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 gen_common.go -output tables.go
  6
  7package language // import "golang.org/x/text/internal/language"
  8
  9// TODO: Remove above NOTE after:
 10// - verifying that tables are dropped correctly (most notably matcher tables).
 11
 12import (
 13	"errors"
 14	"fmt"
 15	"strings"
 16)
 17
 18const (
 19	// maxCoreSize is the maximum size of a BCP 47 tag without variants and
 20	// extensions. Equals max lang (3) + script (4) + max reg (3) + 2 dashes.
 21	maxCoreSize = 12
 22
 23	// max99thPercentileSize is a somewhat arbitrary buffer size that presumably
 24	// is large enough to hold at least 99% of the BCP 47 tags.
 25	max99thPercentileSize = 32
 26
 27	// maxSimpleUExtensionSize is the maximum size of a -u extension with one
 28	// key-type pair. Equals len("-u-") + key (2) + dash + max value (8).
 29	maxSimpleUExtensionSize = 14
 30)
 31
 32// Tag represents a BCP 47 language tag. It is used to specify an instance of a
 33// specific language or locale. All language tag values are guaranteed to be
 34// well-formed. The zero value of Tag is Und.
 35type Tag struct {
 36	// TODO: the following fields have the form TagTypeID. This name is chosen
 37	// to allow refactoring the public package without conflicting with its
 38	// Base, Script, and Region methods. Once the transition is fully completed
 39	// the ID can be stripped from the name.
 40
 41	LangID   Language
 42	RegionID Region
 43	// TODO: we will soon run out of positions for ScriptID. Idea: instead of
 44	// storing lang, region, and ScriptID codes, store only the compact index and
 45	// have a lookup table from this code to its expansion. This greatly speeds
 46	// up table lookup, speed up common variant cases.
 47	// This will also immediately free up 3 extra bytes. Also, the pVariant
 48	// field can now be moved to the lookup table, as the compact index uniquely
 49	// determines the offset of a possible variant.
 50	ScriptID Script
 51	pVariant byte   // offset in str, includes preceding '-'
 52	pExt     uint16 // offset of first extension, includes preceding '-'
 53
 54	// str is the string representation of the Tag. It will only be used if the
 55	// tag has variants or extensions.
 56	str string
 57}
 58
 59// Make is a convenience wrapper for Parse that omits the error.
 60// In case of an error, a sensible default is returned.
 61func Make(s string) Tag {
 62	t, _ := Parse(s)
 63	return t
 64}
 65
 66// Raw returns the raw base language, script and region, without making an
 67// attempt to infer their values.
 68// TODO: consider removing
 69func (t Tag) Raw() (b Language, s Script, r Region) {
 70	return t.LangID, t.ScriptID, t.RegionID
 71}
 72
 73// equalTags compares language, script and region subtags only.
 74func (t Tag) equalTags(a Tag) bool {
 75	return t.LangID == a.LangID && t.ScriptID == a.ScriptID && t.RegionID == a.RegionID
 76}
 77
 78// IsRoot returns true if t is equal to language "und".
 79func (t Tag) IsRoot() bool {
 80	if int(t.pVariant) < len(t.str) {
 81		return false
 82	}
 83	return t.equalTags(Und)
 84}
 85
 86// IsPrivateUse reports whether the Tag consists solely of an IsPrivateUse use
 87// tag.
 88func (t Tag) IsPrivateUse() bool {
 89	return t.str != "" && t.pVariant == 0
 90}
 91
 92// RemakeString is used to update t.str in case lang, script or region changed.
 93// It is assumed that pExt and pVariant still point to the start of the
 94// respective parts.
 95func (t *Tag) RemakeString() {
 96	if t.str == "" {
 97		return
 98	}
 99	extra := t.str[t.pVariant:]
100	if t.pVariant > 0 {
101		extra = extra[1:]
102	}
103	if t.equalTags(Und) && strings.HasPrefix(extra, "x-") {
104		t.str = extra
105		t.pVariant = 0
106		t.pExt = 0
107		return
108	}
109	var buf [max99thPercentileSize]byte // avoid extra memory allocation in most cases.
110	b := buf[:t.genCoreBytes(buf[:])]
111	if extra != "" {
112		diff := len(b) - int(t.pVariant)
113		b = append(b, '-')
114		b = append(b, extra...)
115		t.pVariant = uint8(int(t.pVariant) + diff)
116		t.pExt = uint16(int(t.pExt) + diff)
117	} else {
118		t.pVariant = uint8(len(b))
119		t.pExt = uint16(len(b))
120	}
121	t.str = string(b)
122}
123
124// genCoreBytes writes a string for the base languages, script and region tags
125// to the given buffer and returns the number of bytes written. It will never
126// write more than maxCoreSize bytes.
127func (t *Tag) genCoreBytes(buf []byte) int {
128	n := t.LangID.StringToBuf(buf[:])
129	if t.ScriptID != 0 {
130		n += copy(buf[n:], "-")
131		n += copy(buf[n:], t.ScriptID.String())
132	}
133	if t.RegionID != 0 {
134		n += copy(buf[n:], "-")
135		n += copy(buf[n:], t.RegionID.String())
136	}
137	return n
138}
139
140// String returns the canonical string representation of the language tag.
141func (t Tag) String() string {
142	if t.str != "" {
143		return t.str
144	}
145	if t.ScriptID == 0 && t.RegionID == 0 {
146		return t.LangID.String()
147	}
148	buf := [maxCoreSize]byte{}
149	return string(buf[:t.genCoreBytes(buf[:])])
150}
151
152// MarshalText implements encoding.TextMarshaler.
153func (t Tag) MarshalText() (text []byte, err error) {
154	if t.str != "" {
155		text = append(text, t.str...)
156	} else if t.ScriptID == 0 && t.RegionID == 0 {
157		text = append(text, t.LangID.String()...)
158	} else {
159		buf := [maxCoreSize]byte{}
160		text = buf[:t.genCoreBytes(buf[:])]
161	}
162	return text, nil
163}
164
165// UnmarshalText implements encoding.TextUnmarshaler.
166func (t *Tag) UnmarshalText(text []byte) error {
167	tag, err := Parse(string(text))
168	*t = tag
169	return err
170}
171
172// Variants returns the part of the tag holding all variants or the empty string
173// if there are no variants defined.
174func (t Tag) Variants() string {
175	if t.pVariant == 0 {
176		return ""
177	}
178	return t.str[t.pVariant:t.pExt]
179}
180
181// VariantOrPrivateUseTags returns variants or private use tags.
182func (t Tag) VariantOrPrivateUseTags() string {
183	if t.pExt > 0 {
184		return t.str[t.pVariant:t.pExt]
185	}
186	return t.str[t.pVariant:]
187}
188
189// HasString reports whether this tag defines more than just the raw
190// components.
191func (t Tag) HasString() bool {
192	return t.str != ""
193}
194
195// Parent returns the CLDR parent of t. In CLDR, missing fields in data for a
196// specific language are substituted with fields from the parent language.
197// The parent for a language may change for newer versions of CLDR.
198func (t Tag) Parent() Tag {
199	if t.str != "" {
200		// Strip the variants and extensions.
201		b, s, r := t.Raw()
202		t = Tag{LangID: b, ScriptID: s, RegionID: r}
203		if t.RegionID == 0 && t.ScriptID != 0 && t.LangID != 0 {
204			base, _ := addTags(Tag{LangID: t.LangID})
205			if base.ScriptID == t.ScriptID {
206				return Tag{LangID: t.LangID}
207			}
208		}
209		return t
210	}
211	if t.LangID != 0 {
212		if t.RegionID != 0 {
213			maxScript := t.ScriptID
214			if maxScript == 0 {
215				max, _ := addTags(t)
216				maxScript = max.ScriptID
217			}
218
219			for i := range parents {
220				if Language(parents[i].lang) == t.LangID && Script(parents[i].maxScript) == maxScript {
221					for _, r := range parents[i].fromRegion {
222						if Region(r) == t.RegionID {
223							return Tag{
224								LangID:   t.LangID,
225								ScriptID: Script(parents[i].script),
226								RegionID: Region(parents[i].toRegion),
227							}
228						}
229					}
230				}
231			}
232
233			// Strip the script if it is the default one.
234			base, _ := addTags(Tag{LangID: t.LangID})
235			if base.ScriptID != maxScript {
236				return Tag{LangID: t.LangID, ScriptID: maxScript}
237			}
238			return Tag{LangID: t.LangID}
239		} else if t.ScriptID != 0 {
240			// The parent for an base-script pair with a non-default script is
241			// "und" instead of the base language.
242			base, _ := addTags(Tag{LangID: t.LangID})
243			if base.ScriptID != t.ScriptID {
244				return Und
245			}
246			return Tag{LangID: t.LangID}
247		}
248	}
249	return Und
250}
251
252// ParseExtension parses s as an extension and returns it on success.
253func ParseExtension(s string) (ext string, err error) {
254	scan := makeScannerString(s)
255	var end int
256	if n := len(scan.token); n != 1 {
257		return "", ErrSyntax
258	}
259	scan.toLower(0, len(scan.b))
260	end = parseExtension(&scan)
261	if end != len(s) {
262		return "", ErrSyntax
263	}
264	return string(scan.b), nil
265}
266
267// HasVariants reports whether t has variants.
268func (t Tag) HasVariants() bool {
269	return uint16(t.pVariant) < t.pExt
270}
271
272// HasExtensions reports whether t has extensions.
273func (t Tag) HasExtensions() bool {
274	return int(t.pExt) < len(t.str)
275}
276
277// Extension returns the extension of type x for tag t. It will return
278// false for ok if t does not have the requested extension. The returned
279// extension will be invalid in this case.
280func (t Tag) Extension(x byte) (ext string, ok bool) {
281	for i := int(t.pExt); i < len(t.str)-1; {
282		var ext string
283		i, ext = getExtension(t.str, i)
284		if ext[0] == x {
285			return ext, true
286		}
287	}
288	return "", false
289}
290
291// Extensions returns all extensions of t.
292func (t Tag) Extensions() []string {
293	e := []string{}
294	for i := int(t.pExt); i < len(t.str)-1; {
295		var ext string
296		i, ext = getExtension(t.str, i)
297		e = append(e, ext)
298	}
299	return e
300}
301
302// TypeForKey returns the type associated with the given key, where key and type
303// are of the allowed values defined for the Unicode locale extension ('u') in
304// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
305// TypeForKey will traverse the inheritance chain to get the correct value.
306//
307// If there are multiple types associated with a key, only the first will be
308// returned. If there is no type associated with a key, it returns the empty
309// string.
310func (t Tag) TypeForKey(key string) string {
311	if _, start, end, _ := t.findTypeForKey(key); end != start {
312		s := t.str[start:end]
313		if p := strings.IndexByte(s, '-'); p >= 0 {
314			s = s[:p]
315		}
316		return s
317	}
318	return ""
319}
320
321var (
322	errPrivateUse       = errors.New("cannot set a key on a private use tag")
323	errInvalidArguments = errors.New("invalid key or type")
324)
325
326// SetTypeForKey returns a new Tag with the key set to type, where key and type
327// are of the allowed values defined for the Unicode locale extension ('u') in
328// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
329// An empty value removes an existing pair with the same key.
330func (t Tag) SetTypeForKey(key, value string) (Tag, error) {
331	if t.IsPrivateUse() {
332		return t, errPrivateUse
333	}
334	if len(key) != 2 {
335		return t, errInvalidArguments
336	}
337
338	// Remove the setting if value is "".
339	if value == "" {
340		start, sep, end, _ := t.findTypeForKey(key)
341		if start != sep {
342			// Remove a possible empty extension.
343			switch {
344			case t.str[start-2] != '-': // has previous elements.
345			case end == len(t.str), // end of string
346				end+2 < len(t.str) && t.str[end+2] == '-': // end of extension
347				start -= 2
348			}
349			if start == int(t.pVariant) && end == len(t.str) {
350				t.str = ""
351				t.pVariant, t.pExt = 0, 0
352			} else {
353				t.str = fmt.Sprintf("%s%s", t.str[:start], t.str[end:])
354			}
355		}
356		return t, nil
357	}
358
359	if len(value) < 3 || len(value) > 8 {
360		return t, errInvalidArguments
361	}
362
363	var (
364		buf    [maxCoreSize + maxSimpleUExtensionSize]byte
365		uStart int // start of the -u extension.
366	)
367
368	// Generate the tag string if needed.
369	if t.str == "" {
370		uStart = t.genCoreBytes(buf[:])
371		buf[uStart] = '-'
372		uStart++
373	}
374
375	// Create new key-type pair and parse it to verify.
376	b := buf[uStart:]
377	copy(b, "u-")
378	copy(b[2:], key)
379	b[4] = '-'
380	b = b[:5+copy(b[5:], value)]
381	scan := makeScanner(b)
382	if parseExtensions(&scan); scan.err != nil {
383		return t, scan.err
384	}
385
386	// Assemble the replacement string.
387	if t.str == "" {
388		t.pVariant, t.pExt = byte(uStart-1), uint16(uStart-1)
389		t.str = string(buf[:uStart+len(b)])
390	} else {
391		s := t.str
392		start, sep, end, hasExt := t.findTypeForKey(key)
393		if start == sep {
394			if hasExt {
395				b = b[2:]
396			}
397			t.str = fmt.Sprintf("%s-%s%s", s[:sep], b, s[end:])
398		} else {
399			t.str = fmt.Sprintf("%s-%s%s", s[:start+3], value, s[end:])
400		}
401	}
402	return t, nil
403}
404
405// findKeyAndType returns the start and end position for the type corresponding
406// to key or the point at which to insert the key-value pair if the type
407// wasn't found. The hasExt return value reports whether an -u extension was present.
408// Note: the extensions are typically very small and are likely to contain
409// only one key-type pair.
410func (t Tag) findTypeForKey(key string) (start, sep, end int, hasExt bool) {
411	p := int(t.pExt)
412	if len(key) != 2 || p == len(t.str) || p == 0 {
413		return p, p, p, false
414	}
415	s := t.str
416
417	// Find the correct extension.
418	for p++; s[p] != 'u'; p++ {
419		if s[p] > 'u' {
420			p--
421			return p, p, p, false
422		}
423		if p = nextExtension(s, p); p == len(s) {
424			return len(s), len(s), len(s), false
425		}
426	}
427	// Proceed to the hyphen following the extension name.
428	p++
429
430	// curKey is the key currently being processed.
431	curKey := ""
432
433	// Iterate over keys until we get the end of a section.
434	for {
435		end = p
436		for p++; p < len(s) && s[p] != '-'; p++ {
437		}
438		n := p - end - 1
439		if n <= 2 && curKey == key {
440			if sep < end {
441				sep++
442			}
443			return start, sep, end, true
444		}
445		switch n {
446		case 0, // invalid string
447			1: // next extension
448			return end, end, end, true
449		case 2:
450			// next key
451			curKey = s[end+1 : p]
452			if curKey > key {
453				return end, end, end, true
454			}
455			start = end
456			sep = p
457		}
458	}
459}
460
461// ParseBase parses a 2- or 3-letter ISO 639 code.
462// It returns a ValueError if s is a well-formed but unknown language identifier
463// or another error if another error occurred.
464func ParseBase(s string) (Language, error) {
465	if n := len(s); n < 2 || 3 < n {
466		return 0, ErrSyntax
467	}
468	var buf [3]byte
469	return getLangID(buf[:copy(buf[:], s)])
470}
471
472// ParseScript parses a 4-letter ISO 15924 code.
473// It returns a ValueError if s is a well-formed but unknown script identifier
474// or another error if another error occurred.
475func ParseScript(s string) (Script, error) {
476	if len(s) != 4 {
477		return 0, ErrSyntax
478	}
479	var buf [4]byte
480	return getScriptID(script, buf[:copy(buf[:], s)])
481}
482
483// EncodeM49 returns the Region for the given UN M.49 code.
484// It returns an error if r is not a valid code.
485func EncodeM49(r int) (Region, error) {
486	return getRegionM49(r)
487}
488
489// ParseRegion parses a 2- or 3-letter ISO 3166-1 or a UN M.49 code.
490// It returns a ValueError if s is a well-formed but unknown region identifier
491// or another error if another error occurred.
492func ParseRegion(s string) (Region, error) {
493	if n := len(s); n < 2 || 3 < n {
494		return 0, ErrSyntax
495	}
496	var buf [3]byte
497	return getRegionID(buf[:copy(buf[:], s)])
498}
499
500// IsCountry returns whether this region is a country or autonomous area. This
501// includes non-standard definitions from CLDR.
502func (r Region) IsCountry() bool {
503	if r == 0 || r.IsGroup() || r.IsPrivateUse() && r != _XK {
504		return false
505	}
506	return true
507}
508
509// IsGroup returns whether this region defines a collection of regions. This
510// includes non-standard definitions from CLDR.
511func (r Region) IsGroup() bool {
512	if r == 0 {
513		return false
514	}
515	return int(regionInclusion[r]) < len(regionContainment)
516}
517
518// Contains returns whether Region c is contained by Region r. It returns true
519// if c == r.
520func (r Region) Contains(c Region) bool {
521	if r == c {
522		return true
523	}
524	g := regionInclusion[r]
525	if g >= nRegionGroups {
526		return false
527	}
528	m := regionContainment[g]
529
530	d := regionInclusion[c]
531	b := regionInclusionBits[d]
532
533	// A contained country may belong to multiple disjoint groups. Matching any
534	// of these indicates containment. If the contained region is a group, it
535	// must strictly be a subset.
536	if d >= nRegionGroups {
537		return b&m != 0
538	}
539	return b&^m == 0
540}
541
542var errNoTLD = errors.New("language: region is not a valid ccTLD")
543
544// TLD returns the country code top-level domain (ccTLD). UK is returned for GB.
545// In all other cases it returns either the region itself or an error.
546//
547// This method may return an error for a region for which there exists a
548// canonical form with a ccTLD. To get that ccTLD canonicalize r first. The
549// region will already be canonicalized it was obtained from a Tag that was
550// obtained using any of the default methods.
551func (r Region) TLD() (Region, error) {
552	// See http://en.wikipedia.org/wiki/Country_code_top-level_domain for the
553	// difference between ISO 3166-1 and IANA ccTLD.
554	if r == _GB {
555		r = _UK
556	}
557	if (r.typ() & ccTLD) == 0 {
558		return 0, errNoTLD
559	}
560	return r, nil
561}
562
563// Canonicalize returns the region or a possible replacement if the region is
564// deprecated. It will not return a replacement for deprecated regions that
565// are split into multiple regions.
566func (r Region) Canonicalize() Region {
567	if cr := normRegion(r); cr != 0 {
568		return cr
569	}
570	return r
571}
572
573// Variant represents a registered variant of a language as defined by BCP 47.
574type Variant struct {
575	ID  uint8
576	str string
577}
578
579// ParseVariant parses and returns a Variant. An error is returned if s is not
580// a valid variant.
581func ParseVariant(s string) (Variant, error) {
582	s = strings.ToLower(s)
583	if id, ok := variantIndex[s]; ok {
584		return Variant{id, s}, nil
585	}
586	return Variant{}, NewValueError([]byte(s))
587}
588
589// String returns the string representation of the variant.
590func (v Variant) String() string {
591	return v.str
592}