--- /dev/null
+// 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])
+ }
+ }
+}
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