1 /*
2  * Hunt - A refined core library for D programming language.
3  *
4  * Copyright (C) 2018-2019 HuntLabs
5  *
6  * Website: https://www.huntlabs.net/
7  *
8  * Licensed under the Apache-2.0 License.
9  *
10  */
11 
12 module hunt.util.Locale;
13 
14 import hunt.Exceptions;
15 import hunt.Functions;
16 import hunt.stream.Common;
17 import hunt.logging.ConsoleLogger;
18 import hunt.collection;
19 import hunt.system.Environment;
20 import hunt.util.StringBuilder;
21 import hunt.util.Common;
22 import hunt.util.Configuration;
23 
24 import std.array;
25 import std.concurrency : initOnce;
26 import std.string;
27 
28 /**
29  * A <code>Locale</code> object represents a specific geographical, political,
30  * or cultural region. An operation that requires a <code>Locale</code> to perform
31  * its task is called <em>locale-sensitive</em> and uses the <code>Locale</code>
32  * to tailor information for the user. For example, displaying a number
33  * is a locale-sensitive operation&mdash; the number should be formatted
34  * according to the customs and conventions of the user's native country,
35  * region, or culture.
36  *
37  * <p> The {@code Locale} class implements IETF BCP 47 which is composed of
38  * <a href="http://tools.ietf.org/html/rfc4647">RFC 4647 "Matching of Language
39  * Tags"</a> and <a href="http://tools.ietf.org/html/rfc5646">RFC 5646 "Tags
40  * for Identifying Languages"</a> with support for the LDML (UTS#35, "Unicode
41  * Locale Data Markup Language") BCP 47-compatible extensions for locale data
42  * exchange.
43  *
44  * <p> A <code>Locale</code> object logically consists of the fields
45  * described below.
46  *
47  * <dl>
48  *   <dt><a id="def_language"><b>language</b></a></dt>
49  *
50  *   <dd>ISO 639 alpha-2 or alpha-3 language code, or registered
51  *   language subtags up to 8 alpha letters (for future enhancements).
52  *   When a language has both an alpha-2 code and an alpha-3 code, the
53  *   alpha-2 code must be used.  You can find a full list of valid
54  *   language codes in the IANA Language Subtag Registry (search for
55  *   "Type: language").  The language field is case insensitive, but
56  *   <code>Locale</code> always canonicalizes to lower case.</dd>
57  *
58  *   <dd>Well-formed language values have the form
59  *   <code>[a-zA-Z]{2,8}</code>.  Note that this is not the full
60  *   BCP47 language production, since it excludes extlang.  They are
61  *   not needed since modern three-letter language codes replace
62  *   them.</dd>
63  *
64  *   <dd>Example: "en" (English), "ja" (Japanese), "kok" (Konkani)</dd>
65  *
66  *   <dt><a id="def_script"><b>script</b></a></dt>
67  *
68  *   <dd>ISO 15924 alpha-4 script code.  You can find a full list of
69  *   valid script codes in the IANA Language Subtag Registry (search
70  *   for "Type: script").  The script field is case insensitive, but
71  *   <code>Locale</code> always canonicalizes to title case (the first
72  *   letter is upper case and the rest of the letters are lower
73  *   case).</dd>
74  *
75  *   <dd>Well-formed script values have the form
76  *   <code>[a-zA-Z]{4}</code></dd>
77  *
78  *   <dd>Example: "Latn" (Latin), "Cyrl" (Cyrillic)</dd>
79  *
80  *   <dt><a id="def_region"><b>country (region)</b></a></dt>
81  *
82  *   <dd>ISO 3166 alpha-2 country code or UN M.49 numeric-3 area code.
83  *   You can find a full list of valid country and region codes in the
84  *   IANA Language Subtag Registry (search for "Type: region").  The
85  *   country (region) field is case insensitive, but
86  *   <code>Locale</code> always canonicalizes to upper case.</dd>
87  *
88  *   <dd>Well-formed country/region values have
89  *   the form <code>[a-zA-Z]{2} | [0-9]{3}</code></dd>
90  *
91  *   <dd>Example: "US" (United States), "FR" (France), "029"
92  *   (Caribbean)</dd>
93  *
94  *   <dt><a id="def_variant"><b>variant</b></a></dt>
95  *
96  *   <dd>Any arbitrary value used to indicate a variation of a
97  *   <code>Locale</code>.  Where there are two or more variant values
98  *   each indicating its own semantics, these values should be ordered
99  *   by importance, with most important first, separated by
100  *   underscore('_').  The variant field is case sensitive.</dd>
101  *
102  *   <dd>Note: IETF BCP 47 places syntactic restrictions on variant
103  *   subtags.  Also BCP 47 subtags are strictly used to indicate
104  *   additional variations that define a language or its dialects that
105  *   are not covered by any combinations of language, script and
106  *   region subtags.  You can find a full list of valid variant codes
107  *   in the IANA Language Subtag Registry (search for "Type: variant").
108  *
109  *   <p>However, the variant field in <code>Locale</code> has
110  *   historically been used for any kind of variation, not just
111  *   language variations.  For example, some supported variants
112  *   available in Java SE Runtime Environments indicate alternative
113  *   cultural behaviors such as calendar type or number script.  In
114  *   BCP 47 this kind of information, which does not identify the
115  *   language, is supported by extension subtags or private use
116  *   subtags.</dd>
117  *
118  *   <dd>Well-formed variant values have the form <code>SUBTAG
119  *   (('_'|'-') SUBTAG)*</code> where <code>SUBTAG =
120  *   [0-9][0-9a-zA-Z]{3} | [0-9a-zA-Z]{5,8}</code>. (Note: BCP 47 only
121  *   uses hyphen ('-') as a delimiter, this is more lenient).</dd>
122  *
123  *   <dd>Example: "polyton" (Polytonic Greek), "POSIX"</dd>
124  *
125  *   <dt><a id="def_extensions"><b>extensions</b></a></dt>
126  *
127  *   <dd>A map from single character keys to string values, indicating
128  *   extensions apart from language identification.  The extensions in
129  *   <code>Locale</code> implement the semantics and syntax of BCP 47
130  *   extension subtags and private use subtags. The extensions are
131  *   case insensitive, but <code>Locale</code> canonicalizes all
132  *   extension keys and values to lower case. Note that extensions
133  *   cannot have empty values.</dd>
134  *
135  *   <dd>Well-formed keys are single characters from the set
136  *   <code>[0-9a-zA-Z]</code>.  Well-formed values have the form
137  *   <code>SUBTAG ('-' SUBTAG)*</code> where for the key 'x'
138  *   <code>SUBTAG = [0-9a-zA-Z]{1,8}</code> and for other keys
139  *   <code>SUBTAG = [0-9a-zA-Z]{2,8}</code> (that is, 'x' allows
140  *   single-character subtags).</dd>
141  *
142  *   <dd>Example: key="u"/value="ca-japanese" (Japanese Calendar),
143  *   key="x"/value="java-1-7"</dd>
144  * </dl>
145  *
146  * <b>Note:</b> Although BCP 47 requires field values to be registered
147  * in the IANA Language Subtag Registry, the <code>Locale</code> class
148  * does not provide any validation features.  The <code>Builder</code>
149  * only checks if an individual field satisfies the syntactic
150  * requirement (is well-formed), but does not validate the value
151  * itself.  See {@link Builder} for details.
152  *
153  * <h3><a id="def_locale_extension">Unicode locale/language extension</a></h3>
154  *
155  * <p>UTS#35, "Unicode Locale Data Markup Language" defines optional
156  * attributes and keywords to override or refine the default behavior
157  * associated with a locale.  A keyword is represented by a pair of
158  * key and type.  For example, "nu-thai" indicates that Thai local
159  * digits (value:"thai") should be used for formatting numbers
160  * (key:"nu").
161  *
162  * <p>The keywords are mapped to a BCP 47 extension value using the
163  * extension key 'u' ({@link #UNICODE_LOCALE_EXTENSION}).  The above
164  * example, "nu-thai", becomes the extension "u-nu-thai".
165  *
166  * <p>Thus, when a <code>Locale</code> object contains Unicode locale
167  * attributes and keywords,
168  * <code>getExtension(UNICODE_LOCALE_EXTENSION)</code> will return a
169  * string representing this information, for example, "nu-thai".  The
170  * <code>Locale</code> class also provides {@link
171  * #getUnicodeLocaleAttributes}, {@link #getUnicodeLocaleKeys}, and
172  * {@link #getUnicodeLocaleType} which allow you to access Unicode
173  * locale attributes and key/type pairs directly.  When represented as
174  * a string, the Unicode Locale Extension lists attributes
175  * alphabetically, followed by key/type sequences with keys listed
176  * alphabetically (the order of subtags comprising a key's type is
177  * fixed when the type is defined)
178  *
179  * <p>A well-formed locale key has the form
180  * <code>[0-9a-zA-Z]{2}</code>.  A well-formed locale type has the
181  * form <code>"" | [0-9a-zA-Z]{3,8} ('-' [0-9a-zA-Z]{3,8})*</code> (it
182  * can be empty, or a series of subtags 3-8 alphanums in length).  A
183  * well-formed locale attribute has the form
184  * <code>[0-9a-zA-Z]{3,8}</code> (it is a single subtag with the same
185  * form as a locale type subtag).
186  *
187  * <p>The Unicode locale extension specifies optional behavior in
188  * locale-sensitive services.  Although the LDML specification defines
189  * various keys and values, actual locale-sensitive service
190  * implementations in a Java Runtime Environment might not support any
191  * particular Unicode locale attributes or key/type pairs.
192  *
193  * <h4>Creating a Locale</h4>
194  *
195  * <p>There are several different ways to create a <code>Locale</code>
196  * object.
197  *
198  * <h5>Builder</h5>
199  *
200  * <p>Using {@link Builder} you can construct a <code>Locale</code> object
201  * that conforms to BCP 47 syntax.
202  *
203  * <h5>Constructors</h5>
204  *
205  * <p>The <code>Locale</code> class provides three constructors:
206  * <blockquote>
207  * <pre>
208  *     {@link #Locale(string language)}
209  *     {@link #Locale(string language, string country)}
210  *     {@link #Locale(string language, string country, string variant)}
211  * </pre>
212  * </blockquote>
213  * These constructors allow you to create a <code>Locale</code> object
214  * with language, country and variant, but you cannot specify
215  * script or extensions.
216  *
217  * <h5>Factory Methods</h5>
218  *
219  * <p>The method {@link #forLanguageTag} creates a <code>Locale</code>
220  * object for a well-formed BCP 47 language tag.
221  *
222  * <h5>Locale Constants</h5>
223  *
224  * <p>The <code>Locale</code> class provides a number of convenient constants
225  * that you can use to create <code>Locale</code> objects for commonly used
226  * locales. For example, the following creates a <code>Locale</code> object
227  * for the United States:
228  * <blockquote>
229  * <pre>
230  *     Locale.US
231  * </pre>
232  * </blockquote>
233  *
234  * <h4><a id="LocaleMatching">Locale Matching</a></h4>
235  *
236  * <p>If an application or a system is internationalized and provides localized
237  * resources for multiple locales, it sometimes needs to find one or more
238  * locales (or language tags) which meet each user's specific preferences. Note
239  * that a term "language tag" is used interchangeably with "locale" in this
240  * locale matching documentation.
241  *
242  * <p>In order to do matching a user's preferred locales to a set of language
243  * tags, <a href="http://tools.ietf.org/html/rfc4647">RFC 4647 Matching of
244  * Language Tags</a> defines two mechanisms: filtering and lookup.
245  * <em>Filtering</em> is used to get all matching locales, whereas
246  * <em>lookup</em> is to choose the best matching locale.
247  * Matching is done case-insensitively. These matching mechanisms are described
248  * in the following sections.
249  *
250  * <p>A user's preference is called a <em>Language Priority List</em> and is
251  * expressed as a list of language ranges. There are syntactically two types of
252  * language ranges: basic and extended. See
253  * {@link Locale.LanguageRange Locale.LanguageRange} for details.
254  *
255  * <h5>Filtering</h5>
256  *
257  * <p>The filtering operation returns all matching language tags. It is defined
258  * in RFC 4647 as follows:
259  * "In filtering, each language range represents the least specific language
260  * tag (that is, the language tag with fewest number of subtags) that is an
261  * acceptable match. All of the language tags in the matching set of tags will
262  * have an equal or greater number of subtags than the language range. Every
263  * non-wildcard subtag in the language range will appear in every one of the
264  * matching language tags."
265  *
266  * <p>There are two types of filtering: filtering for basic language ranges
267  * (called "basic filtering") and filtering for extended language ranges
268  * (called "extended filtering"). They may return different results by what
269  * kind of language ranges are included in the given Language Priority List.
270  * {@link Locale.FilteringMode} is a parameter to specify how filtering should
271  * be done.
272  *
273  * <h5>Lookup</h5>
274  *
275  * <p>The lookup operation returns the best matching language tags. It is
276  * defined in RFC 4647 as follows:
277  * "By contrast with filtering, each language range represents the most
278  * specific tag that is an acceptable match.  The first matching tag found,
279  * according to the user's priority, is considered the closest match and is the
280  * item returned."
281  *
282  * <p>For example, if a Language Priority List consists of two language ranges,
283  * {@code "zh-Hant-TW"} and {@code "en-US"}, in prioritized order, lookup
284  * method progressively searches the language tags below in order to find the
285  * best matching language tag.
286  * <blockquote>
287  * <pre>
288  *    1. zh-Hant-TW
289  *    2. zh-Hant
290  *    3. zh
291  *    4. en-US
292  *    5. en
293  * </pre>
294  * </blockquote>
295  * If there is a language tag which matches completely to a language range
296  * above, the language tag is returned.
297  *
298  * <p>{@code "*"} is the special language range, and it is ignored in lookup.
299  *
300  * <p>If multiple language tags match as a result of the subtag {@code '*'}
301  * included in a language range, the first matching language tag returned by
302  * an {@link Iterator} over a {@link Collection} of language tags is treated as
303  * the best matching one.
304  *
305  * <h4>Use of Locale</h4>
306  *
307  * <p>Once you've created a <code>Locale</code> you can query it for information
308  * about itself. Use <code>getCountry</code> to get the country (or region)
309  * code and <code>getLanguage</code> to get the language code.
310  * You can use <code>getDisplayCountry</code> to get the
311  * name of the country suitable for displaying to the user. Similarly,
312  * you can use <code>getDisplayLanguage</code> to get the name of
313  * the language suitable for displaying to the user. Interestingly,
314  * the <code>getDisplayXXX</code> methods are themselves locale-sensitive
315  * and have two versions: one that uses the default
316  * {@link LocaleCategory#DISPLAY DISPLAY} locale and one
317  * that uses the locale specified as an argument.
318  *
319  * <p>The Java Platform provides a number of classes that perform locale-sensitive
320  * operations. For example, the <code>NumberFormat</code> class formats
321  * numbers, currency, and percentages in a locale-sensitive manner. Classes
322  * such as <code>NumberFormat</code> have several convenience methods
323  * for creating a default object of that type. For example, the
324  * <code>NumberFormat</code> class provides these three convenience methods
325  * for creating a default <code>NumberFormat</code> object:
326  * <blockquote>
327  * <pre>
328  *     NumberFormat.getInstance()
329  *     NumberFormat.getCurrencyInstance()
330  *     NumberFormat.getPercentInstance()
331  * </pre>
332  * </blockquote>
333  * Each of these methods has two variants; one with an explicit locale
334  * and one without; the latter uses the default
335  * {@link LocaleCategory#FORMAT FORMAT} locale:
336  * <blockquote>
337  * <pre>
338  *     NumberFormat.getInstance(myLocale)
339  *     NumberFormat.getCurrencyInstance(myLocale)
340  *     NumberFormat.getPercentInstance(myLocale)
341  * </pre>
342  * </blockquote>
343  * A <code>Locale</code> is the mechanism for identifying the kind of object
344  * (<code>NumberFormat</code>) that you would like to get. The locale is
345  * <STRONG>just</STRONG> a mechanism for identifying objects,
346  * <STRONG>not</STRONG> a container for the objects themselves.
347  *
348  * <h4>Compatibility</h4>
349  *
350  * <p>In order to maintain compatibility with existing usage, Locale's
351  * constructors retain their behavior prior to the Java Runtime
352  * Environment version 1.7.  The same is largely true for the
353  * <code>toString</code> method. Thus Locale objects can continue to
354  * be used as they were. In particular, clients who parse the output
355  * of toString into language, country, and variant fields can continue
356  * to do so (although this is strongly discouraged), although the
357  * variant field will have additional information in it if script or
358  * extensions are present.
359  *
360  * <p>In addition, BCP 47 imposes syntax restrictions that are not
361  * imposed by Locale's constructors. This means that conversions
362  * between some Locales and BCP 47 language tags cannot be made without
363  * losing information. Thus <code>toLanguageTag</code> cannot
364  * represent the state of locales whose language, country, or variant
365  * do not conform to BCP 47.
366  *
367  * <p>Because of these issues, it is recommended that clients migrate
368  * away from constructing non-conforming locales and use the
369  * <code>forLanguageTag</code> and <code>Locale.Builder</code> APIs instead.
370  * Clients desiring a string representation of the complete locale can
371  * then always rely on <code>toLanguageTag</code> for this purpose.
372  *
373  * <h5><a id="special_cases_constructor">Special cases</a></h5>
374  *
375  * <p>For compatibility reasons, two
376  * non-conforming locales are treated as special cases.  These are
377  * <b>{@code ja_JP_JP}</b> and <b>{@code th_TH_TH}</b>. These are ill-formed
378  * in BCP 47 since the variants are too short. To ease migration to BCP 47,
379  * these are treated specially during construction.  These two cases (and only
380  * these) cause a constructor to generate an extension, all other values behave
381  * exactly as they did prior to Java 7.
382  *
383  * <p>Java has used {@code ja_JP_JP} to represent Japanese as used in
384  * Japan together with the Japanese Imperial calendar. This is now
385  * representable using a Unicode locale extension, by specifying the
386  * Unicode locale key {@code ca} (for "calendar") and type
387  * {@code japanese}. When the Locale constructor is called with the
388  * arguments "ja", "JP", "JP", the extension "u-ca-japanese" is
389  * automatically added.
390  *
391  * <p>Java has used {@code th_TH_TH} to represent Thai as used in
392  * Thailand together with Thai digits. This is also now representable using
393  * a Unicode locale extension, by specifying the Unicode locale key
394  * {@code nu} (for "number") and value {@code thai}. When the Locale
395  * constructor is called with the arguments "th", "TH", "TH", the
396  * extension "u-nu-thai" is automatically added.
397  *
398  * <h5>Serialization</h5>
399  *
400  * <p>During serialization, writeObject writes all fields to the output
401  * stream, including extensions.
402  *
403  * <p>During deserialization, readResolve adds extensions as described
404  * in <a href="#special_cases_constructor">Special Cases</a>, only
405  * for the two cases th_TH_TH and ja_JP_JP.
406  *
407  * <h5>Legacy language codes</h5>
408  *
409  * <p>Locale's constructor has always converted three language codes to
410  * their earlier, obsoleted forms: {@code he} maps to {@code iw},
411  * {@code yi} maps to {@code ji}, and {@code id} maps to
412  * {@code in}.  This continues to be the case, in order to not break
413  * backwards compatibility.
414  *
415  * <p>The APIs added in 1.7 map between the old and new language codes,
416  * maintaining the old codes internal to Locale (so that
417  * <code>getLanguage</code> and <code>toString</code> reflect the old
418  * code), but using the new codes in the BCP 47 language tag APIs (so
419  * that <code>toLanguageTag</code> reflects the new one). This
420  * preserves the equivalence between Locales no matter which code or
421  * API is used to construct them. Java's default resource bundle
422  * lookup mechanism also implements this mapping, so that resources
423  * can be named using either convention, see {@link ResourceBundle.Control}.
424  *
425  * <h5>Three-letter language/country(region) codes</h5>
426  *
427  * <p>The Locale constructors have always specified that the language
428  * and the country param be two characters in length, although in
429  * practice they have accepted any length.  The specification has now
430  * been relaxed to allow language codes of two to eight characters and
431  * country (region) codes of two to three characters, and in
432  * particular, three-letter language codes and three-digit region
433  * codes as specified in the IANA Language Subtag Registry.  For
434  * compatibility, the implementation still does not impose a length
435  * constraint.
436  *
437  * @see Builder
438  * @see ResourceBundle
439  * @see java.text.Format
440  * @see java.text.NumberFormat
441  * @see java.text.Collator
442  * @author Mark Davis
443  */
444 final class Locale // : Cloneable
445 {
446 
447     private __gshared  Locale[size_t]  LOCALECACHE;
448 
449     /** Useful constant for language.
450      */
451     static Locale ENGLISH() {
452         __gshared Locale m;
453         return initOnce!(m)(createConstant("en", ""));
454     }
455 
456     /** Useful constant for language.
457      */
458     static Locale FRENCH() {
459         __gshared Locale m;
460         return initOnce!(m)(createConstant("fr", ""));
461     }
462 
463     /** Useful constant for language.
464      */
465     static Locale GERMAN() {
466         __gshared Locale m;
467         return initOnce!(m)(createConstant("de", ""));
468     }
469 
470     /** Useful constant for language.
471      */
472     static Locale ITALIAN() {
473         __gshared Locale m;
474         return initOnce!(m)(createConstant("it", ""));
475     }
476 
477     /** Useful constant for language.
478      */
479     static Locale JAPANESE() {
480         __gshared Locale m;
481         return initOnce!(m)(createConstant("ja", ""));
482     }
483 
484     /** Useful constant for language.
485      */
486     static Locale KOREAN() {
487         __gshared Locale m;
488         return initOnce!(m)(createConstant("ko", ""));
489     }
490 
491     /** Useful constant for language.
492      */
493     static Locale CHINESE() {
494         __gshared Locale m;
495         return initOnce!(m)(createConstant("zh", ""));
496     }
497 
498     /** Useful constant for language.
499      */
500     static Locale SIMPLIFIED_CHINESE() {
501         __gshared Locale m;
502         return initOnce!(m)(createConstant("zh", "CN"));
503     }
504 
505     /** Useful constant for language.
506      */
507     static Locale TRADITIONAL_CHINESE() {
508         __gshared Locale m;
509         return initOnce!(m)(createConstant("zh", "TW"));
510     }
511 
512     /** Useful constant for country.
513      */
514     static Locale FRANCE() {
515         __gshared Locale m;
516         return initOnce!(m)(createConstant("fr", "FR"));
517     }
518 
519     /** Useful constant for country.
520      */
521     static Locale GERMANY() {
522         __gshared Locale m;
523         return initOnce!(m)(createConstant("de", "DE"));
524     }
525 
526     /** Useful constant for country.
527      */
528     static Locale ITALY() {
529         __gshared Locale m;
530         return initOnce!(m)(createConstant("it", "IT"));
531     }
532 
533     /** Useful constant for country.
534      */
535     static Locale JAPAN() {
536         __gshared Locale m;
537         return initOnce!(m)(createConstant("ja", "JP"));
538     }
539 
540     /** Useful constant for country.
541      */
542     static Locale KOREA() {
543         __gshared Locale m;
544         return initOnce!(m)(createConstant("ko", "KR"));
545     }
546 
547     /** Useful constant for country.
548      */
549     
550     alias CHINA = SIMPLIFIED_CHINESE;
551 
552     /** Useful constant for country.
553      */
554     alias PRC = SIMPLIFIED_CHINESE;
555 
556     /** Useful constant for country.
557      */
558     alias TAIWAN = TRADITIONAL_CHINESE;
559 
560 
561     /** Useful constant for country.
562      */
563     static Locale UK() {
564         __gshared Locale m;
565         return initOnce!(m)(createConstant("en", "GB"));
566     }
567 
568     /** Useful constant for country.
569      */
570     static Locale US() {
571         __gshared Locale m;
572         return initOnce!(m)(createConstant("en", "US"));
573     }
574 
575     /** Useful constant for country.
576      */
577     static Locale CANADA() {
578         __gshared Locale m;
579         return initOnce!(m)(createConstant("en", "CA"));
580     }
581 
582     /** Useful constant for country.
583      */
584     static Locale CANADA_FRENCH() {
585         __gshared Locale m;
586         return initOnce!(m)(createConstant("fr", "CA"));
587     }
588 
589     /**
590      * Useful constant for the root locale.  The root locale is the locale whose
591      * language, country, and variant are empty ("") strings.  This is regarded
592      * as the base locale of all locales, and is used as the language/country
593      * neutral locale for the locale sensitive operations.
594      *
595      */
596     static Locale ROOT() {
597         __gshared Locale m;
598         return initOnce!(m)(createConstant("", ""));
599     }
600 
601     /**
602      * The key for the private use extension ('x').
603      *
604      * @see #getExtension(char)
605      * @see Builder#setExtension(char, string)
606      */
607     enum char PRIVATE_USE_EXTENSION = 'x';
608 
609     /**
610      * The key for Unicode locale extension ('u').
611      *
612      * @see #getExtension(char)
613      * @see Builder#setExtension(char, string)
614      */
615     enum char UNICODE_LOCALE_EXTENSION = 'u';
616 
617 
618     /**
619      * Enum for specifying the type defined in ISO 3166. This enum is used to
620      * retrieve the two-letter ISO3166-1 alpha-2, three-letter ISO3166-1
621      * alpha-3, four-letter ISO3166-3 country codes.
622      *
623      * @see #getISOCountries(Locale.IsoCountryCode)
624      */
625     static class IsoCountryCode
626     {
627         /**
628          * PART1_ALPHA2 is used to represent the ISO3166-1 alpha-2 two letter
629          * country codes.
630          */
631         __gshared IsoCountryCode PART1_ALPHA2;
632 
633         shared static this()
634         {
635             PART1_ALPHA2 = new class IsoCountryCode
636             {
637                 override Set!(string) createCountryCodeSet()
638                 {
639                     implementationMissing();
640                     return null;
641                     // return Set.of(Locale.getISOCountries());
642                 }
643             };
644             PART1_ALPHA3 = new class IsoCountryCode
645             {
646                 override Set!(string) createCountryCodeSet()
647                 {
648                      implementationMissing();
649                     return null;
650                     // return LocaleISOData.computeISO3166_1Alpha3Countries();
651                 }
652             };
653 
654             PART3 = new class IsoCountryCode
655             {
656                 override Set!(string) createCountryCodeSet()
657                 {
658                      implementationMissing();
659                     return null;
660                     // return Set.of(LocaleISOData.ISO3166_3);
661                 }
662             };
663         }
664 
665         /**
666          *
667          * PART1_ALPHA3 is used to represent the ISO3166-1 alpha-3 three letter
668          * country codes.
669          */
670         __gshared IsoCountryCode PART1_ALPHA3;
671 
672         /**
673          * PART3 is used to represent the ISO3166-3 four letter country codes.
674          */
675         __gshared IsoCountryCode PART3;
676 
677         /**
678          * Concrete implementation of this method attempts to compute value
679          * for iso3166CodesMap for each IsoCountryCode type key.
680          */
681         abstract Set!(string) createCountryCodeSet();
682 
683         /**
684          * Map to hold country codes for each ISO3166 part.
685          */
686         private __gshared Map!(IsoCountryCode, Set!(string)) iso3166CodesMap;
687 
688         shared static this()
689         {
690             iso3166CodesMap = new HashMap!(IsoCountryCode, Set!(string))();
691         }
692 
693         /**
694          * This method is called from Locale class to retrieve country code set
695          * for getISOCountries(type)
696          */
697         static Set!(string) retrieveISOCountryCodes(IsoCountryCode type)
698         {
699             implementationMissing();
700             return null;
701             // return iso3166CodesMap.computeIfAbsent(type, IsoCountryCode.createCountryCodeSet);
702         }
703     }
704 
705     /**
706      * Display types for retrieving localized names from the name providers.
707      */
708     private enum int DISPLAY_LANGUAGE = 0;
709     private enum int DISPLAY_COUNTRY = 1;
710     private enum int DISPLAY_VARIANT = 2;
711     private enum int DISPLAY_SCRIPT = 3;
712     private enum int DISPLAY_UEXT_KEY = 4;
713     private enum int DISPLAY_UEXT_TYPE = 5;
714 
715     private string language;
716     private string script;
717     private string region;
718     private string variant;
719 
720     /**
721      * Private constructor used by getInstance method
722      */
723     // private this(BaseLocale baseLocale, LocaleExtensions extensions) {
724     //     this.baseLocale = baseLocale;
725     //     this.localeExtensions = extensions;
726     // }
727 
728     /**
729      * Construct a locale from language, country and variant.
730      * This constructor normalizes the language value to lowercase and
731      * the country value to uppercase.
732      * <p>
733      * <b>Note:</b>
734      * <ul>
735      * <li>ISO 639 is not a stable standard; some of the language codes it defines
736      * (specifically "iw", "ji", and "in") have changed.  This constructor accepts both the
737      * old codes ("iw", "ji", and "in") and the new codes ("he", "yi", and "id"), but all other
738      * API on Locale will return only the OLD codes.
739      * <li>For backward compatibility reasons, this constructor does not make
740      * any syntactic checks on the input.
741      * <li>The two cases ("ja", "JP", "JP") and ("th", "TH", "TH") are handled specially,
742      * see <a href="#special_cases_constructor">Special Cases</a> for more information.
743      * </ul>
744      *
745      * @param language An ISO 639 alpha-2 or alpha-3 language code, or a language subtag
746      * up to 8 characters in length.  See the <code>Locale</code> class description about
747      * valid language values.
748      * @param country An ISO 3166 alpha-2 country code or a UN M.49 numeric-3 area code.
749      * See the <code>Locale</code> class description about valid country values.
750      * @param variant Any arbitrary value used to indicate a variation of a <code>Locale</code>.
751      * See the <code>Locale</code> class description for the details.
752      * @exception NullPointerException thrown if any argument is null.
753      */
754     this(string language, string country, string variant)
755     {
756         if (language is null || country is null || variant is null)
757         {
758             throw new NullPointerException();
759         }
760 
761         this.language = convertOldISOCodes(language);        
762         this.region = country;
763         this.variant = variant;
764     }
765 
766     /**
767      * Construct a locale from language and country.
768      * This constructor normalizes the language value to lowercase and
769      * the country value to uppercase.
770      * <p>
771      * <b>Note:</b>
772      * <ul>
773      * <li>ISO 639 is not a stable standard; some of the language codes it defines
774      * (specifically "iw", "ji", and "in") have changed.  This constructor accepts both the
775      * old codes ("iw", "ji", and "in") and the new codes ("he", "yi", and "id"), but all other
776      * API on Locale will return only the OLD codes.
777      * <li>For backward compatibility reasons, this constructor does not make
778      * any syntactic checks on the input.
779      * </ul>
780      *
781      * @param language An ISO 639 alpha-2 or alpha-3 language code, or a language subtag
782      * up to 8 characters in length.  See the <code>Locale</code> class description about
783      * valid language values.
784      * @param country An ISO 3166 alpha-2 country code or a UN M.49 numeric-3 area code.
785      * See the <code>Locale</code> class description about valid country values.
786      * @exception NullPointerException thrown if either argument is null.
787      */
788     this(string language, string country)
789     {
790         this(language, country, "");
791     }
792 
793     /**
794      * Construct a locale from a language code.
795      * This constructor normalizes the language value to lowercase.
796      * <p>
797      * <b>Note:</b>
798      * <ul>
799      * <li>ISO 639 is not a stable standard; some of the language codes it defines
800      * (specifically "iw", "ji", and "in") have changed.  This constructor accepts both the
801      * old codes ("iw", "ji", and "in") and the new codes ("he", "yi", and "id"), but all other
802      * API on Locale will return only the OLD codes.
803      * <li>For backward compatibility reasons, this constructor does not make
804      * any syntactic checks on the input.
805      * </ul>
806      *
807      * @param language An ISO 639 alpha-2 or alpha-3 language code, or a language subtag
808      * up to 8 characters in length.  See the <code>Locale</code> class description about
809      * valid language values.
810      * @exception NullPointerException thrown if argument is null.
811      */
812     this(string language)
813     {
814         this(language, "", "");
815     }
816 
817     /**
818      * This method must be called only for creating the Locale.*
819      * constants due to making shortcuts.
820      */
821     private static Locale createConstant(string lang, string country)
822     {
823         // BaseLocale base = BaseLocale.createInstance(lang, country);
824         // return getInstance(base, null);
825         Locale le = new Locale(lang, country);
826         size_t key = hashOf(lang, country) ;
827         LOCALECACHE[key] = le;
828 
829         return le;
830     }
831 
832     static size_t hashOf(string language, string country, string script = null, string variant = null) {
833         size_t r = 0;
834         if(language !is null)
835             r += .hashOf(language.toLower());
836         if(country !is null)
837             r += .hashOf(country.toLower());
838         if(script !is null)
839             r += .hashOf(script.toLower());
840         if(variant !is null)
841             r += .hashOf(variant.toLower());
842         return r;
843     }
844 
845     /**
846      * Returns a <code>Locale</code> constructed from the given
847      * <code>language</code>, <code>country</code> and
848      * <code>variant</code>. If the same <code>Locale</code> instance
849      * is available in the cache, then that instance is
850      * returned. Otherwise, a new <code>Locale</code> instance is
851      * created and cached.
852      *
853      * @param language lowercase 2 to 8 language code.
854      * @param country uppercase two-letter ISO-3166 code and numeric-3 UN M.49 area code.
855      * @param variant vendor and browser specific code. See class description.
856      * @return the <code>Locale</code> instance requested
857      * @exception NullPointerException if any argument is null.
858      */
859     static Locale getInstance(string language, string country, string variant) {
860         return getInstance(language, "", country, variant);
861     }
862 
863     static Locale getInstance(string language, string script, string country, string variant) {
864         if (language is null || script is null || country is null || variant is null) {
865             throw new NullPointerException();
866         }
867 
868         version(HUNT_DEBUG) {
869             tracef("language=%s, script=%s, country=%s, variant=%s", 
870                 language, script, country, variant);
871         }
872         size_t key = hashOf(language, country, script, variant);
873         Locale le = LOCALECACHE.get(key, null);
874         if(le is null)  {
875             le = new Locale(language,  country, variant);
876             LOCALECACHE[key] = le;
877         }
878         return le;
879     }
880 
881     /**
882      * Gets the current value of the default locale for this instance
883      * of the Java Virtual Machine.
884      * <p>
885      * The Java Virtual Machine sets the default locale during startup
886      * based on the host environment. It is used by many locale-sensitive
887      * methods if no locale is explicitly specified.
888      * It can be changed using the
889      * {@link #setDefault(java.util.Locale) setDefault} method.
890      *
891      * @return the default locale for this instance of the Java Virtual Machine
892      */
893     static Locale getDefault()
894     {
895         return initOnce!(defaultLocale)(initDefault());
896         // do not synchronize this method - see 4071298
897     }
898     private __gshared Locale defaultLocale;
899 
900     /**
901      * Gets the current value of the default locale for the specified Category
902      * for this instance of the Java Virtual Machine.
903      * <p>
904      * The Java Virtual Machine sets the default locale during startup based
905      * on the host environment. It is used by many locale-sensitive methods
906      * if no locale is explicitly specified. It can be changed using the
907      * setDefault(LocaleCategory, Locale) method.
908      *
909      * @param category - the specified category to get the default locale
910      * @throws NullPointerException if category is null
911      * @return the default locale for the specified Category for this instance
912      *     of the Java Virtual Machine
913      * @see #setDefault(LocaleCategory, Locale)
914      */
915     static Locale getDefault(LocaleCategory category) {
916         // do not synchronize this method - see 4071298
917         if(category == LocaleCategory.DISPLAY) {
918             if (defaultDisplayLocale is null) {
919                 synchronized {
920                     if (defaultDisplayLocale is null) {
921                         defaultDisplayLocale = initDefault(category);
922                     }
923                 }
924             }
925             return defaultDisplayLocale;
926         } else if(category == LocaleCategory.FORMAT) {
927             if (defaultFormatLocale is null) {
928                 synchronized {
929                     if (defaultFormatLocale is null) {
930                         defaultFormatLocale = initDefault(category);
931                     }
932                 }
933             }
934             return defaultFormatLocale;
935         } else {
936             assert(false, "Unknown locale category");
937         }
938     }
939 
940     private static Locale initDefault() {
941         ConfigBuilder props = Environment.getProperties();
942         string language = props.getProperty("user.language", "en");
943         string script = props.getProperty("user.script", "");
944         string country = props.getProperty("user.country", "");
945         string variant = props.getProperty("user.variant", "");
946 
947         return getInstance(language, script, country, variant);
948     }
949 
950     private static Locale initDefault(LocaleCategory category) {
951         ConfigBuilder props = Environment.getProperties();
952         Locale defaultLocale = getDefault();
953 
954         return getInstance(
955             props.getProperty(category.languageKey,
956                     defaultLocale.getLanguage()),
957             props.getProperty(category.scriptKey,
958                     defaultLocale.getScript()),
959             props.getProperty(category.countryKey,
960                     defaultLocale.getCountry()),
961             props.getProperty(category.variantKey,
962                     defaultLocale.getVariant()));
963     }
964 
965 
966     /**
967      * Sets the default locale for this instance of the Java Virtual Machine.
968      * This does not affect the host locale.
969      * <p>
970      * If there is a security manager, its <code>checkPermission</code>
971      * method is called with a <code>PropertyPermission("user.language", "write")</code>
972      * permission before the default locale is changed.
973      * <p>
974      * The Java Virtual Machine sets the default locale during startup
975      * based on the host environment. It is used by many locale-sensitive
976      * methods if no locale is explicitly specified.
977      * <p>
978      * Since changing the default locale may affect many different areas
979      * of functionality, this method should only be used if the caller
980      * is prepared to reinitialize locale-sensitive code running
981      * within the same Java Virtual Machine.
982      * <p>
983      * By setting the default locale with this method, all of the default
984      * locales for each Category are also set to the specified default locale.
985      *
986      * @throws SecurityException
987      *        if a security manager exists and its
988      *        <code>checkPermission</code> method doesn't allow the operation.
989      * @throws NullPointerException if <code>newLocale</code> is null
990      * @param newLocale the new default locale
991      * @see SecurityManager#checkPermission
992      * @see java.util.PropertyPermission
993      */
994     static void setDefault(Locale newLocale) {
995         setDefault(LocaleCategory.DISPLAY, newLocale);
996         setDefault(LocaleCategory.FORMAT, newLocale);
997         defaultLocale = newLocale;
998     }
999 
1000     /**
1001      * Sets the default locale for the specified Category for this instance
1002      * of the Java Virtual Machine. This does not affect the host locale.
1003      * <p>
1004      * If there is a security manager, its checkPermission method is called
1005      * with a PropertyPermission("user.language", "write") permission before
1006      * the default locale is changed.
1007      * <p>
1008      * The Java Virtual Machine sets the default locale during startup based
1009      * on the host environment. It is used by many locale-sensitive methods
1010      * if no locale is explicitly specified.
1011      * <p>
1012      * Since changing the default locale may affect many different areas of
1013      * functionality, this method should only be used if the caller is
1014      * prepared to reinitialize locale-sensitive code running within the
1015      * same Java Virtual Machine.
1016      *
1017      * @param category - the specified category to set the default locale
1018      * @param newLocale - the new default locale
1019      * @throws SecurityException if a security manager exists and its
1020      *     checkPermission method doesn't allow the operation.
1021      * @throws NullPointerException if category and/or newLocale is null
1022      * @see SecurityManager#checkPermission(java.security.Permission)
1023      * @see PropertyPermission
1024      * @see #getDefault(LocaleCategory)
1025      */
1026     static void setDefault(LocaleCategory category, Locale newLocale) {
1027         implementationMissing(false);
1028         // if (category is null)
1029         //     throw new NullPointerException("Category cannot be NULL");
1030         // if (newLocale is null)
1031         //     throw new NullPointerException("Can't set default locale to NULL");
1032 
1033         // SecurityManager sm = System.getSecurityManager();
1034         // if (sm !is null) sm.checkPermission(new PropertyPermission
1035         //                 ("user.language", "write"));
1036         // switch (category) {
1037         // case DISPLAY:
1038         //     defaultDisplayLocale = newLocale;
1039         //     break;
1040         // case FORMAT:
1041         //     defaultFormatLocale = newLocale;
1042         //     break;
1043         // default:
1044         //     assert false: "Unknown Category";
1045         // }
1046     }
1047 
1048     // /**
1049     //  * Returns an array of all installed locales.
1050     //  * The returned array represents the union of locales supported
1051     //  * by the Java runtime environment and by installed
1052     //  * {@link java.util.spi.LocaleServiceProvider LocaleServiceProvider}
1053     //  * implementations.  It must contain at least a <code>Locale</code>
1054     //  * instance equal to {@link java.util.Locale#US Locale.US}.
1055     //  *
1056     //  * @return An array of installed locales.
1057     //  */
1058     // static Locale[] getAvailableLocales() {
1059     //     return LocaleServiceProviderPool.getAllAvailableLocales();
1060     // }
1061 
1062     // /**
1063     //  * Returns a list of all 2-letter country codes defined in ISO 3166.
1064     //  * Can be used to create Locales.
1065     //  * This method is equivalent to {@link #getISOCountries(Locale.IsoCountryCode type)}
1066     //  * with {@code type}  {@link IsoCountryCode#PART1_ALPHA2}.
1067     //  * <p>
1068     //  * <b>Note:</b> The <code>Locale</code> class also supports other codes for
1069     //  * country (region), such as 3-letter numeric UN M.49 area codes.
1070     //  * Therefore, the list returned by this method does not contain ALL valid
1071     //  * codes that can be used to create Locales.
1072     //  * <p>
1073     //  * Note that this method does not return obsolete 2-letter country codes.
1074     //  * ISO3166-3 codes which designate country codes for those obsolete codes,
1075     //  * can be retrieved from {@link #getISOCountries(Locale.IsoCountryCode type)} with
1076     //  * {@code type}  {@link IsoCountryCode#PART3}.
1077     //  * @return An array of ISO 3166 two-letter country codes.
1078     //  */
1079     // static string[] getISOCountries() {
1080     //     if (isoCountries is null) {
1081     //         isoCountries = getISO2Table(LocaleISOData.isoCountryTable);
1082     //     }
1083     //     string[] result = new string[isoCountries.length];
1084     //     System.arraycopy(isoCountries, 0, result, 0, isoCountries.length);
1085     //     return result;
1086     // }
1087 
1088     // /**
1089     //  * Returns a {@code Set} of ISO3166 country codes for the specified type.
1090     //  *
1091     //  * @param type {@link Locale.IsoCountryCode} specified ISO code type.
1092     //  * @see java.util.Locale.IsoCountryCode
1093     //  * @throws NullPointerException if type is null
1094     //  * @return a {@code Set} of ISO country codes for the specified type.
1095     //  */
1096     // static Set!(string) getISOCountries(IsoCountryCode type) {
1097     //     assert(type);
1098     //     return IsoCountryCode.retrieveISOCountryCodes(type);
1099     // }
1100 
1101     // /**
1102     //  * Returns a list of all 2-letter language codes defined in ISO 639.
1103     //  * Can be used to create Locales.
1104     //  * <p>
1105     //  * <b>Note:</b>
1106     //  * <ul>
1107     //  * <li>ISO 639 is not a stable standard&mdash; some languages' codes have changed.
1108     //  * The list this function returns includes both the new and the old codes for the
1109     //  * languages whose codes have changed.
1110     //  * <li>The <code>Locale</code> class also supports language codes up to
1111     //  * 8 characters in length.  Therefore, the list returned by this method does
1112     //  * not contain ALL valid codes that can be used to create Locales.
1113     //  * </ul>
1114     //  *
1115     //  * @return An array of ISO 639 two-letter language codes.
1116     //  */
1117     // static string[] getISOLanguages() {
1118     //     if (isoLanguages is null) {
1119     //         isoLanguages = getISO2Table(LocaleISOData.isoLanguageTable);
1120     //     }
1121     //     string[] result = new string[isoLanguages.length];
1122     //     System.arraycopy(isoLanguages, 0, result, 0, isoLanguages.length);
1123     //     return result;
1124     // }
1125 
1126     // private static string[] getISO2Table(string table) {
1127     //     int len = table.length() / 5;
1128     //     string[] isoTable = new string[len];
1129     //     for (int i = 0, j = 0; i < len; i++, j += 5) {
1130     //         isoTable[i] = table.substring(j, j + 2);
1131     //     }
1132     //     return isoTable;
1133     // }
1134 
1135     /**
1136      * Returns the language code of this Locale.
1137      *
1138      * <p><b>Note:</b> ISO 639 is not a stable standard&mdash; some languages' codes have changed.
1139      * Locale's constructor recognizes both the new and the old codes for the languages
1140      * whose codes have changed, but this function always returns the old code.  If you
1141      * want to check for a specific language whose code has changed, don't do
1142      * <pre>
1143      * if (locale.getLanguage().equals("he")) // BAD!
1144      *    ...
1145      * </pre>
1146      * Instead, do
1147      * <pre>
1148      * if (locale.getLanguage().equals(new Locale("he").getLanguage()))
1149      *    ...
1150      * </pre>
1151      * @return The language code, or the empty string if none is defined.
1152      * @see #getDisplayLanguage
1153      */
1154     string getLanguage() {
1155         return language;
1156     }
1157 
1158     /**
1159      * Returns the script for this locale, which should
1160      * either be the empty string or an ISO 15924 4-letter script
1161      * code. The first letter is uppercase and the rest are
1162      * lowercase, for example, 'Latn', 'Cyrl'.
1163      *
1164      * @return The script code, or the empty string if none is defined.
1165      * @see #getDisplayScript
1166      */
1167     string getScript() {
1168         return script;
1169     }
1170 
1171     /**
1172      * Returns the country/region code for this locale, which should
1173      * either be the empty string, an uppercase ISO 3166 2-letter code,
1174      * or a UN M.49 3-digit code.
1175      *
1176      * @return The country/region code, or the empty string if none is defined.
1177      * @see #getDisplayCountry
1178      */
1179     string getCountry() {
1180         return region;
1181     }
1182 
1183     /**
1184      * Returns the variant code for this locale.
1185      *
1186      * @return The variant code, or the empty string if none is defined.
1187      * @see #getDisplayVariant
1188      */
1189     string getVariant() {
1190         return variant;
1191     }
1192 
1193     /**
1194      * Returns {@code true} if this {@code Locale} has any <a href="#def_extensions">
1195      * extensions</a>.
1196      *
1197      * @return {@code true} if this {@code Locale} has any extensions
1198      */
1199     bool hasExtensions() {
1200         return false;
1201     }
1202 
1203     // /**
1204     //  * Returns a copy of this {@code Locale} with no <a href="#def_extensions">
1205     //  * extensions</a>. If this {@code Locale} has no extensions, this {@code Locale}
1206     //  * is returned.
1207     //  *
1208     //  * @return a copy of this {@code Locale} with no extensions, or {@code this}
1209     //  *         if {@code this} has no extensions
1210     //  */
1211     // Locale stripExtensions() {
1212     //     return hasExtensions() ? Locale.getInstance(baseLocale, null) : this;
1213     // }
1214 
1215     // /**
1216     //  * Returns the extension (or private use) value associated with
1217     //  * the specified key, or null if there is no extension
1218     //  * associated with the key. To be well-formed, the key must be one
1219     //  * of <code>[0-9A-Za-z]</code>. Keys are case-insensitive, so
1220     //  * for example 'z' and 'Z' represent the same extension.
1221     //  *
1222     //  * @param key the extension key
1223     //  * @return The extension, or null if this locale defines no
1224     //  * extension for the specified key.
1225     //  * @throws IllegalArgumentException if key is not well-formed
1226     //  * @see #PRIVATE_USE_EXTENSION
1227     //  * @see #UNICODE_LOCALE_EXTENSION
1228     //  */
1229     // string getExtension(char key) {
1230     //     if (!LocaleExtensions.isValidKey(key)) {
1231     //         throw new IllegalArgumentException("Ill-formed extension key: " ~ key);
1232     //     }
1233     //     return hasExtensions() ? localeExtensions.getExtensionValue(key) : null;
1234     // }
1235 
1236     // /**
1237     //  * Returns the set of extension keys associated with this locale, or the
1238     //  * empty set if it has no extensions. The returned set is unmodifiable.
1239     //  * The keys will all be lower-case.
1240     //  *
1241     //  * @return The set of extension keys, or the empty set if this locale has
1242     //  * no extensions.
1243     //  */
1244     // Set<Character> getExtensionKeys() {
1245     //     if (!hasExtensions()) {
1246     //         return Collections.emptySet();
1247     //     }
1248     //     return localeExtensions.getKeys();
1249     // }
1250 
1251     // /**
1252     //  * Returns the set of unicode locale attributes associated with
1253     //  * this locale, or the empty set if it has no attributes. The
1254     //  * returned set is unmodifiable.
1255     //  *
1256     //  * @return The set of attributes.
1257     //  */
1258     // Set!(string) getUnicodeLocaleAttributes() {
1259     //     if (!hasExtensions()) {
1260     //         return Collections.emptySet();
1261     //     }
1262     //     return localeExtensions.getUnicodeLocaleAttributes();
1263     // }
1264 
1265     // /**
1266     //  * Returns the Unicode locale type associated with the specified Unicode locale key
1267     //  * for this locale. Returns the empty string for keys that are defined with no type.
1268     //  * Returns null if the key is not defined. Keys are case-insensitive. The key must
1269     //  * be two alphanumeric characters ([0-9a-zA-Z]), or an IllegalArgumentException is
1270     //  * thrown.
1271     //  *
1272     //  * @param key the Unicode locale key
1273     //  * @return The Unicode locale type associated with the key, or null if the
1274     //  * locale does not define the key.
1275     //  * @throws IllegalArgumentException if the key is not well-formed
1276     //  * @throws NullPointerException if <code>key</code> is null
1277     //  */
1278     string getUnicodeLocaleType(string key) {
1279         /* if (!isUnicodeExtensionKey(key)) {
1280             throw new IllegalArgumentException("Ill-formed Unicode locale key: " ~ key);
1281         }
1282         return hasExtensions() ? localeExtensions.getUnicodeLocaleType(key) : null; */
1283         return "iso";
1284     }
1285 
1286     // /**
1287     //  * Returns the set of Unicode locale keys defined by this locale, or the empty set if
1288     //  * this locale has none.  The returned set is immutable.  Keys are all lower case.
1289     //  *
1290     //  * @return The set of Unicode locale keys, or the empty set if this locale has
1291     //  * no Unicode locale keywords.
1292     //  */
1293     // Set!(string) getUnicodeLocaleKeys() {
1294     //     if (localeExtensions is null) {
1295     //         return Collections.emptySet();
1296     //     }
1297     //     return localeExtensions.getUnicodeLocaleKeys();
1298     // }
1299 
1300     // /**
1301     //  * Package locale method returning the Locale's BaseLocale,
1302     //  * used by ResourceBundle
1303     //  * @return base locale of this Locale
1304     //  */
1305     // BaseLocale getBaseLocale() {
1306     //     return baseLocale;
1307     // }
1308 
1309     // /**
1310     //  * Package private method returning the Locale's LocaleExtensions,
1311     //  * used by ResourceBundle.
1312     //  * @return locale extensions of this Locale,
1313     //  *         or {@code null} if no extensions are defined
1314     //  */
1315     //  LocaleExtensions getLocaleExtensions() {
1316     //      return localeExtensions;
1317     //  }
1318 
1319     /**
1320      * Returns a string representation of this <code>Locale</code>
1321      * object, consisting of language, country, variant, script,
1322      * and extensions as below:
1323      * <blockquote>
1324      * language ~ "_" ~ country ~ "_" ~ (variant ~ "_#" | "#") + script ~ "_" ~ extensions
1325      * </blockquote>
1326      *
1327      * Language is always lower case, country is always upper case, script is always title
1328      * case, and extensions are always lower case.  Extensions and private use subtags
1329      * will be in canonical order as explained in {@link #toLanguageTag}.
1330      *
1331      * <p>When the locale has neither script nor extensions, the result is the same as in
1332      * Java 6 and prior.
1333      *
1334      * <p>If both the language and country fields are missing, this function will return
1335      * the empty string, even if the variant, script, or extensions field is present (you
1336      * can't have a locale with just a variant, the variant must accompany a well-formed
1337      * language or country code).
1338      *
1339      * <p>If script or extensions are present and variant is missing, no underscore is
1340      * added before the "#".
1341      *
1342      * <p>This behavior is designed to support debugging and to be compatible with
1343      * previous uses of <code>toString</code> that expected language, country, and variant
1344      * fields only.  To represent a Locale as a string for interchange purposes, use
1345      * {@link #toLanguageTag}.
1346      *
1347      * <p>Examples: <ul>
1348      * <li>{@code en}</li>
1349      * <li>{@code de_DE}</li>
1350      * <li>{@code _GB}</li>
1351      * <li>{@code en_US_WIN}</li>
1352      * <li>{@code de__POSIX}</li>
1353      * <li>{@code zh_CN_#Hans}</li>
1354      * <li>{@code zh_TW_#Hant_x-java}</li>
1355      * <li>{@code th_TH_TH_#u-nu-thai}</li></ul>
1356      *
1357      * @return A string representation of the Locale, for debugging.
1358      * @see #getDisplayName
1359      * @see #toLanguageTag
1360      */
1361     override string toString() {
1362 
1363         bool l = (language.length != 0);
1364         bool s = (script.length != 0);
1365         bool r = (region.length != 0);
1366         bool v = (variant.length != 0);
1367         // bool e = (localeExtensions !is null && localeExtensions.getID().length() != 0);
1368 
1369         StringBuilder result = new StringBuilder(language);
1370         if (r || (l && (v || s ))) {
1371             result.append('_')
1372                 .append(region); // This may just append '_'
1373         }
1374         if (v && (l || r)) {
1375             result.append('_')
1376                 .append(variant);
1377         }
1378 
1379         if (s && (l || r)) {
1380             result.append("_#")
1381                 .append(script);
1382         }
1383 
1384         return result.toString();
1385     }
1386 
1387     // /**
1388     //  * Returns a well-formed IETF BCP 47 language tag representing
1389     //  * this locale.
1390     //  *
1391     //  * <p>If this <code>Locale</code> has a language, country, or
1392     //  * variant that does not satisfy the IETF BCP 47 language tag
1393     //  * syntax requirements, this method handles these fields as
1394     //  * described below:
1395     //  *
1396     //  * <p><b>Language:</b> If language is empty, or not <a
1397     //  * href="#def_language" >well-formed</a> (for example "a" or
1398     //  * "e2"), it will be emitted as "und" (Undetermined).
1399     //  *
1400     //  * <p><b>Country:</b> If country is not <a
1401     //  * href="#def_region">well-formed</a> (for example "12" or "USA"),
1402     //  * it will be omitted.
1403     //  *
1404     //  * <p><b>Variant:</b> If variant <b>is</b> <a
1405     //  * href="#def_variant">well-formed</a>, each sub-segment
1406     //  * (delimited by '-' or '_') is emitted as a subtag.  Otherwise:
1407     //  * <ul>
1408     //  *
1409     //  * <li>if all sub-segments match <code>[0-9a-zA-Z]{1,8}</code>
1410     //  * (for example "WIN" or "Oracle_JDK_Standard_Edition"), the first
1411     //  * ill-formed sub-segment and all following will be appended to
1412     //  * the private use subtag.  The first appended subtag will be
1413     //  * "lvariant", followed by the sub-segments in order, separated by
1414     //  * hyphen. For example, "x-lvariant-WIN",
1415     //  * "Oracle-x-lvariant-JDK-Standard-Edition".
1416     //  *
1417     //  * <li>if any sub-segment does not match
1418     //  * <code>[0-9a-zA-Z]{1,8}</code>, the variant will be truncated
1419     //  * and the problematic sub-segment and all following sub-segments
1420     //  * will be omitted.  If the remainder is non-empty, it will be
1421     //  * emitted as a private use subtag as above (even if the remainder
1422     //  * turns out to be well-formed).  For example,
1423     //  * "Solaris_isjustthecoolestthing" is emitted as
1424     //  * "x-lvariant-Solaris", not as "solaris".</li></ul>
1425     //  *
1426     //  * <p><b>Special Conversions:</b> Java supports some old locale
1427     //  * representations, including deprecated ISO language codes,
1428     //  * for compatibility. This method performs the following
1429     //  * conversions:
1430     //  * <ul>
1431     //  *
1432     //  * <li>Deprecated ISO language codes "iw", "ji", and "in" are
1433     //  * converted to "he", "yi", and "id", respectively.
1434     //  *
1435     //  * <li>A locale with language "no", country "NO", and variant
1436     //  * "NY", representing Norwegian Nynorsk (Norway), is converted
1437     //  * to a language tag "nn-NO".</li></ul>
1438     //  *
1439     //  * <p><b>Note:</b> Although the language tag created by this
1440     //  * method is well-formed (satisfies the syntax requirements
1441     //  * defined by the IETF BCP 47 specification), it is not
1442     //  * necessarily a valid BCP 47 language tag.  For example,
1443     //  * <pre>
1444     //  *   new Locale("xx", "YY").toLanguageTag();</pre>
1445     //  *
1446     //  * will return "xx-YY", but the language subtag "xx" and the
1447     //  * region subtag "YY" are invalid because they are not registered
1448     //  * in the IANA Language Subtag Registry.
1449     //  *
1450     //  * @return a BCP47 language tag representing the locale
1451     //  * @see #forLanguageTag(string)
1452     //  */
1453     // string toLanguageTag() {
1454     //     if (languageTag !is null) {
1455     //         return languageTag;
1456     //     }
1457 
1458     //     LanguageTag tag = LanguageTag.parseLocale(baseLocale, localeExtensions);
1459     //     StringBuilder buf = new StringBuilder();
1460 
1461     //     string subtag = tag.getLanguage();
1462     //     if (subtag.length() > 0) {
1463     //         buf.append(LanguageTag.canonicalizeLanguage(subtag));
1464     //     }
1465 
1466     //     subtag = tag.getScript();
1467     //     if (subtag.length() > 0) {
1468     //         buf.append(LanguageTag.SEP);
1469     //         buf.append(LanguageTag.canonicalizeScript(subtag));
1470     //     }
1471 
1472     //     subtag = tag.getRegion();
1473     //     if (subtag.length() > 0) {
1474     //         buf.append(LanguageTag.SEP);
1475     //         buf.append(LanguageTag.canonicalizeRegion(subtag));
1476     //     }
1477 
1478     //     List<string>subtags = tag.getVariants();
1479     //     for (string s : subtags) {
1480     //         buf.append(LanguageTag.SEP);
1481     //         // preserve casing
1482     //         buf.append(s);
1483     //     }
1484 
1485     //     subtags = tag.getExtensions();
1486     //     for (string s : subtags) {
1487     //         buf.append(LanguageTag.SEP);
1488     //         buf.append(LanguageTag.canonicalizeExtension(s));
1489     //     }
1490 
1491     //     subtag = tag.getPrivateuse();
1492     //     if (subtag.length() > 0) {
1493     //         if (buf.length() > 0) {
1494     //             buf.append(LanguageTag.SEP);
1495     //         }
1496     //         buf.append(LanguageTag.PRIVATEUSE).append(LanguageTag.SEP);
1497     //         // preserve casing
1498     //         buf.append(subtag);
1499     //     }
1500 
1501     //     string langTag = buf.toString();
1502     //     synchronized (this) {
1503     //         if (languageTag is null) {
1504     //             languageTag = langTag;
1505     //         }
1506     //     }
1507     //     return languageTag;
1508     // }
1509 
1510     // /**
1511     //  * Returns a locale for the specified IETF BCP 47 language tag string.
1512     //  *
1513     //  * <p>If the specified language tag contains any ill-formed subtags,
1514     //  * the first such subtag and all following subtags are ignored.  Compare
1515     //  * to {@link Locale.Builder#setLanguageTag} which throws an exception
1516     //  * in this case.
1517     //  *
1518     //  * <p>The following <b>conversions</b> are performed:<ul>
1519     //  *
1520     //  * <li>The language code "und" is mapped to language "".
1521     //  *
1522     //  * <li>The language codes "he", "yi", and "id" are mapped to "iw",
1523     //  * "ji", and "in" respectively. (This is the same canonicalization
1524     //  * that's done in Locale's constructors.)
1525     //  *
1526     //  * <li>The portion of a private use subtag prefixed by "lvariant",
1527     //  * if any, is removed and appended to the variant field in the
1528     //  * result locale (without case normalization).  If it is then
1529     //  * empty, the private use subtag is discarded:
1530     //  *
1531     //  * <pre>
1532     //  *     Locale loc;
1533     //  *     loc = Locale.forLanguageTag("en-US-x-lvariant-POSIX");
1534     //  *     loc.getVariant(); // returns "POSIX"
1535     //  *     loc.getExtension('x'); // returns null
1536     //  *
1537     //  *     loc = Locale.forLanguageTag("de-POSIX-x-URP-lvariant-Abc-Def");
1538     //  *     loc.getVariant(); // returns "POSIX_Abc_Def"
1539     //  *     loc.getExtension('x'); // returns "urp"
1540     //  * </pre>
1541     //  *
1542     //  * <li>When the languageTag argument contains an extlang subtag,
1543     //  * the first such subtag is used as the language, and the primary
1544     //  * language subtag and other extlang subtags are ignored:
1545     //  *
1546     //  * <pre>
1547     //  *     Locale.forLanguageTag("ar-aao").getLanguage(); // returns "aao"
1548     //  *     Locale.forLanguageTag("en-abc-def-us").toString(); // returns "abc_US"
1549     //  * </pre>
1550     //  *
1551     //  * <li>Case is normalized except for variant tags, which are left
1552     //  * unchanged.  Language is normalized to lower case, script to
1553     //  * title case, country to upper case, and extensions to lower
1554     //  * case.
1555     //  *
1556     //  * <li>If, after processing, the locale would exactly match either
1557     //  * ja_JP_JP or th_TH_TH with no extensions, the appropriate
1558     //  * extensions are added as though the constructor had been called:
1559     //  *
1560     //  * <pre>
1561     //  *    Locale.forLanguageTag("ja-JP-x-lvariant-JP").toLanguageTag();
1562     //  *    // returns "ja-JP-u-ca-japanese-x-lvariant-JP"
1563     //  *    Locale.forLanguageTag("th-TH-x-lvariant-TH").toLanguageTag();
1564     //  *    // returns "th-TH-u-nu-thai-x-lvariant-TH"
1565     //  * </pre></ul>
1566     //  *
1567     //  * <p>This implements the 'Language-Tag' production of BCP47, and
1568     //  * so supports grandfathered (regular and irregular) as well as
1569     //  * private use language tags.  Stand alone private use tags are
1570     //  * represented as empty language and extension 'x-whatever',
1571     //  * and grandfathered tags are converted to their canonical replacements
1572     //  * where they exist.
1573     //  *
1574     //  * <p>Grandfathered tags with canonical replacements are as follows:
1575     //  *
1576     //  * <table class="striped">
1577     //  * <caption style="display:none">Grandfathered tags with canonical replacements</caption>
1578     //  * <thead style="text-align:center">
1579     //  * <tr><th scope="col" style="padding: 0 2px">grandfathered tag</th><th scope="col" style="padding: 0 2px">modern replacement</th></tr>
1580     //  * </thead>
1581     //  * <tbody style="text-align:center">
1582     //  * <tr><th scope="row">art-lojban</th><td>jbo</td></tr>
1583     //  * <tr><th scope="row">i-ami</th><td>ami</td></tr>
1584     //  * <tr><th scope="row">i-bnn</th><td>bnn</td></tr>
1585     //  * <tr><th scope="row">i-hak</th><td>hak</td></tr>
1586     //  * <tr><th scope="row">i-klingon</th><td>tlh</td></tr>
1587     //  * <tr><th scope="row">i-lux</th><td>lb</td></tr>
1588     //  * <tr><th scope="row">i-navajo</th><td>nv</td></tr>
1589     //  * <tr><th scope="row">i-pwn</th><td>pwn</td></tr>
1590     //  * <tr><th scope="row">i-tao</th><td>tao</td></tr>
1591     //  * <tr><th scope="row">i-tay</th><td>tay</td></tr>
1592     //  * <tr><th scope="row">i-tsu</th><td>tsu</td></tr>
1593     //  * <tr><th scope="row">no-bok</th><td>nb</td></tr>
1594     //  * <tr><th scope="row">no-nyn</th><td>nn</td></tr>
1595     //  * <tr><th scope="row">sgn-BE-FR</th><td>sfb</td></tr>
1596     //  * <tr><th scope="row">sgn-BE-NL</th><td>vgt</td></tr>
1597     //  * <tr><th scope="row">sgn-CH-DE</th><td>sgg</td></tr>
1598     //  * <tr><th scope="row">zh-guoyu</th><td>cmn</td></tr>
1599     //  * <tr><th scope="row">zh-hakka</th><td>hak</td></tr>
1600     //  * <tr><th scope="row">zh-min-nan</th><td>nan</td></tr>
1601     //  * <tr><th scope="row">zh-xiang</th><td>hsn</td></tr>
1602     //  * </tbody>
1603     //  * </table>
1604     //  *
1605     //  * <p>Grandfathered tags with no modern replacement will be
1606     //  * converted as follows:
1607     //  *
1608     //  * <table class="striped">
1609     //  * <caption style="display:none">Grandfathered tags with no modern replacement</caption>
1610     //  * <thead style="text-align:center">
1611     //  * <tr><th scope="col" style="padding: 0 2px">grandfathered tag</th><th scope="col" style="padding: 0 2px">converts to</th></tr>
1612     //  * </thead>
1613     //  * <tbody style="text-align:center">
1614     //  * <tr><th scope="row">cel-gaulish</th><td>xtg-x-cel-gaulish</td></tr>
1615     //  * <tr><th scope="row">en-GB-oed</th><td>en-GB-x-oed</td></tr>
1616     //  * <tr><th scope="row">i-default</th><td>en-x-i-default</td></tr>
1617     //  * <tr><th scope="row">i-enochian</th><td>und-x-i-enochian</td></tr>
1618     //  * <tr><th scope="row">i-mingo</th><td>see-x-i-mingo</td></tr>
1619     //  * <tr><th scope="row">zh-min</th><td>nan-x-zh-min</td></tr>
1620     //  * </tbody>
1621     //  * </table>
1622     //  *
1623     //  * <p>For a list of all grandfathered tags, see the
1624     //  * IANA Language Subtag Registry (search for "Type: grandfathered").
1625     //  *
1626     //  * <p><b>Note</b>: there is no guarantee that <code>toLanguageTag</code>
1627     //  * and <code>forLanguageTag</code> will round-trip.
1628     //  *
1629     //  * @param languageTag the language tag
1630     //  * @return The locale that best represents the language tag.
1631     //  * @throws NullPointerException if <code>languageTag</code> is <code>null</code>
1632     //  * @see #toLanguageTag()
1633     //  * @see java.util.Locale.Builder#setLanguageTag(string)
1634     //  */
1635     // static Locale forLanguageTag(string languageTag) {
1636     //     LanguageTag tag = LanguageTag.parse(languageTag, null);
1637     //     InternalLocaleBuilder bldr = new InternalLocaleBuilder();
1638     //     bldr.setLanguageTag(tag);
1639     //     BaseLocale base = bldr.getBaseLocale();
1640     //     LocaleExtensions exts = bldr.getLocaleExtensions();
1641     //     if (exts is null && base.getVariant().length() > 0) {
1642     //         exts = getCompatibilityExtensions(base.getLanguage(), base.getScript(),
1643     //                                           base.getRegion(), base.getVariant());
1644     //     }
1645     //     return getInstance(base, exts);
1646     // }
1647 
1648     // /**
1649     //  * Returns a three-letter abbreviation of this locale's language.
1650     //  * If the language matches an ISO 639-1 two-letter code, the
1651     //  * corresponding ISO 639-2/T three-letter lowercase code is
1652     //  * returned.  The ISO 639-2 language codes can be found on-line,
1653     //  * see "Codes for the Representation of Names of Languages Part 2:
1654     //  * Alpha-3 Code".  If the locale specifies a three-letter
1655     //  * language, the language is returned as is.  If the locale does
1656     //  * not specify a language the empty string is returned.
1657     //  *
1658     //  * @return A three-letter abbreviation of this locale's language.
1659     //  * @exception MissingResourceException Throws MissingResourceException if
1660     //  * three-letter language abbreviation is not available for this locale.
1661     //  */
1662     // string getISO3Language() throws MissingResourceException {
1663     //     string lang = language;
1664     //     if (lang.length() == 3) {
1665     //         return lang;
1666     //     }
1667 
1668     //     string language3 = getISO3Code(lang, LocaleISOData.isoLanguageTable);
1669     //     if (language3 is null) {
1670     //         throw new MissingResourceException("Couldn't find 3-letter language code for "
1671     //                 + lang, "FormatData_" ~ toString(), "ShortLanguage");
1672     //     }
1673     //     return language3;
1674     // }
1675 
1676     // /**
1677     //  * Returns a three-letter abbreviation for this locale's country.
1678     //  * If the country matches an ISO 3166-1 alpha-2 code, the
1679     //  * corresponding ISO 3166-1 alpha-3 uppercase code is returned.
1680     //  * If the locale doesn't specify a country, this will be the empty
1681     //  * string.
1682     //  *
1683     //  * <p>The ISO 3166-1 codes can be found on-line.
1684     //  *
1685     //  * @return A three-letter abbreviation of this locale's country.
1686     //  * @exception MissingResourceException Throws MissingResourceException if the
1687     //  * three-letter country abbreviation is not available for this locale.
1688     //  */
1689     // string getISO3Country() throws MissingResourceException {
1690     //     string country3 = getISO3Code(region, LocaleISOData.isoCountryTable);
1691     //     if (country3 is null) {
1692     //         throw new MissingResourceException("Couldn't find 3-letter country code for "
1693     //                 + region, "FormatData_" ~ toString(), "ShortCountry");
1694     //     }
1695     //     return country3;
1696     // }
1697 
1698     // private static string getISO3Code(string iso2Code, string table) {
1699     //     int codeLength = iso2Code.length();
1700     //     if (codeLength == 0) {
1701     //         return "";
1702     //     }
1703 
1704     //     int tableLength = table.length();
1705     //     int index = tableLength;
1706     //     if (codeLength == 2) {
1707     //         char c1 = iso2Code[0];
1708     //         char c2 = iso2Code[1];
1709     //         for (index = 0; index < tableLength; index += 5) {
1710     //             if (table[index] == c1
1711     //                 && table[index + 1] == c2) {
1712     //                 break;
1713     //             }
1714     //         }
1715     //     }
1716     //     return index < tableLength ? table.substring(index + 2, index + 5) : null;
1717     // }
1718 
1719     // /**
1720     //  * Returns a name for the locale's language that is appropriate for display to the
1721     //  * user.
1722     //  * If possible, the name returned will be localized for the default
1723     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale.
1724     //  * For example, if the locale is fr_FR and the default
1725     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale
1726     //  * is en_US, getDisplayLanguage() will return "French"; if the locale is en_US and
1727     //  * the default {@link LocaleCategory#DISPLAY DISPLAY} locale is fr_FR,
1728     //  * getDisplayLanguage() will return "anglais".
1729     //  * If the name returned cannot be localized for the default
1730     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale,
1731     //  * (say, we don't have a Japanese name for Croatian),
1732     //  * this function falls back on the English name, and uses the ISO code as a last-resort
1733     //  * value.  If the locale doesn't specify a language, this function returns the empty string.
1734     //  *
1735     //  * @return The name of the display language.
1736     //  */
1737     // final string getDisplayLanguage() {
1738     //     return getDisplayLanguage(getDefault(Category.DISPLAY));
1739     // }
1740 
1741     // /**
1742     //  * Returns a name for the locale's language that is appropriate for display to the
1743     //  * user.
1744     //  * If possible, the name returned will be localized according to inLocale.
1745     //  * For example, if the locale is fr_FR and inLocale
1746     //  * is en_US, getDisplayLanguage() will return "French"; if the locale is en_US and
1747     //  * inLocale is fr_FR, getDisplayLanguage() will return "anglais".
1748     //  * If the name returned cannot be localized according to inLocale,
1749     //  * (say, we don't have a Japanese name for Croatian),
1750     //  * this function falls back on the English name, and finally
1751     //  * on the ISO code as a last-resort value.  If the locale doesn't specify a language,
1752     //  * this function returns the empty string.
1753     //  *
1754     //  * @param inLocale The locale for which to retrieve the display language.
1755     //  * @return The name of the display language appropriate to the given locale.
1756     //  * @exception NullPointerException if <code>inLocale</code> is <code>null</code>
1757     //  */
1758     // string getDisplayLanguage(Locale inLocale) {
1759     //     return getDisplaystring(language, null, inLocale, DISPLAY_LANGUAGE);
1760     // }
1761 
1762     // /**
1763     //  * Returns a name for the locale's script that is appropriate for display to
1764     //  * the user. If possible, the name will be localized for the default
1765     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale.  Returns
1766     //  * the empty string if this locale doesn't specify a script code.
1767     //  *
1768     //  * @return the display name of the script code for the current default
1769     //  *     {@link LocaleCategory#DISPLAY DISPLAY} locale
1770     //  */
1771     // string getDisplayScript() {
1772     //     return getDisplayScript(getDefault(Category.DISPLAY));
1773     // }
1774 
1775     // /**
1776     //  * Returns a name for the locale's script that is appropriate
1777     //  * for display to the user. If possible, the name will be
1778     //  * localized for the given locale. Returns the empty string if
1779     //  * this locale doesn't specify a script code.
1780     //  *
1781     //  * @param inLocale The locale for which to retrieve the display script.
1782     //  * @return the display name of the script code for the current default
1783     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale
1784     //  * @throws NullPointerException if <code>inLocale</code> is <code>null</code>
1785     //  */
1786     // string getDisplayScript(Locale inLocale) {
1787     //     return getDisplaystring(script, null, inLocale, DISPLAY_SCRIPT);
1788     // }
1789 
1790     // /**
1791     //  * Returns a name for the locale's country that is appropriate for display to the
1792     //  * user.
1793     //  * If possible, the name returned will be localized for the default
1794     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale.
1795     //  * For example, if the locale is fr_FR and the default
1796     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale
1797     //  * is en_US, getDisplayCountry() will return "France"; if the locale is en_US and
1798     //  * the default {@link LocaleCategory#DISPLAY DISPLAY} locale is fr_FR,
1799     //  * getDisplayCountry() will return "Etats-Unis".
1800     //  * If the name returned cannot be localized for the default
1801     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale,
1802     //  * (say, we don't have a Japanese name for Croatia),
1803     //  * this function falls back on the English name, and uses the ISO code as a last-resort
1804     //  * value.  If the locale doesn't specify a country, this function returns the empty string.
1805     //  *
1806     //  * @return The name of the country appropriate to the locale.
1807     //  */
1808     // final string getDisplayCountry() {
1809     //     return getDisplayCountry(getDefault(Category.DISPLAY));
1810     // }
1811 
1812     // /**
1813     //  * Returns a name for the locale's country that is appropriate for display to the
1814     //  * user.
1815     //  * If possible, the name returned will be localized according to inLocale.
1816     //  * For example, if the locale is fr_FR and inLocale
1817     //  * is en_US, getDisplayCountry() will return "France"; if the locale is en_US and
1818     //  * inLocale is fr_FR, getDisplayCountry() will return "Etats-Unis".
1819     //  * If the name returned cannot be localized according to inLocale.
1820     //  * (say, we don't have a Japanese name for Croatia),
1821     //  * this function falls back on the English name, and finally
1822     //  * on the ISO code as a last-resort value.  If the locale doesn't specify a country,
1823     //  * this function returns the empty string.
1824     //  *
1825     //  * @param inLocale The locale for which to retrieve the display country.
1826     //  * @return The name of the country appropriate to the given locale.
1827     //  * @exception NullPointerException if <code>inLocale</code> is <code>null</code>
1828     //  */
1829     // string getDisplayCountry(Locale inLocale) {
1830     //     return getDisplaystring(region, null, inLocale, DISPLAY_COUNTRY);
1831     // }
1832 
1833     // private string getDisplaystring(string code, string cat, Locale inLocale, int type) {
1834     //     assert(inLocale);
1835     //     assert(code);
1836 
1837     //     if (code.isEmpty()) {
1838     //         return "";
1839     //     }
1840 
1841     //     LocaleServiceProviderPool pool =
1842     //         LocaleServiceProviderPool.getPool(LocaleNameProvider.class);
1843     //     string rbKey = (type == DISPLAY_VARIANT ? "%%"+code : code);
1844     //     string result = pool.getLocalizedObject(
1845     //                             LocaleNameGetter.INSTANCE,
1846     //                             inLocale, rbKey, type, code, cat);
1847     //     return result !is null ? result : code;
1848     // }
1849 
1850     // /**
1851     //  * Returns a name for the locale's variant code that is appropriate for display to the
1852     //  * user.  If possible, the name will be localized for the default
1853     //  * {@link LocaleCategory#DISPLAY DISPLAY} locale.  If the locale
1854     //  * doesn't specify a variant code, this function returns the empty string.
1855     //  *
1856     //  * @return The name of the display variant code appropriate to the locale.
1857     //  */
1858     // final string getDisplayVariant() {
1859     //     return getDisplayVariant(getDefault(Category.DISPLAY));
1860     // }
1861 
1862     // /**
1863     //  * Returns a name for the locale's variant code that is appropriate for display to the
1864     //  * user.  If possible, the name will be localized for inLocale.  If the locale
1865     //  * doesn't specify a variant code, this function returns the empty string.
1866     //  *
1867     //  * @param inLocale The locale for which to retrieve the display variant code.
1868     //  * @return The name of the display variant code appropriate to the given locale.
1869     //  * @exception NullPointerException if <code>inLocale</code> is <code>null</code>
1870     //  */
1871     // string getDisplayVariant(Locale inLocale) {
1872     //     if (variant.length() == 0)
1873     //         return "";
1874 
1875     //     LocaleResources lr = LocaleProviderAdapter
1876     //         .getResourceBundleBased()
1877     //         .getLocaleResources(inLocale);
1878 
1879     //     string names[] = getDisplayVariantArray(inLocale);
1880 
1881     //     // Get the localized patterns for formatting a list, and use
1882     //     // them to format the list.
1883     //     return formatList(names,
1884     //                       lr.getLocaleName("ListCompositionPattern"));
1885     // }
1886 
1887     // /**
1888     //  * Returns a name for the locale that is appropriate for display to the
1889     //  * user. This will be the values returned by getDisplayLanguage(),
1890     //  * getDisplayScript(), getDisplayCountry(), getDisplayVariant() and
1891     //  * optional <a href="./Locale.html#def_locale_extension">Unicode extensions</a>
1892     //  * assembled into a single string. The non-empty values are used in order, with
1893     //  * the second and subsequent names in parentheses.  For example:
1894     //  * <blockquote>
1895     //  * language (script, country, variant(, extension)*)<br>
1896     //  * language (country(, extension)*)<br>
1897     //  * language (variant(, extension)*)<br>
1898     //  * script (country(, extension)*)<br>
1899     //  * country (extension)*<br>
1900     //  * </blockquote>
1901     //  * depending on which fields are specified in the locale. The field
1902     //  * separator in the above parentheses, denoted as a comma character, may
1903     //  * be localized depending on the locale. If the language, script, country,
1904     //  * and variant fields are all empty, this function returns the empty string.
1905     //  *
1906     //  * @return The name of the locale appropriate to display.
1907     //  */
1908     // final string getDisplayName() {
1909     //     return getDisplayName(getDefault(Category.DISPLAY));
1910     // }
1911 
1912     // /**
1913     //  * Returns a name for the locale that is appropriate for display
1914     //  * to the user.  This will be the values returned by
1915     //  * getDisplayLanguage(), getDisplayScript(),getDisplayCountry()
1916     //  * getDisplayVariant(), and optional <a href="./Locale.html#def_locale_extension">
1917     //  * Unicode extensions</a> assembled into a single string. The non-empty
1918     //  * values are used in order, with the second and subsequent names in
1919     //  * parentheses.  For example:
1920     //  * <blockquote>
1921     //  * language (script, country, variant(, extension)*)<br>
1922     //  * language (country(, extension)*)<br>
1923     //  * language (variant(, extension)*)<br>
1924     //  * script (country(, extension)*)<br>
1925     //  * country (extension)*<br>
1926     //  * </blockquote>
1927     //  * depending on which fields are specified in the locale. The field
1928     //  * separator in the above parentheses, denoted as a comma character, may
1929     //  * be localized depending on the locale. If the language, script, country,
1930     //  * and variant fields are all empty, this function returns the empty string.
1931     //  *
1932     //  * @param inLocale The locale for which to retrieve the display name.
1933     //  * @return The name of the locale appropriate to display.
1934     //  * @throws NullPointerException if <code>inLocale</code> is <code>null</code>
1935     //  */
1936     // string getDisplayName(Locale inLocale) {
1937     //     LocaleResources lr =  LocaleProviderAdapter
1938     //         .getResourceBundleBased()
1939     //         .getLocaleResources(inLocale);
1940 
1941     //     string languageName = getDisplayLanguage(inLocale);
1942     //     string scriptName = getDisplayScript(inLocale);
1943     //     string countryName = getDisplayCountry(inLocale);
1944     //     string[] variantNames = getDisplayVariantArray(inLocale);
1945 
1946     //     // Get the localized patterns for formatting a display name.
1947     //     string displayNamePattern = lr.getLocaleName("DisplayNamePattern");
1948     //     string listCompositionPattern = lr.getLocaleName("ListCompositionPattern");
1949 
1950     //     // The display name consists of a main name, followed by qualifiers.
1951     //     // Typically, the format is "MainName (Qualifier, Qualifier)" but this
1952     //     // depends on what pattern is stored in the display locale.
1953     //     string   mainName       = null;
1954     //     string[] qualifierNames = null;
1955 
1956     //     // The main name is the language, or if there is no language, the script,
1957     //     // then if no script, the country. If there is no language/script/country
1958     //     // (an anomalous situation) then the display name is simply the variant's
1959     //     // display name.
1960     //     if (languageName.length() == 0 && scriptName.length() == 0 && countryName.length() == 0) {
1961     //         if (variantNames.length == 0) {
1962     //             return "";
1963     //         } else {
1964     //             return formatList(variantNames, listCompositionPattern);
1965     //         }
1966     //     }
1967     //     ArrayList<string> names = new ArrayList<>(4);
1968     //     if (languageName.length() != 0) {
1969     //         names.add(languageName);
1970     //     }
1971     //     if (scriptName.length() != 0) {
1972     //         names.add(scriptName);
1973     //     }
1974     //     if (countryName.length() != 0) {
1975     //         names.add(countryName);
1976     //     }
1977     //     if (variantNames.length != 0) {
1978     //         names.addAll(Arrays.asList(variantNames));
1979     //     }
1980 
1981     //     // add Unicode extensions
1982     //     if (localeExtensions !is null) {
1983     //         localeExtensions.getUnicodeLocaleAttributes().stream()
1984     //             .map(key -> getDisplaystring(key, null, inLocale, DISPLAY_UEXT_KEY))
1985     //             .forEach(names::add);
1986     //         localeExtensions.getUnicodeLocaleKeys().stream()
1987     //             .map(key -> getDisplayKeyTypeExtensionstring(key, lr, inLocale))
1988     //             .forEach(names::add);
1989     //     }
1990 
1991     //     // The first one in the main name
1992     //     mainName = names.get(0);
1993 
1994     //     // Others are qualifiers
1995     //     int numNames = names.size();
1996     //     qualifierNames = (numNames > 1) ?
1997     //             names.subList(1, numNames).toArray(new string[numNames - 1]) : new string[0];
1998 
1999     //     // Create an array whose first element is the number of remaining
2000     //     // elements.  This serves as a selector into a ChoiceFormat pattern from
2001     //     // the resource.  The second and third elements are the main name and
2002     //     // the qualifier; if there are no qualifiers, the third element is
2003     //     // unused by the format pattern.
2004     //     Object[] displayNames = {
2005     //         qualifierNames.length != 0 ? 2 : 1,
2006     //         mainName,
2007     //         // We could also just call formatList() and have it handle the empty
2008     //         // list case, but this is more efficient, and we want it to be
2009     //         // efficient since all the language-only locales will not have any
2010     //         // qualifiers.
2011     //         qualifierNames.length != 0 ? formatList(qualifierNames, listCompositionPattern) : null
2012     //     };
2013 
2014     //     if (displayNamePattern !is null) {
2015     //         return new MessageFormat(displayNamePattern).format(displayNames);
2016     //     }
2017     //     else {
2018     //         // If we cannot get the message format pattern, then we use a simple
2019     //         // hard-coded pattern.  This should not occur in practice unless the
2020     //         // installation is missing some core files (FormatData etc.).
2021     //         StringBuilder result = new StringBuilder();
2022     //         result.append((string)displayNames[1]);
2023     //         if (displayNames.length > 2) {
2024     //             result.append(" (");
2025     //             result.append((string)displayNames[2]);
2026     //             result.append(')');
2027     //         }
2028     //         return result.toString();
2029     //     }
2030     // }
2031 
2032     // /**
2033     //  * Overrides Cloneable.
2034     //  */
2035     // override
2036     // Object clone()
2037     // {
2038     //     try {
2039     //         Locale that = (Locale)super.clone();
2040     //         return that;
2041     //     } catch (CloneNotSupportedException e) {
2042     //         throw new InternalError(e);
2043     //     }
2044     // }
2045 
2046     // /**
2047     //  * Override hashCode.
2048     //  * Since Locales are often used in hashtables, caches the value
2049     //  * for speed.
2050     //  */
2051     // override
2052     // int hashCode() {
2053     //     int hc = hashCodeValue;
2054     //     if (hc == 0) {
2055     //         hc = baseLocale.hashCode();
2056     //         if (localeExtensions !is null) {
2057     //             hc ^= localeExtensions.hashCode();
2058     //         }
2059     //         hashCodeValue = hc;
2060     //     }
2061     //     return hc;
2062     // }
2063 
2064     // // Overrides
2065 
2066     // /**
2067     //  * Returns true if this Locale is equal to another object.  A Locale is
2068     //  * deemed equal to another Locale with identical language, script, country,
2069     //  * variant and extensions, and unequal to all other objects.
2070     //  *
2071     //  * @return true if this Locale is equal to the specified object.
2072     //  */
2073     // override
2074     // bool equals(Object obj) {
2075     //     if (this is obj)                      // quick check
2076     //         return true;
2077     //     if (!(obj instanceof Locale))
2078     //         return false;
2079     //     BaseLocale otherBase = ((Locale)obj).baseLocale;
2080     //     if (!baseLocale.equals(otherBase)) {
2081     //         return false;
2082     //     }
2083     //     if (localeExtensions is null) {
2084     //         return ((Locale)obj).localeExtensions is null;
2085     //     }
2086     //     return localeExtensions.equals(((Locale)obj).localeExtensions);
2087     // }
2088 
2089     // // ================= privates =====================================
2090 
2091     // private BaseLocale baseLocale;
2092     // private LocaleExtensions localeExtensions;
2093 
2094     /**
2095      * Calculated hashcode
2096      */
2097     private int hashCodeValue;
2098 
2099     // private __gshared Locale _defaultLocale;
2100     private __gshared Locale defaultDisplayLocale;
2101     private __gshared Locale defaultFormatLocale;
2102 
2103     private string languageTag;
2104 
2105     // /**
2106     //  * Return an array of the display names of the variant.
2107     //  * @param bundle the ResourceBundle to use to get the display names
2108     //  * @return an array of display names, possible of zero length.
2109     //  */
2110     // private string[] getDisplayVariantArray(Locale inLocale) {
2111     //     // Split the variant name into tokens separated by '_'.
2112     //     stringTokenizer tokenizer = new stringTokenizer(variant, "_");
2113     //     string[] names = new string[tokenizer.countTokens()];
2114 
2115     //     // For each variant token, lookup the display name.  If
2116     //     // not found, use the variant name itself.
2117     //     for (int i=0; i<names.length; ++i) {
2118     //         names[i] = getDisplaystring(tokenizer.nextToken(), null,
2119     //                             inLocale, DISPLAY_VARIANT);
2120     //     }
2121 
2122     //     return names;
2123     // }
2124 
2125     // private string getDisplayKeyTypeExtensionstring(string key, LocaleResources lr, Locale inLocale) {
2126     //     string type = localeExtensions.getUnicodeLocaleType(key);
2127     //     string ret = getDisplaystring(type, key, inLocale, DISPLAY_UEXT_TYPE);
2128 
2129     //     if (ret is null || ret.equals(type)) {
2130     //         // no localization for this type. try combining key/type separately
2131     //         string displayType = type;
2132     //         switch (key) {
2133     //         case "cu":
2134     //             displayType = lr.getCurrencyName(type.toLowerCase(Locale.ROOT));
2135     //             break;
2136     //         case "rg":
2137     //             if (type !is null &&
2138     //                 // UN M.49 code should not be allowed here
2139     //                 type.matches("^[a-zA-Z]{2}[zZ]{4}$")) {
2140     //                     displayType = lr.getLocaleName(type.substring(0, 2).toUpperCase(Locale.ROOT));
2141     //             }
2142     //             break;
2143     //         case "tz":
2144     //             displayType = TimeZoneNameUtility.convertLDMLShortID(type)
2145     //                 .map(id -> TimeZoneNameUtility.retrieveGenericDisplayName(id, TimeZone.LONG, inLocale))
2146     //                 .orElse(type);
2147     //             break;
2148     //         }
2149     //         ret = MessageFormat.format(lr.getLocaleName("ListKeyTypePattern"),
2150     //             getDisplaystring(key, null, inLocale, DISPLAY_UEXT_KEY),
2151     //             Optional.ofNullable(displayType).orElse(type));
2152     //     }
2153 
2154     //     return ret;
2155     // }
2156 
2157     // /**
2158     //  * Format a list using given pattern strings.
2159     //  * If either of the patterns is null, then a the list is
2160     //  * formatted by concatenation with the delimiter ','.
2161     //  * @param stringList the list of strings to be formatted.
2162     //  * and formatting them into a list.
2163     //  * @param pattern should take 2 arguments for reduction
2164     //  * @return a string representing the list.
2165     //  */
2166     // private static string formatList(string[] stringList, string pattern) {
2167     //     // If we have no list patterns, compose the list in a simple,
2168     //     // non-localized way.
2169     //     if (pattern is null) {
2170     //         return Arrays.stream(stringList).collect(Collectors.joining(","));
2171     //     }
2172 
2173     //     switch (stringList.length) {
2174     //         case 0:
2175     //             return "";
2176     //         case 1:
2177     //             return stringList[0];
2178     //         default:
2179     //             return Arrays.stream(stringList).reduce("",
2180     //                 (s1, s2) -> {
2181     //                     if (s1.equals("")) {
2182     //                         return s2;
2183     //                     }
2184     //                     if (s2.equals("")) {
2185     //                         return s1;
2186     //                     }
2187     //                     return MessageFormat.format(pattern, s1, s2);
2188     //                 });
2189     //     }
2190     // }
2191 
2192     // // Duplicate of sun.util.locale.UnicodeLocaleExtension.isKey in order to
2193     // // avoid its class loading.
2194     // private static bool isUnicodeExtensionKey(string s) {
2195     //     // 2alphanum
2196     //     return (s.length() == 2) && LocaleUtils.isAlphaNumericstring(s);
2197     // }
2198 
2199     // /**
2200     //  * @serialField language    string
2201     //  *      language subtag in lower case.
2202     //  *      (See <a href="java.base/java/util/Locale.html#getLanguage()">getLanguage()</a>)
2203     //  * @serialField country     string
2204     //  *      country subtag in upper case.
2205     //  *      (See <a href="java.base/java/util/Locale.html#getCountry()">getCountry()</a>)
2206     //  * @serialField variant     string
2207     //  *      variant subtags separated by LOWLINE characters.
2208     //  *      (See <a href="java.base/java/util/Locale.html#getVariant()">getVariant()</a>)
2209     //  * @serialField hashcode    int
2210     //  *      deprecated, for forward compatibility only
2211     //  * @serialField script      string
2212     //  *      script subtag in title case
2213     //  *      (See <a href="java.base/java/util/Locale.html#getScript()">getScript()</a>)
2214     //  * @serialField extensions  string
2215     //  *      canonical representation of extensions, that is,
2216     //  *      BCP47 extensions in alphabetical order followed by
2217     //  *      BCP47 private use subtags, all in lower case letters
2218     //  *      separated by HYPHEN-MINUS characters.
2219     //  *      (See <a href="java.base/java/util/Locale.html#getExtensionKeys()">getExtensionKeys()</a>,
2220     //  *      <a href="java.base/java/util/Locale.html#getExtension(char)">getExtension(char)</a>)
2221     //  */
2222     // private static final ObjectStreamField[] serialPersistentFields = {
2223     //     new ObjectStreamField("language", string.class),
2224     //     new ObjectStreamField("country", string.class),
2225     //     new ObjectStreamField("variant", string.class),
2226     //     new ObjectStreamField("hashcode", int.class),
2227     //     new ObjectStreamField("script", string.class),
2228     //     new ObjectStreamField("extensions", string.class),
2229     // };
2230 
2231     // /**
2232     //  * Serializes this <code>Locale</code> to the specified <code>ObjectOutputStream</code>.
2233     //  * @param out the <code>ObjectOutputStream</code> to write
2234     //  * @throws IOException
2235     //  */
2236     // private void writeObject(ObjectOutputStream out) throws IOException {
2237     //     ObjectOutputStream.PutField fields = out.putFields();
2238     //     fields.put("language", language);
2239     //     fields.put("script", script);
2240     //     fields.put("country", region);
2241     //     fields.put("variant", variant);
2242     //     fields.put("extensions", localeExtensions is null ? "" : localeExtensions.getID());
2243     //     fields.put("hashcode", -1); // place holder just for backward support
2244     //     out.writeFields();
2245     // }
2246 
2247     // /**
2248     //  * Deserializes this <code>Locale</code>.
2249     //  * @param in the <code>ObjectInputStream</code> to read
2250     //  * @throws IOException
2251     //  * @throws ClassNotFoundException
2252     //  * @throws IllformedLocaleException
2253     //  */
2254     // private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
2255     //     ObjectInputStream.GetField fields = in.readFields();
2256     //     string language = (string)fields.get("language", "");
2257     //     string script = (string)fields.get("script", "");
2258     //     string country = (string)fields.get("country", "");
2259     //     string variant = (string)fields.get("variant", "");
2260     //     string extStr = (string)fields.get("extensions", "");
2261     //     baseLocale = BaseLocale.getInstance(convertOldISOCodes(language), script, country, variant);
2262     //     if (extStr.length() > 0) {
2263     //         try {
2264     //             InternalLocaleBuilder bldr = new InternalLocaleBuilder();
2265     //             bldr.setExtensions(extStr);
2266     //             localeExtensions = bldr.getLocaleExtensions();
2267     //         } catch (LocaleSyntaxException e) {
2268     //             throw new IllformedLocaleException(e.getMessage());
2269     //         }
2270     //     } else {
2271     //         localeExtensions = null;
2272     //     }
2273     // }
2274 
2275     // /**
2276     //  * Returns a cached <code>Locale</code> instance equivalent to
2277     //  * the deserialized <code>Locale</code>. When serialized
2278     //  * language, country and variant fields read from the object data stream
2279     //  * are exactly "ja", "JP", "JP" or "th", "TH", "TH" and script/extensions
2280     //  * fields are empty, this method supplies <code>UNICODE_LOCALE_EXTENSION</code>
2281     //  * "ca"/"japanese" (calendar type is "japanese") or "nu"/"thai" (number script
2282     //  * type is "thai"). See <a href="Locale.html#special_cases_constructor">Special Cases</a>
2283     //  * for more information.
2284     //  *
2285     //  * @return an instance of <code>Locale</code> equivalent to
2286     //  * the deserialized <code>Locale</code>.
2287     //  * @throws java.io.ObjectStreamException
2288     //  */
2289     // private Object readResolve() throws java.io.ObjectStreamException {
2290     //     return getInstance(language, script,
2291     //             region, variant, localeExtensions);
2292     // }
2293 
2294     // private static string[] isoLanguages;
2295 
2296     // private static string[] isoCountries;
2297 
2298     private static string convertOldISOCodes(string language) {
2299         // we accept both the old and the new ISO codes for the languages whose ISO
2300         // codes have changed, but we always store the OLD code, for backward compatibility
2301         language = language.toLower();
2302         if (language == "he") {
2303             return "iw";
2304         } else if (language == "yi") {
2305             return "ji";
2306         } else if (language == "id") {
2307             return "in";
2308         } else {
2309             return language;
2310         }
2311     }
2312 
2313     // private static LocaleExtensions getCompatibilityExtensions(string language,
2314     //                                                            string script,
2315     //                                                            string country,
2316     //                                                            string variant) {
2317     //     LocaleExtensions extensions = null;
2318     //     // Special cases for backward compatibility support
2319     //     if (LocaleUtils.caseIgnoreMatch(language, "ja")
2320     //             && script.length() == 0
2321     //             && LocaleUtils.caseIgnoreMatch(country, "jp")
2322     //             && "JP".equals(variant)) {
2323     //         // ja_JP_JP -> u-ca-japanese (calendar = japanese)
2324     //         extensions = LocaleExtensions.CALENDAR_JAPANESE;
2325     //     } else if (LocaleUtils.caseIgnoreMatch(language, "th")
2326     //             && script.length() == 0
2327     //             && LocaleUtils.caseIgnoreMatch(country, "th")
2328     //             && "TH".equals(variant)) {
2329     //         // th_TH_TH -> u-nu-thai (numbersystem = thai)
2330     //         extensions = LocaleExtensions.NUMBER_THAI;
2331     //     }
2332     //     return extensions;
2333     // }
2334 
2335     // /**
2336     //  * Obtains a localized locale names from a LocaleNameProvider
2337     //  * implementation.
2338     //  */
2339     // private static class LocaleNameGetter
2340     //     implements LocaleServiceProviderPool.LocalizedObjectGetter<LocaleNameProvider, string> {
2341     //     private static final LocaleNameGetter INSTANCE = new LocaleNameGetter();
2342 
2343     //     override
2344     //     string getObject(LocaleNameProvider localeNameProvider,
2345     //                             Locale locale,
2346     //                             string key,
2347     //                             Object... params) {
2348     //         assert params.length == 3;
2349     //         int type = (Integer)params[0];
2350     //         string code = (string)params[1];
2351     //         string cat = (string)params[2];
2352 
2353     //         switch(type) {
2354     //         case DISPLAY_LANGUAGE:
2355     //             return localeNameProvider.getDisplayLanguage(code, locale);
2356     //         case DISPLAY_COUNTRY:
2357     //             return localeNameProvider.getDisplayCountry(code, locale);
2358     //         case DISPLAY_VARIANT:
2359     //             return localeNameProvider.getDisplayVariant(code, locale);
2360     //         case DISPLAY_SCRIPT:
2361     //             return localeNameProvider.getDisplayScript(code, locale);
2362     //         case DISPLAY_UEXT_KEY:
2363     //             return localeNameProvider.getDisplayUnicodeExtensionKey(code, locale);
2364     //         case DISPLAY_UEXT_TYPE:
2365     //             return localeNameProvider.getDisplayUnicodeExtensionType(code, cat, locale);
2366     //         default:
2367     //             assert false; // shouldn't happen
2368     //         }
2369 
2370     //         return null;
2371     //     }
2372     // }
2373 
2374     
2375     // /**
2376     //  * <code>Builder</code> is used to build instances of <code>Locale</code>
2377     //  * from values configured by the setters.  Unlike the <code>Locale</code>
2378     //  * constructors, the <code>Builder</code> checks if a value configured by a
2379     //  * setter satisfies the syntax requirements defined by the <code>Locale</code>
2380     //  * class.  A <code>Locale</code> object created by a <code>Builder</code> is
2381     //  * well-formed and can be transformed to a well-formed IETF BCP 47 language tag
2382     //  * without losing information.
2383     //  *
2384     //  * <p><b>Note:</b> The <code>Locale</code> class does not provide any
2385     //  * syntactic restrictions on variant, while BCP 47 requires each variant
2386     //  * subtag to be 5 to 8 alphanumerics or a single numeric followed by 3
2387     //  * alphanumerics.  The method <code>setVariant</code> throws
2388     //  * <code>IllformedLocaleException</code> for a variant that does not satisfy
2389     //  * this restriction. If it is necessary to support such a variant, use a
2390     //  * Locale constructor.  However, keep in mind that a <code>Locale</code>
2391     //  * object created this way might lose the variant information when
2392     //  * transformed to a BCP 47 language tag.
2393     //  *
2394     //  * <p>The following example shows how to create a <code>Locale</code> object
2395     //  * with the <code>Builder</code>.
2396     //  * <blockquote>
2397     //  * <pre>
2398     //  *     Locale aLocale = new Builder().setLanguage("sr").setScript("Latn").setRegion("RS").build();
2399     //  * </pre>
2400     //  * </blockquote>
2401     //  *
2402     //  * <p>Builders can be reused; <code>clear()</code> resets all
2403     //  * fields to their default values.
2404     //  *
2405     //  * @see Locale#forLanguageTag
2406     //  */
2407     // static final class Builder {
2408     //     private final InternalLocaleBuilder localeBuilder;
2409 
2410     //     /**
2411     //      * Constructs an empty Builder. The default value of all
2412     //      * fields, extensions, and private use information is the
2413     //      * empty string.
2414     //      */
2415     //     Builder() {
2416     //         localeBuilder = new InternalLocaleBuilder();
2417     //     }
2418 
2419     //     /**
2420     //      * Resets the <code>Builder</code> to match the provided
2421     //      * <code>locale</code>.  Existing state is discarded.
2422     //      *
2423     //      * <p>All fields of the locale must be well-formed, see {@link Locale}.
2424     //      *
2425     //      * <p>Locales with any ill-formed fields cause
2426     //      * <code>IllformedLocaleException</code> to be thrown, except for the
2427     //      * following three cases which are accepted for compatibility
2428     //      * reasons:<ul>
2429     //      * <li>Locale("ja", "JP", "JP") is treated as "ja-JP-u-ca-japanese"
2430     //      * <li>Locale("th", "TH", "TH") is treated as "th-TH-u-nu-thai"
2431     //      * <li>Locale("no", "NO", "NY") is treated as "nn-NO"</ul>
2432     //      *
2433     //      * @param locale the locale
2434     //      * @return This builder.
2435     //      * @throws IllformedLocaleException if <code>locale</code> has
2436     //      * any ill-formed fields.
2437     //      * @throws NullPointerException if <code>locale</code> is null.
2438     //      */
2439     //     Builder setLocale(Locale locale) {
2440     //         try {
2441     //             localeBuilder.setLocale(locale.baseLocale, locale.localeExtensions);
2442     //         } catch (LocaleSyntaxException e) {
2443     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2444     //         }
2445     //         return this;
2446     //     }
2447 
2448     //     /**
2449     //      * Resets the Builder to match the provided IETF BCP 47
2450     //      * language tag.  Discards the existing state.  Null and the
2451     //      * empty string cause the builder to be reset, like {@link
2452     //      * #clear}.  Grandfathered tags (see {@link
2453     //      * Locale#forLanguageTag}) are converted to their canonical
2454     //      * form before being processed.  Otherwise, the language tag
2455     //      * must be well-formed (see {@link Locale}) or an exception is
2456     //      * thrown (unlike <code>Locale.forLanguageTag</code>, which
2457     //      * just discards ill-formed and following portions of the
2458     //      * tag).
2459     //      *
2460     //      * @param languageTag the language tag
2461     //      * @return This builder.
2462     //      * @throws IllformedLocaleException if <code>languageTag</code> is ill-formed
2463     //      * @see Locale#forLanguageTag(string)
2464     //      */
2465     //     Builder setLanguageTag(string languageTag) {
2466     //         ParseStatus sts = new ParseStatus();
2467     //         LanguageTag tag = LanguageTag.parse(languageTag, sts);
2468     //         if (sts.isError()) {
2469     //             throw new IllformedLocaleException(sts.getErrorMessage(), sts.getErrorIndex());
2470     //         }
2471     //         localeBuilder.setLanguageTag(tag);
2472     //         return this;
2473     //     }
2474 
2475     //     /**
2476     //      * Sets the language.  If <code>language</code> is the empty string or
2477     //      * null, the language in this <code>Builder</code> is removed.  Otherwise,
2478     //      * the language must be <a href="./Locale.html#def_language">well-formed</a>
2479     //      * or an exception is thrown.
2480     //      *
2481     //      * <p>The typical language value is a two or three-letter language
2482     //      * code as defined in ISO639.
2483     //      *
2484     //      * @param language the language
2485     //      * @return This builder.
2486     //      * @throws IllformedLocaleException if <code>language</code> is ill-formed
2487     //      */
2488     //     Builder setLanguage(string language) {
2489     //         try {
2490     //             localeBuilder.setLanguage(language);
2491     //         } catch (LocaleSyntaxException e) {
2492     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2493     //         }
2494     //         return this;
2495     //     }
2496 
2497     //     /**
2498     //      * Sets the script. If <code>script</code> is null or the empty string,
2499     //      * the script in this <code>Builder</code> is removed.
2500     //      * Otherwise, the script must be <a href="./Locale.html#def_script">well-formed</a> or an
2501     //      * exception is thrown.
2502     //      *
2503     //      * <p>The typical script value is a four-letter script code as defined by ISO 15924.
2504     //      *
2505     //      * @param script the script
2506     //      * @return This builder.
2507     //      * @throws IllformedLocaleException if <code>script</code> is ill-formed
2508     //      */
2509     //     Builder setScript(string script) {
2510     //         try {
2511     //             localeBuilder.setScript(script);
2512     //         } catch (LocaleSyntaxException e) {
2513     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2514     //         }
2515     //         return this;
2516     //     }
2517 
2518     //     /**
2519     //      * Sets the region.  If region is null or the empty string, the region
2520     //      * in this <code>Builder</code> is removed.  Otherwise,
2521     //      * the region must be <a href="./Locale.html#def_region">well-formed</a> or an
2522     //      * exception is thrown.
2523     //      *
2524     //      * <p>The typical region value is a two-letter ISO 3166 code or a
2525     //      * three-digit UN M.49 area code.
2526     //      *
2527     //      * <p>The country value in the <code>Locale</code> created by the
2528     //      * <code>Builder</code> is always normalized to upper case.
2529     //      *
2530     //      * @param region the region
2531     //      * @return This builder.
2532     //      * @throws IllformedLocaleException if <code>region</code> is ill-formed
2533     //      */
2534     //     Builder setRegion(string region) {
2535     //         try {
2536     //             localeBuilder.setRegion(region);
2537     //         } catch (LocaleSyntaxException e) {
2538     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2539     //         }
2540     //         return this;
2541     //     }
2542 
2543     //     /**
2544     //      * Sets the variant.  If variant is null or the empty string, the
2545     //      * variant in this <code>Builder</code> is removed.  Otherwise, it
2546     //      * must consist of one or more <a href="./Locale.html#def_variant">well-formed</a>
2547     //      * subtags, or an exception is thrown.
2548     //      *
2549     //      * <p><b>Note:</b> This method checks if <code>variant</code>
2550     //      * satisfies the IETF BCP 47 variant subtag's syntax requirements,
2551     //      * and normalizes the value to lowercase letters.  However,
2552     //      * the <code>Locale</code> class does not impose any syntactic
2553     //      * restriction on variant, and the variant value in
2554     //      * <code>Locale</code> is case sensitive.  To set such a variant,
2555     //      * use a Locale constructor.
2556     //      *
2557     //      * @param variant the variant
2558     //      * @return This builder.
2559     //      * @throws IllformedLocaleException if <code>variant</code> is ill-formed
2560     //      */
2561     //     Builder setVariant(string variant) {
2562     //         try {
2563     //             localeBuilder.setVariant(variant);
2564     //         } catch (LocaleSyntaxException e) {
2565     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2566     //         }
2567     //         return this;
2568     //     }
2569 
2570     //     /**
2571     //      * Sets the extension for the given key. If the value is null or the
2572     //      * empty string, the extension is removed.  Otherwise, the extension
2573     //      * must be <a href="./Locale.html#def_extensions">well-formed</a> or an exception
2574     //      * is thrown.
2575     //      *
2576     //      * <p><b>Note:</b> The key {@link Locale#UNICODE_LOCALE_EXTENSION
2577     //      * UNICODE_LOCALE_EXTENSION} ('u') is used for the Unicode locale extension.
2578     //      * Setting a value for this key replaces any existing Unicode locale key/type
2579     //      * pairs with those defined in the extension.
2580     //      *
2581     //      * <p><b>Note:</b> The key {@link Locale#PRIVATE_USE_EXTENSION
2582     //      * PRIVATE_USE_EXTENSION} ('x') is used for the private use code. To be
2583     //      * well-formed, the value for this key needs only to have subtags of one to
2584     //      * eight alphanumeric characters, not two to eight as in the general case.
2585     //      *
2586     //      * @param key the extension key
2587     //      * @param value the extension value
2588     //      * @return This builder.
2589     //      * @throws IllformedLocaleException if <code>key</code> is illegal
2590     //      * or <code>value</code> is ill-formed
2591     //      * @see #setUnicodeLocaleKeyword(string, string)
2592     //      */
2593     //     Builder setExtension(char key, string value) {
2594     //         try {
2595     //             localeBuilder.setExtension(key, value);
2596     //         } catch (LocaleSyntaxException e) {
2597     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2598     //         }
2599     //         return this;
2600     //     }
2601 
2602     //     /**
2603     //      * Sets the Unicode locale keyword type for the given key.  If the type
2604     //      * is null, the Unicode keyword is removed.  Otherwise, the key must be
2605     //      * non-null and both key and type must be <a
2606     //      * href="./Locale.html#def_locale_extension">well-formed</a> or an exception
2607     //      * is thrown.
2608     //      *
2609     //      * <p>Keys and types are converted to lower case.
2610     //      *
2611     //      * <p><b>Note</b>:Setting the 'u' extension via {@link #setExtension}
2612     //      * replaces all Unicode locale keywords with those defined in the
2613     //      * extension.
2614     //      *
2615     //      * @param key the Unicode locale key
2616     //      * @param type the Unicode locale type
2617     //      * @return This builder.
2618     //      * @throws IllformedLocaleException if <code>key</code> or <code>type</code>
2619     //      * is ill-formed
2620     //      * @throws NullPointerException if <code>key</code> is null
2621     //      * @see #setExtension(char, string)
2622     //      */
2623     //     Builder setUnicodeLocaleKeyword(string key, string type) {
2624     //         try {
2625     //             localeBuilder.setUnicodeLocaleKeyword(key, type);
2626     //         } catch (LocaleSyntaxException e) {
2627     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2628     //         }
2629     //         return this;
2630     //     }
2631 
2632     //     /**
2633     //      * Adds a unicode locale attribute, if not already present, otherwise
2634     //      * has no effect.  The attribute must not be null and must be <a
2635     //      * href="./Locale.html#def_locale_extension">well-formed</a> or an exception
2636     //      * is thrown.
2637     //      *
2638     //      * @param attribute the attribute
2639     //      * @return This builder.
2640     //      * @throws NullPointerException if <code>attribute</code> is null
2641     //      * @throws IllformedLocaleException if <code>attribute</code> is ill-formed
2642     //      * @see #setExtension(char, string)
2643     //      */
2644     //     Builder addUnicodeLocaleAttribute(string attribute) {
2645     //         try {
2646     //             localeBuilder.addUnicodeLocaleAttribute(attribute);
2647     //         } catch (LocaleSyntaxException e) {
2648     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2649     //         }
2650     //         return this;
2651     //     }
2652 
2653     //     /**
2654     //      * Removes a unicode locale attribute, if present, otherwise has no
2655     //      * effect.  The attribute must not be null and must be <a
2656     //      * href="./Locale.html#def_locale_extension">well-formed</a> or an exception
2657     //      * is thrown.
2658     //      *
2659     //      * <p>Attribute comparison for removal is case-insensitive.
2660     //      *
2661     //      * @param attribute the attribute
2662     //      * @return This builder.
2663     //      * @throws NullPointerException if <code>attribute</code> is null
2664     //      * @throws IllformedLocaleException if <code>attribute</code> is ill-formed
2665     //      * @see #setExtension(char, string)
2666     //      */
2667     //     Builder removeUnicodeLocaleAttribute(string attribute) {
2668     //         assert(attribute);
2669     //         try {
2670     //             localeBuilder.removeUnicodeLocaleAttribute(attribute);
2671     //         } catch (LocaleSyntaxException e) {
2672     //             throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
2673     //         }
2674     //         return this;
2675     //     }
2676 
2677     //     /**
2678     //      * Resets the builder to its initial, empty state.
2679     //      *
2680     //      * @return This builder.
2681     //      */
2682     //     Builder clear() {
2683     //         localeBuilder.clear();
2684     //         return this;
2685     //     }
2686 
2687     //     /**
2688     //      * Resets the extensions to their initial, empty state.
2689     //      * Language, script, region and variant are unchanged.
2690     //      *
2691     //      * @return This builder.
2692     //      * @see #setExtension(char, string)
2693     //      */
2694     //     Builder clearExtensions() {
2695     //         localeBuilder.clearExtensions();
2696     //         return this;
2697     //     }
2698 
2699     //     /**
2700     //      * Returns an instance of <code>Locale</code> created from the fields set
2701     //      * on this builder.
2702     //      *
2703     //      * <p>This applies the conversions listed in {@link Locale#forLanguageTag}
2704     //      * when constructing a Locale. (Grandfathered tags are handled in
2705     //      * {@link #setLanguageTag}.)
2706     //      *
2707     //      * @return A Locale.
2708     //      */
2709     //     Locale build() {
2710     //         BaseLocale baseloc = localeBuilder.getBaseLocale();
2711     //         LocaleExtensions extensions = localeBuilder.getLocaleExtensions();
2712     //         if (extensions is null && baseloc.getVariant().length() > 0) {
2713     //             extensions = getCompatibilityExtensions(baseloc.getLanguage(), baseloc.getScript(),
2714     //                     baseloc.getRegion(), baseloc.getVariant());
2715     //         }
2716     //         return Locale.getInstance(baseloc, extensions);
2717     //     }
2718     // }
2719 
2720     // /**
2721     //  * This enum provides constants to select a filtering mode for locale
2722     //  * matching. Refer to <a href="http://tools.ietf.org/html/rfc4647">RFC 4647
2723     //  * Matching of Language Tags</a> for details.
2724     //  *
2725     //  * <p>As an example, think of two Language Priority Lists each of which
2726     //  * includes only one language range and a set of following language tags:
2727     //  *
2728     //  * <pre>
2729     //  *    de (German)
2730     //  *    de-DE (German, Germany)
2731     //  *    de-Deva (German, in Devanagari script)
2732     //  *    de-Deva-DE (German, in Devanagari script, Germany)
2733     //  *    de-DE-1996 (German, Germany, orthography of 1996)
2734     //  *    de-Latn-DE (German, in Latin script, Germany)
2735     //  *    de-Latn-DE-1996 (German, in Latin script, Germany, orthography of 1996)
2736     //  * </pre>
2737     //  *
2738     //  * The filtering method will behave as follows:
2739     //  *
2740     //  * <table class="striped">
2741     //  * <caption>Filtering method behavior</caption>
2742     //  * <thead>
2743     //  * <tr>
2744     //  * <th scope="col">Filtering Mode</th>
2745     //  * <th scope="col">Language Priority List: {@code "de-DE"}</th>
2746     //  * <th scope="col">Language Priority List: {@code "de-*-DE"}</th>
2747     //  * </tr>
2748     //  * </thead>
2749     //  * <tbody>
2750     //  * <tr>
2751     //  * <th scope="row" style="vertical-align:top">
2752     //  * {@link FilteringMode#AUTOSELECT_FILTERING AUTOSELECT_FILTERING}
2753     //  * </th>
2754     //  * <td style="vertical-align:top">
2755     //  * Performs <em>basic</em> filtering and returns {@code "de-DE"} and
2756     //  * {@code "de-DE-1996"}.
2757     //  * </td>
2758     //  * <td style="vertical-align:top">
2759     //  * Performs <em>extended</em> filtering and returns {@code "de-DE"},
2760     //  * {@code "de-Deva-DE"}, {@code "de-DE-1996"}, {@code "de-Latn-DE"}, and
2761     //  * {@code "de-Latn-DE-1996"}.
2762     //  * </td>
2763     //  * </tr>
2764     //  * <tr>
2765     //  * <th scope="row" style="vertical-align:top">
2766     //  * {@link FilteringMode#EXTENDED_FILTERING EXTENDED_FILTERING}
2767     //  * </th>
2768     //  * <td style="vertical-align:top">
2769     //  * Performs <em>extended</em> filtering and returns {@code "de-DE"},
2770     //  * {@code "de-Deva-DE"}, {@code "de-DE-1996"}, {@code "de-Latn-DE"}, and
2771     //  * {@code "de-Latn-DE-1996"}.
2772     //  * </td>
2773     //  * <td style="vertical-align:top">Same as above.</td>
2774     //  * </tr>
2775     //  * <tr>
2776     //  * <th scope="row" style="vertical-align:top">
2777     //  * {@link FilteringMode#IGNORE_EXTENDED_RANGES IGNORE_EXTENDED_RANGES}
2778     //  * </th>
2779     //  * <td style="vertical-align:top">
2780     //  * Performs <em>basic</em> filtering and returns {@code "de-DE"} and
2781     //  * {@code "de-DE-1996"}.
2782     //  * </td>
2783     //  * <td style="vertical-align:top">
2784     //  * Performs <em>basic</em> filtering and returns {@code null} because
2785     //  * nothing matches.
2786     //  * </td>
2787     //  * </tr>
2788     //  * <tr>
2789     //  * <th scope="row" style="vertical-align:top">
2790     //  * {@link FilteringMode#MAP_EXTENDED_RANGES MAP_EXTENDED_RANGES}
2791     //  * </th>
2792     //  * <td style="vertical-align:top">Same as above.</td>
2793     //  * <td style="vertical-align:top">
2794     //  * Performs <em>basic</em> filtering and returns {@code "de-DE"} and
2795     //  * {@code "de-DE-1996"} because {@code "de-*-DE"} is mapped to
2796     //  * {@code "de-DE"}.
2797     //  * </td>
2798     //  * </tr>
2799     //  * <tr>
2800     //  * <th scope="row" style="vertical-align:top">
2801     //  * {@link FilteringMode#REJECT_EXTENDED_RANGES REJECT_EXTENDED_RANGES}
2802     //  * </th>
2803     //  * <td style="vertical-align:top">Same as above.</td>
2804     //  * <td style="vertical-align:top">
2805     //  * Throws {@link IllegalArgumentException} because {@code "de-*-DE"} is
2806     //  * not a valid basic language range.
2807     //  * </td>
2808     //  * </tr>
2809     //  * </tbody>
2810     //  * </table>
2811     //  *
2812     //  * @see #filter(List, Collection, FilteringMode)
2813     //  * @see #filterTags(List, Collection, FilteringMode)
2814     //  *
2815     //  */
2816     // static enum FilteringMode {
2817     //     /**
2818     //      * Specifies automatic filtering mode based on the given Language
2819     //      * Priority List consisting of language ranges. If all of the ranges
2820     //      * are basic, basic filtering is selected. Otherwise, extended
2821     //      * filtering is selected.
2822     //      */
2823     //     AUTOSELECT_FILTERING,
2824 
2825     //     /**
2826     //      * Specifies extended filtering.
2827     //      */
2828     //     EXTENDED_FILTERING,
2829 
2830     //     /**
2831     //      * Specifies basic filtering: Note that any extended language ranges
2832     //      * included in the given Language Priority List are ignored.
2833     //      */
2834     //     IGNORE_EXTENDED_RANGES,
2835 
2836     //     /**
2837     //      * Specifies basic filtering: If any extended language ranges are
2838     //      * included in the given Language Priority List, they are mapped to the
2839     //      * basic language range. Specifically, a language range starting with a
2840     //      * subtag {@code "*"} is treated as a language range {@code "*"}. For
2841     //      * example, {@code "*-US"} is treated as {@code "*"}. If {@code "*"} is
2842     //      * not the first subtag, {@code "*"} and extra {@code "-"} are removed.
2843     //      * For example, {@code "ja-*-JP"} is mapped to {@code "ja-JP"}.
2844     //      */
2845     //     MAP_EXTENDED_RANGES,
2846 
2847     //     /**
2848     //      * Specifies basic filtering: If any extended language ranges are
2849     //      * included in the given Language Priority List, the list is rejected
2850     //      * and the filtering method throws {@link IllegalArgumentException}.
2851     //      */
2852     //     REJECT_EXTENDED_RANGES
2853     // };
2854 
2855     // /**
2856     //  * This class expresses a <em>Language Range</em> defined in
2857     //  * <a href="http://tools.ietf.org/html/rfc4647">RFC 4647 Matching of
2858     //  * Language Tags</a>. A language range is an identifier which is used to
2859     //  * select language tag(s) meeting specific requirements by using the
2860     //  * mechanisms described in <a href="Locale.html#LocaleMatching">Locale
2861     //  * Matching</a>. A list which represents a user's preferences and consists
2862     //  * of language ranges is called a <em>Language Priority List</em>.
2863     //  *
2864     //  * <p>There are two types of language ranges: basic and extended. In RFC
2865     //  * 4647, the syntax of language ranges is expressed in
2866     //  * <a href="http://tools.ietf.org/html/rfc4234">ABNF</a> as follows:
2867     //  * <blockquote>
2868     //  * <pre>
2869     //  *     basic-language-range    = (1*8ALPHA *("-" 1*8alphanum)) / "*"
2870     //  *     extended-language-range = (1*8ALPHA / "*")
2871     //  *                               *("-" (1*8alphanum / "*"))
2872     //  *     alphanum                = ALPHA / DIGIT
2873     //  * </pre>
2874     //  * </blockquote>
2875     //  * For example, {@code "en"} (English), {@code "ja-JP"} (Japanese, Japan),
2876     //  * {@code "*"} (special language range which matches any language tag) are
2877     //  * basic language ranges, whereas {@code "*-CH"} (any languages,
2878     //  * Switzerland), {@code "es-*"} (Spanish, any regions), and
2879     //  * {@code "zh-Hant-*"} (Traditional Chinese, any regions) are extended
2880     //  * language ranges.
2881     //  *
2882     //  * @see #filter
2883     //  * @see #filterTags
2884     //  * @see #lookup
2885     //  * @see #lookupTag
2886     //  *
2887     //  */
2888     // static final class LanguageRange {
2889 
2890     //    /**
2891     //     * A constant holding the maximum value of weight, 1.0, which indicates
2892     //     * that the language range is a good fit for the user.
2893     //     */
2894     //     static final double MAX_WEIGHT = 1.0;
2895 
2896     //    /**
2897     //     * A constant holding the minimum value of weight, 0.0, which indicates
2898     //     * that the language range is not a good fit for the user.
2899     //     */
2900     //     static final double MIN_WEIGHT = 0.0;
2901 
2902     //     private final string range;
2903     //     private final double weight;
2904 
2905     //     private int hash;
2906 
2907     //     /**
2908     //      * Constructs a {@code LanguageRange} using the given {@code range}.
2909     //      * Note that no validation is done against the IANA Language Subtag
2910     //      * Registry at time of construction.
2911     //      *
2912     //      * <p>This is equivalent to {@code LanguageRange(range, MAX_WEIGHT)}.
2913     //      *
2914     //      * @param range a language range
2915     //      * @throws NullPointerException if the given {@code range} is
2916     //      *     {@code null}
2917     //      * @throws IllegalArgumentException if the given {@code range} does not
2918     //      * comply with the syntax of the language range mentioned in RFC 4647
2919     //      */
2920     //     LanguageRange(string range) {
2921     //         this(range, MAX_WEIGHT);
2922     //     }
2923 
2924     //     /**
2925     //      * Constructs a {@code LanguageRange} using the given {@code range} and
2926     //      * {@code weight}. Note that no validation is done against the IANA
2927     //      * Language Subtag Registry at time of construction.
2928     //      *
2929     //      * @param range  a language range
2930     //      * @param weight a weight value between {@code MIN_WEIGHT} and
2931     //      *     {@code MAX_WEIGHT}
2932     //      * @throws NullPointerException if the given {@code range} is
2933     //      *     {@code null}
2934     //      * @throws IllegalArgumentException if the given {@code range} does not
2935     //      * comply with the syntax of the language range mentioned in RFC 4647
2936     //      * or if the given {@code weight} is less than {@code MIN_WEIGHT}
2937     //      * or greater than {@code MAX_WEIGHT}
2938     //      */
2939     //     LanguageRange(string range, double weight) {
2940     //         if (range is null) {
2941     //             throw new NullPointerException();
2942     //         }
2943     //         if (weight < MIN_WEIGHT || weight > MAX_WEIGHT) {
2944     //             throw new IllegalArgumentException("weight=" ~ weight);
2945     //         }
2946 
2947     //         range = range.toLowerCase(Locale.ROOT);
2948 
2949     //         // Do syntax check.
2950     //         bool isIllFormed = false;
2951     //         string[] subtags = range.split("-");
2952     //         if (isSubtagIllFormed(subtags[0], true)
2953     //             || range.endsWith("-")) {
2954     //             isIllFormed = true;
2955     //         } else {
2956     //             for (int i = 1; i < subtags.length; i++) {
2957     //                 if (isSubtagIllFormed(subtags[i], false)) {
2958     //                     isIllFormed = true;
2959     //                     break;
2960     //                 }
2961     //             }
2962     //         }
2963     //         if (isIllFormed) {
2964     //             throw new IllegalArgumentException("range=" ~ range);
2965     //         }
2966 
2967     //         this.range = range;
2968     //         this.weight = weight;
2969     //     }
2970 
2971     //     private static bool isSubtagIllFormed(string subtag,
2972     //                                              bool isFirstSubtag) {
2973     //         if (subtag.equals("") || subtag.length() > 8) {
2974     //             return true;
2975     //         } else if (subtag.equals("*")) {
2976     //             return false;
2977     //         }
2978     //         char[] charArray = subtag.toCharArray();
2979     //         if (isFirstSubtag) { // ALPHA
2980     //             for (char c : charArray) {
2981     //                 if (c < 'a' || c > 'z') {
2982     //                     return true;
2983     //                 }
2984     //             }
2985     //         } else { // ALPHA / DIGIT
2986     //             for (char c : charArray) {
2987     //                 if (c < '0' || (c > '9' && c < 'a') || c > 'z') {
2988     //                     return true;
2989     //                 }
2990     //             }
2991     //         }
2992     //         return false;
2993     //     }
2994 
2995     //     /**
2996     //      * Returns the language range of this {@code LanguageRange}.
2997     //      *
2998     //      * @return the language range.
2999     //      */
3000     //     string getRange() {
3001     //         return range;
3002     //     }
3003 
3004     //     /**
3005     //      * Returns the weight of this {@code LanguageRange}.
3006     //      *
3007     //      * @return the weight value.
3008     //      */
3009     //     double getWeight() {
3010     //         return weight;
3011     //     }
3012 
3013     //     /**
3014     //      * Parses the given {@code ranges} to generate a Language Priority List.
3015     //      *
3016     //      * <p>This method performs a syntactic check for each language range in
3017     //      * the given {@code ranges} but doesn't do validation using the IANA
3018     //      * Language Subtag Registry.
3019     //      *
3020     //      * <p>The {@code ranges} to be given can take one of the following
3021     //      * forms:
3022     //      *
3023     //      * <pre>
3024     //      *   "Accept-Language: ja,en;q=0.4"  (weighted list with Accept-Language prefix)
3025     //      *   "ja,en;q=0.4"                   (weighted list)
3026     //      *   "ja,en"                         (prioritized list)
3027     //      * </pre>
3028     //      *
3029     //      * In a weighted list, each language range is given a weight value.
3030     //      * The weight value is identical to the "quality value" in
3031     //      * <a href="http://tools.ietf.org/html/rfc2616">RFC 2616</a>, and it
3032     //      * expresses how much the user prefers  the language. A weight value is
3033     //      * specified after a corresponding language range followed by
3034     //      * {@code ";q="}, and the default weight value is {@code MAX_WEIGHT}
3035     //      * when it is omitted.
3036     //      *
3037     //      * <p>Unlike a weighted list, language ranges in a prioritized list
3038     //      * are sorted in the descending order based on its priority. The first
3039     //      * language range has the highest priority and meets the user's
3040     //      * preference most.
3041     //      *
3042     //      * <p>In either case, language ranges are sorted in descending order in
3043     //      * the Language Priority List based on priority or weight. If a
3044     //      * language range appears in the given {@code ranges} more than once,
3045     //      * only the first one is included on the Language Priority List.
3046     //      *
3047     //      * <p>The returned list consists of language ranges from the given
3048     //      * {@code ranges} and their equivalents found in the IANA Language
3049     //      * Subtag Registry. For example, if the given {@code ranges} is
3050     //      * {@code "Accept-Language: iw,en-us;q=0.7,en;q=0.3"}, the elements in
3051     //      * the list to be returned are:
3052     //      *
3053     //      * <pre>
3054     //      *  <b>Range</b>                                   <b>Weight</b>
3055     //      *    "iw" (older tag for Hebrew)             1.0
3056     //      *    "he" (new preferred code for Hebrew)    1.0
3057     //      *    "en-us" (English, United States)        0.7
3058     //      *    "en" (English)                          0.3
3059     //      * </pre>
3060     //      *
3061     //      * Two language ranges, {@code "iw"} and {@code "he"}, have the same
3062     //      * highest priority in the list. By adding {@code "he"} to the user's
3063     //      * Language Priority List, locale-matching method can find Hebrew as a
3064     //      * matching locale (or language tag) even if the application or system
3065     //      * offers only {@code "he"} as a supported locale (or language tag).
3066     //      *
3067     //      * @param ranges a list of comma-separated language ranges or a list of
3068     //      *     language ranges in the form of the "Accept-Language" header
3069     //      *     defined in <a href="http://tools.ietf.org/html/rfc2616">RFC
3070     //      *     2616</a>
3071     //      * @return a Language Priority List consisting of language ranges
3072     //      *     included in the given {@code ranges} and their equivalent
3073     //      *     language ranges if available. The list is modifiable.
3074     //      * @throws NullPointerException if {@code ranges} is null
3075     //      * @throws IllegalArgumentException if a language range or a weight
3076     //      *     found in the given {@code ranges} is ill-formed
3077     //      */
3078     //     static List<LanguageRange> parse(string ranges) {
3079     //         return LocaleMatcher.parse(ranges);
3080     //     }
3081 
3082     //     /**
3083     //      * Parses the given {@code ranges} to generate a Language Priority
3084     //      * List, and then customizes the list using the given {@code map}.
3085     //      * This method is equivalent to
3086     //      * {@code mapEquivalents(parse(ranges), map)}.
3087     //      *
3088     //      * @param ranges a list of comma-separated language ranges or a list
3089     //      *     of language ranges in the form of the "Accept-Language" header
3090     //      *     defined in <a href="http://tools.ietf.org/html/rfc2616">RFC
3091     //      *     2616</a>
3092     //      * @param map a map containing information to customize language ranges
3093     //      * @return a Language Priority List with customization. The list is
3094     //      *     modifiable.
3095     //      * @throws NullPointerException if {@code ranges} is null
3096     //      * @throws IllegalArgumentException if a language range or a weight
3097     //      *     found in the given {@code ranges} is ill-formed
3098     //      * @see #parse(string)
3099     //      * @see #mapEquivalents
3100     //      */
3101     //     static List<LanguageRange> parse(string ranges,
3102     //                                             Map<string, List<string>> map) {
3103     //         return mapEquivalents(parse(ranges), map);
3104     //     }
3105 
3106     //     /**
3107     //      * Generates a new customized Language Priority List using the given
3108     //      * {@code priorityList} and {@code map}. If the given {@code map} is
3109     //      * empty, this method returns a copy of the given {@code priorityList}.
3110     //      *
3111     //      * <p>In the map, a key represents a language range whereas a value is
3112     //      * a list of equivalents of it. {@code '*'} cannot be used in the map.
3113     //      * Each equivalent language range has the same weight value as its
3114     //      * original language range.
3115     //      *
3116     //      * <pre>
3117     //      *  An example of map:
3118     //      *    <b>Key</b>                            <b>Value</b>
3119     //      *      "zh" (Chinese)                 "zh",
3120     //      *                                     "zh-Hans"(Simplified Chinese)
3121     //      *      "zh-HK" (Chinese, Hong Kong)   "zh-HK"
3122     //      *      "zh-TW" (Chinese, Taiwan)      "zh-TW"
3123     //      * </pre>
3124     //      *
3125     //      * The customization is performed after modification using the IANA
3126     //      * Language Subtag Registry.
3127     //      *
3128     //      * <p>For example, if a user's Language Priority List consists of five
3129     //      * language ranges ({@code "zh"}, {@code "zh-CN"}, {@code "en"},
3130     //      * {@code "zh-TW"}, and {@code "zh-HK"}), the newly generated Language
3131     //      * Priority List which is customized using the above map example will
3132     //      * consists of {@code "zh"}, {@code "zh-Hans"}, {@code "zh-CN"},
3133     //      * {@code "zh-Hans-CN"}, {@code "en"}, {@code "zh-TW"}, and
3134     //      * {@code "zh-HK"}.
3135     //      *
3136     //      * <p>{@code "zh-HK"} and {@code "zh-TW"} aren't converted to
3137     //      * {@code "zh-Hans-HK"} nor {@code "zh-Hans-TW"} even if they are
3138     //      * included in the Language Priority List. In this example, mapping
3139     //      * is used to clearly distinguish Simplified Chinese and Traditional
3140     //      * Chinese.
3141     //      *
3142     //      * <p>If the {@code "zh"}-to-{@code "zh"} mapping isn't included in the
3143     //      * map, a simple replacement will be performed and the customized list
3144     //      * won't include {@code "zh"} and {@code "zh-CN"}.
3145     //      *
3146     //      * @param priorityList user's Language Priority List
3147     //      * @param map a map containing information to customize language ranges
3148     //      * @return a new Language Priority List with customization. The list is
3149     //      *     modifiable.
3150     //      * @throws NullPointerException if {@code priorityList} is {@code null}
3151     //      * @see #parse(string, Map)
3152     //      */
3153     //     static List<LanguageRange> mapEquivalents(
3154     //                                           List<LanguageRange>priorityList,
3155     //                                           Map<string, List<string>> map) {
3156     //         return LocaleMatcher.mapEquivalents(priorityList, map);
3157     //     }
3158 
3159     //     /**
3160     //      * Returns a hash code value for the object.
3161     //      *
3162     //      * @return  a hash code value for this object.
3163     //      */
3164     //     override
3165     //     int hashCode() {
3166     //         int h = hash;
3167     //         if (h == 0) {
3168     //             h = 17;
3169     //             h = 37*h + range.hashCode();
3170     //             long bitsWeight = Double.doubleToLongBits(weight);
3171     //             h = 37*h + (int)(bitsWeight ^ (bitsWeight >>> 32));
3172     //             if (h != 0) {
3173     //                 hash = h;
3174     //             }
3175     //         }
3176     //         return h;
3177     //     }
3178 
3179     //     /**
3180     //      * Compares this object to the specified object. The result is true if
3181     //      * and only if the argument is not {@code null} and is a
3182     //      * {@code LanguageRange} object that contains the same {@code range}
3183     //      * and {@code weight} values as this object.
3184     //      *
3185     //      * @param obj the object to compare with
3186     //      * @return  {@code true} if this object's {@code range} and
3187     //      *     {@code weight} are the same as the {@code obj}'s; {@code false}
3188     //      *     otherwise.
3189     //      */
3190     //     override
3191     //     bool equals(Object obj) {
3192     //         if (this is obj) {
3193     //             return true;
3194     //         }
3195     //         if (!(obj instanceof LanguageRange)) {
3196     //             return false;
3197     //         }
3198     //         LanguageRange other = (LanguageRange)obj;
3199     //         return hash == other.hash
3200     //                && range.equals(other.range)
3201     //                && weight == other.weight;
3202     //     }
3203 
3204     //     /**
3205     //      * Returns an informative string representation of this {@code LanguageRange}
3206     //      * object, consisting of language range and weight if the range is
3207     //      * weighted and the weight is less than the max weight.
3208     //      *
3209     //      * @return a string representation of this {@code LanguageRange} object.
3210     //      */
3211     //     override
3212     //     string toString() {
3213     //         return (weight == MAX_WEIGHT) ? range : range ~ ";q=" ~ weight;
3214     //     }
3215     // }
3216 
3217     // /**
3218     //  * Returns a list of matching {@code Locale} instances using the filtering
3219     //  * mechanism defined in RFC 4647.
3220     //  *
3221     //  * This filter operation on the given {@code locales} ensures that only
3222     //  * unique matching locale(s) are returned.
3223     //  *
3224     //  * @param priorityList user's Language Priority List in which each language
3225     //  *     tag is sorted in descending order based on priority or weight
3226     //  * @param locales {@code Locale} instances used for matching
3227     //  * @param mode filtering mode
3228     //  * @return a list of {@code Locale} instances for matching language tags
3229     //  *     sorted in descending order based on priority or weight, or an empty
3230     //  *     list if nothing matches. The list is modifiable.
3231     //  * @throws NullPointerException if {@code priorityList} or {@code locales}
3232     //  *     is {@code null}
3233     //  * @throws IllegalArgumentException if one or more extended language ranges
3234     //  *     are included in the given list when
3235     //  *     {@link FilteringMode#REJECT_EXTENDED_RANGES} is specified
3236     //  *
3237     //  */
3238     // static List<Locale> filter(List<LanguageRange> priorityList,
3239     //                                   Collection<Locale> locales,
3240     //                                   FilteringMode mode) {
3241     //     return LocaleMatcher.filter(priorityList, locales, mode);
3242     // }
3243 
3244     // /**
3245     //  * Returns a list of matching {@code Locale} instances using the filtering
3246     //  * mechanism defined in RFC 4647. This is equivalent to
3247     //  * {@link #filter(List, Collection, FilteringMode)} when {@code mode} is
3248     //  * {@link FilteringMode#AUTOSELECT_FILTERING}.
3249     //  *
3250     //  * This filter operation on the given {@code locales} ensures that only
3251     //  * unique matching locale(s) are returned.
3252     //  *
3253     //  * @param priorityList user's Language Priority List in which each language
3254     //  *     tag is sorted in descending order based on priority or weight
3255     //  * @param locales {@code Locale} instances used for matching
3256     //  * @return a list of {@code Locale} instances for matching language tags
3257     //  *     sorted in descending order based on priority or weight, or an empty
3258     //  *     list if nothing matches. The list is modifiable.
3259     //  * @throws NullPointerException if {@code priorityList} or {@code locales}
3260     //  *     is {@code null}
3261     //  *
3262     //  */
3263     // static List<Locale> filter(List<LanguageRange> priorityList,
3264     //                                   Collection<Locale> locales) {
3265     //     return filter(priorityList, locales, FilteringMode.AUTOSELECT_FILTERING);
3266     // }
3267 
3268     // /**
3269     //  * Returns a list of matching languages tags using the basic filtering
3270     //  * mechanism defined in RFC 4647.
3271     //  *
3272     //  * This filter operation on the given {@code tags} ensures that only
3273     //  * unique matching tag(s) are returned with preserved case. In case of
3274     //  * duplicate matching tags with the case difference, the first matching
3275     //  * tag with preserved case is returned.
3276     //  * For example, "de-ch" is returned out of the duplicate matching tags
3277     //  * "de-ch" and "de-CH", if "de-ch" is checked first for matching in the
3278     //  * given {@code tags}. Note that if the given {@code tags} is an unordered
3279     //  * {@code Collection}, the returned matching tag out of duplicate tags is
3280     //  * subject to change, depending on the implementation of the
3281     //  * {@code Collection}.
3282     //  *
3283     //  * @param priorityList user's Language Priority List in which each language
3284     //  *     tag is sorted in descending order based on priority or weight
3285     //  * @param tags language tags
3286     //  * @param mode filtering mode
3287     //  * @return a list of matching language tags sorted in descending order
3288     //  *     based on priority or weight, or an empty list if nothing matches.
3289     //  *     The list is modifiable.
3290     //  * @throws NullPointerException if {@code priorityList} or {@code tags} is
3291     //  *     {@code null}
3292     //  * @throws IllegalArgumentException if one or more extended language ranges
3293     //  *     are included in the given list when
3294     //  *     {@link FilteringMode#REJECT_EXTENDED_RANGES} is specified
3295     //  *
3296     //  */
3297     // static List<string> filterTags(List<LanguageRange> priorityList,
3298     //                                       Collection<string> tags,
3299     //                                       FilteringMode mode) {
3300     //     return LocaleMatcher.filterTags(priorityList, tags, mode);
3301     // }
3302 
3303     // /**
3304     //  * Returns a list of matching languages tags using the basic filtering
3305     //  * mechanism defined in RFC 4647. This is equivalent to
3306     //  * {@link #filterTags(List, Collection, FilteringMode)} when {@code mode}
3307     //  * is {@link FilteringMode#AUTOSELECT_FILTERING}.
3308     //  *
3309     //  * This filter operation on the given {@code tags} ensures that only
3310     //  * unique matching tag(s) are returned with preserved case. In case of
3311     //  * duplicate matching tags with the case difference, the first matching
3312     //  * tag with preserved case is returned.
3313     //  * For example, "de-ch" is returned out of the duplicate matching tags
3314     //  * "de-ch" and "de-CH", if "de-ch" is checked first for matching in the
3315     //  * given {@code tags}. Note that if the given {@code tags} is an unordered
3316     //  * {@code Collection}, the returned matching tag out of duplicate tags is
3317     //  * subject to change, depending on the implementation of the
3318     //  * {@code Collection}.
3319     //  *
3320     //  * @param priorityList user's Language Priority List in which each language
3321     //  *     tag is sorted in descending order based on priority or weight
3322     //  * @param tags language tags
3323     //  * @return a list of matching language tags sorted in descending order
3324     //  *     based on priority or weight, or an empty list if nothing matches.
3325     //  *     The list is modifiable.
3326     //  * @throws NullPointerException if {@code priorityList} or {@code tags} is
3327     //  *     {@code null}
3328     //  *
3329     //  */
3330     // static List<string> filterTags(List<LanguageRange> priorityList,
3331     //                                       Collection<string> tags) {
3332     //     return filterTags(priorityList, tags, FilteringMode.AUTOSELECT_FILTERING);
3333     // }
3334 
3335     // /**
3336     //  * Returns a {@code Locale} instance for the best-matching language
3337     //  * tag using the lookup mechanism defined in RFC 4647.
3338     //  *
3339     //  * @param priorityList user's Language Priority List in which each language
3340     //  *     tag is sorted in descending order based on priority or weight
3341     //  * @param locales {@code Locale} instances used for matching
3342     //  * @return the best matching <code>Locale</code> instance chosen based on
3343     //  *     priority or weight, or {@code null} if nothing matches.
3344     //  * @throws NullPointerException if {@code priorityList} or {@code tags} is
3345     //  *     {@code null}
3346     //  *
3347     //  */
3348     // static Locale lookup(List<LanguageRange> priorityList,
3349     //                             Collection<Locale> locales) {
3350     //     return LocaleMatcher.lookup(priorityList, locales);
3351     // }
3352 
3353     // /**
3354     //  * Returns the best-matching language tag using the lookup mechanism
3355     //  * defined in RFC 4647.
3356     //  *
3357     //  * This lookup operation on the given {@code tags} ensures that the
3358     //  * first matching tag with preserved case is returned.
3359     //  *
3360     //  * @param priorityList user's Language Priority List in which each language
3361     //  *     tag is sorted in descending order based on priority or weight
3362     //  * @param tags language tangs used for matching
3363     //  * @return the best matching language tag chosen based on priority or
3364     //  *     weight, or {@code null} if nothing matches.
3365     //  * @throws NullPointerException if {@code priorityList} or {@code tags} is
3366     //  *     {@code null}
3367     //  *
3368     //  */
3369     // static string lookupTag(List<LanguageRange> priorityList,
3370     //                                Collection<string> tags) {
3371     //     return LocaleMatcher.lookupTag(priorityList, tags);
3372     // }
3373 
3374 }
3375 
3376 /**
3377  * Enum for locale categories.  These locale categories are used to get/set
3378  * the default locale for the specific functionality represented by the
3379  * category.
3380  *
3381  * @see #getDefault(LocaleCategory)
3382  * @see #setDefault(LocaleCategory, Locale)
3383  */
3384 struct LocaleCategory {
3385 
3386     /**
3387      * Category used to represent the default locale for
3388      * displaying user interfaces.
3389      */
3390    enum LocaleCategory DISPLAY = LocaleCategory("user.language.display",
3391             "user.script.display",
3392             "user.country.display",
3393             "user.variant.display",
3394             "user.extensions.display");
3395 
3396     /**
3397      * Category used to represent the default locale for
3398      * formatting dates, numbers, and/or currencies.
3399      */
3400    enum LocaleCategory FORMAT = LocaleCategory("user.language.format",
3401            "user.script.format",
3402            "user.country.format",
3403            "user.variant.format",
3404            "user.extensions.format");
3405 
3406     this(string languageKey, string scriptKey, string countryKey,
3407             string variantKey, string extensionsKey) {
3408         this.languageKey = languageKey;
3409         this.scriptKey = scriptKey;
3410         this.countryKey = countryKey;
3411         this.variantKey = variantKey;
3412         this.extensionsKey = extensionsKey;
3413     }
3414 
3415    string languageKey;
3416    string scriptKey;
3417    string countryKey;
3418    string variantKey;
3419    string extensionsKey;
3420 
3421    //  bool opEquals(const LocaleCategory h) nothrow {
3422    //      return this.languageKey == h.languageKey && 
3423    //       // this.scriptKey == h.scriptKey &&
3424    //       this.countryKey == h.countryKey;
3425    //  }
3426 
3427    //  bool opEquals(ref const LocaleCategory h) nothrow {
3428    //      return this.languageKey == h.languageKey && 
3429    //       // this.scriptKey == h.scriptKey &&
3430    //       this.countryKey == h.countryKey;
3431    //  }
3432 }