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// Copyright 2017 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 cldrtree
import (
"golang.org/x/text/internal/language/compact"
"golang.org/x/text/language"
)
const (
inheritOffsetShift = 12
inheritMask uint16 = 0x8000
inheritValueMask uint16 = 0x0FFF
missingValue uint16 = 0xFFFF
)
// Tree holds a tree of CLDR data.
type Tree struct {
Locales []uint32
Indices []uint16
Buckets []string
}
// Lookup looks up CLDR data for the given path. The lookup adheres to the alias
// and locale inheritance rules as defined in CLDR.
//
// Each subsequent element in path indicates which subtree to select data from.
// The last element of the path must select a leaf node. All other elements
// of the path select a subindex.
func (t *Tree) Lookup(tag compact.ID, path ...uint16) string {
return t.lookup(tag, false, path...)
}
// LookupFeature is like Lookup, but will first check whether a value of "other"
// as a fallback before traversing the inheritance chain.
func (t *Tree) LookupFeature(tag compact.ID, path ...uint16) string {
return t.lookup(tag, true, path...)
}
func (t *Tree) lookup(tag compact.ID, isFeature bool, path ...uint16) string {
origLang := tag
outer:
for {
index := t.Indices[t.Locales[tag]:]
k := uint16(0)
for i := range path {
max := index[k]
if i < len(path)-1 {
// index (non-leaf)
if path[i] >= max {
break
}
k = index[k+1+path[i]]
if k == 0 {
break
}
if v := k &^ inheritMask; k != v {
offset := v >> inheritOffsetShift
value := v & inheritValueMask
path[uint16(i)-offset] = value
tag = origLang
continue outer
}
} else {
// leaf value
offset := missingValue
if path[i] < max {
offset = index[k+2+path[i]]
}
if offset == missingValue {
if !isFeature {
break
}
// "other" feature must exist
offset = index[k+2]
}
data := t.Buckets[index[k+1]]
n := uint16(data[offset])
return data[offset+1 : offset+n+1]
}
}
if tag == 0 {
break
}
tag = tag.Parent()
}
return ""
}
func build(b *Builder) (*Tree, error) {
var t Tree
t.Locales = make([]uint32, language.NumCompactTags)
for _, loc := range b.locales {
tag, _ := language.CompactIndex(loc.tag)
t.Locales[tag] = uint32(len(t.Indices))
var x indexBuilder
x.add(loc.root)
t.Indices = append(t.Indices, x.index...)
}
// Set locales for which we don't have data to the parent's data.
for i, v := range t.Locales {
p := compact.ID(i)
for v == 0 && p != 0 {
p = p.Parent()
v = t.Locales[p]
}
t.Locales[i] = v
}
for _, b := range b.buckets {
t.Buckets = append(t.Buckets, string(b))
}
if b.err != nil {
return nil, b.err
}
return &t, nil
}
type indexBuilder struct {
index []uint16
}
func (b *indexBuilder) add(i *Index) uint16 {
offset := len(b.index)
max := enumIndex(0)
switch {
case len(i.values) > 0:
for _, v := range i.values {
if v.key > max {
max = v.key
}
}
b.index = append(b.index, make([]uint16, max+3)...)
b.index[offset] = uint16(max) + 1
b.index[offset+1] = i.values[0].value.bucket
for i := offset + 2; i < len(b.index); i++ {
b.index[i] = missingValue
}
for _, v := range i.values {
b.index[offset+2+int(v.key)] = v.value.bucketPos
}
return uint16(offset)
case len(i.subIndex) > 0:
for _, s := range i.subIndex {
if s.meta.index > max {
max = s.meta.index
}
}
b.index = append(b.index, make([]uint16, max+2)...)
b.index[offset] = uint16(max) + 1
for _, s := range i.subIndex {
x := b.add(s)
b.index[offset+int(s.meta.index)+1] = x
}
return uint16(offset)
case i.meta.inheritOffset < 0:
v := uint16(-(i.meta.inheritOffset + 1)) << inheritOffsetShift
p := i.meta
for k := i.meta.inheritOffset; k < 0; k++ {
p = p.parent
}
v += uint16(p.typeInfo.enum.lookup(i.meta.inheritIndex))
v |= inheritMask
return v
}
return 0
}
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