diff options
Diffstat (limited to 'vendor/golang.org/x/text/language/language.go')
| -rw-r--r-- | vendor/golang.org/x/text/language/language.go | 975 |
1 files changed, 975 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/language/language.go b/vendor/golang.org/x/text/language/language.go new file mode 100644 index 00000000..5eecceb6 --- /dev/null +++ b/vendor/golang.org/x/text/language/language.go @@ -0,0 +1,975 @@ +// 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 maketables.go gen_common.go -output tables.go +//go:generate go run gen_index.go + +// Package language implements BCP 47 language tags and related functionality. +// +// The Tag type, which is used to represent languages, is agnostic to the +// meaning of its subtags. Tags are not fully canonicalized to preserve +// information that may be valuable in certain contexts. As a consequence, two +// different tags may represent identical languages. +// +// Initializing language- or locale-specific components usually consists of +// two steps. The first step is to select a display language based on the +// preferred languages of the user and the languages supported by an application. +// The second step is to create the language-specific services based on +// this selection. Each is discussed in more details below. +// +// Matching preferred against supported languages +// +// An application may support various languages. This list is typically limited +// by the languages for which there exists translations of the user interface. +// Similarly, a user may provide a list of preferred languages which is limited +// by the languages understood by this user. +// An application should use a Matcher to find the best supported language based +// on the user's preferred list. +// Matchers are aware of the intricacies of equivalence between languages. +// The default Matcher implementation takes into account things such as +// deprecated subtags, legacy tags, and mutual intelligibility between scripts +// and languages. +// +// A Matcher for English, Australian English, Danish, and standard Mandarin can +// be defined as follows: +// +// var matcher = language.NewMatcher([]language.Tag{ +// language.English, // The first language is used as fallback. +// language.MustParse("en-AU"), +// language.Danish, +// language.Chinese, +// }) +// +// The following code selects the best match for someone speaking Spanish and +// Norwegian: +// +// preferred := []language.Tag{ language.Spanish, language.Norwegian } +// tag, _, _ := matcher.Match(preferred...) +// +// In this case, the best match is Danish, as Danish is sufficiently a match to +// Norwegian to not have to fall back to the default. +// See ParseAcceptLanguage on how to handle the Accept-Language HTTP header. +// +// Selecting language-specific services +// +// One should always use the Tag returned by the Matcher to create an instance +// of any of the language-specific services provided by the text repository. +// This prevents the mixing of languages, such as having a different language for +// messages and display names, as well as improper casing or sorting order for +// the selected language. +// Using the returned Tag also allows user-defined settings, such as collation +// order or numbering system to be transparently passed as options. +// +// If you have language-specific data in your application, however, it will in +// most cases suffice to use the index returned by the matcher to identify +// the user language. +// The following loop provides an alternative in case this is not sufficient: +// +// supported := map[language.Tag]data{ +// language.English: enData, +// language.MustParse("en-AU"): enAUData, +// language.Danish: daData, +// language.Chinese: zhData, +// } +// tag, _, _ := matcher.Match(preferred...) +// for ; tag != language.Und; tag = tag.Parent() { +// if v, ok := supported[tag]; ok { +// return v +// } +// } +// return enData // should not reach here +// +// Repeatedly taking the Parent of the tag returned by Match will eventually +// match one of the tags used to initialize the Matcher. +// +// Canonicalization +// +// By default, only legacy and deprecated tags are converted into their +// canonical equivalent. All other information is preserved. This approach makes +// the confidence scores more accurate and allows matchers to distinguish +// between variants that are otherwise lost. +// +// As a consequence, two tags that should be treated as identical according to +// BCP 47 or CLDR, like "en-Latn" and "en", will be represented differently. The +// Matchers will handle such distinctions, though, and are aware of the +// equivalence relations. The CanonType type can be used to alter the +// canonicalization form. +// +// References +// +// BCP 47 - Tags for Identifying Languages +// http://tools.ietf.org/html/bcp47 +package language // import "golang.org/x/text/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. +type Tag struct { + lang langID + region regionID + script scriptID + 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 { + 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) { + return Base{t.lang}, Script{t.script}, Region{t.region} +} + +// equalTags compares language, script and region subtags only. +func (t Tag) equalTags(a Tag) bool { + return t.lang == a.lang && t.script == a.script && t.region == a.region +} + +// 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) +} + +// private reports whether the Tag consists solely of a private use tag. +func (t Tag) private() bool { + return t.str != "" && t.pVariant == 0 +} + +// 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 (t Tag) canonicalize(c CanonType) (Tag, bool) { + if c == Raw { + return t, false + } + changed := false + if c&SuppressScript != 0 { + if t.lang < langNoIndexOffset && uint8(t.script) == suppressScript[t.lang] { + t.script = 0 + changed = true + } + } + if c&canonLang != 0 { + for { + if l, aliasType := normLang(t.lang); l != t.lang { + switch aliasType { + case langLegacy: + if c&Legacy != 0 { + if t.lang == _sh && t.script == 0 { + t.script = _Latn + } + t.lang = l + changed = true + } + case langMacro: + 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 http://unicode.org/cldr/trac/ticket/2698 and also + // http://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.lang != _nb { + changed = true + t.lang = l + } + } + case langDeprecated: + if c&DeprecatedBase != 0 { + if t.lang == _mo && t.region == 0 { + t.region = _MD + } + t.lang = l + changed = true + // Other canonicalization types may still apply. + continue + } + } + } else if c&Legacy != 0 && t.lang == _no && c&CLDR != 0 { + t.lang = _nb + changed = true + } + break + } + } + if c&DeprecatedScript != 0 { + if t.script == _Qaai { + changed = true + t.script = _Zinh + } + } + if c&DeprecatedRegion != 0 { + if r := normRegion(t.region); r != 0 { + changed = true + t.region = r + } + } + return t, changed +} + +// Canonicalize returns the canonicalized equivalent of the tag. +func (c CanonType) Canonicalize(t Tag) (Tag, error) { + t, changed := t.canonicalize(c) + if changed { + t.remakeString() + } + 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] +} + +// 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.lang.stringToBuf(buf[:]) + if t.script != 0 { + n += copy(buf[n:], "-") + n += copy(buf[n:], t.script.String()) + } + if t.region != 0 { + n += copy(buf[n:], "-") + n += copy(buf[n:], t.region.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.script == 0 && t.region == 0 { + return t.lang.String() + } + buf := [maxCoreSize]byte{} + return string(buf[:t.genCoreBytes(buf[:])]) +} + +// 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 t.lang != 0 { + return Base{t.lang}, Exact + } + c := High + if t.script == 0 && !(Region{t.region}).IsCountry() { + c = Low + } + if tag, err := addTags(t); err == nil && tag.lang != 0 { + return Base{tag.lang}, 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 http://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 t.script != 0 { + return Script{t.script}, Exact + } + sc, c := scriptID(_Zzzz), No + if t.lang < langNoIndexOffset { + if scr := scriptID(suppressScript[t.lang]); 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 t.region == 0 { + return Script{scriptID(scr)}, High + } + sc, c = scr, High + } + } + if tag, err := addTags(t); err == nil { + if tag.script != sc { + sc, c = tag.script, Low + } + } else { + t, _ = (Deprecated | Macro).Canonicalize(t) + if tag, err := addTags(t); err == nil && tag.script != sc { + sc, c = tag.script, 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 t.region != 0 { + return Region{t.region}, Exact + } + if t, err := addTags(t); err == nil { + return Region{t.region}, Low // TODO: differentiate between high and low. + } + t, _ = (Deprecated | Macro).Canonicalize(t) + if tag, err := addTags(t); err == nil { + return Region{tag.region}, Low + } + return Region{_ZZ}, No // TODO: return world instead of undetermined? +} + +// Variant returns the variants specified explicitly for this language tag. +// or nil if no variant was specified. +func (t Tag) Variants() []Variant { + v := []Variant{} + if int(t.pVariant) < int(t.pExt) { + for x, str := "", t.str[t.pVariant:t.pExt]; 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. +func (t Tag) Parent() Tag { + if t.str != "" { + // Strip the variants and extensions. + t, _ = Raw.Compose(t.Raw()) + if t.region == 0 && t.script != 0 && t.lang != 0 { + base, _ := addTags(Tag{lang: t.lang}) + if base.script == t.script { + return Tag{lang: t.lang} + } + } + return t + } + if t.lang != 0 { + if t.region != 0 { + maxScript := t.script + if maxScript == 0 { + max, _ := addTags(t) + maxScript = max.script + } + + for i := range parents { + if langID(parents[i].lang) == t.lang && scriptID(parents[i].maxScript) == maxScript { + for _, r := range parents[i].fromRegion { + if regionID(r) == t.region { + return Tag{ + lang: t.lang, + script: scriptID(parents[i].script), + region: regionID(parents[i].toRegion), + } + } + } + } + } + + // Strip the script if it is the default one. + base, _ := addTags(Tag{lang: t.lang}) + if base.script != maxScript { + return Tag{lang: t.lang, script: maxScript} + } + return Tag{lang: t.lang} + } else if t.script != 0 { + // The parent for an base-script pair with a non-default script is + // "und" instead of the base language. + base, _ := addTags(Tag{lang: t.lang}) + if base.script != t.script { + return und + } + return Tag{lang: t.lang} + } + } + return und +} + +// 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) { + scan := makeScannerString(s) + var end int + if n := len(scan.token); n != 1 { + return Extension{}, errSyntax + } + scan.toLower(0, len(scan.b)) + end = parseExtension(&scan) + if end != len(s) { + return Extension{}, errSyntax + } + return Extension{string(scan.b)}, nil +} + +// 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) { + for i := int(t.pExt); i < len(t.str)-1; { + var ext string + i, ext = getExtension(t.str, i) + if ext[0] == x { + return Extension{ext}, true + } + } + return Extension{}, false +} + +// Extensions returns all extensions of t. +func (t Tag) Extensions() []Extension { + e := []Extension{} + for i := int(t.pExt); i < len(t.str)-1; { + var ext string + i, ext = getExtension(t.str, i) + 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 +// http://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 start, end, _ := t.findTypeForKey(key); end != start { + return t.str[start:end] + } + 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 +// http://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.private() { + return t, errPrivateUse + } + if len(key) != 2 { + return t, errInvalidArguments + } + + // Remove the setting if value is "". + if value == "" { + start, end, _ := t.findTypeForKey(key) + if start != end { + // Remove key tag and leading '-'. + start -= 4 + + // Remove a possible empty extension. + if (end == len(t.str) || t.str[end+2] == '-') && t.str[start-2] == '-' { + 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, end, hasExt := t.findTypeForKey(key) + if start == end { + if hasExt { + b = b[2:] + } + t.str = fmt.Sprintf("%s-%s%s", s[:start], b, s[end:]) + } else { + t.str = fmt.Sprintf("%s%s%s", s[:start], value, s[end:]) + } + } + return t, nil +} + +// findKeyAndType 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, end int, hasExt bool) { + p := int(t.pExt) + if len(key) != 2 || p == len(t.str) || p == 0 { + return p, p, false + } + s := t.str + + // Find the correct extension. + for p++; s[p] != 'u'; p++ { + if s[p] > 'u' { + p-- + return p, p, false + } + if p = nextExtension(s, p); p == len(s) { + return 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 { + // p points to the hyphen preceding the current token. + if p3 := p + 3; s[p3] == '-' { + // Found a key. + // Check whether we just processed the key that was requested. + if curKey == key { + return start, p, true + } + // Set to the next key and continue scanning type tokens. + curKey = s[p+1 : p3] + if curKey > key { + return p, p, true + } + // Start of the type token sequence. + start = p + 4 + // A type is at least 3 characters long. + p += 7 // 4 + 3 + } else { + // Attribute or type, which is at least 3 characters long. + p += 4 + } + // p points past the third character of a type or attribute. + max := p + 5 // maximum length of token plus hyphen. + if len(s) < max { + max = len(s) + } + for ; p < max && s[p] != '-'; p++ { + } + // Bail if we have exhausted all tokens or if the next token starts + // a new extension. + if p == len(s) || s[p+2] == '-' { + if curKey == key { + return start, p, true + } + return p, p, true + } + } +} + +// 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. Extensions, except for the +// 'va' type of the 'u' extension, are ignored. It will return 0, false if no +// compact tag exists, where 0 is the index for the root language (Und). +func CompactIndex(t Tag) (index int, ok bool) { + // TODO: perhaps give more frequent tags a lower index. + // TODO: we could make the indexes stable. This will excluded some + // possibilities for optimization, so don't do this quite yet. + b, s, r := t.Raw() + if len(t.str) > 0 { + if strings.HasPrefix(t.str, "x-") { + // We have no entries for user-defined tags. + return 0, false + } + if uint16(t.pVariant) != t.pExt { + // There are no tags with variants and an u-va type. + if t.TypeForKey("va") != "" { + return 0, false + } + t, _ = Raw.Compose(b, s, r, t.Variants()) + } else if _, ok := t.Extension('u'); ok { + // Strip all but the 'va' entry. + variant := t.TypeForKey("va") + t, _ = Raw.Compose(b, s, r) + t, _ = t.SetTypeForKey("va", variant) + } + if len(t.str) > 0 { + // We have some variants. + for i, s := range specialTags { + if s == t { + return i + 1, true + } + } + return 0, false + } + } + // No variants specified: just compare core components. + // The key has the form lllssrrr, where l, s, and r are nibbles for + // respectively the langID, scriptID, and regionID. + key := uint32(b.langID) << (8 + 12) + key |= uint32(s.scriptID) << 12 + key |= uint32(r.regionID) + x, ok := coreTags[key] + return int(x), ok +} + +// Base is an ISO 639 language code, used for encoding the base language +// of a language tag. +type Base struct { + langID +} + +// 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) { + if n := len(s); n < 2 || 3 < n { + return Base{}, errSyntax + } + var buf [3]byte + l, err := getLangID(buf[:copy(buf[:], s)]) + return Base{l}, err +} + +// Script is a 4-letter ISO 15924 code for representing scripts. +// It is idiomatically represented in title case. +type Script struct { + scriptID +} + +// 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) { + if len(s) != 4 { + return Script{}, errSyntax + } + var buf [4]byte + sc, err := getScriptID(script, buf[:copy(buf[:], s)]) + return Script{sc}, err +} + +// Region is an ISO 3166-1 or UN M.49 code for representing countries and regions. +type Region struct { + regionID +} + +// 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 := getRegionM49(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) { + if n := len(s); n < 2 || 3 < n { + return Region{}, errSyntax + } + var buf [3]byte + r, err := getRegionID(buf[:copy(buf[:], s)]) + return Region{r}, err +} + +// 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.regionID == 0 || r.IsGroup() || r.IsPrivateUse() && r.regionID != _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.regionID == 0 { + return false + } + return int(regionInclusion[r.regionID]) < 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 { + return r.regionID.contains(c.regionID) +} + +func (r regionID) contains(c regionID) 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.regionID == _GB { + r = Region{_UK} + } + if (r.typ() & ccTLD) == 0 { + return Region{}, 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.regionID); cr != 0 { + return Region{cr} + } + return r +} + +// 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) { + s = strings.ToLower(s) + if _, ok := variantIndex[s]; ok { + return Variant{s}, nil + } + return Variant{}, mkErrInvalid([]byte(s)) +} + +// String returns the string representation of the variant. +func (v Variant) String() string { + return v.variant +} |