initial add - go fmt on grpc
Change-Id: Ib0afadd2fe5571d1456a091f94f5644458f7d3f4
diff --git a/vendor/golang.org/x/text/language/match.go b/vendor/golang.org/x/text/language/match.go
new file mode 100644
index 0000000..f734921
--- /dev/null
+++ b/vendor/golang.org/x/text/language/match.go
@@ -0,0 +1,735 @@
+// 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.
+
+package language
+
+import (
+ "errors"
+ "strings"
+
+ "golang.org/x/text/internal/language"
+)
+
+// A MatchOption configures a Matcher.
+type MatchOption func(*matcher)
+
+// PreferSameScript will, in the absence of a match, result in the first
+// preferred tag with the same script as a supported tag to match this supported
+// tag. The default is currently true, but this may change in the future.
+func PreferSameScript(preferSame bool) MatchOption {
+ return func(m *matcher) { m.preferSameScript = preferSame }
+}
+
+// TODO(v1.0.0): consider making Matcher a concrete type, instead of interface.
+// There doesn't seem to be too much need for multiple types.
+// Making it a concrete type allows MatchStrings to be a method, which will
+// improve its discoverability.
+
+// MatchStrings parses and matches the given strings until one of them matches
+// the language in the Matcher. A string may be an Accept-Language header as
+// handled by ParseAcceptLanguage. The default language is returned if no
+// other language matched.
+func MatchStrings(m Matcher, lang ...string) (tag Tag, index int) {
+ for _, accept := range lang {
+ desired, _, err := ParseAcceptLanguage(accept)
+ if err != nil {
+ continue
+ }
+ if tag, index, conf := m.Match(desired...); conf != No {
+ return tag, index
+ }
+ }
+ tag, index, _ = m.Match()
+ return
+}
+
+// Matcher is the interface that wraps the Match method.
+//
+// Match returns the best match for any of the given tags, along with
+// a unique index associated with the returned tag and a confidence
+// score.
+type Matcher interface {
+ Match(t ...Tag) (tag Tag, index int, c Confidence)
+}
+
+// Comprehends reports the confidence score for a speaker of a given language
+// to being able to comprehend the written form of an alternative language.
+func Comprehends(speaker, alternative Tag) Confidence {
+ _, _, c := NewMatcher([]Tag{alternative}).Match(speaker)
+ return c
+}
+
+// NewMatcher returns a Matcher that matches an ordered list of preferred tags
+// against a list of supported tags based on written intelligibility, closeness
+// of dialect, equivalence of subtags and various other rules. It is initialized
+// with the list of supported tags. The first element is used as the default
+// value in case no match is found.
+//
+// Its Match method matches the first of the given Tags to reach a certain
+// confidence threshold. The tags passed to Match should therefore be specified
+// in order of preference. Extensions are ignored for matching.
+//
+// The index returned by the Match method corresponds to the index of the
+// matched tag in t, but is augmented with the Unicode extension ('u')of the
+// corresponding preferred tag. This allows user locale options to be passed
+// transparently.
+func NewMatcher(t []Tag, options ...MatchOption) Matcher {
+ return newMatcher(t, options)
+}
+
+func (m *matcher) Match(want ...Tag) (t Tag, index int, c Confidence) {
+ var tt language.Tag
+ match, w, c := m.getBest(want...)
+ if match != nil {
+ tt, index = match.tag, match.index
+ } else {
+ // TODO: this should be an option
+ tt = m.default_.tag
+ if m.preferSameScript {
+ outer:
+ for _, w := range want {
+ script, _ := w.Script()
+ if script.scriptID == 0 {
+ // Don't do anything if there is no script, such as with
+ // private subtags.
+ continue
+ }
+ for i, h := range m.supported {
+ if script.scriptID == h.maxScript {
+ tt, index = h.tag, i
+ break outer
+ }
+ }
+ }
+ }
+ // TODO: select first language tag based on script.
+ }
+ if w.RegionID != tt.RegionID && w.RegionID != 0 {
+ if w.RegionID != 0 && tt.RegionID != 0 && tt.RegionID.Contains(w.RegionID) {
+ tt.RegionID = w.RegionID
+ tt.RemakeString()
+ } else if r := w.RegionID.String(); len(r) == 2 {
+ // TODO: also filter macro and deprecated.
+ tt, _ = tt.SetTypeForKey("rg", strings.ToLower(r)+"zzzz")
+ }
+ }
+ // Copy options from the user-provided tag into the result tag. This is hard
+ // to do after the fact, so we do it here.
+ // TODO: add in alternative variants to -u-va-.
+ // TODO: add preferred region to -u-rg-.
+ if e := w.Extensions(); len(e) > 0 {
+ b := language.Builder{}
+ b.SetTag(tt)
+ for _, e := range e {
+ b.AddExt(e)
+ }
+ tt = b.Make()
+ }
+ return makeTag(tt), index, c
+}
+
+// ErrMissingLikelyTagsData indicates no information was available
+// to compute likely values of missing tags.
+var ErrMissingLikelyTagsData = errors.New("missing likely tags data")
+
+// func (t *Tag) setTagsFrom(id Tag) {
+// t.LangID = id.LangID
+// t.ScriptID = id.ScriptID
+// t.RegionID = id.RegionID
+// }
+
+// Tag Matching
+// CLDR defines an algorithm for finding the best match between two sets of language
+// tags. The basic algorithm defines how to score a possible match and then find
+// the match with the best score
+// (see https://www.unicode.org/reports/tr35/#LanguageMatching).
+// Using scoring has several disadvantages. The scoring obfuscates the importance of
+// the various factors considered, making the algorithm harder to understand. Using
+// scoring also requires the full score to be computed for each pair of tags.
+//
+// We will use a different algorithm which aims to have the following properties:
+// - clarity on the precedence of the various selection factors, and
+// - improved performance by allowing early termination of a comparison.
+//
+// Matching algorithm (overview)
+// Input:
+// - supported: a set of supported tags
+// - default: the default tag to return in case there is no match
+// - desired: list of desired tags, ordered by preference, starting with
+// the most-preferred.
+//
+// Algorithm:
+// 1) Set the best match to the lowest confidence level
+// 2) For each tag in "desired":
+// a) For each tag in "supported":
+// 1) compute the match between the two tags.
+// 2) if the match is better than the previous best match, replace it
+// with the new match. (see next section)
+// b) if the current best match is Exact and pin is true the result will be
+// frozen to the language found thusfar, although better matches may
+// still be found for the same language.
+// 3) If the best match so far is below a certain threshold, return "default".
+//
+// Ranking:
+// We use two phases to determine whether one pair of tags are a better match
+// than another pair of tags. First, we determine a rough confidence level. If the
+// levels are different, the one with the highest confidence wins.
+// Second, if the rough confidence levels are identical, we use a set of tie-breaker
+// rules.
+//
+// The confidence level of matching a pair of tags is determined by finding the
+// lowest confidence level of any matches of the corresponding subtags (the
+// result is deemed as good as its weakest link).
+// We define the following levels:
+// Exact - An exact match of a subtag, before adding likely subtags.
+// MaxExact - An exact match of a subtag, after adding likely subtags.
+// [See Note 2].
+// High - High level of mutual intelligibility between different subtag
+// variants.
+// Low - Low level of mutual intelligibility between different subtag
+// variants.
+// No - No mutual intelligibility.
+//
+// The following levels can occur for each type of subtag:
+// Base: Exact, MaxExact, High, Low, No
+// Script: Exact, MaxExact [see Note 3], Low, No
+// Region: Exact, MaxExact, High
+// Variant: Exact, High
+// Private: Exact, No
+//
+// Any result with a confidence level of Low or higher is deemed a possible match.
+// Once a desired tag matches any of the supported tags with a level of MaxExact
+// or higher, the next desired tag is not considered (see Step 2.b).
+// Note that CLDR provides languageMatching data that defines close equivalence
+// classes for base languages, scripts and regions.
+//
+// Tie-breaking
+// If we get the same confidence level for two matches, we apply a sequence of
+// tie-breaking rules. The first that succeeds defines the result. The rules are
+// applied in the following order.
+// 1) Original language was defined and was identical.
+// 2) Original region was defined and was identical.
+// 3) Distance between two maximized regions was the smallest.
+// 4) Original script was defined and was identical.
+// 5) Distance from want tag to have tag using the parent relation [see Note 5.]
+// If there is still no winner after these rules are applied, the first match
+// found wins.
+//
+// Notes:
+// [2] In practice, as matching of Exact is done in a separate phase from
+// matching the other levels, we reuse the Exact level to mean MaxExact in
+// the second phase. As a consequence, we only need the levels defined by
+// the Confidence type. The MaxExact confidence level is mapped to High in
+// the public API.
+// [3] We do not differentiate between maximized script values that were derived
+// from suppressScript versus most likely tag data. We determined that in
+// ranking the two, one ranks just after the other. Moreover, the two cannot
+// occur concurrently. As a consequence, they are identical for practical
+// purposes.
+// [4] In case of deprecated, macro-equivalents and legacy mappings, we assign
+// the MaxExact level to allow iw vs he to still be a closer match than
+// en-AU vs en-US, for example.
+// [5] In CLDR a locale inherits fields that are unspecified for this locale
+// from its parent. Therefore, if a locale is a parent of another locale,
+// it is a strong measure for closeness, especially when no other tie
+// breaker rule applies. One could also argue it is inconsistent, for
+// example, when pt-AO matches pt (which CLDR equates with pt-BR), even
+// though its parent is pt-PT according to the inheritance rules.
+//
+// Implementation Details:
+// There are several performance considerations worth pointing out. Most notably,
+// we preprocess as much as possible (within reason) at the time of creation of a
+// matcher. This includes:
+// - creating a per-language map, which includes data for the raw base language
+// and its canonicalized variant (if applicable),
+// - expanding entries for the equivalence classes defined in CLDR's
+// languageMatch data.
+// The per-language map ensures that typically only a very small number of tags
+// need to be considered. The pre-expansion of canonicalized subtags and
+// equivalence classes reduces the amount of map lookups that need to be done at
+// runtime.
+
+// matcher keeps a set of supported language tags, indexed by language.
+type matcher struct {
+ default_ *haveTag
+ supported []*haveTag
+ index map[language.Language]*matchHeader
+ passSettings bool
+ preferSameScript bool
+}
+
+// matchHeader has the lists of tags for exact matches and matches based on
+// maximized and canonicalized tags for a given language.
+type matchHeader struct {
+ haveTags []*haveTag
+ original bool
+}
+
+// haveTag holds a supported Tag and its maximized script and region. The maximized
+// or canonicalized language is not stored as it is not needed during matching.
+type haveTag struct {
+ tag language.Tag
+
+ // index of this tag in the original list of supported tags.
+ index int
+
+ // conf is the maximum confidence that can result from matching this haveTag.
+ // When conf < Exact this means it was inserted after applying a CLDR equivalence rule.
+ conf Confidence
+
+ // Maximized region and script.
+ maxRegion language.Region
+ maxScript language.Script
+
+ // altScript may be checked as an alternative match to maxScript. If altScript
+ // matches, the confidence level for this match is Low. Theoretically there
+ // could be multiple alternative scripts. This does not occur in practice.
+ altScript language.Script
+
+ // nextMax is the index of the next haveTag with the same maximized tags.
+ nextMax uint16
+}
+
+func makeHaveTag(tag language.Tag, index int) (haveTag, language.Language) {
+ max := tag
+ if tag.LangID != 0 || tag.RegionID != 0 || tag.ScriptID != 0 {
+ max, _ = canonicalize(All, max)
+ max, _ = max.Maximize()
+ max.RemakeString()
+ }
+ return haveTag{tag, index, Exact, max.RegionID, max.ScriptID, altScript(max.LangID, max.ScriptID), 0}, max.LangID
+}
+
+// altScript returns an alternative script that may match the given script with
+// a low confidence. At the moment, the langMatch data allows for at most one
+// script to map to another and we rely on this to keep the code simple.
+func altScript(l language.Language, s language.Script) language.Script {
+ for _, alt := range matchScript {
+ // TODO: also match cases where language is not the same.
+ if (language.Language(alt.wantLang) == l || language.Language(alt.haveLang) == l) &&
+ language.Script(alt.haveScript) == s {
+ return language.Script(alt.wantScript)
+ }
+ }
+ return 0
+}
+
+// addIfNew adds a haveTag to the list of tags only if it is a unique tag.
+// Tags that have the same maximized values are linked by index.
+func (h *matchHeader) addIfNew(n haveTag, exact bool) {
+ h.original = h.original || exact
+ // Don't add new exact matches.
+ for _, v := range h.haveTags {
+ if equalsRest(v.tag, n.tag) {
+ return
+ }
+ }
+ // Allow duplicate maximized tags, but create a linked list to allow quickly
+ // comparing the equivalents and bail out.
+ for i, v := range h.haveTags {
+ if v.maxScript == n.maxScript &&
+ v.maxRegion == n.maxRegion &&
+ v.tag.VariantOrPrivateUseTags() == n.tag.VariantOrPrivateUseTags() {
+ for h.haveTags[i].nextMax != 0 {
+ i = int(h.haveTags[i].nextMax)
+ }
+ h.haveTags[i].nextMax = uint16(len(h.haveTags))
+ break
+ }
+ }
+ h.haveTags = append(h.haveTags, &n)
+}
+
+// header returns the matchHeader for the given language. It creates one if
+// it doesn't already exist.
+func (m *matcher) header(l language.Language) *matchHeader {
+ if h := m.index[l]; h != nil {
+ return h
+ }
+ h := &matchHeader{}
+ m.index[l] = h
+ return h
+}
+
+func toConf(d uint8) Confidence {
+ if d <= 10 {
+ return High
+ }
+ if d < 30 {
+ return Low
+ }
+ return No
+}
+
+// newMatcher builds an index for the given supported tags and returns it as
+// a matcher. It also expands the index by considering various equivalence classes
+// for a given tag.
+func newMatcher(supported []Tag, options []MatchOption) *matcher {
+ m := &matcher{
+ index: make(map[language.Language]*matchHeader),
+ preferSameScript: true,
+ }
+ for _, o := range options {
+ o(m)
+ }
+ if len(supported) == 0 {
+ m.default_ = &haveTag{}
+ return m
+ }
+ // Add supported languages to the index. Add exact matches first to give
+ // them precedence.
+ for i, tag := range supported {
+ tt := tag.tag()
+ pair, _ := makeHaveTag(tt, i)
+ m.header(tt.LangID).addIfNew(pair, true)
+ m.supported = append(m.supported, &pair)
+ }
+ m.default_ = m.header(supported[0].lang()).haveTags[0]
+ // Keep these in two different loops to support the case that two equivalent
+ // languages are distinguished, such as iw and he.
+ for i, tag := range supported {
+ tt := tag.tag()
+ pair, max := makeHaveTag(tt, i)
+ if max != tt.LangID {
+ m.header(max).addIfNew(pair, true)
+ }
+ }
+
+ // update is used to add indexes in the map for equivalent languages.
+ // update will only add entries to original indexes, thus not computing any
+ // transitive relations.
+ update := func(want, have uint16, conf Confidence) {
+ if hh := m.index[language.Language(have)]; hh != nil {
+ if !hh.original {
+ return
+ }
+ hw := m.header(language.Language(want))
+ for _, ht := range hh.haveTags {
+ v := *ht
+ if conf < v.conf {
+ v.conf = conf
+ }
+ v.nextMax = 0 // this value needs to be recomputed
+ if v.altScript != 0 {
+ v.altScript = altScript(language.Language(want), v.maxScript)
+ }
+ hw.addIfNew(v, conf == Exact && hh.original)
+ }
+ }
+ }
+
+ // Add entries for languages with mutual intelligibility as defined by CLDR's
+ // languageMatch data.
+ for _, ml := range matchLang {
+ update(ml.want, ml.have, toConf(ml.distance))
+ if !ml.oneway {
+ update(ml.have, ml.want, toConf(ml.distance))
+ }
+ }
+
+ // Add entries for possible canonicalizations. This is an optimization to
+ // ensure that only one map lookup needs to be done at runtime per desired tag.
+ // First we match deprecated equivalents. If they are perfect equivalents
+ // (their canonicalization simply substitutes a different language code, but
+ // nothing else), the match confidence is Exact, otherwise it is High.
+ for i, lm := range language.AliasMap {
+ // If deprecated codes match and there is no fiddling with the script or
+ // or region, we consider it an exact match.
+ conf := Exact
+ if language.AliasTypes[i] != language.Macro {
+ if !isExactEquivalent(language.Language(lm.From)) {
+ conf = High
+ }
+ update(lm.To, lm.From, conf)
+ }
+ update(lm.From, lm.To, conf)
+ }
+ return m
+}
+
+// getBest gets the best matching tag in m for any of the given tags, taking into
+// account the order of preference of the given tags.
+func (m *matcher) getBest(want ...Tag) (got *haveTag, orig language.Tag, c Confidence) {
+ best := bestMatch{}
+ for i, ww := range want {
+ w := ww.tag()
+ var max language.Tag
+ // Check for exact match first.
+ h := m.index[w.LangID]
+ if w.LangID != 0 {
+ if h == nil {
+ continue
+ }
+ // Base language is defined.
+ max, _ = canonicalize(Legacy|Deprecated|Macro, w)
+ // A region that is added through canonicalization is stronger than
+ // a maximized region: set it in the original (e.g. mo -> ro-MD).
+ if w.RegionID != max.RegionID {
+ w.RegionID = max.RegionID
+ }
+ // TODO: should we do the same for scripts?
+ // See test case: en, sr, nl ; sh ; sr
+ max, _ = max.Maximize()
+ } else {
+ // Base language is not defined.
+ if h != nil {
+ for i := range h.haveTags {
+ have := h.haveTags[i]
+ if equalsRest(have.tag, w) {
+ return have, w, Exact
+ }
+ }
+ }
+ if w.ScriptID == 0 && w.RegionID == 0 {
+ // We skip all tags matching und for approximate matching, including
+ // private tags.
+ continue
+ }
+ max, _ = w.Maximize()
+ if h = m.index[max.LangID]; h == nil {
+ continue
+ }
+ }
+ pin := true
+ for _, t := range want[i+1:] {
+ if w.LangID == t.lang() {
+ pin = false
+ break
+ }
+ }
+ // Check for match based on maximized tag.
+ for i := range h.haveTags {
+ have := h.haveTags[i]
+ best.update(have, w, max.ScriptID, max.RegionID, pin)
+ if best.conf == Exact {
+ for have.nextMax != 0 {
+ have = h.haveTags[have.nextMax]
+ best.update(have, w, max.ScriptID, max.RegionID, pin)
+ }
+ return best.have, best.want, best.conf
+ }
+ }
+ }
+ if best.conf <= No {
+ if len(want) != 0 {
+ return nil, want[0].tag(), No
+ }
+ return nil, language.Tag{}, No
+ }
+ return best.have, best.want, best.conf
+}
+
+// bestMatch accumulates the best match so far.
+type bestMatch struct {
+ have *haveTag
+ want language.Tag
+ conf Confidence
+ pinnedRegion language.Region
+ pinLanguage bool
+ sameRegionGroup bool
+ // Cached results from applying tie-breaking rules.
+ origLang bool
+ origReg bool
+ paradigmReg bool
+ regGroupDist uint8
+ origScript bool
+}
+
+// update updates the existing best match if the new pair is considered to be a
+// better match. To determine if the given pair is a better match, it first
+// computes the rough confidence level. If this surpasses the current match, it
+// will replace it and update the tie-breaker rule cache. If there is a tie, it
+// proceeds with applying a series of tie-breaker rules. If there is no
+// conclusive winner after applying the tie-breaker rules, it leaves the current
+// match as the preferred match.
+//
+// If pin is true and have and tag are a strong match, it will henceforth only
+// consider matches for this language. This corresponds to the nothing that most
+// users have a strong preference for the first defined language. A user can
+// still prefer a second language over a dialect of the preferred language by
+// explicitly specifying dialects, e.g. "en, nl, en-GB". In this case pin should
+// be false.
+func (m *bestMatch) update(have *haveTag, tag language.Tag, maxScript language.Script, maxRegion language.Region, pin bool) {
+ // Bail if the maximum attainable confidence is below that of the current best match.
+ c := have.conf
+ if c < m.conf {
+ return
+ }
+ // Don't change the language once we already have found an exact match.
+ if m.pinLanguage && tag.LangID != m.want.LangID {
+ return
+ }
+ // Pin the region group if we are comparing tags for the same language.
+ if tag.LangID == m.want.LangID && m.sameRegionGroup {
+ _, sameGroup := regionGroupDist(m.pinnedRegion, have.maxRegion, have.maxScript, m.want.LangID)
+ if !sameGroup {
+ return
+ }
+ }
+ if c == Exact && have.maxScript == maxScript {
+ // If there is another language and then another entry of this language,
+ // don't pin anything, otherwise pin the language.
+ m.pinLanguage = pin
+ }
+ if equalsRest(have.tag, tag) {
+ } else if have.maxScript != maxScript {
+ // There is usually very little comprehension between different scripts.
+ // In a few cases there may still be Low comprehension. This possibility
+ // is pre-computed and stored in have.altScript.
+ if Low < m.conf || have.altScript != maxScript {
+ return
+ }
+ c = Low
+ } else if have.maxRegion != maxRegion {
+ if High < c {
+ // There is usually a small difference between languages across regions.
+ c = High
+ }
+ }
+
+ // We store the results of the computations of the tie-breaker rules along
+ // with the best match. There is no need to do the checks once we determine
+ // we have a winner, but we do still need to do the tie-breaker computations.
+ // We use "beaten" to keep track if we still need to do the checks.
+ beaten := false // true if the new pair defeats the current one.
+ if c != m.conf {
+ if c < m.conf {
+ return
+ }
+ beaten = true
+ }
+
+ // Tie-breaker rules:
+ // We prefer if the pre-maximized language was specified and identical.
+ origLang := have.tag.LangID == tag.LangID && tag.LangID != 0
+ if !beaten && m.origLang != origLang {
+ if m.origLang {
+ return
+ }
+ beaten = true
+ }
+
+ // We prefer if the pre-maximized region was specified and identical.
+ origReg := have.tag.RegionID == tag.RegionID && tag.RegionID != 0
+ if !beaten && m.origReg != origReg {
+ if m.origReg {
+ return
+ }
+ beaten = true
+ }
+
+ regGroupDist, sameGroup := regionGroupDist(have.maxRegion, maxRegion, maxScript, tag.LangID)
+ if !beaten && m.regGroupDist != regGroupDist {
+ if regGroupDist > m.regGroupDist {
+ return
+ }
+ beaten = true
+ }
+
+ paradigmReg := isParadigmLocale(tag.LangID, have.maxRegion)
+ if !beaten && m.paradigmReg != paradigmReg {
+ if !paradigmReg {
+ return
+ }
+ beaten = true
+ }
+
+ // Next we prefer if the pre-maximized script was specified and identical.
+ origScript := have.tag.ScriptID == tag.ScriptID && tag.ScriptID != 0
+ if !beaten && m.origScript != origScript {
+ if m.origScript {
+ return
+ }
+ beaten = true
+ }
+
+ // Update m to the newly found best match.
+ if beaten {
+ m.have = have
+ m.want = tag
+ m.conf = c
+ m.pinnedRegion = maxRegion
+ m.sameRegionGroup = sameGroup
+ m.origLang = origLang
+ m.origReg = origReg
+ m.paradigmReg = paradigmReg
+ m.origScript = origScript
+ m.regGroupDist = regGroupDist
+ }
+}
+
+func isParadigmLocale(lang language.Language, r language.Region) bool {
+ for _, e := range paradigmLocales {
+ if language.Language(e[0]) == lang && (r == language.Region(e[1]) || r == language.Region(e[2])) {
+ return true
+ }
+ }
+ return false
+}
+
+// regionGroupDist computes the distance between two regions based on their
+// CLDR grouping.
+func regionGroupDist(a, b language.Region, script language.Script, lang language.Language) (dist uint8, same bool) {
+ const defaultDistance = 4
+
+ aGroup := uint(regionToGroups[a]) << 1
+ bGroup := uint(regionToGroups[b]) << 1
+ for _, ri := range matchRegion {
+ if language.Language(ri.lang) == lang && (ri.script == 0 || language.Script(ri.script) == script) {
+ group := uint(1 << (ri.group &^ 0x80))
+ if 0x80&ri.group == 0 {
+ if aGroup&bGroup&group != 0 { // Both regions are in the group.
+ return ri.distance, ri.distance == defaultDistance
+ }
+ } else {
+ if (aGroup|bGroup)&group == 0 { // Both regions are not in the group.
+ return ri.distance, ri.distance == defaultDistance
+ }
+ }
+ }
+ }
+ return defaultDistance, true
+}
+
+// equalsRest compares everything except the language.
+func equalsRest(a, b language.Tag) bool {
+ // TODO: don't include extensions in this comparison. To do this efficiently,
+ // though, we should handle private tags separately.
+ return a.ScriptID == b.ScriptID && a.RegionID == b.RegionID && a.VariantOrPrivateUseTags() == b.VariantOrPrivateUseTags()
+}
+
+// isExactEquivalent returns true if canonicalizing the language will not alter
+// the script or region of a tag.
+func isExactEquivalent(l language.Language) bool {
+ for _, o := range notEquivalent {
+ if o == l {
+ return false
+ }
+ }
+ return true
+}
+
+var notEquivalent []language.Language
+
+func init() {
+ // Create a list of all languages for which canonicalization may alter the
+ // script or region.
+ for _, lm := range language.AliasMap {
+ tag := language.Tag{LangID: language.Language(lm.From)}
+ if tag, _ = canonicalize(All, tag); tag.ScriptID != 0 || tag.RegionID != 0 {
+ notEquivalent = append(notEquivalent, language.Language(lm.From))
+ }
+ }
+ // Maximize undefined regions of paradigm locales.
+ for i, v := range paradigmLocales {
+ t := language.Tag{LangID: language.Language(v[0])}
+ max, _ := t.Maximize()
+ if v[1] == 0 {
+ paradigmLocales[i][1] = uint16(max.RegionID)
+ }
+ if v[2] == 0 {
+ paradigmLocales[i][2] = uint16(max.RegionID)
+ }
+ }
+}