diff options
Diffstat (limited to 'vendor/golang.org/x/text/language/match.go')
| -rw-r--r-- | vendor/golang.org/x/text/language/match.go | 136 |
1 files changed, 108 insertions, 28 deletions
diff --git a/vendor/golang.org/x/text/language/match.go b/vendor/golang.org/x/text/language/match.go index bb4fff24d..63bc744a3 100644 --- a/vendor/golang.org/x/text/language/match.go +++ b/vendor/golang.org/x/text/language/match.go @@ -6,6 +6,16 @@ package language import "errors" +// 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 } +} + // Matcher is the interface that wraps the Match method. // // Match returns the best match for any of the given tags, along with @@ -36,23 +46,44 @@ func Comprehends(speaker, alternative Tag) Confidence { // 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 NewMatcher(t []Tag, options ...MatchOption) Matcher { + return newMatcher(t, options) } 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 { + if match != nil { t, index = match.tag, match.index + } else { + // TODO: this should be an option + t = 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 { + t, index = h.tag, i + break outer + } + } + } + } + // TODO: select first language tag based on script. + } + if w.region != 0 && t.region != 0 && t.region.contains(w.region) { + t, _ = Raw.Compose(t, Region{w.region}) } // 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? + // TODO: add in alternative variants to -u-va-. + // TODO: add preferred region to -u-rg-. + // TODO: add other extensions. Merge with existing extensions. if u, ok := w.Extension('u'); ok { t, _ = Raw.Compose(t, u) } @@ -388,9 +419,11 @@ func minimizeTags(t Tag) (Tag, error) { // matcher keeps a set of supported language tags, indexed by language. type matcher struct { - default_ *haveTag - index map[langID]*matchHeader - passSettings bool + default_ *haveTag + supported []*haveTag + index map[langID]*matchHeader + passSettings bool + preferSameScript bool } // matchHeader has the lists of tags for exact matches and matches based on @@ -501,9 +534,13 @@ func toConf(d uint8) Confidence { // 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 { +func newMatcher(supported []Tag, options []MatchOption) *matcher { m := &matcher{ - index: make(map[langID]*matchHeader), + index: make(map[langID]*matchHeader), + preferSameScript: true, + } + for _, o := range options { + o(m) } if len(supported) == 0 { m.default_ = &haveTag{} @@ -514,6 +551,7 @@ func newMatcher(supported []Tag) *matcher { for i, tag := range supported { pair, _ := makeHaveTag(tag, i) m.header(tag.lang).addIfNew(pair, true) + m.supported = append(m.supported, &pair) } m.default_ = m.header(supported[0].lang).exact[0] for i, tag := range supported { @@ -523,6 +561,9 @@ func newMatcher(supported []Tag) *matcher { } } + // TODO: include alt script. + // - don't replace regions, but allow regions to be made more specific. + // 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. @@ -648,11 +689,12 @@ type bestMatch struct { 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. + origLang bool + origReg bool + regGroupDist uint8 + 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 @@ -706,6 +748,14 @@ func (m *bestMatch) update(have *haveTag, tag Tag, maxScript scriptID, maxRegion beaten = true } + regGroupDist := regionGroupDist(have.maxRegion, maxRegion, maxScript, tag.lang) + if !beaten && m.regGroupDist != regGroupDist { + if regGroupDist > m.regGroupDist { + 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 { @@ -715,8 +765,22 @@ func (m *bestMatch) update(have *haveTag, tag Tag, maxScript scriptID, maxRegion beaten = true } - // Next we prefer smaller distances between regions, as defined by regionDist. - regDist := regionDist(have.maxRegion, maxRegion, tag.lang) + // TODO: remove the region distance rule. Region distance has been replaced + // by the region grouping rule. For now we leave it as it still seems to + // have a net positive effect when applied after the grouping rule. + // Possible solutions: + // - apply the primary locale rule first to effectively disable region + // region distance if groups are defined. + // - express the following errors in terms of grouping (if possible) + // - find another method of handling the following cases. + // maximization of legacy: find mo in + // "sr-Cyrl, sr-Latn, ro, ro-MD": have ro; want ro-MD (High) + // region distance French: find fr-US in + // "en, fr, fr-CA, fr-CH": have fr; want fr-CA (High) + + // Next we prefer smaller distances between regions, as defined by + // regionDist. + regDist := uint8(regionDistance(have.maxRegion, maxRegion)) if !beaten && m.regDist != regDist { if regDist > m.regDist { return @@ -734,6 +798,9 @@ func (m *bestMatch) update(have *haveTag, tag Tag, maxScript scriptID, maxRegion } // Finally we prefer tags which have a closer parent relationship. + // TODO: the parent relationship no longer seems necessary. It doesn't hurt + // to leave it in as the final tie-breaker, though, especially until the + // grouping data has further matured. parentDist := parentDistance(have.tag.region, tag) if !beaten && m.parentDist != parentDist { if parentDist > m.parentDist { @@ -750,6 +817,7 @@ func (m *bestMatch) update(have *haveTag, tag Tag, maxScript scriptID, maxRegion m.origLang = origLang m.origReg = origReg m.origScript = origScript + m.regGroupDist = regGroupDist m.regDist = regDist m.parentDist = parentDist } @@ -772,15 +840,27 @@ func parentDistance(haveRegion regionID, tag Tag) uint8 { 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 +// regionGroupDist computes the distance between two regions based on their +// CLDR grouping. +func regionGroupDist(a, b regionID, script scriptID, lang langID) uint8 { + aGroup := uint(regionToGroups[a]) << 1 + bGroup := uint(regionToGroups[b]) << 1 + for _, ri := range matchRegion { + if langID(ri.lang) == lang && (ri.script == 0 || scriptID(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 + } + } else { + if (aGroup|bGroup)&group == 0 { // Both regions are not in the group. + return ri.distance + } + } } } - return uint8(regionDistance(a, b)) + const defaultDistance = 4 + return defaultDistance } // regionDistance computes the distance between two regions based on the |