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-rw-r--r--Godeps/_workspace/src/golang.org/x/text/language/match.go840
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diff --git a/Godeps/_workspace/src/golang.org/x/text/language/match.go b/Godeps/_workspace/src/golang.org/x/text/language/match.go
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--- a/Godeps/_workspace/src/golang.org/x/text/language/match.go
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@@ -1,840 +0,0 @@
-// 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"
-
-// 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) Matcher {
- return newMatcher(t)
-}
-
-func (m *matcher) Match(want ...Tag) (t Tag, index int, c Confidence) {
- match, w, c := m.getBest(want...)
- if match == nil {
- t = m.default_.tag
- } else {
- t, index = match.tag, match.index
- }
- // 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: consider also adding in variants that are compatible with the
- // matched language.
- // TODO: Add back region if it is non-ambiguous? Or create another tag to
- // preserve the region?
- if u, ok := w.Extension('u'); ok {
- t, _ = Raw.Compose(t, u)
- }
- return t, index, c
-}
-
-type scriptRegionFlags uint8
-
-const (
- isList = 1 << iota
- scriptInFrom
- regionInFrom
-)
-
-func (t *Tag) setUndefinedLang(id langID) {
- if t.lang == 0 {
- t.lang = id
- }
-}
-
-func (t *Tag) setUndefinedScript(id scriptID) {
- if t.script == 0 {
- t.script = id
- }
-}
-
-func (t *Tag) setUndefinedRegion(id regionID) {
- if t.region == 0 || t.region.contains(id) {
- t.region = id
- }
-}
-
-// ErrMissingLikelyTagsData indicates no information was available
-// to compute likely values of missing tags.
-var ErrMissingLikelyTagsData = errors.New("missing likely tags data")
-
-// addLikelySubtags sets subtags to their most likely value, given the locale.
-// In most cases this means setting fields for unknown values, but in some
-// cases it may alter a value. It returns a ErrMissingLikelyTagsData error
-// if the given locale cannot be expanded.
-func (t Tag) addLikelySubtags() (Tag, error) {
- id, err := addTags(t)
- if err != nil {
- return t, err
- } else if id.equalTags(t) {
- return t, nil
- }
- id.remakeString()
- return id, nil
-}
-
-// specializeRegion attempts to specialize a group region.
-func specializeRegion(t *Tag) bool {
- if i := regionInclusion[t.region]; i < nRegionGroups {
- x := likelyRegionGroup[i]
- if langID(x.lang) == t.lang && scriptID(x.script) == t.script {
- t.region = regionID(x.region)
- }
- return true
- }
- return false
-}
-
-func addTags(t Tag) (Tag, error) {
- // We leave private use identifiers alone.
- if t.private() {
- return t, nil
- }
- if t.script != 0 && t.region != 0 {
- if t.lang != 0 {
- // already fully specified
- specializeRegion(&t)
- return t, nil
- }
- // Search matches for und-script-region. Note that for these cases
- // region will never be a group so there is no need to check for this.
- list := likelyRegion[t.region : t.region+1]
- if x := list[0]; x.flags&isList != 0 {
- list = likelyRegionList[x.lang : x.lang+uint16(x.script)]
- }
- for _, x := range list {
- // Deviating from the spec. See match_test.go for details.
- if scriptID(x.script) == t.script {
- t.setUndefinedLang(langID(x.lang))
- return t, nil
- }
- }
- }
- if t.lang != 0 {
- // Search matches for lang-script and lang-region, where lang != und.
- if t.lang < langNoIndexOffset {
- x := likelyLang[t.lang]
- if x.flags&isList != 0 {
- list := likelyLangList[x.region : x.region+uint16(x.script)]
- if t.script != 0 {
- for _, x := range list {
- if scriptID(x.script) == t.script && x.flags&scriptInFrom != 0 {
- t.setUndefinedRegion(regionID(x.region))
- return t, nil
- }
- }
- } else if t.region != 0 {
- count := 0
- goodScript := true
- tt := t
- for _, x := range list {
- // We visit all entries for which the script was not
- // defined, including the ones where the region was not
- // defined. This allows for proper disambiguation within
- // regions.
- if x.flags&scriptInFrom == 0 && t.region.contains(regionID(x.region)) {
- tt.region = regionID(x.region)
- tt.setUndefinedScript(scriptID(x.script))
- goodScript = goodScript && tt.script == scriptID(x.script)
- count++
- }
- }
- if count == 1 {
- return tt, nil
- }
- // Even if we fail to find a unique Region, we might have
- // an unambiguous script.
- if goodScript {
- t.script = tt.script
- }
- }
- }
- }
- } else {
- // Search matches for und-script.
- if t.script != 0 {
- x := likelyScript[t.script]
- if x.region != 0 {
- t.setUndefinedRegion(regionID(x.region))
- t.setUndefinedLang(langID(x.lang))
- return t, nil
- }
- }
- // Search matches for und-region. If und-script-region exists, it would
- // have been found earlier.
- if t.region != 0 {
- if i := regionInclusion[t.region]; i < nRegionGroups {
- x := likelyRegionGroup[i]
- if x.region != 0 {
- t.setUndefinedLang(langID(x.lang))
- t.setUndefinedScript(scriptID(x.script))
- t.region = regionID(x.region)
- }
- } else {
- x := likelyRegion[t.region]
- if x.flags&isList != 0 {
- x = likelyRegionList[x.lang]
- }
- if x.script != 0 && x.flags != scriptInFrom {
- t.setUndefinedLang(langID(x.lang))
- t.setUndefinedScript(scriptID(x.script))
- return t, nil
- }
- }
- }
- }
-
- // Search matches for lang.
- if t.lang < langNoIndexOffset {
- x := likelyLang[t.lang]
- if x.flags&isList != 0 {
- x = likelyLangList[x.region]
- }
- if x.region != 0 {
- t.setUndefinedScript(scriptID(x.script))
- t.setUndefinedRegion(regionID(x.region))
- }
- specializeRegion(&t)
- if t.lang == 0 {
- t.lang = _en // default language
- }
- return t, nil
- }
- return t, ErrMissingLikelyTagsData
-}
-
-func (t *Tag) setTagsFrom(id Tag) {
- t.lang = id.lang
- t.script = id.script
- t.region = id.region
-}
-
-// minimize removes the region or script subtags from t such that
-// t.addLikelySubtags() == t.minimize().addLikelySubtags().
-func (t Tag) minimize() (Tag, error) {
- t, err := minimizeTags(t)
- if err != nil {
- return t, err
- }
- t.remakeString()
- return t, nil
-}
-
-// minimizeTags mimics the behavior of the ICU 51 C implementation.
-func minimizeTags(t Tag) (Tag, error) {
- if t.equalTags(und) {
- return t, nil
- }
- max, err := addTags(t)
- if err != nil {
- return t, err
- }
- for _, id := range [...]Tag{
- {lang: t.lang},
- {lang: t.lang, region: t.region},
- {lang: t.lang, script: t.script},
- } {
- if x, err := addTags(id); err == nil && max.equalTags(x) {
- t.setTagsFrom(id)
- break
- }
- }
- return t, nil
-}
-
-// 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 http://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 above a certain threshold, return this
-// match without proceeding to the next tag in "desired". [See Note 1]
-// 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:
-// [1] Note that even if we may not have a perfect match, if a match is above a
-// certain threshold, it is considered a better match than any other match
-// to a tag later in the list of preferred language tags.
-// [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
- index map[langID]*matchHeader
- passSettings 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 {
- exact []haveTag
- max []haveTag
-}
-
-// 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 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 regionID
- maxScript scriptID
-
- // 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 scriptID
-
- // nextMax is the index of the next haveTag with the same maximized tags.
- nextMax uint16
-}
-
-func makeHaveTag(tag Tag, index int) (haveTag, langID) {
- max := tag
- if tag.lang != 0 {
- max, _ = max.canonicalize(All)
- max, _ = addTags(max)
- max.remakeString()
- }
- return haveTag{tag, index, Exact, max.region, max.script, altScript(max.lang, max.script), 0}, max.lang
-}
-
-// 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 langID, s scriptID) scriptID {
- for _, alt := range matchScript {
- if (alt.lang == 0 || langID(alt.lang) == l) && scriptID(alt.have) == s {
- return scriptID(alt.want)
- }
- }
- 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) {
- // Don't add new exact matches.
- for _, v := range h.exact {
- if v.tag.equalsRest(n.tag) {
- return
- }
- }
- if exact {
- h.exact = append(h.exact, n)
- }
- // Allow duplicate maximized tags, but create a linked list to allow quickly
- // comparing the equivalents and bail out.
- for i, v := range h.max {
- if v.maxScript == n.maxScript &&
- v.maxRegion == n.maxRegion &&
- v.tag.variantOrPrivateTagStr() == n.tag.variantOrPrivateTagStr() {
- for h.max[i].nextMax != 0 {
- i = int(h.max[i].nextMax)
- }
- h.max[i].nextMax = uint16(len(h.max))
- break
- }
- }
- h.max = append(h.max, n)
-}
-
-// header returns the matchHeader for the given language. It creates one if
-// it doesn't already exist.
-func (m *matcher) header(l langID) *matchHeader {
- if h := m.index[l]; h != nil {
- return h
- }
- h := &matchHeader{}
- m.index[l] = h
- return h
-}
-
-// 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) *matcher {
- m := &matcher{
- index: make(map[langID]*matchHeader),
- }
- 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 {
- pair, _ := makeHaveTag(tag, i)
- m.header(tag.lang).addIfNew(pair, true)
- }
- m.default_ = &m.header(supported[0].lang).exact[0]
- for i, tag := range supported {
- pair, max := makeHaveTag(tag, i)
- if max != tag.lang {
- m.header(max).addIfNew(pair, false)
- }
- }
-
- // update is used to add indexes in the map for equivalent languages.
- // If force is true, the update will also apply to derived entries. To
- // avoid applying a "transitive closure", use false.
- update := func(want, have uint16, conf Confidence, force bool) {
- if hh := m.index[langID(have)]; hh != nil {
- if !force && len(hh.exact) == 0 {
- return
- }
- hw := m.header(langID(want))
- for _, v := range hh.max {
- if conf < v.conf {
- v.conf = conf
- }
- v.nextMax = 0 // this value needs to be recomputed
- if v.altScript != 0 {
- v.altScript = altScript(langID(want), v.maxScript)
- }
- hw.addIfNew(v, conf == Exact && len(hh.exact) > 0)
- }
- }
- }
-
- // Add entries for languages with mutual intelligibility as defined by CLDR's
- // languageMatch data.
- for _, ml := range matchLang {
- update(ml.want, ml.have, Confidence(ml.conf), false)
- if !ml.oneway {
- update(ml.have, ml.want, Confidence(ml.conf), false)
- }
- }
-
- // 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 langAliasMap {
- if lm.from == _sh {
- continue
- }
-
- // If deprecated codes match and there is no fiddling with the script or
- // or region, we consider it an exact match.
- conf := Exact
- if langAliasTypes[i] != langMacro {
- if !isExactEquivalent(langID(lm.from)) {
- conf = High
- }
- update(lm.to, lm.from, conf, true)
- }
- update(lm.from, lm.to, conf, true)
- }
- 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 Tag, c Confidence) {
- best := bestMatch{}
- for _, w := range want {
- var max Tag
- // Check for exact match first.
- h := m.index[w.lang]
- if w.lang != 0 {
- // Base language is defined.
- if h == nil {
- continue
- }
- for i := range h.exact {
- have := &h.exact[i]
- if have.tag.equalsRest(w) {
- return have, w, Exact
- }
- }
- max, _ = w.canonicalize(Legacy | Deprecated)
- max, _ = addTags(max)
- } else {
- // Base language is not defined.
- if h != nil {
- for i := range h.exact {
- have := &h.exact[i]
- if have.tag.equalsRest(w) {
- return have, w, Exact
- }
- }
- }
- if w.script == 0 && w.region == 0 {
- // We skip all tags matching und for approximate matching, including
- // private tags.
- continue
- }
- max, _ = addTags(w)
- if h = m.index[max.lang]; h == nil {
- continue
- }
- }
- // Check for match based on maximized tag.
- for i := range h.max {
- have := &h.max[i]
- best.update(have, w, max.script, max.region)
- if best.conf == Exact {
- for have.nextMax != 0 {
- have = &h.max[have.nextMax]
- best.update(have, w, max.script, max.region)
- }
- return best.have, best.want, High
- }
- }
- }
- if best.conf <= No {
- if len(want) != 0 {
- return nil, want[0], No
- }
- return nil, Tag{}, No
- }
- return best.have, best.want, best.conf
-}
-
-// bestMatch accumulates the best match so far.
-type bestMatch struct {
- have *haveTag
- want Tag
- conf Confidence
- // Cached results from applying tie-breaking rules.
- origLang bool
- origReg bool
- regDist uint8
- origScript bool
- parentDist uint8 // 255 if have is not an ancestor of want tag.
-}
-
-// 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.
-func (m *bestMatch) update(have *haveTag, tag Tag, maxScript scriptID, maxRegion regionID) {
- // Bail if the maximum attainable confidence is below that of the current best match.
- c := have.conf
- if c < m.conf {
- return
- }
- 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 {
- // There is usually a small difference between languages across regions.
- // We use the region distance (below) to disambiguate between equal matches.
- if High < c {
- 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.lang == tag.lang && tag.lang != 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.region == tag.region && tag.region != 0
- if !beaten && m.origReg != origReg {
- if m.origReg {
- return
- }
- beaten = true
- }
-
- // Next we prefer smaller distances between regions, as defined by regionDist.
- regDist := regionDist(have.maxRegion, maxRegion, tag.lang)
- if !beaten && m.regDist != regDist {
- if regDist > m.regDist {
- return
- }
- beaten = true
- }
-
- // Next we prefer if the pre-maximized script was specified and identical.
- origScript := have.tag.script == tag.script && tag.script != 0
- if !beaten && m.origScript != origScript {
- if m.origScript {
- return
- }
- beaten = true
- }
-
- // Finally we prefer tags which have a closer parent relationship.
- parentDist := parentDistance(have.tag.region, tag)
- if !beaten && m.parentDist != parentDist {
- if parentDist > m.parentDist {
- return
- }
- beaten = true
- }
-
- // Update m to the newly found best match.
- if beaten {
- m.have = have
- m.want = tag
- m.conf = c
- m.origLang = origLang
- m.origReg = origReg
- m.origScript = origScript
- m.regDist = regDist
- m.parentDist = parentDist
- }
-}
-
-// parentDistance returns the number of times Parent must be called before the
-// regions match. It is assumed that it has already been checked that lang and
-// script are identical. If haveRegion does not occur in the ancestor chain of
-// tag, it returns 255.
-func parentDistance(haveRegion regionID, tag Tag) uint8 {
- p := tag.Parent()
- d := uint8(1)
- for haveRegion != p.region {
- if p.region == 0 {
- return 255
- }
- p = p.Parent()
- d++
- }
- return d
-}
-
-// regionDist wraps regionDistance with some exceptions to the algorithmic distance.
-func regionDist(a, b regionID, lang langID) uint8 {
- if lang == _en {
- // Two variants of non-US English are close to each other, regardless of distance.
- if a != _US && b != _US {
- return 2
- }
- }
- return uint8(regionDistance(a, b))
-}
-
-// regionDistance computes the distance between two regions based on the
-// distance in the graph of region containments as defined in CLDR. It iterates
-// over increasingly inclusive sets of groups, represented as bit vectors, until
-// the source bit vector has bits in common with the destination vector.
-func regionDistance(a, b regionID) int {
- if a == b {
- return 0
- }
- p, q := regionInclusion[a], regionInclusion[b]
- if p < nRegionGroups {
- p, q = q, p
- }
- set := regionInclusionBits
- if q < nRegionGroups && set[p]&(1<<q) != 0 {
- return 1
- }
- d := 2
- for goal := set[q]; set[p]&goal == 0; p = regionInclusionNext[p] {
- d++
- }
- return d
-}
-
-func (t Tag) variants() string {
- if t.pVariant == 0 {
- return ""
- }
- return t.str[t.pVariant:t.pExt]
-}
-
-// variantOrPrivateTagStr returns variants or private use tags.
-func (t Tag) variantOrPrivateTagStr() string {
- if t.pExt > 0 {
- return t.str[t.pVariant:t.pExt]
- }
- return t.str[t.pVariant:]
-}
-
-// equalsRest compares everything except the language.
-func (a Tag) equalsRest(b Tag) bool {
- // TODO: don't include extensions in this comparison. To do this efficiently,
- // though, we should handle private tags separately.
- return a.script == b.script && a.region == b.region && a.variantOrPrivateTagStr() == b.variantOrPrivateTagStr()
-}
-
-// isExactEquivalent returns true if canonicalizing the language will not alter
-// the script or region of a tag.
-func isExactEquivalent(l langID) bool {
- for _, o := range notEquivalent {
- if o == l {
- return false
- }
- }
- return true
-}
-
-var notEquivalent []langID
-
-func init() {
- // Create a list of all languages for which canonicalization may alter the
- // script or region.
- for _, lm := range langAliasMap {
- tag := Tag{lang: langID(lm.from)}
- if tag, _ = tag.canonicalize(All); tag.script != 0 || tag.region != 0 {
- notEquivalent = append(notEquivalent, langID(lm.from))
- }
- }
-}