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// Copyright 2015 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 internal
// This file contains matchers that implement CLDR inheritance.
//
// See http://unicode.org/reports/tr35/#Locale_Inheritance.
//
// Some of the inheritance described in this document is already handled by
// the cldr package.
import (
"golang.org/x/text/language"
)
// TODO: consider if (some of the) matching algorithm needs to be public after
// getting some feel about what is generic and what is specific.
// NewInheritanceMatcher returns a matcher that matches based on the inheritance
// chain.
//
// The matcher uses canonicalization and the parent relationship to find a
// match. The resulting match will always be either Und or a language with the
// same language and script as the requested language. It will not match
// languages for which there is understood to be mutual or one-directional
// intelligibility.
//
// A Match will indicate an Exact match if the language matches after
// canonicalization and High if the matched tag is a parent.
func NewInheritanceMatcher(t []language.Tag) *InheritanceMatcher {
tags := &InheritanceMatcher{make(map[language.Tag]int)}
for i, tag := range t {
ct, err := language.All.Canonicalize(tag)
if err != nil {
ct = tag
}
tags.index[ct] = i
}
return tags
}
type InheritanceMatcher struct {
index map[language.Tag]int
}
func (m InheritanceMatcher) Match(want ...language.Tag) (language.Tag, int, language.Confidence) {
for _, t := range want {
ct, err := language.All.Canonicalize(t)
if err != nil {
ct = t
}
conf := language.Exact
for {
if index, ok := m.index[ct]; ok {
return ct, index, conf
}
if ct == language.Und {
break
}
ct = ct.Parent()
conf = language.High
}
}
return language.Und, 0, language.No
}