forked from TrueCloudLab/lego
105 lines
3.4 KiB
Go
105 lines
3.4 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package colltab contains functionality related to collation tables.
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// It is only to be used by the collate and search packages.
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package colltab // import "golang.org/x/text/internal/colltab"
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import (
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"sort"
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"golang.org/x/text/language"
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)
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// MatchLang finds the index of t in tags, using a matching algorithm used for
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// collation and search. tags[0] must be language.Und, the remaining tags should
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// be sorted alphabetically.
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//
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// Language matching for collation and search is different from the matching
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// defined by language.Matcher: the (inferred) base language must be an exact
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// match for the relevant fields. For example, "gsw" should not match "de".
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// Also the parent relation is different, as a parent may have a different
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// script. So usually the parent of zh-Hant is und, whereas for MatchLang it is
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// zh.
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func MatchLang(t language.Tag, tags []language.Tag) int {
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// Canonicalize the values, including collapsing macro languages.
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t, _ = language.All.Canonicalize(t)
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base, conf := t.Base()
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// Estimate the base language, but only use high-confidence values.
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if conf < language.High {
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// The root locale supports "search" and "standard". We assume that any
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// implementation will only use one of both.
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return 0
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}
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// Maximize base and script and normalize the tag.
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if _, s, r := t.Raw(); (r != language.Region{}) {
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p, _ := language.Raw.Compose(base, s, r)
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// Taking the parent forces the script to be maximized.
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p = p.Parent()
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// Add back region and extensions.
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t, _ = language.Raw.Compose(p, r, t.Extensions())
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} else {
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// Set the maximized base language.
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t, _ = language.Raw.Compose(base, s, t.Extensions())
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}
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// Find start index of the language tag.
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start := 1 + sort.Search(len(tags)-1, func(i int) bool {
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b, _, _ := tags[i+1].Raw()
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return base.String() <= b.String()
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})
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if start < len(tags) {
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if b, _, _ := tags[start].Raw(); b != base {
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return 0
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}
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}
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// Besides the base language, script and region, only the collation type and
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// the custom variant defined in the 'u' extension are used to distinguish a
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// locale.
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// Strip all variants and extensions and add back the custom variant.
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tdef, _ := language.Raw.Compose(t.Raw())
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tdef, _ = tdef.SetTypeForKey("va", t.TypeForKey("va"))
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// First search for a specialized collation type, if present.
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try := []language.Tag{tdef}
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if co := t.TypeForKey("co"); co != "" {
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tco, _ := tdef.SetTypeForKey("co", co)
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try = []language.Tag{tco, tdef}
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}
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for _, tx := range try {
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for ; tx != language.Und; tx = parent(tx) {
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for i, t := range tags[start:] {
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if b, _, _ := t.Raw(); b != base {
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break
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}
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if tx == t {
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return start + i
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}
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}
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}
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}
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return 0
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}
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// parent computes the structural parent. This means inheritance may change
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// script. So, unlike the CLDR parent, parent(zh-Hant) == zh.
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func parent(t language.Tag) language.Tag {
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if t.TypeForKey("va") != "" {
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t, _ = t.SetTypeForKey("va", "")
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return t
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}
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result := language.Und
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if b, s, r := t.Raw(); (r != language.Region{}) {
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result, _ = language.Raw.Compose(b, s, t.Extensions())
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} else if (s != language.Script{}) {
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result, _ = language.Raw.Compose(b, t.Extensions())
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} else if (b != language.Base{}) {
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result, _ = language.Raw.Compose(t.Extensions())
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}
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return result
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}
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