vendor/golang.org/x/text/internal/language/lookup.go

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// 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 (
	"bytes"
	"fmt"
	"sort"
	"strconv"

	"golang.org/x/text/internal/tag"
)

// findIndex tries to find the given tag in idx and returns a standardized error
// if it could not be found.
func findIndex(idx tag.Index, key []byte, form string) (index int, err error) {
	if !tag.FixCase(form, key) {
		return 0, ErrSyntax
	}
	i := idx.Index(key)
	if i == -1 {
		return 0, NewValueError(key)
	}
	return i, nil
}

func searchUint(imap []uint16, key uint16) int {
	return sort.Search(len(imap), func(i int) bool {
		return imap[i] >= key
	})
}

type Language uint16

// getLangID returns the langID of s if s is a canonical subtag
// or langUnknown if s is not a canonical subtag.
func getLangID(s []byte) (Language, error) {
	if len(s) == 2 {
		return getLangISO2(s)
	}
	return getLangISO3(s)
}

// TODO language normalization as well as the AliasMaps could be moved to the
// higher level package, but it is a bit tricky to separate the generation.

func (id Language) Canonicalize() (Language, AliasType) {
	return normLang(id)
}

// mapLang returns the mapped langID of id according to mapping m.
func normLang(id Language) (Language, AliasType) {
	k := sort.Search(len(AliasMap), func(i int) bool {
		return AliasMap[i].From >= uint16(id)
	})
	if k < len(AliasMap) && AliasMap[k].From == uint16(id) {
		return Language(AliasMap[k].To), AliasTypes[k]
	}