() - start);
4186 }
4187 
4188 inline int32_t
indexOf(const UnicodeString & text,int32_t start,int32_t _length)4189 UnicodeString::indexOf(const UnicodeString& text,
4190                int32_t start,
4191                int32_t _length) const
4192 { return indexOf(text, 0, text.length(), start, _length); }
4193 
4194 inline int32_t
indexOf(const char16_t * srcChars,int32_t srcLength,int32_t start)4195 UnicodeString::indexOf(const char16_t *srcChars,
4196                int32_t srcLength,
4197                int32_t start) const {
4198   pinIndex(start);
4199   return indexOf(srcChars, 0, srcLength, start, length() - start);
4200 }
4201 
4202 inline int32_t
indexOf(ConstChar16Ptr srcChars,int32_t srcLength,int32_t start,int32_t _length)4203 UnicodeString::indexOf(ConstChar16Ptr srcChars,
4204                int32_t srcLength,
4205                int32_t start,
4206                int32_t _length) const
4207 { return indexOf(srcChars, 0, srcLength, start, _length); }
4208 
4209 inline int32_t
indexOf(char16_t c,int32_t start,int32_t _length)4210 UnicodeString::indexOf(char16_t c,
4211                int32_t start,
4212                int32_t _length) const
4213 { return doIndexOf(c, start, _length); }
4214 
4215 inline int32_t
indexOf(UChar32 c,int32_t start,int32_t _length)4216 UnicodeString::indexOf(UChar32 c,
4217                int32_t start,
4218                int32_t _length) const
4219 { return doIndexOf(c, start, _length); }
4220 
4221 inline int32_t
indexOf(char16_t c)4222 UnicodeString::indexOf(char16_t c) const
4223 { return doIndexOf(c, 0, length()); }
4224 
4225 inline int32_t
indexOf(UChar32 c)4226 UnicodeString::indexOf(UChar32 c) const
4227 { return indexOf(c, 0, length()); }
4228 
4229 inline int32_t
indexOf(char16_t c,int32_t start)4230 UnicodeString::indexOf(char16_t c,
4231                int32_t start) const {
4232   pinIndex(start);
4233   return doIndexOf(c, start, length() - start);
4234 }
4235 
4236 inline int32_t
indexOf(UChar32 c,int32_t start)4237 UnicodeString::indexOf(UChar32 c,
4238                int32_t start) const {
4239   pinIndex(start);
4240   return indexOf(c, start, length() - start);
4241 }
4242 
4243 inline int32_t
lastIndexOf(ConstChar16Ptr srcChars,int32_t srcLength,int32_t start,int32_t _length)4244 UnicodeString::lastIndexOf(ConstChar16Ptr srcChars,
4245                int32_t srcLength,
4246                int32_t start,
4247                int32_t _length) const
4248 { return lastIndexOf(srcChars, 0, srcLength, start, _length); }
4249 
4250 inline int32_t
lastIndexOf(const char16_t * srcChars,int32_t srcLength,int32_t start)4251 UnicodeString::lastIndexOf(const char16_t *srcChars,
4252                int32_t srcLength,
4253                int32_t start) const {
4254   pinIndex(start);
4255   return lastIndexOf(srcChars, 0, srcLength, start, length() - start);
4256 }
4257 
4258 inline int32_t
lastIndexOf(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength,int32_t start,int32_t _length)4259 UnicodeString::lastIndexOf(const UnicodeString& srcText,
4260                int32_t srcStart,
4261                int32_t srcLength,
4262                int32_t start,
4263                int32_t _length) const
4264 {
4265   if(!srcText.isBogus()) {
4266     srcText.pinIndices(srcStart, srcLength);
4267     if(srcLength > 0) {
4268       return lastIndexOf(srcText.getArrayStart(), srcStart, srcLength, start, _length);
4269     }
4270   }
4271   return -1;
4272 }
4273 
4274 inline int32_t
lastIndexOf(const UnicodeString & text,int32_t start,int32_t _length)4275 UnicodeString::lastIndexOf(const UnicodeString& text,
4276                int32_t start,
4277                int32_t _length) const
4278 { return lastIndexOf(text, 0, text.length(), start, _length); }
4279 
4280 inline int32_t
lastIndexOf(const UnicodeString & text,int32_t start)4281 UnicodeString::lastIndexOf(const UnicodeString& text,
4282                int32_t start) const {
4283   pinIndex(start);
4284   return lastIndexOf(text, 0, text.length(), start, length() - start);
4285 }
4286 
4287 inline int32_t
lastIndexOf(const UnicodeString & text)4288 UnicodeString::lastIndexOf(const UnicodeString& text) const
4289 { return lastIndexOf(text, 0, text.length(), 0, length()); }
4290 
4291 inline int32_t
lastIndexOf(char16_t c,int32_t start,int32_t _length)4292 UnicodeString::lastIndexOf(char16_t c,
4293                int32_t start,
4294                int32_t _length) const
4295 { return doLastIndexOf(c, start, _length); }
4296 
4297 inline int32_t
lastIndexOf(UChar32 c,int32_t start,int32_t _length)4298 UnicodeString::lastIndexOf(UChar32 c,
4299                int32_t start,
4300                int32_t _length) const {
4301   return doLastIndexOf(c, start, _length);
4302 }
4303 
4304 inline int32_t
lastIndexOf(char16_t c)4305 UnicodeString::lastIndexOf(char16_t c) const
4306 { return doLastIndexOf(c, 0, length()); }
4307 
4308 inline int32_t
lastIndexOf(UChar32 c)4309 UnicodeString::lastIndexOf(UChar32 c) const {
4310   return lastIndexOf(c, 0, length());
4311 }
4312 
4313 inline int32_t
lastIndexOf(char16_t c,int32_t start)4314 UnicodeString::lastIndexOf(char16_t c,
4315                int32_t start) const {
4316   pinIndex(start);
4317   return doLastIndexOf(c, start, length() - start);
4318 }
4319 
4320 inline int32_t
lastIndexOf(UChar32 c,int32_t start)4321 UnicodeString::lastIndexOf(UChar32 c,
4322                int32_t start) const {
4323   pinIndex(start);
4324   return lastIndexOf(c, start, length() - start);
4325 }
4326 
4327 inline UBool
startsWith(const UnicodeString & text)4328 UnicodeString::startsWith(const UnicodeString& text) const
4329 { return compare(0, text.length(), text, 0, text.length()) == 0; }
4330 
4331 inline UBool
startsWith(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4332 UnicodeString::startsWith(const UnicodeString& srcText,
4333               int32_t srcStart,
4334               int32_t srcLength) const
4335 { return doCompare(0, srcLength, srcText, srcStart, srcLength) == 0; }
4336 
4337 inline UBool
startsWith(ConstChar16Ptr srcChars,int32_t srcLength)4338 UnicodeString::startsWith(ConstChar16Ptr srcChars, int32_t srcLength) const {
4339   if(srcLength < 0) {
4340     srcLength = u_strlen(toUCharPtr(srcChars));
4341   }
4342   return doCompare(0, srcLength, srcChars, 0, srcLength) == 0;
4343 }
4344 
4345 inline UBool
startsWith(const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4346 UnicodeString::startsWith(const char16_t *srcChars, int32_t srcStart, int32_t srcLength) const {
4347   if(srcLength < 0) {
4348     srcLength = u_strlen(toUCharPtr(srcChars));
4349   }
4350   return doCompare(0, srcLength, srcChars, srcStart, srcLength) == 0;
4351 }
4352 
4353 inline UBool
endsWith(const UnicodeString & text)4354 UnicodeString::endsWith(const UnicodeString& text) const
4355 { return doCompare(length() - text.length(), text.length(),
4356            text, 0, text.length()) == 0; }
4357 
4358 inline UBool
endsWith(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4359 UnicodeString::endsWith(const UnicodeString& srcText,
4360             int32_t srcStart,
4361             int32_t srcLength) const {
4362   srcText.pinIndices(srcStart, srcLength);
4363   return doCompare(length() - srcLength, srcLength,
4364                    srcText, srcStart, srcLength) == 0;
4365 }
4366 
4367 inline UBool
endsWith(ConstChar16Ptr srcChars,int32_t srcLength)4368 UnicodeString::endsWith(ConstChar16Ptr srcChars,
4369             int32_t srcLength) const {
4370   if(srcLength < 0) {
4371     srcLength = u_strlen(toUCharPtr(srcChars));
4372   }
4373   return doCompare(length() - srcLength, srcLength,
4374                    srcChars, 0, srcLength) == 0;
4375 }
4376 
4377 inline UBool
endsWith(const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4378 UnicodeString::endsWith(const char16_t *srcChars,
4379             int32_t srcStart,
4380             int32_t srcLength) const {
4381   if(srcLength < 0) {
4382     srcLength = u_strlen(toUCharPtr(srcChars + srcStart));
4383   }
4384   return doCompare(length() - srcLength, srcLength,
4385                    srcChars, srcStart, srcLength) == 0;
4386 }
4387 
4388 //========================================
4389 // replace
4390 //========================================
4391 inline UnicodeString&
replace(int32_t start,int32_t _length,const UnicodeString & srcText)4392 UnicodeString::replace(int32_t start,
4393                int32_t _length,
4394                const UnicodeString& srcText)
4395 { return doReplace(start, _length, srcText, 0, srcText.length()); }
4396 
4397 inline UnicodeString&
replace(int32_t start,int32_t _length,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4398 UnicodeString::replace(int32_t start,
4399                int32_t _length,
4400                const UnicodeString& srcText,
4401                int32_t srcStart,
4402                int32_t srcLength)
4403 { return doReplace(start, _length, srcText, srcStart, srcLength); }
4404 
4405 inline UnicodeString&
replace(int32_t start,int32_t _length,ConstChar16Ptr srcChars,int32_t srcLength)4406 UnicodeString::replace(int32_t start,
4407                int32_t _length,
4408                ConstChar16Ptr srcChars,
4409                int32_t srcLength)
4410 { return doReplace(start, _length, srcChars, 0, srcLength); }
4411 
4412 inline UnicodeString&
replace(int32_t start,int32_t _length,const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4413 UnicodeString::replace(int32_t start,
4414                int32_t _length,
4415                const char16_t *srcChars,
4416                int32_t srcStart,
4417                int32_t srcLength)
4418 { return doReplace(start, _length, srcChars, srcStart, srcLength); }
4419 
4420 inline UnicodeString&
replace(int32_t start,int32_t _length,char16_t srcChar)4421 UnicodeString::replace(int32_t start,
4422                int32_t _length,
4423                char16_t srcChar)
4424 { return doReplace(start, _length, &srcChar, 0, 1); }
4425 
4426 inline UnicodeString&
replaceBetween(int32_t start,int32_t limit,const UnicodeString & srcText)4427 UnicodeString::replaceBetween(int32_t start,
4428                   int32_t limit,
4429                   const UnicodeString& srcText)
4430 { return doReplace(start, limit - start, srcText, 0, srcText.length()); }
4431 
4432 inline UnicodeString&
replaceBetween(int32_t start,int32_t limit,const UnicodeString & srcText,int32_t srcStart,int32_t srcLimit)4433 UnicodeString::replaceBetween(int32_t start,
4434                   int32_t limit,
4435                   const UnicodeString& srcText,
4436                   int32_t srcStart,
4437                   int32_t srcLimit)
4438 { return doReplace(start, limit - start, srcText, srcStart, srcLimit - srcStart); }
4439 
4440 inline UnicodeString&
findAndReplace(const UnicodeString & oldText,const UnicodeString & newText)4441 UnicodeString::findAndReplace(const UnicodeString& oldText,
4442                   const UnicodeString& newText)
4443 { return findAndReplace(0, length(), oldText, 0, oldText.length(),
4444             newText, 0, newText.length()); }
4445 
4446 inline UnicodeString&
findAndReplace(int32_t start,int32_t _length,const UnicodeString & oldText,const UnicodeString & newText)4447 UnicodeString::findAndReplace(int32_t start,
4448                   int32_t _length,
4449                   const UnicodeString& oldText,
4450                   const UnicodeString& newText)
4451 { return findAndReplace(start, _length, oldText, 0, oldText.length(),
4452             newText, 0, newText.length()); }
4453 
4454 // ============================
4455 // extract
4456 // ============================
4457 inline void
doExtract(int32_t start,int32_t _length,UnicodeString & target)4458 UnicodeString::doExtract(int32_t start,
4459              int32_t _length,
4460              UnicodeString& target) const
4461 { target.replace(0, target.length(), *this, start, _length); }
4462 
4463 inline void
extract(int32_t start,int32_t _length,Char16Ptr target,int32_t targetStart)4464 UnicodeString::extract(int32_t start,
4465                int32_t _length,
4466                Char16Ptr target,
4467                int32_t targetStart) const
4468 { doExtract(start, _length, target, targetStart); }
4469 
4470 inline void
extract(int32_t start,int32_t _length,UnicodeString & target)4471 UnicodeString::extract(int32_t start,
4472                int32_t _length,
4473                UnicodeString& target) const
4474 { doExtract(start, _length, target); }
4475 
4476 #if !UCONFIG_NO_CONVERSION
4477 
4478 inline int32_t
extract(int32_t start,int32_t _length,char * dst,const char * codepage)4479 UnicodeString::extract(int32_t start,
4480                int32_t _length,
4481                char *dst,
4482                const char *codepage) const
4483 
4484 {
4485   // This dstSize value will be checked explicitly
4486   return extract(start, _length, dst, dst!=0 ? 0xffffffff : 0, codepage);
4487 }
4488 
4489 #endif
4490 
4491 inline void
extractBetween(int32_t start,int32_t limit,char16_t * dst,int32_t dstStart)4492 UnicodeString::extractBetween(int32_t start,
4493                   int32_t limit,
4494                   char16_t *dst,
4495                   int32_t dstStart) const {
4496   pinIndex(start);
4497   pinIndex(limit);
4498   doExtract(start, limit - start, dst, dstStart);
4499 }
4500 
4501 inline UnicodeString
tempSubStringBetween(int32_t start,int32_t limit)4502 UnicodeString::tempSubStringBetween(int32_t start, int32_t limit) const {
4503     return tempSubString(start, limit - start);
4504 }
4505 
4506 inline char16_t
doCharAt(int32_t offset)4507 UnicodeString::doCharAt(int32_t offset) const
4508 {
4509   if((uint32_t)offset < (uint32_t)length()) {
4510     return getArrayStart()[offset];
4511   } else {
4512     return kInvalidUChar;
4513   }
4514 }
4515 
4516 inline char16_t
charAt(int32_t offset)4517 UnicodeString::charAt(int32_t offset) const
4518 { return doCharAt(offset); }
4519 
4520 inline char16_t
4521 UnicodeString::operator[] (int32_t offset) const
4522 { return doCharAt(offset); }
4523 
4524 inline UBool
isEmpty()4525 UnicodeString::isEmpty() const {
4526   // Arithmetic or logical right shift does not matter: only testing for 0.
4527   return (fUnion.fFields.fLengthAndFlags>>kLengthShift) == 0;
4528 }
4529 
4530 //========================================
4531 // Write implementation methods
4532 //========================================
4533 inline void
setZeroLength()4534 UnicodeString::setZeroLength() {
4535   fUnion.fFields.fLengthAndFlags &= kAllStorageFlags;
4536 }
4537 
4538 inline void
setShortLength(int32_t len)4539 UnicodeString::setShortLength(int32_t len) {
4540   // requires 0 <= len <= kMaxShortLength
4541   fUnion.fFields.fLengthAndFlags =
4542     (int16_t)((fUnion.fFields.fLengthAndFlags & kAllStorageFlags) | (len << kLengthShift));
4543 }
4544 
4545 inline void
setLength(int32_t len)4546 UnicodeString::setLength(int32_t len) {
4547   if(len <= kMaxShortLength) {
4548     setShortLength(len);
4549   } else {
4550     fUnion.fFields.fLengthAndFlags |= kLengthIsLarge;
4551     fUnion.fFields.fLength = len;
4552   }
4553 }
4554 
4555 inline void
setToEmpty()4556 UnicodeString::setToEmpty() {
4557   fUnion.fFields.fLengthAndFlags = kShortString;
4558 }
4559 
4560 inline void
setArray(char16_t * array,int32_t len,int32_t capacity)4561 UnicodeString::setArray(char16_t *array, int32_t len, int32_t capacity) {
4562   setLength(len);
4563   fUnion.fFields.fArray = array;
4564   fUnion.fFields.fCapacity = capacity;
4565 }
4566 
4567 inline UnicodeString&
4568 UnicodeString::operator= (char16_t ch)
4569 { return doReplace(0, length(), &ch, 0, 1); }
4570 
4571 inline UnicodeString&
4572 UnicodeString::operator= (UChar32 ch)
4573 { return replace(0, length(), ch); }
4574 
4575 inline UnicodeString&
setTo(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4576 UnicodeString::setTo(const UnicodeString& srcText,
4577              int32_t srcStart,
4578              int32_t srcLength)
4579 {
4580   unBogus();
4581   return doReplace(0, length(), srcText, srcStart, srcLength);
4582 }
4583 
4584 inline UnicodeString&
setTo(const UnicodeString & srcText,int32_t srcStart)4585 UnicodeString::setTo(const UnicodeString& srcText,
4586              int32_t srcStart)
4587 {
4588   unBogus();
4589   srcText.pinIndex(srcStart);
4590   return doReplace(0, length(), srcText, srcStart, srcText.length() - srcStart);
4591 }
4592 
4593 inline UnicodeString&
setTo(const UnicodeString & srcText)4594 UnicodeString::setTo(const UnicodeString& srcText)
4595 {
4596   return copyFrom(srcText);
4597 }
4598 
4599 inline UnicodeString&
setTo(const char16_t * srcChars,int32_t srcLength)4600 UnicodeString::setTo(const char16_t *srcChars,
4601              int32_t srcLength)
4602 {
4603   unBogus();
4604   return doReplace(0, length(), srcChars, 0, srcLength);
4605 }
4606 
4607 inline UnicodeString&
setTo(char16_t srcChar)4608 UnicodeString::setTo(char16_t srcChar)
4609 {
4610   unBogus();
4611   return doReplace(0, length(), &srcChar, 0, 1);
4612 }
4613 
4614 inline UnicodeString&
setTo(UChar32 srcChar)4615 UnicodeString::setTo(UChar32 srcChar)
4616 {
4617   unBogus();
4618   return replace(0, length(), srcChar);
4619 }
4620 
4621 inline UnicodeString&
append(const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4622 UnicodeString::append(const UnicodeString& srcText,
4623               int32_t srcStart,
4624               int32_t srcLength)
4625 { return doAppend(srcText, srcStart, srcLength); }
4626 
4627 inline UnicodeString&
append(const UnicodeString & srcText)4628 UnicodeString::append(const UnicodeString& srcText)
4629 { return doAppend(srcText, 0, srcText.length()); }
4630 
4631 inline UnicodeString&
append(const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4632 UnicodeString::append(const char16_t *srcChars,
4633               int32_t srcStart,
4634               int32_t srcLength)
4635 { return doAppend(srcChars, srcStart, srcLength); }
4636 
4637 inline UnicodeString&
append(ConstChar16Ptr srcChars,int32_t srcLength)4638 UnicodeString::append(ConstChar16Ptr srcChars,
4639               int32_t srcLength)
4640 { return doAppend(srcChars, 0, srcLength); }
4641 
4642 inline UnicodeString&
append(char16_t srcChar)4643 UnicodeString::append(char16_t srcChar)
4644 { return doAppend(&srcChar, 0, 1); }
4645 
4646 inline UnicodeString&
4647 UnicodeString::operator+= (char16_t ch)
4648 { return doAppend(&ch, 0, 1); }
4649 
4650 inline UnicodeString&
4651 UnicodeString::operator+= (UChar32 ch) {
4652   return append(ch);
4653 }
4654 
4655 inline UnicodeString&
4656 UnicodeString::operator+= (const UnicodeString& srcText)
4657 { return doAppend(srcText, 0, srcText.length()); }
4658 
4659 inline UnicodeString&
insert(int32_t start,const UnicodeString & srcText,int32_t srcStart,int32_t srcLength)4660 UnicodeString::insert(int32_t start,
4661               const UnicodeString& srcText,
4662               int32_t srcStart,
4663               int32_t srcLength)
4664 { return doReplace(start, 0, srcText, srcStart, srcLength); }
4665 
4666 inline UnicodeString&
insert(int32_t start,const UnicodeString & srcText)4667 UnicodeString::insert(int32_t start,
4668               const UnicodeString& srcText)
4669 { return doReplace(start, 0, srcText, 0, srcText.length()); }
4670 
4671 inline UnicodeString&
insert(int32_t start,const char16_t * srcChars,int32_t srcStart,int32_t srcLength)4672 UnicodeString::insert(int32_t start,
4673               const char16_t *srcChars,
4674               int32_t srcStart,
4675               int32_t srcLength)
4676 { return doReplace(start, 0, srcChars, srcStart, srcLength); }
4677 
4678 inline UnicodeString&
insert(int32_t start,ConstChar16Ptr srcChars,int32_t srcLength)4679 UnicodeString::insert(int32_t start,
4680               ConstChar16Ptr srcChars,
4681               int32_t srcLength)
4682 { return doReplace(start, 0, srcChars, 0, srcLength); }
4683 
4684 inline UnicodeString&
insert(int32_t start,char16_t srcChar)4685 UnicodeString::insert(int32_t start,
4686               char16_t srcChar)
4687 { return doReplace(start, 0, &srcChar, 0, 1); }
4688 
4689 inline UnicodeString&
insert(int32_t start,UChar32 srcChar)4690 UnicodeString::insert(int32_t start,
4691               UChar32 srcChar)
4692 { return replace(start, 0, srcChar); }
4693 
4694 
4695 inline UnicodeString&
remove()4696 UnicodeString::remove()
4697 {
4698   // remove() of a bogus string makes the string empty and non-bogus
4699   if(isBogus()) {
4700     setToEmpty();
4701   } else {
4702     setZeroLength();
4703   }
4704   return *this;
4705 }
4706 
4707 inline UnicodeString&
remove(int32_t start,int32_t _length)4708 UnicodeString::remove(int32_t start,
4709              int32_t _length)
4710 {
4711     if(start <= 0 && _length == INT32_MAX) {
4712         // remove(guaranteed everything) of a bogus string makes the string empty and non-bogus
4713         return remove();
4714     }
4715     return doReplace(start, _length, NULL, 0, 0);
4716 }
4717 
4718 inline UnicodeString&
removeBetween(int32_t start,int32_t limit)4719 UnicodeString::removeBetween(int32_t start,
4720                 int32_t limit)
4721 { return doReplace(start, limit - start, NULL, 0, 0); }
4722 
4723 inline UnicodeString &
retainBetween(int32_t start,int32_t limit)4724 UnicodeString::retainBetween(int32_t start, int32_t limit) {
4725   truncate(limit);
4726   return doReplace(0, start, NULL, 0, 0);
4727 }
4728 
4729 inline UBool
truncate(int32_t targetLength)4730 UnicodeString::truncate(int32_t targetLength)
4731 {
4732   if(isBogus() && targetLength == 0) {
4733     // truncate(0) of a bogus string makes the string empty and non-bogus
4734     unBogus();
4735     return FALSE;
4736   } else if((uint32_t)targetLength < (uint32_t)length()) {
4737     setLength(targetLength);
4738     return TRUE;
4739   } else {
4740     return FALSE;
4741   }
4742 }
4743 
4744 inline UnicodeString&
reverse()4745 UnicodeString::reverse()
4746 { return doReverse(0, length()); }
4747 
4748 inline UnicodeString&
reverse(int32_t start,int32_t _length)4749 UnicodeString::reverse(int32_t start,
4750                int32_t _length)
4751 { return doReverse(start, _length); }
4752 
4753 U_NAMESPACE_END
4754 
4755 #endif /* U_SHOW_CPLUSPLUS_API */
4756 
4757 #endif
4758