gtsocial-umbx

language.go (17174B)

---

 // 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 gen_common.go -output tables.go
 
 package language // import "golang.org/x/text/internal/language"
 
 // TODO: Remove above NOTE after:
 // - verifying that tables are dropped correctly (most notably matcher tables).
 
 import (
 	"errors"
 	"fmt"
 	"strings"
 )
 
 const (
 	// maxCoreSize is the maximum size of a BCP 47 tag without variants and
 	// extensions. Equals max lang (3) + script (4) + max reg (3) + 2 dashes.
 	maxCoreSize = 12
 
 	// max99thPercentileSize is a somewhat arbitrary buffer size that presumably
 	// is large enough to hold at least 99% of the BCP 47 tags.
 	max99thPercentileSize = 32
 
 	// maxSimpleUExtensionSize is the maximum size of a -u extension with one
 	// key-type pair. Equals len("-u-") + key (2) + dash + max value (8).
 	maxSimpleUExtensionSize = 14
 )
 
 // 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. The zero value of Tag is Und.
 type Tag struct {
 	// TODO: the following fields have the form TagTypeID. This name is chosen
 	// to allow refactoring the public package without conflicting with its
 	// Base, Script, and Region methods. Once the transition is fully completed
 	// the ID can be stripped from the name.
 
 	LangID   Language
 	RegionID Region
 	// TODO: we will soon run out of positions for ScriptID. Idea: instead of
 	// storing lang, region, and ScriptID codes, store only the compact index and
 	// have a lookup table from this code to its expansion. This greatly speeds
 	// up table lookup, speed up common variant cases.
 	// This will also immediately free up 3 extra bytes. Also, the pVariant
 	// field can now be moved to the lookup table, as the compact index uniquely
 	// determines the offset of a possible variant.
 	ScriptID Script
 	pVariant byte   // offset in str, includes preceding '-'
 	pExt     uint16 // offset of first extension, includes preceding '-'
 
 	// str is the string representation of the Tag. It will only be used if the
 	// tag has variants or extensions.
 	str string
 }
 
 // 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 {
 	t, _ := Parse(s)
 	return t
 }
 
 // Raw returns the raw base language, script and region, without making an
 // attempt to infer their values.
 // TODO: consider removing
 func (t Tag) Raw() (b Language, s Script, r Region) {
 	return t.LangID, t.ScriptID, t.RegionID
 }
 
 // equalTags compares language, script and region subtags only.
 func (t Tag) equalTags(a Tag) bool {
 	return t.LangID == a.LangID && t.ScriptID == a.ScriptID && t.RegionID == a.RegionID
 }
 
 // IsRoot returns true if t is equal to language "und".
 func (t Tag) IsRoot() bool {
 	if int(t.pVariant) < len(t.str) {
 		return false
 	}
 	return t.equalTags(Und)
 }
 
 // IsPrivateUse reports whether the Tag consists solely of an IsPrivateUse use
 // tag.
 func (t Tag) IsPrivateUse() bool {
 	return t.str != "" && t.pVariant == 0
 }
 
 // RemakeString is used to update t.str in case lang, script or region changed.
 // It is assumed that pExt and pVariant still point to the start of the
 // respective parts.
 func (t *Tag) RemakeString() {
 	if t.str == "" {
 		return
 	}
 	extra := t.str[t.pVariant:]
 	if t.pVariant > 0 {
 		extra = extra[1:]
 	}
 	if t.equalTags(Und) && strings.HasPrefix(extra, "x-") {
 		t.str = extra
 		t.pVariant = 0
 		t.pExt = 0
 		return
 	}
 	var buf [max99thPercentileSize]byte // avoid extra memory allocation in most cases.
 	b := buf[:t.genCoreBytes(buf[:])]
 	if extra != "" {
 		diff := len(b) - int(t.pVariant)
 		b = append(b, '-')
 		b = append(b, extra...)
 		t.pVariant = uint8(int(t.pVariant) + diff)
 		t.pExt = uint16(int(t.pExt) + diff)
 	} else {
 		t.pVariant = uint8(len(b))
 		t.pExt = uint16(len(b))
 	}
 	t.str = string(b)
 }
 
 // genCoreBytes writes a string for the base languages, script and region tags
 // to the given buffer and returns the number of bytes written. It will never
 // write more than maxCoreSize bytes.
 func (t *Tag) genCoreBytes(buf []byte) int {
 	n := t.LangID.StringToBuf(buf[:])
 	if t.ScriptID != 0 {
 		n += copy(buf[n:], "-")
 		n += copy(buf[n:], t.ScriptID.String())
 	}
 	if t.RegionID != 0 {
 		n += copy(buf[n:], "-")
 		n += copy(buf[n:], t.RegionID.String())
 	}
 	return n
 }
 
 // String returns the canonical string representation of the language tag.
 func (t Tag) String() string {
 	if t.str != "" {
 		return t.str
 	}
 	if t.ScriptID == 0 && t.RegionID == 0 {
 		return t.LangID.String()
 	}
 	buf := [maxCoreSize]byte{}
 	return string(buf[:t.genCoreBytes(buf[:])])
 }
 
 // MarshalText implements encoding.TextMarshaler.
 func (t Tag) MarshalText() (text []byte, err error) {
 	if t.str != "" {
 		text = append(text, t.str...)
 	} else if t.ScriptID == 0 && t.RegionID == 0 {
 		text = append(text, t.LangID.String()...)
 	} else {
 		buf := [maxCoreSize]byte{}
 		text = buf[:t.genCoreBytes(buf[:])]
 	}
 	return text, nil
 }
 
 // UnmarshalText implements encoding.TextUnmarshaler.
 func (t *Tag) UnmarshalText(text []byte) error {
 	tag, err := Parse(string(text))
 	*t = tag
 	return err
 }
 
 // Variants returns the part of the tag holding all variants or the empty string
 // if there are no variants defined.
 func (t Tag) Variants() string {
 	if t.pVariant == 0 {
 		return ""
 	}
 	return t.str[t.pVariant:t.pExt]
 }
 
 // VariantOrPrivateUseTags returns variants or private use tags.
 func (t Tag) VariantOrPrivateUseTags() string {
 	if t.pExt > 0 {
 		return t.str[t.pVariant:t.pExt]
 	}
 	return t.str[t.pVariant:]
 }
 
 // HasString reports whether this tag defines more than just the raw
 // components.
 func (t Tag) HasString() bool {
 	return t.str != ""
 }
 
 // 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.
 func (t Tag) Parent() Tag {
 	if t.str != "" {
 		// Strip the variants and extensions.
 		b, s, r := t.Raw()
 		t = Tag{LangID: b, ScriptID: s, RegionID: r}
 		if t.RegionID == 0 && t.ScriptID != 0 && t.LangID != 0 {
 			base, _ := addTags(Tag{LangID: t.LangID})
 			if base.ScriptID == t.ScriptID {
 				return Tag{LangID: t.LangID}
 			}
 		}
 		return t
 	}
 	if t.LangID != 0 {
 		if t.RegionID != 0 {
 			maxScript := t.ScriptID
 			if maxScript == 0 {
 				max, _ := addTags(t)
 				maxScript = max.ScriptID
 			}
 
 			for i := range parents {
 				if Language(parents[i].lang) == t.LangID && Script(parents[i].maxScript) == maxScript {
 					for _, r := range parents[i].fromRegion {
 						if Region(r) == t.RegionID {
 							return Tag{
 								LangID:   t.LangID,
 								ScriptID: Script(parents[i].script),
 								RegionID: Region(parents[i].toRegion),
 							}
 						}
 					}
 				}
 			}
 
 			// Strip the script if it is the default one.
 			base, _ := addTags(Tag{LangID: t.LangID})
 			if base.ScriptID != maxScript {
 				return Tag{LangID: t.LangID, ScriptID: maxScript}
 			}
 			return Tag{LangID: t.LangID}
 		} else if t.ScriptID != 0 {
 			// The parent for an base-script pair with a non-default script is
 			// "und" instead of the base language.
 			base, _ := addTags(Tag{LangID: t.LangID})
 			if base.ScriptID != t.ScriptID {
 				return Und
 			}
 			return Tag{LangID: t.LangID}
 		}
 	}
 	return Und
 }
 
 // ParseExtension parses s as an extension and returns it on success.
 func ParseExtension(s string) (ext string, err error) {
 	defer func() {
 		if recover() != nil {
 			ext = ""
 			err = ErrSyntax
 		}
 	}()
 
 	scan := makeScannerString(s)
 	var end int
 	if n := len(scan.token); n != 1 {
 		return "", ErrSyntax
 	}
 	scan.toLower(0, len(scan.b))
 	end = parseExtension(&scan)
 	if end != len(s) {
 		return "", ErrSyntax
 	}
 	return string(scan.b), nil
 }
 
 // HasVariants reports whether t has variants.
 func (t Tag) HasVariants() bool {
 	return uint16(t.pVariant) < t.pExt
 }
 
 // HasExtensions reports whether t has extensions.
 func (t Tag) HasExtensions() bool {
 	return int(t.pExt) < len(t.str)
 }
 
 // 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 string, ok bool) {
 	for i := int(t.pExt); i < len(t.str)-1; {
 		var ext string
 		i, ext = getExtension(t.str, i)
 		if ext[0] == x {
 			return ext, true
 		}
 	}
 	return "", false
 }
 
 // Extensions returns all extensions of t.
 func (t Tag) Extensions() []string {
 	e := []string{}
 	for i := int(t.pExt); i < len(t.str)-1; {
 		var ext string
 		i, ext = getExtension(t.str, i)
 		e = append(e, 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.
 //
 // If there are multiple types associated with a key, only the first will be
 // returned. If there is no type associated with a key, it returns the empty
 // string.
 func (t Tag) TypeForKey(key string) string {
 	if _, start, end, _ := t.findTypeForKey(key); end != start {
 		s := t.str[start:end]
 		if p := strings.IndexByte(s, '-'); p >= 0 {
 			s = s[:p]
 		}
 		return s
 	}
 	return ""
 }
 
 var (
 	errPrivateUse       = errors.New("cannot set a key on a private use tag")
 	errInvalidArguments = errors.New("invalid key or type")
 )
 
 // 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) {
 	if t.IsPrivateUse() {
 		return t, errPrivateUse
 	}
 	if len(key) != 2 {
 		return t, errInvalidArguments
 	}
 
 	// Remove the setting if value is "".
 	if value == "" {
 		start, sep, end, _ := t.findTypeForKey(key)
 		if start != sep {
 			// Remove a possible empty extension.
 			switch {
 			case t.str[start-2] != '-': // has previous elements.
 			case end == len(t.str), // end of string
 				end+2 < len(t.str) && t.str[end+2] == '-': // end of extension
 				start -= 2
 			}
 			if start == int(t.pVariant) && end == len(t.str) {
 				t.str = ""
 				t.pVariant, t.pExt = 0, 0
 			} else {
 				t.str = fmt.Sprintf("%s%s", t.str[:start], t.str[end:])
 			}
 		}
 		return t, nil
 	}
 
 	if len(value) < 3 || len(value) > 8 {
 		return t, errInvalidArguments
 	}
 
 	var (
 		buf    [maxCoreSize + maxSimpleUExtensionSize]byte
 		uStart int // start of the -u extension.
 	)
 
 	// Generate the tag string if needed.
 	if t.str == "" {
 		uStart = t.genCoreBytes(buf[:])
 		buf[uStart] = '-'
 		uStart++
 	}
 
 	// Create new key-type pair and parse it to verify.
 	b := buf[uStart:]
 	copy(b, "u-")
 	copy(b[2:], key)
 	b[4] = '-'
 	b = b[:5+copy(b[5:], value)]
 	scan := makeScanner(b)
 	if parseExtensions(&scan); scan.err != nil {
 		return t, scan.err
 	}
 
 	// Assemble the replacement string.
 	if t.str == "" {
 		t.pVariant, t.pExt = byte(uStart-1), uint16(uStart-1)
 		t.str = string(buf[:uStart+len(b)])
 	} else {
 		s := t.str
 		start, sep, end, hasExt := t.findTypeForKey(key)
 		if start == sep {
 			if hasExt {
 				b = b[2:]
 			}
 			t.str = fmt.Sprintf("%s-%s%s", s[:sep], b, s[end:])
 		} else {
 			t.str = fmt.Sprintf("%s-%s%s", s[:start+3], value, s[end:])
 		}
 	}
 	return t, nil
 }
 
 // findTypeForKey returns the start and end position for the type corresponding
 // to key or the point at which to insert the key-value pair if the type
 // wasn't found. The hasExt return value reports whether an -u extension was present.
 // Note: the extensions are typically very small and are likely to contain
 // only one key-type pair.
 func (t Tag) findTypeForKey(key string) (start, sep, end int, hasExt bool) {
 	p := int(t.pExt)
 	if len(key) != 2 || p == len(t.str) || p == 0 {
 		return p, p, p, false
 	}
 	s := t.str
 
 	// Find the correct extension.
 	for p++; s[p] != 'u'; p++ {
 		if s[p] > 'u' {
 			p--
 			return p, p, p, false
 		}
 		if p = nextExtension(s, p); p == len(s) {
 			return len(s), len(s), len(s), false
 		}
 	}
 	// Proceed to the hyphen following the extension name.
 	p++
 
 	// curKey is the key currently being processed.
 	curKey := ""
 
 	// Iterate over keys until we get the end of a section.
 	for {
 		end = p
 		for p++; p < len(s) && s[p] != '-'; p++ {
 		}
 		n := p - end - 1
 		if n <= 2 && curKey == key {
 			if sep < end {
 				sep++
 			}
 			return start, sep, end, true
 		}
 		switch n {
 		case 0, // invalid string
 			1: // next extension
 			return end, end, end, true
 		case 2:
 			// next key
 			curKey = s[end+1 : p]
 			if curKey > key {
 				return end, end, end, true
 			}
 			start = end
 			sep = p
 		}
 	}
 }
 
 // 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) (l Language, err error) {
 	defer func() {
 		if recover() != nil {
 			l = 0
 			err = ErrSyntax
 		}
 	}()
 
 	if n := len(s); n < 2 || 3 < n {
 		return 0, ErrSyntax
 	}
 	var buf [3]byte
 	return getLangID(buf[:copy(buf[:], s)])
 }
 
 // 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) (scr Script, err error) {
 	defer func() {
 		if recover() != nil {
 			scr = 0
 			err = ErrSyntax
 		}
 	}()
 
 	if len(s) != 4 {
 		return 0, ErrSyntax
 	}
 	var buf [4]byte
 	return getScriptID(script, buf[:copy(buf[:], s)])
 }
 
 // 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) {
 	return getRegionM49(r)
 }
 
 // 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) (r Region, err error) {
 	defer func() {
 		if recover() != nil {
 			r = 0
 			err = ErrSyntax
 		}
 	}()
 
 	if n := len(s); n < 2 || 3 < n {
 		return 0, ErrSyntax
 	}
 	var buf [3]byte
 	return getRegionID(buf[:copy(buf[:], s)])
 }
 
 // IsCountry returns whether this region is a country or autonomous area. This
 // includes non-standard definitions from CLDR.
 func (r Region) IsCountry() bool {
 	if r == 0 || r.IsGroup() || r.IsPrivateUse() && r != _XK {
 		return false
 	}
 	return true
 }
 
 // IsGroup returns whether this region defines a collection of regions. This
 // includes non-standard definitions from CLDR.
 func (r Region) IsGroup() bool {
 	if r == 0 {
 		return false
 	}
 	return int(regionInclusion[r]) < len(regionContainment)
 }
 
 // Contains returns whether Region c is contained by Region r. It returns true
 // if c == r.
 func (r Region) Contains(c Region) bool {
 	if r == c {
 		return true
 	}
 	g := regionInclusion[r]
 	if g >= nRegionGroups {
 		return false
 	}
 	m := regionContainment[g]
 
 	d := regionInclusion[c]
 	b := regionInclusionBits[d]
 
 	// A contained country may belong to multiple disjoint groups. Matching any
 	// of these indicates containment. If the contained region is a group, it
 	// must strictly be a subset.
 	if d >= nRegionGroups {
 		return b&m != 0
 	}
 	return b&^m == 0
 }
 
 var errNoTLD = errors.New("language: region is not a valid ccTLD")
 
 // 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) {
 	// See http://en.wikipedia.org/wiki/Country_code_top-level_domain for the
 	// difference between ISO 3166-1 and IANA ccTLD.
 	if r == _GB {
 		r = _UK
 	}
 	if (r.typ() & ccTLD) == 0 {
 		return 0, errNoTLD
 	}
 	return r, nil
 }
 
 // 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 {
 	if cr := normRegion(r); cr != 0 {
 		return cr
 	}
 	return r
 }
 
 // Variant represents a registered variant of a language as defined by BCP 47.
 type Variant struct {
 	ID  uint8
 	str string
 }
 
 // ParseVariant parses and returns a Variant. An error is returned if s is not
 // a valid variant.
 func ParseVariant(s string) (v Variant, err error) {
 	defer func() {
 		if recover() != nil {
 			v = Variant{}
 			err = ErrSyntax
 		}
 	}()
 
 	s = strings.ToLower(s)
 	if id, ok := variantIndex[s]; ok {
 		return Variant{id, s}, nil
 	}
 	return Variant{}, NewValueError([]byte(s))
 }
 
 // String returns the string representation of the variant.
 func (v Variant) String() string {
 	return v.str
 }