github.com/liquid-dev/text@v0.3.3-liquid/language/language.go (about) 1 // Copyright 2013 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:generate go run gen.go -output tables.go 6 7 package language 8 9 // TODO: Remove above NOTE after: 10 // - verifying that tables are dropped correctly (most notably matcher tables). 11 12 import ( 13 "strings" 14 15 "github.com/liquid-dev/text/internal/language" 16 "github.com/liquid-dev/text/internal/language/compact" 17 ) 18 19 // Tag represents a BCP 47 language tag. It is used to specify an instance of a 20 // specific language or locale. All language tag values are guaranteed to be 21 // well-formed. 22 type Tag compact.Tag 23 24 func makeTag(t language.Tag) (tag Tag) { 25 return Tag(compact.Make(t)) 26 } 27 28 func (t *Tag) tag() language.Tag { 29 return (*compact.Tag)(t).Tag() 30 } 31 32 func (t *Tag) isCompact() bool { 33 return (*compact.Tag)(t).IsCompact() 34 } 35 36 // TODO: improve performance. 37 func (t *Tag) lang() language.Language { return t.tag().LangID } 38 func (t *Tag) region() language.Region { return t.tag().RegionID } 39 func (t *Tag) script() language.Script { return t.tag().ScriptID } 40 41 // Make is a convenience wrapper for Parse that omits the error. 42 // In case of an error, a sensible default is returned. 43 func Make(s string) Tag { 44 return Default.Make(s) 45 } 46 47 // Make is a convenience wrapper for c.Parse that omits the error. 48 // In case of an error, a sensible default is returned. 49 func (c CanonType) Make(s string) Tag { 50 t, _ := c.Parse(s) 51 return t 52 } 53 54 // Raw returns the raw base language, script and region, without making an 55 // attempt to infer their values. 56 func (t Tag) Raw() (b Base, s Script, r Region) { 57 tt := t.tag() 58 return Base{tt.LangID}, Script{tt.ScriptID}, Region{tt.RegionID} 59 } 60 61 // IsRoot returns true if t is equal to language "und". 62 func (t Tag) IsRoot() bool { 63 return compact.Tag(t).IsRoot() 64 } 65 66 // CanonType can be used to enable or disable various types of canonicalization. 67 type CanonType int 68 69 const ( 70 // Replace deprecated base languages with their preferred replacements. 71 DeprecatedBase CanonType = 1 << iota 72 // Replace deprecated scripts with their preferred replacements. 73 DeprecatedScript 74 // Replace deprecated regions with their preferred replacements. 75 DeprecatedRegion 76 // Remove redundant scripts. 77 SuppressScript 78 // Normalize legacy encodings. This includes legacy languages defined in 79 // CLDR as well as bibliographic codes defined in ISO-639. 80 Legacy 81 // Map the dominant language of a macro language group to the macro language 82 // subtag. For example cmn -> zh. 83 Macro 84 // The CLDR flag should be used if full compatibility with CLDR is required. 85 // There are a few cases where language.Tag may differ from CLDR. To follow all 86 // of CLDR's suggestions, use All|CLDR. 87 CLDR 88 89 // Raw can be used to Compose or Parse without Canonicalization. 90 Raw CanonType = 0 91 92 // Replace all deprecated tags with their preferred replacements. 93 Deprecated = DeprecatedBase | DeprecatedScript | DeprecatedRegion 94 95 // All canonicalizations recommended by BCP 47. 96 BCP47 = Deprecated | SuppressScript 97 98 // All canonicalizations. 99 All = BCP47 | Legacy | Macro 100 101 // Default is the canonicalization used by Parse, Make and Compose. To 102 // preserve as much information as possible, canonicalizations that remove 103 // potentially valuable information are not included. The Matcher is 104 // designed to recognize similar tags that would be the same if 105 // they were canonicalized using All. 106 Default = Deprecated | Legacy 107 108 canonLang = DeprecatedBase | Legacy | Macro 109 110 // TODO: LikelyScript, LikelyRegion: suppress similar to ICU. 111 ) 112 113 // canonicalize returns the canonicalized equivalent of the tag and 114 // whether there was any change. 115 func canonicalize(c CanonType, t language.Tag) (language.Tag, bool) { 116 if c == Raw { 117 return t, false 118 } 119 changed := false 120 if c&SuppressScript != 0 { 121 if t.LangID.SuppressScript() == t.ScriptID { 122 t.ScriptID = 0 123 changed = true 124 } 125 } 126 if c&canonLang != 0 { 127 for { 128 if l, aliasType := t.LangID.Canonicalize(); l != t.LangID { 129 switch aliasType { 130 case language.Legacy: 131 if c&Legacy != 0 { 132 if t.LangID == _sh && t.ScriptID == 0 { 133 t.ScriptID = _Latn 134 } 135 t.LangID = l 136 changed = true 137 } 138 case language.Macro: 139 if c&Macro != 0 { 140 // We deviate here from CLDR. The mapping "nb" -> "no" 141 // qualifies as a typical Macro language mapping. However, 142 // for legacy reasons, CLDR maps "no", the macro language 143 // code for Norwegian, to the dominant variant "nb". This 144 // change is currently under consideration for CLDR as well. 145 // See https://unicode.org/cldr/trac/ticket/2698 and also 146 // https://unicode.org/cldr/trac/ticket/1790 for some of the 147 // practical implications. TODO: this check could be removed 148 // if CLDR adopts this change. 149 if c&CLDR == 0 || t.LangID != _nb { 150 changed = true 151 t.LangID = l 152 } 153 } 154 case language.Deprecated: 155 if c&DeprecatedBase != 0 { 156 if t.LangID == _mo && t.RegionID == 0 { 157 t.RegionID = _MD 158 } 159 t.LangID = l 160 changed = true 161 // Other canonicalization types may still apply. 162 continue 163 } 164 } 165 } else if c&Legacy != 0 && t.LangID == _no && c&CLDR != 0 { 166 t.LangID = _nb 167 changed = true 168 } 169 break 170 } 171 } 172 if c&DeprecatedScript != 0 { 173 if t.ScriptID == _Qaai { 174 changed = true 175 t.ScriptID = _Zinh 176 } 177 } 178 if c&DeprecatedRegion != 0 { 179 if r := t.RegionID.Canonicalize(); r != t.RegionID { 180 changed = true 181 t.RegionID = r 182 } 183 } 184 return t, changed 185 } 186 187 // Canonicalize returns the canonicalized equivalent of the tag. 188 func (c CanonType) Canonicalize(t Tag) (Tag, error) { 189 // First try fast path. 190 if t.isCompact() { 191 if _, changed := canonicalize(c, compact.Tag(t).Tag()); !changed { 192 return t, nil 193 } 194 } 195 // It is unlikely that one will canonicalize a tag after matching. So do 196 // a slow but simple approach here. 197 if tag, changed := canonicalize(c, t.tag()); changed { 198 tag.RemakeString() 199 return makeTag(tag), nil 200 } 201 return t, nil 202 203 } 204 205 // Confidence indicates the level of certainty for a given return value. 206 // For example, Serbian may be written in Cyrillic or Latin script. 207 // The confidence level indicates whether a value was explicitly specified, 208 // whether it is typically the only possible value, or whether there is 209 // an ambiguity. 210 type Confidence int 211 212 const ( 213 No Confidence = iota // full confidence that there was no match 214 Low // most likely value picked out of a set of alternatives 215 High // value is generally assumed to be the correct match 216 Exact // exact match or explicitly specified value 217 ) 218 219 var confName = []string{"No", "Low", "High", "Exact"} 220 221 func (c Confidence) String() string { 222 return confName[c] 223 } 224 225 // String returns the canonical string representation of the language tag. 226 func (t Tag) String() string { 227 return t.tag().String() 228 } 229 230 // MarshalText implements encoding.TextMarshaler. 231 func (t Tag) MarshalText() (text []byte, err error) { 232 return t.tag().MarshalText() 233 } 234 235 // UnmarshalText implements encoding.TextUnmarshaler. 236 func (t *Tag) UnmarshalText(text []byte) error { 237 var tag language.Tag 238 err := tag.UnmarshalText(text) 239 *t = makeTag(tag) 240 return err 241 } 242 243 // Base returns the base language of the language tag. If the base language is 244 // unspecified, an attempt will be made to infer it from the context. 245 // It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change. 246 func (t Tag) Base() (Base, Confidence) { 247 if b := t.lang(); b != 0 { 248 return Base{b}, Exact 249 } 250 tt := t.tag() 251 c := High 252 if tt.ScriptID == 0 && !tt.RegionID.IsCountry() { 253 c = Low 254 } 255 if tag, err := tt.Maximize(); err == nil && tag.LangID != 0 { 256 return Base{tag.LangID}, c 257 } 258 return Base{0}, No 259 } 260 261 // Script infers the script for the language tag. If it was not explicitly given, it will infer 262 // a most likely candidate. 263 // If more than one script is commonly used for a language, the most likely one 264 // is returned with a low confidence indication. For example, it returns (Cyrl, Low) 265 // for Serbian. 266 // If a script cannot be inferred (Zzzz, No) is returned. We do not use Zyyy (undetermined) 267 // as one would suspect from the IANA registry for BCP 47. In a Unicode context Zyyy marks 268 // common characters (like 1, 2, 3, '.', etc.) and is therefore more like multiple scripts. 269 // See https://www.unicode.org/reports/tr24/#Values for more details. Zzzz is also used for 270 // unknown value in CLDR. (Zzzz, Exact) is returned if Zzzz was explicitly specified. 271 // Note that an inferred script is never guaranteed to be the correct one. Latin is 272 // almost exclusively used for Afrikaans, but Arabic has been used for some texts 273 // in the past. Also, the script that is commonly used may change over time. 274 // It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change. 275 func (t Tag) Script() (Script, Confidence) { 276 if scr := t.script(); scr != 0 { 277 return Script{scr}, Exact 278 } 279 tt := t.tag() 280 sc, c := language.Script(_Zzzz), No 281 if scr := tt.LangID.SuppressScript(); scr != 0 { 282 // Note: it is not always the case that a language with a suppress 283 // script value is only written in one script (e.g. kk, ms, pa). 284 if tt.RegionID == 0 { 285 return Script{scr}, High 286 } 287 sc, c = scr, High 288 } 289 if tag, err := tt.Maximize(); err == nil { 290 if tag.ScriptID != sc { 291 sc, c = tag.ScriptID, Low 292 } 293 } else { 294 tt, _ = canonicalize(Deprecated|Macro, tt) 295 if tag, err := tt.Maximize(); err == nil && tag.ScriptID != sc { 296 sc, c = tag.ScriptID, Low 297 } 298 } 299 return Script{sc}, c 300 } 301 302 // Region returns the region for the language tag. If it was not explicitly given, it will 303 // infer a most likely candidate from the context. 304 // It uses a variant of CLDR's Add Likely Subtags algorithm. This is subject to change. 305 func (t Tag) Region() (Region, Confidence) { 306 if r := t.region(); r != 0 { 307 return Region{r}, Exact 308 } 309 tt := t.tag() 310 if tt, err := tt.Maximize(); err == nil { 311 return Region{tt.RegionID}, Low // TODO: differentiate between high and low. 312 } 313 tt, _ = canonicalize(Deprecated|Macro, tt) 314 if tag, err := tt.Maximize(); err == nil { 315 return Region{tag.RegionID}, Low 316 } 317 return Region{_ZZ}, No // TODO: return world instead of undetermined? 318 } 319 320 // Variants returns the variants specified explicitly for this language tag. 321 // or nil if no variant was specified. 322 func (t Tag) Variants() []Variant { 323 if !compact.Tag(t).MayHaveVariants() { 324 return nil 325 } 326 v := []Variant{} 327 x, str := "", t.tag().Variants() 328 for str != "" { 329 x, str = nextToken(str) 330 v = append(v, Variant{x}) 331 } 332 return v 333 } 334 335 // Parent returns the CLDR parent of t. In CLDR, missing fields in data for a 336 // specific language are substituted with fields from the parent language. 337 // The parent for a language may change for newer versions of CLDR. 338 // 339 // Parent returns a tag for a less specific language that is mutually 340 // intelligible or Und if there is no such language. This may not be the same as 341 // simply stripping the last BCP 47 subtag. For instance, the parent of "zh-TW" 342 // is "zh-Hant", and the parent of "zh-Hant" is "und". 343 func (t Tag) Parent() Tag { 344 return Tag(compact.Tag(t).Parent()) 345 } 346 347 // returns token t and the rest of the string. 348 func nextToken(s string) (t, tail string) { 349 p := strings.Index(s[1:], "-") 350 if p == -1 { 351 return s[1:], "" 352 } 353 p++ 354 return s[1:p], s[p:] 355 } 356 357 // Extension is a single BCP 47 extension. 358 type Extension struct { 359 s string 360 } 361 362 // String returns the string representation of the extension, including the 363 // type tag. 364 func (e Extension) String() string { 365 return e.s 366 } 367 368 // ParseExtension parses s as an extension and returns it on success. 369 func ParseExtension(s string) (e Extension, err error) { 370 ext, err := language.ParseExtension(s) 371 return Extension{ext}, err 372 } 373 374 // Type returns the one-byte extension type of e. It returns 0 for the zero 375 // exception. 376 func (e Extension) Type() byte { 377 if e.s == "" { 378 return 0 379 } 380 return e.s[0] 381 } 382 383 // Tokens returns the list of tokens of e. 384 func (e Extension) Tokens() []string { 385 return strings.Split(e.s, "-") 386 } 387 388 // Extension returns the extension of type x for tag t. It will return 389 // false for ok if t does not have the requested extension. The returned 390 // extension will be invalid in this case. 391 func (t Tag) Extension(x byte) (ext Extension, ok bool) { 392 if !compact.Tag(t).MayHaveExtensions() { 393 return Extension{}, false 394 } 395 e, ok := t.tag().Extension(x) 396 return Extension{e}, ok 397 } 398 399 // Extensions returns all extensions of t. 400 func (t Tag) Extensions() []Extension { 401 if !compact.Tag(t).MayHaveExtensions() { 402 return nil 403 } 404 e := []Extension{} 405 for _, ext := range t.tag().Extensions() { 406 e = append(e, Extension{ext}) 407 } 408 return e 409 } 410 411 // TypeForKey returns the type associated with the given key, where key and type 412 // are of the allowed values defined for the Unicode locale extension ('u') in 413 // https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers. 414 // TypeForKey will traverse the inheritance chain to get the correct value. 415 func (t Tag) TypeForKey(key string) string { 416 if !compact.Tag(t).MayHaveExtensions() { 417 if key != "rg" && key != "va" { 418 return "" 419 } 420 } 421 return t.tag().TypeForKey(key) 422 } 423 424 // SetTypeForKey returns a new Tag with the key set to type, where key and type 425 // are of the allowed values defined for the Unicode locale extension ('u') in 426 // https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers. 427 // An empty value removes an existing pair with the same key. 428 func (t Tag) SetTypeForKey(key, value string) (Tag, error) { 429 tt, err := t.tag().SetTypeForKey(key, value) 430 return makeTag(tt), err 431 } 432 433 // NumCompactTags is the number of compact tags. The maximum tag is 434 // NumCompactTags-1. 435 const NumCompactTags = compact.NumCompactTags 436 437 // CompactIndex returns an index, where 0 <= index < NumCompactTags, for tags 438 // for which data exists in the text repository.The index will change over time 439 // and should not be stored in persistent storage. If t does not match a compact 440 // index, exact will be false and the compact index will be returned for the 441 // first match after repeatedly taking the Parent of t. 442 func CompactIndex(t Tag) (index int, exact bool) { 443 id, exact := compact.LanguageID(compact.Tag(t)) 444 return int(id), exact 445 } 446 447 var root = language.Tag{} 448 449 // Base is an ISO 639 language code, used for encoding the base language 450 // of a language tag. 451 type Base struct { 452 langID language.Language 453 } 454 455 // ParseBase parses a 2- or 3-letter ISO 639 code. 456 // It returns a ValueError if s is a well-formed but unknown language identifier 457 // or another error if another error occurred. 458 func ParseBase(s string) (Base, error) { 459 l, err := language.ParseBase(s) 460 return Base{l}, err 461 } 462 463 // String returns the BCP 47 representation of the base language. 464 func (b Base) String() string { 465 return b.langID.String() 466 } 467 468 // ISO3 returns the ISO 639-3 language code. 469 func (b Base) ISO3() string { 470 return b.langID.ISO3() 471 } 472 473 // IsPrivateUse reports whether this language code is reserved for private use. 474 func (b Base) IsPrivateUse() bool { 475 return b.langID.IsPrivateUse() 476 } 477 478 // Script is a 4-letter ISO 15924 code for representing scripts. 479 // It is idiomatically represented in title case. 480 type Script struct { 481 scriptID language.Script 482 } 483 484 // ParseScript parses a 4-letter ISO 15924 code. 485 // It returns a ValueError if s is a well-formed but unknown script identifier 486 // or another error if another error occurred. 487 func ParseScript(s string) (Script, error) { 488 sc, err := language.ParseScript(s) 489 return Script{sc}, err 490 } 491 492 // String returns the script code in title case. 493 // It returns "Zzzz" for an unspecified script. 494 func (s Script) String() string { 495 return s.scriptID.String() 496 } 497 498 // IsPrivateUse reports whether this script code is reserved for private use. 499 func (s Script) IsPrivateUse() bool { 500 return s.scriptID.IsPrivateUse() 501 } 502 503 // Region is an ISO 3166-1 or UN M.49 code for representing countries and regions. 504 type Region struct { 505 regionID language.Region 506 } 507 508 // EncodeM49 returns the Region for the given UN M.49 code. 509 // It returns an error if r is not a valid code. 510 func EncodeM49(r int) (Region, error) { 511 rid, err := language.EncodeM49(r) 512 return Region{rid}, err 513 } 514 515 // ParseRegion parses a 2- or 3-letter ISO 3166-1 or a UN M.49 code. 516 // It returns a ValueError if s is a well-formed but unknown region identifier 517 // or another error if another error occurred. 518 func ParseRegion(s string) (Region, error) { 519 r, err := language.ParseRegion(s) 520 return Region{r}, err 521 } 522 523 // String returns the BCP 47 representation for the region. 524 // It returns "ZZ" for an unspecified region. 525 func (r Region) String() string { 526 return r.regionID.String() 527 } 528 529 // ISO3 returns the 3-letter ISO code of r. 530 // Note that not all regions have a 3-letter ISO code. 531 // In such cases this method returns "ZZZ". 532 func (r Region) ISO3() string { 533 return r.regionID.ISO3() 534 } 535 536 // M49 returns the UN M.49 encoding of r, or 0 if this encoding 537 // is not defined for r. 538 func (r Region) M49() int { 539 return r.regionID.M49() 540 } 541 542 // IsPrivateUse reports whether r has the ISO 3166 User-assigned status. This 543 // may include private-use tags that are assigned by CLDR and used in this 544 // implementation. So IsPrivateUse and IsCountry can be simultaneously true. 545 func (r Region) IsPrivateUse() bool { 546 return r.regionID.IsPrivateUse() 547 } 548 549 // IsCountry returns whether this region is a country or autonomous area. This 550 // includes non-standard definitions from CLDR. 551 func (r Region) IsCountry() bool { 552 return r.regionID.IsCountry() 553 } 554 555 // IsGroup returns whether this region defines a collection of regions. This 556 // includes non-standard definitions from CLDR. 557 func (r Region) IsGroup() bool { 558 return r.regionID.IsGroup() 559 } 560 561 // Contains returns whether Region c is contained by Region r. It returns true 562 // if c == r. 563 func (r Region) Contains(c Region) bool { 564 return r.regionID.Contains(c.regionID) 565 } 566 567 // TLD returns the country code top-level domain (ccTLD). UK is returned for GB. 568 // In all other cases it returns either the region itself or an error. 569 // 570 // This method may return an error for a region for which there exists a 571 // canonical form with a ccTLD. To get that ccTLD canonicalize r first. The 572 // region will already be canonicalized it was obtained from a Tag that was 573 // obtained using any of the default methods. 574 func (r Region) TLD() (Region, error) { 575 tld, err := r.regionID.TLD() 576 return Region{tld}, err 577 } 578 579 // Canonicalize returns the region or a possible replacement if the region is 580 // deprecated. It will not return a replacement for deprecated regions that 581 // are split into multiple regions. 582 func (r Region) Canonicalize() Region { 583 return Region{r.regionID.Canonicalize()} 584 } 585 586 // Variant represents a registered variant of a language as defined by BCP 47. 587 type Variant struct { 588 variant string 589 } 590 591 // ParseVariant parses and returns a Variant. An error is returned if s is not 592 // a valid variant. 593 func ParseVariant(s string) (Variant, error) { 594 v, err := language.ParseVariant(s) 595 return Variant{v.String()}, err 596 } 597 598 // String returns the string representation of the variant. 599 func (v Variant) String() string { 600 return v.variant 601 }