summaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/text/language/language.go
blob: abfa17f66db1cb38f3cf6c9997bdb0ab9fe9dddd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run gen.go -output tables.go

package language

// TODO: Remove above NOTE after:
// - verifying that tables are dropped correctly (most notably matcher tables).

import (
	"strings"

	"golang.org/x/text/internal/language"
	"golang.org/x/text/internal/language/compact"
)

// Tag represents a BCP 47 language tag. It is used to specify an instance of a
// specific language or locale. All language tag values are guaranteed to be
// well-formed.
type Tag compact.Tag

func makeTag(t language.Tag) (tag Tag) {
	return Tag(compact.Make(t))
}

func (t *Tag) tag() language.Tag {
	return (*compact.Tag)(t).Tag()
}

func (t *Tag) isCompact() bool {
	return (*compact.Tag)(t).IsCompact()
}

// TODO: improve performance.
func (t *Tag) lang() language.Language { return t.tag().LangID }
func (t *Tag) region() language.Region { return t.tag().RegionID }
func (t *Tag) script() language.Script { return t.tag().ScriptID }

// Make is a convenience wrapper for Parse that omits the error.
// In case of an error, a sensible default is returned.
func Make(s string) Tag {
	return Default.Make(s)
}

// Make is a convenience wrapper for c.Parse that omits the error.
// In case of an error, a sensible default is returned.
func (c CanonType) Make(s string) Tag {
	t, _ := c.Parse(s)
	return t
}

// Raw returns the raw base language, script and region, without making an
// attempt to infer their values.
func (t Tag) Raw() (b Base, s Script, r Region) {
	tt := t.tag()
	return Base{tt.LangID}, Script{tt.ScriptID}, Region{tt.RegionID}
}

// IsRoot returns true if t is equal to language "und".
func (t Tag) IsRoot() bool {
	return compact.Tag(t).IsRoot()
}

// CanonType can be used to enable or disable various types of canonicalization.
type CanonType int

const (
	// Replace deprecated base languages with their preferred replacements.
	DeprecatedBase CanonType = 1 << iota
	// Replace deprecated scripts with their preferred replacements.
	DeprecatedScript
	// Replace deprecated regions with their preferred replacements.
	DeprecatedRegion
	// Remove redundant scripts.
	SuppressScript
	// Normalize legacy encodings. This includes legacy languages defined in
	// CLDR as well as bibliographic codes defined in ISO-639.
	Legacy
	// Map the dominant language of a macro language group to the macro language
	// subtag. For example cmn -> zh.
	Macro
	// The CLDR flag should be used if full compatibility with CLDR is required.
	// There are a few cases where language.Tag may differ from CLDR. To follow all
	// of CLDR's suggestions, use All|CLDR.
	CLDR

	// Raw can be used to Compose or Parse without Canonicalization.
	Raw CanonType = 0

	// Replace all deprecated tags with their preferred replacements.
	Deprecated = DeprecatedBase | DeprecatedScript | DeprecatedRegion

	// All canonicalizations recommended by BCP 47.
	BCP47 = Deprecated | SuppressScript

	// All canonicalizations.
	All = BCP47 | Legacy | Macro

	// Default is the canonicalization used by Parse, Make and Compose. To
	// preserve as much information as possible, canonicalizations that remove
	// potentially valuable information are not included. The Matcher is
	// designed to recognize similar tags that would be the same if
	// they were canonicalized using All.
	Default = Deprecated | Legacy

	canonLang = DeprecatedBase | Legacy | Macro

	// TODO: LikelyScript, LikelyRegion: suppress similar to ICU.
)

// canonicalize returns the canonicalized equivalent of the tag and
// whether there was any change.
func canonicalize(c CanonType, t language.Tag) (language.Tag, bool) {
	if c == Raw {
		return t, false
	}
	changed := false
	if c&SuppressScript != 0 {
		if t.LangID.SuppressScript() == t.ScriptID {
			t.ScriptID = 0
			changed = true
		}
	}
	if c&canonLang != 0 {
		for {
			if l, aliasType := t.LangID.Canonicalize(); l != t.LangID {
				switch aliasType {
				case language.Legacy:
					if c&Legacy != 0 {
						if t.LangID == _sh && t.ScriptID == 0 {
							t.ScriptID = _Latn
						}
						t.LangID = l
						changed = true
					}
				case language.Macro:
					if c&Macro != 0 {
						// We deviate here from CLDR. The mapping "nb" -> "no"
						// qualifies as a typical Macro language mapping.  However,
						// for legacy reasons, CLDR maps "no", the macro language
						// code for Norwegian, to the dominant variant "nb". This
						// change is currently under consideration for CLDR as well.
						// See https://unicode.org/cldr/trac/ticket/2698 and also
						// https://unicode.org/cldr/trac/ticket/1790 for some of the
						// practical implications. TODO: this check could be removed
						// if CLDR adopts this change.
						if c&CLDR == 0 || t.LangID != _nb {
							changed = true
							t.LangID = l
						}
					}
				case language.Deprecated:
					if c&DeprecatedBase != 0 {
						if t.LangID == _mo && t.RegionID == 0 {
							t.RegionID = _MD
						}
						t.LangID = l
						changed = true
						// Other canonicalization types may still apply.
						continue
					}
				}
			} else if c&Legacy != 0 && t.LangID == _no && c&CLDR != 0 {
				t.LangID = _nb
				changed = true
			}
			break
		}
	}
	if c&DeprecatedScript != 0 {
		if t.ScriptID == _Qaai {
			changed = true
			t.ScriptID = _Zinh
		}
	}
	if c&DeprecatedRegion != 0 {
		if r := t.RegionID.Canonicalize(); r != t.RegionID {
			changed = true
			t.RegionID = r
		}
	}
	return t, changed
}

// Canonicalize returns the canonicalized equivalent of the tag.
func (c CanonType) Canonicalize(t Tag) (Tag, error) {
	// First try fast path.
	if t.isCompact() {
		if _, changed := canonicalize(c, compact.Tag(t).Tag()); !changed {
			return t, nil
		}
	}
	// It is unlikely that one will canonicalize a tag after matching. So do
	// a slow but simple approach here.
	if tag, changed := canonicalize(c, t.tag()); changed {
		tag.RemakeString()
		return makeTag(tag), nil
	}
	return t, nil

}

// Confidence indicates the level of certainty for a given return value.
// For example, Serbian may be written in Cyrillic or Latin script.
// The confidence level indicates whether a value was explicitly specified,
// whether it is typically the only possible value, or whether there is
// an ambiguity.
type Confidence int

const (
	No    Confidence = iota // full confidence that there was no match
	Low                     // most likely value picked out of a set of alternatives
	High                    // value is generally assumed to be the correct match
	Exact                   // exact match or explicitly specified value
)

var confName = []string{"No", "Low", "High", "Exact"}

func (c Confidence) String() string {
	return confName[c]
}

// String returns the canonical string representation of the language tag.
func (t Tag) String() string {
	return t.tag().String()
}

// MarshalText implements encoding.TextMarshaler.
func (t Tag) MarshalText() (text []byte, err error) {
	return t.tag().MarshalText()
}

// UnmarshalText implements encoding.TextUnmarshaler.
func (t *Tag) UnmarshalText(text []byte) error {
	var tag language.Tag
	err := tag.UnmarshalText(text)
	*t = makeTag(tag)
	return err
}

// Base returns the base language of the language tag. If the base language is
// unspecified, an attempt will be made to infer it from the context.
// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
func (t Tag) Base() (Base, Confidence) {
	if b := t.lang(); b != 0 {
		return Base{b}, Exact
	}
	tt := t.tag()
	c := High
	if tt.ScriptID == 0 && !tt.RegionID.IsCountry() {
		c = Low
	}
	if tag, err := tt.Maximize(); err == nil && tag.LangID != 0 {
		return Base{tag.LangID}, c
	}
	return Base{0}, No
}

// Script infers the script for the language tag. If it was not explicitly given, it will infer
// a most likely candidate.
// If more than one script is commonly used for a language, the most likely one
// is returned with a low confidence indication. For example, it returns (Cyrl, Low)
// for Serbian.
// If a script cannot be inferred (Zzzz, No) is returned. We do not use Zyyy (undetermined)
// as one would suspect from the IANA registry for BCP 47. In a Unicode context Zyyy marks
// common characters (like 1, 2, 3, '.', etc.) and is therefore more like multiple scripts.
// See https://www.unicode.org/reports/tr24/#Values for more details. Zzzz is also used for
// unknown value in CLDR.  (Zzzz, Exact) is returned if Zzzz was explicitly specified.
// Note that an inferred script is never guaranteed to be the correct one. Latin is
// almost exclusively used for Afrikaans, but Arabic has been used for some texts
// in the past.  Also, the script that is commonly used may change over time.
// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
func (t Tag) Script() (Script, Confidence) {
	if scr := t.script(); scr != 0 {
		return Script{scr}, Exact
	}
	tt := t.tag()
	sc, c := language.Script(_Zzzz), No
	if scr := tt.LangID.SuppressScript(); scr != 0 {
		// Note: it is not always the case that a language with a suppress
		// script value is only written in one script (e.g. kk, ms, pa).
		if tt.RegionID == 0 {
			return Script{scr}, High
		}
		sc, c = scr, High
	}
	if tag, err := tt.Maximize(); err == nil {
		if tag.ScriptID != sc {
			sc, c = tag.ScriptID, Low
		}
	} else {
		tt, _ = canonicalize(Deprecated|Macro, tt)
		if tag, err := tt.Maximize(); err == nil && tag.ScriptID != sc {
			sc, c = tag.ScriptID, Low
		}
	}
	return Script{sc}, c
}

// Region returns the region for the language tag. If it was not explicitly given, it will
// infer a most likely candidate from the context.
// It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change.
func (t Tag) Region() (Region, Confidence) {
	if r := t.region(); r != 0 {
		return Region{r}, Exact
	}
	tt := t.tag()
	if tt, err := tt.Maximize(); err == nil {
		return Region{tt.RegionID}, Low // TODO: differentiate between high and low.
	}
	tt, _ = canonicalize(Deprecated|Macro, tt)
	if tag, err := tt.Maximize(); err == nil {
		return Region{tag.RegionID}, Low
	}
	return Region{_ZZ}, No // TODO: return world instead of undetermined?
}

// Variants returns the variants specified explicitly for this language tag.
// or nil if no variant was specified.
func (t Tag) Variants() []Variant {
	if !compact.Tag(t).MayHaveVariants() {
		return nil
	}
	v := []Variant{}
	x, str := "", t.tag().Variants()
	for str != "" {
		x, str = nextToken(str)
		v = append(v, Variant{x})
	}
	return v
}

// Parent returns the CLDR parent of t. In CLDR, missing fields in data for a
// specific language are substituted with fields from the parent language.
// The parent for a language may change for newer versions of CLDR.
//
// Parent returns a tag for a less specific language that is mutually
// intelligible or Und if there is no such language. This may not be the same as
// simply stripping the last BCP 47 subtag. For instance, the parent of "zh-TW"
// is "zh-Hant", and the parent of "zh-Hant" is "und".
func (t Tag) Parent() Tag {
	return Tag(compact.Tag(t).Parent())
}

// returns token t and the rest of the string.
func nextToken(s string) (t, tail string) {
	p := strings.Index(s[1:], "-")
	if p == -1 {
		return s[1:], ""
	}
	p++
	return s[1:p], s[p:]
}

// Extension is a single BCP 47 extension.
type Extension struct {
	s string
}

// String returns the string representation of the extension, including the
// type tag.
func (e Extension) String() string {
	return e.s
}

// ParseExtension parses s as an extension and returns it on success.
func ParseExtension(s string) (e Extension, err error) {
	ext, err := language.ParseExtension(s)
	return Extension{ext}, err
}

// Type returns the one-byte extension type of e. It returns 0 for the zero
// exception.
func (e Extension) Type() byte {
	if e.s == "" {
		return 0
	}
	return e.s[0]
}

// Tokens returns the list of tokens of e.
func (e Extension) Tokens() []string {
	return strings.Split(e.s, "-")
}

// Extension returns the extension of type x for tag t. It will return
// false for ok if t does not have the requested extension. The returned
// extension will be invalid in this case.
func (t Tag) Extension(x byte) (ext Extension, ok bool) {
	if !compact.Tag(t).MayHaveExtensions() {
		return Extension{}, false
	}
	e, ok := t.tag().Extension(x)
	return Extension{e}, ok
}

// Extensions returns all extensions of t.
func (t Tag) Extensions() []Extension {
	if !compact.Tag(t).MayHaveExtensions() {
		return nil
	}
	e := []Extension{}
	for _, ext := range t.tag().Extensions() {
		e = append(e, Extension{ext})
	}
	return e
}

// TypeForKey returns the type associated with the given key, where key and type
// are of the allowed values defined for the Unicode locale extension ('u') in
// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
// TypeForKey will traverse the inheritance chain to get the correct value.
func (t Tag) TypeForKey(key string) string {
	if !compact.Tag(t).MayHaveExtensions() {
		if key != "rg" && key != "va" {
			return ""
		}
	}
	return t.tag().TypeForKey(key)
}

// SetTypeForKey returns a new Tag with the key set to type, where key and type
// are of the allowed values defined for the Unicode locale extension ('u') in
// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
// An empty value removes an existing pair with the same key.
func (t Tag) SetTypeForKey(key, value string) (Tag, error) {
	tt, err := t.tag().SetTypeForKey(key, value)
	return makeTag(tt), err
}

// NumCompactTags is the number of compact tags. The maximum tag is
// NumCompactTags-1.
const NumCompactTags = compact.NumCompactTags

// CompactIndex returns an index, where 0 <= index < NumCompactTags, for tags
// for which data exists in the text repository.The index will change over time
// and should not be stored in persistent storage. If t does not match a compact
// index, exact will be false and the compact index will be returned for the
// first match after repeatedly taking the Parent of t.
func CompactIndex(t Tag) (index int, exact bool) {
	id, exact := compact.LanguageID(compact.Tag(t))
	return int(id), exact
}

var root = language.Tag{}

// Base is an ISO 639 language code, used for encoding the base language
// of a language tag.
type Base struct {
	langID language.Language
}

// ParseBase parses a 2- or 3-letter ISO 639 code.
// It returns a ValueError if s is a well-formed but unknown language identifier
// or another error if another error occurred.
func ParseBase(s string) (Base, error) {
	l, err := language.ParseBase(s)
	return Base{l}, err
}

// String returns the BCP 47 representation of the base language.
func (b Base) String() string {
	return b.langID.String()
}

// ISO3 returns the ISO 639-3 language code.
func (b Base) ISO3() string {
	return b.langID.ISO3()
}

// IsPrivateUse reports whether this language code is reserved for private use.
func (b Base) IsPrivateUse() bool {
	return b.langID.IsPrivateUse()
}

// Script is a 4-letter ISO 15924 code for representing scripts.
// It is idiomatically represented in title case.
type Script struct {
	scriptID language.Script
}

// ParseScript parses a 4-letter ISO 15924 code.
// It returns a ValueError if s is a well-formed but unknown script identifier
// or another error if another error occurred.
func ParseScript(s string) (Script, error) {
	sc, err := language.ParseScript(s)
	return Script{sc}, err
}

// String returns the script code in title case.
// It returns "Zzzz" for an unspecified script.
func (s Script) String() string {
	return s.scriptID.String()
}

// IsPrivateUse reports whether this script code is reserved for private use.
func (s Script) IsPrivateUse() bool {
	return s.scriptID.IsPrivateUse()
}

// Region is an ISO 3166-1 or UN M.49 code for representing countries and regions.
type Region struct {
	regionID language.Region
}

// EncodeM49 returns the Region for the given UN M.49 code.
// It returns an error if r is not a valid code.
func EncodeM49(r int) (Region, error) {
	rid, err := language.EncodeM49(r)
	return Region{rid}, err
}

// ParseRegion parses a 2- or 3-letter ISO 3166-1 or a UN M.49 code.
// It returns a ValueError if s is a well-formed but unknown region identifier
// or another error if another error occurred.
func ParseRegion(s string) (Region, error) {
	r, err := language.ParseRegion(s)
	return Region{r}, err
}

// String returns the BCP 47 representation for the region.
// It returns "ZZ" for an unspecified region.
func (r Region) String() string {
	return r.regionID.String()
}

// ISO3 returns the 3-letter ISO code of r.
// Note that not all regions have a 3-letter ISO code.
// In such cases this method returns "ZZZ".
func (r Region) ISO3() string {
	return r.regionID.ISO3()
}

// M49 returns the UN M.49 encoding of r, or 0 if this encoding
// is not defined for r.
func (r Region) M49() int {
	return r.regionID.M49()
}

// IsPrivateUse reports whether r has the ISO 3166 User-assigned status. This
// may include private-use tags that are assigned by CLDR and used in this
// implementation. So IsPrivateUse and IsCountry can be simultaneously true.
func (r Region) IsPrivateUse() bool {
	return r.regionID.IsPrivateUse()
}

// IsCountry returns whether this region is a country or autonomous area. This
// includes non-standard definitions from CLDR.
func (r Region) IsCountry() bool {
	return r.regionID.IsCountry()
}

// IsGroup returns whether this region defines a collection of regions. This
// includes non-standard definitions from CLDR.
func (r Region) IsGroup() bool {
	return r.regionID.IsGroup()
}

// Contains returns whether Region c is contained by Region r. It returns true
// if c == r.
func (r Region) Contains(c Region) bool {
	return r.regionID.Contains(c.regionID)
}

// TLD returns the country code top-level domain (ccTLD). UK is returned for GB.
// In all other cases it returns either the region itself or an error.
//
// This method may return an error for a region for which there exists a
// canonical form with a ccTLD. To get that ccTLD canonicalize r first. The
// region will already be canonicalized it was obtained from a Tag that was
// obtained using any of the default methods.
func (r Region) TLD() (Region, error) {
	tld, err := r.regionID.TLD()
	return Region{tld}, err
}

// Canonicalize returns the region or a possible replacement if the region is
// deprecated. It will not return a replacement for deprecated regions that
// are split into multiple regions.
func (r Region) Canonicalize() Region {
	return Region{r.regionID.Canonicalize()}
}

// Variant represents a registered variant of a language as defined by BCP 47.
type Variant struct {
	variant string
}

// ParseVariant parses and returns a Variant. An error is returned if s is not
// a valid variant.
func ParseVariant(s string) (Variant, error) {
	v, err := language.ParseVariant(s)
	return Variant{v.String()}, err
}

// String returns the string representation of the variant.
func (v Variant) String() string {
	return v.variant
}