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// Copyright 2014 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 display
// This file contains common lookup code that is shared between the various
// implementations of Namer and Dictionaries.
import (
"fmt"
"sort"
"strings"
"golang.org/x/text/language"
)
type namer interface {
// name gets the string for the given index. It should walk the
// inheritance chain if a value is not present in the base index.
name(idx int) string
}
func nameLanguage(n namer, x interface{}) string {
t, _ := language.All.Compose(x)
for {
i, _, _ := langTagSet.index(t.Raw())
if s := n.name(i); s != "" {
return s
}
if t = t.Parent(); t == language.Und {
return ""
}
}
}
func nameScript(n namer, x interface{}) string {
t, _ := language.DeprecatedScript.Compose(x)
_, s, _ := t.Raw()
return n.name(scriptIndex.index(s.String()))
}
func nameRegion(n namer, x interface{}) string {
t, _ := language.DeprecatedRegion.Compose(x)
_, _, r := t.Raw()
return n.name(regionIndex.index(r.String()))
}
func nameTag(langN, scrN, regN namer, x interface{}) string {
t, ok := x.(language.Tag)
if !ok {
return ""
}
const form = language.All &^ language.SuppressScript
if c, err := form.Canonicalize(t); err == nil {
t = c
}
_, sRaw, rRaw := t.Raw()
i, scr, reg := langTagSet.index(t.Raw())
for i != -1 {
if str := langN.name(i); str != "" {
if hasS, hasR := (scr != language.Script{}), (reg != language.Region{}); hasS || hasR {
ss, sr := "", ""
if hasS {
ss = scrN.name(scriptIndex.index(scr.String()))
}
if hasR {
sr = regN.name(regionIndex.index(reg.String()))
}
// TODO: use patterns in CLDR or at least confirm they are the
// same for all languages.
if ss != "" && sr != "" {
return fmt.Sprintf("%s (%s, %s)", str, ss, sr)
}
if ss != "" || sr != "" {
return fmt.Sprintf("%s (%s%s)", str, ss, sr)
}
}
return str
}
scr, reg = sRaw, rRaw
if t = t.Parent(); t == language.Und {
return ""
}
i, _, _ = langTagSet.index(t.Raw())
}
return ""
}
// header contains the data and indexes for a single namer.
// data contains a series of strings concatenated into one. index contains the
// offsets for a string in data. For example, consider a header that defines
// strings for the languages de, el, en, fi, and nl:
//
// header{
// data: "GermanGreekEnglishDutch",
// index: []uint16{ 0, 6, 11, 18, 18, 23 },
// }
//
// For a language with index i, the string is defined by
// data[index[i]:index[i+1]]. So the number of elements in index is always one
// greater than the number of languages for which header defines a value.
// A string for a language may be empty, which means the name is undefined. In
// the above example, the name for fi (Finnish) is undefined.
type header struct {
data string
index []uint16
}
// name looks up the name for a tag in the dictionary, given its index.
func (h *header) name(i int) string {
if 0 <= i && i < len(h.index)-1 {
return h.data[h.index[i]:h.index[i+1]]
}
return ""
}
// tagSet is used to find the index of a language in a set of tags.
type tagSet struct {
single tagIndex
long []string
}
var (
langTagSet = tagSet{
single: langIndex,
long: langTagsLong,
}
// selfTagSet is used for indexing the language strings in their own
// language.
selfTagSet = tagSet{
single: selfIndex,
long: selfTagsLong,
}
zzzz = language.MustParseScript("Zzzz")
zz = language.MustParseRegion("ZZ")
)
// index returns the index of the tag for the given base, script and region or
// its parent if the tag is not available. If the match is for a parent entry,
// the excess script and region are returned.
func (ts *tagSet) index(base language.Base, scr language.Script, reg language.Region) (int, language.Script, language.Region) {
lang := base.String()
index := -1
if (scr != language.Script{} || reg != language.Region{}) {
if scr == zzzz {
scr = language.Script{}
}
if reg == zz {
reg = language.Region{}
}
i := sort.SearchStrings(ts.long, lang)
// All entries have either a script or a region and not both.
scrStr, regStr := scr.String(), reg.String()
for ; i < len(ts.long) && strings.HasPrefix(ts.long[i], lang); i++ {
if s := ts.long[i][len(lang)+1:]; s == scrStr {
scr = language.Script{}
index = i + ts.single.len()
break
} else if s == regStr {
reg = language.Region{}
index = i + ts.single.len()
break
}
}
}
if index == -1 {
index = ts.single.index(lang)
}
return index, scr, reg
}
func (ts *tagSet) Tags() []language.Tag {
tags := make([]language.Tag, 0, ts.single.len()+len(ts.long))
ts.single.keys(func(s string) {
tags = append(tags, language.Raw.MustParse(s))
})
for _, s := range ts.long {
tags = append(tags, language.Raw.MustParse(s))
}
return tags
}
func supportedScripts() []language.Script {
scr := make([]language.Script, 0, scriptIndex.len())
scriptIndex.keys(func(s string) {
scr = append(scr, language.MustParseScript(s))
})
return scr
}
func supportedRegions() []language.Region {
reg := make([]language.Region, 0, regionIndex.len())
regionIndex.keys(func(s string) {
reg = append(reg, language.MustParseRegion(s))
})
return reg
}
// tagIndex holds a concatenated lists of subtags of length 2 to 4, one string
// for each length, which can be used in combination with binary search to get
// the index associated with a tag.
// For example, a tagIndex{
// "arenesfrruzh", // 6 2-byte tags.
// "barwae", // 2 3-byte tags.
// "",
// }
// would mean that the 2-byte tag "fr" had an index of 3, and the 3-byte tag
// "wae" had an index of 7.
type tagIndex [3]string
func (t *tagIndex) index(s string) int {
sz := len(s)
if sz < 2 || 4 < sz {
return -1
}
a := t[sz-2]
index := sort.Search(len(a)/sz, func(i int) bool {
p := i * sz
return a[p:p+sz] >= s
})
p := index * sz
if end := p + sz; end > len(a) || a[p:end] != s {
return -1
}
// Add the number of tags for smaller sizes.
for i := 0; i < sz-2; i++ {
index += len(t[i]) / (i + 2)
}
return index
}
// len returns the number of tags that are contained in the tagIndex.
func (t *tagIndex) len() (n int) {
for i, s := range t {
n += len(s) / (i + 2)
}
return n
}
// keys calls f for each tag.
func (t *tagIndex) keys(f func(key string)) {
for i, s := range *t {
for ; s != ""; s = s[i+2:] {
f(s[:i+2])
}
}
}