compact.go

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package compact defines a compact representation of language tags.
     6  //
     7  // Common language tags (at least all for which locale information is defined
     8  // in CLDR) are assigned a unique index. Each Tag is associated with such an
     9  // ID for selecting language-related resources (such as translations) as well
    10  // as one for selecting regional defaults (currency, number formatting, etc.)
    11  //
    12  // It may want to export this functionality at some point, but at this point
    13  // this is only available for use within x/text.
    14  package compact // import "golang.org/x/text/internal/language/compact"
    15  
    16  import (
    17  	"sort"
    18  	"strings"
    19  
    20  	"golang.org/x/text/internal/language"
    21  )
    22  
    23  // ID is an integer identifying a single tag.
    24  type ID uint16
    25  
    26  func getCoreIndex(t language.Tag) (id ID, ok bool) {
    27  	cci, ok := language.GetCompactCore(t)
    28  	if !ok {
    29  		return 0, false
    30  	}
    31  	i := sort.Search(len(coreTags), func(i int) bool {
    32  		return cci <= coreTags[i]
    33  	})
    34  	if i == len(coreTags) || coreTags[i] != cci {
    35  		return 0, false
    36  	}
    37  	return ID(i), true
    38  }
    39  
    40  // Parent returns the ID of the parent or the root ID if id is already the root.
    41  func (id ID) Parent() ID {
    42  	return parents[id]
    43  }
    44  
    45  // Tag converts id to an internal language Tag.
    46  func (id ID) Tag() language.Tag {
    47  	if int(id) >= len(coreTags) {
    48  		return specialTags[int(id)-len(coreTags)]
    49  	}
    50  	return coreTags[id].Tag()
    51  }
    52  
    53  var specialTags []language.Tag
    54  
    55  func init() {
    56  	tags := strings.Split(specialTagsStr, " ")
    57  	specialTags = make([]language.Tag, len(tags))
    58  	for i, t := range tags {
    59  		specialTags[i] = language.MustParse(t)
    60  	}
    61  }
    62
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