344 lines
10 KiB
Go
344 lines
10 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:generate go run maketables.go -output tables.go
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// Package display provides display names for languages, scripts and regions in
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// a requested language.
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//
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// The data is based on CLDR's localeDisplayNames. It includes the names of the
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// draft level "contributed" or "approved". The resulting tables are quite
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// large. The display package is designed so that users can reduce the linked-in
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// table sizes by cherry picking the languages one wishes to support. There is a
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// Dictionary defined for a selected set of common languages for this purpose.
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package display // import "golang.org/x/text/language/display"
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import (
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"strings"
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"golang.org/x/text/language"
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)
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/*
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TODO:
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All fairly low priority at the moment:
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- Include alternative and variants as an option (using func options).
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- Option for returning the empty string for undefined values.
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- Support variants, currencies, time zones, option names and other data
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provided in CLDR.
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- Do various optimizations:
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- Reduce size of offset tables.
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- Consider compressing infrequently used languages and decompress on demand.
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*/
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// A Namer is used to get the name for a given value, such as a Tag, Language,
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// Script or Region.
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type Namer interface {
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// Name returns a display string for the given value. A Namer returns an
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// empty string for values it does not support. A Namer may support naming
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// an unspecified value. For example, when getting the name for a region for
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// a tag that does not have a defined Region, it may return the name for an
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// unknown region. It is up to the user to filter calls to Name for values
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// for which one does not want to have a name string.
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Name(x interface{}) string
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}
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var (
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// Supported lists the languages for which names are defined.
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Supported language.Coverage
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// The set of all possible values for which names are defined. Note that not
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// all Namer implementations will cover all the values of a given type.
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// A Namer will return the empty string for unsupported values.
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Values language.Coverage
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matcher language.Matcher
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)
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func init() {
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tags := make([]language.Tag, numSupported)
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s := supported
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for i := range tags {
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p := strings.IndexByte(s, '|')
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tags[i] = language.Raw.Make(s[:p])
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s = s[p+1:]
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}
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matcher = language.NewMatcher(tags)
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Supported = language.NewCoverage(tags)
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Values = language.NewCoverage(langTagSet.Tags, supportedScripts, supportedRegions)
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}
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// Languages returns a Namer for naming languages. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either language.Base
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// or language.Tag. Note that the result may differ between passing a tag or its
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// base language. For example, for English, passing "nl-BE" would return Flemish
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// whereas passing "nl" returns "Dutch".
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func Languages(t language.Tag) Namer {
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if _, index, conf := matcher.Match(t); conf != language.No {
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return languageNamer(index)
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}
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return nil
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}
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type languageNamer int
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func (n languageNamer) name(i int) string {
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return lookup(langHeaders[:], int(n), i)
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}
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// Name implements the Namer interface for language names.
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func (n languageNamer) Name(x interface{}) string {
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return nameLanguage(n, x)
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}
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// nonEmptyIndex walks up the parent chain until a non-empty header is found.
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// It returns -1 if no index could be found.
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func nonEmptyIndex(h []header, index int) int {
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for ; index != -1 && h[index].data == ""; index = int(parents[index]) {
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}
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return index
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}
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// Scripts returns a Namer for naming scripts. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either a
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// language.Script or a language.Tag. It will not attempt to infer a script for
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// tags with an unspecified script.
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func Scripts(t language.Tag) Namer {
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if _, index, conf := matcher.Match(t); conf != language.No {
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if index = nonEmptyIndex(scriptHeaders[:], index); index != -1 {
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return scriptNamer(index)
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}
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}
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return nil
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}
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type scriptNamer int
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func (n scriptNamer) name(i int) string {
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return lookup(scriptHeaders[:], int(n), i)
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}
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// Name implements the Namer interface for script names.
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func (n scriptNamer) Name(x interface{}) string {
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return nameScript(n, x)
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}
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// Regions returns a Namer for naming regions. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either a
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// language.Region or a language.Tag. It will not attempt to infer a region for
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// tags with an unspecified region.
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func Regions(t language.Tag) Namer {
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if _, index, conf := matcher.Match(t); conf != language.No {
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if index = nonEmptyIndex(regionHeaders[:], index); index != -1 {
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return regionNamer(index)
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}
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}
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return nil
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}
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type regionNamer int
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func (n regionNamer) name(i int) string {
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return lookup(regionHeaders[:], int(n), i)
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}
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// Name implements the Namer interface for region names.
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func (n regionNamer) Name(x interface{}) string {
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return nameRegion(n, x)
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}
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// Tags returns a Namer for giving a full description of a tag. The names of
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// scripts and regions that are not already implied by the language name will
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// in appended within parentheses. It returns nil if there is not data for the
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// given tag. The type passed to Name must be a tag.
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func Tags(t language.Tag) Namer {
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if _, index, conf := matcher.Match(t); conf != language.No {
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return tagNamer(index)
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}
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return nil
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}
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type tagNamer int
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// Name implements the Namer interface for tag names.
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func (n tagNamer) Name(x interface{}) string {
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return nameTag(languageNamer(n), scriptNamer(n), regionNamer(n), x)
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}
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// lookup finds the name for an entry in a global table, traversing the
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// inheritance hierarchy if needed.
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func lookup(table []header, dict, want int) string {
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for dict != -1 {
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if s := table[dict].name(want); s != "" {
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return s
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}
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dict = int(parents[dict])
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}
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return ""
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}
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// A Dictionary holds a collection of Namers for a single language. One can
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// reduce the amount of data linked in to a binary by only referencing
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// Dictionaries for the languages one needs to support instead of using the
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// generic Namer factories.
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type Dictionary struct {
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parent *Dictionary
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lang header
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script header
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region header
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}
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// Tags returns a Namer for giving a full description of a tag. The names of
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// scripts and regions that are not already implied by the language name will
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// in appended within parentheses. It returns nil if there is not data for the
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// given tag. The type passed to Name must be a tag.
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func (d *Dictionary) Tags() Namer {
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return dictTags{d}
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}
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type dictTags struct {
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d *Dictionary
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}
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// Name implements the Namer interface for tag names.
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func (n dictTags) Name(x interface{}) string {
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return nameTag(dictLanguages{n.d}, dictScripts{n.d}, dictRegions{n.d}, x)
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}
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// Languages returns a Namer for naming languages. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either language.Base
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// or language.Tag. Note that the result may differ between passing a tag or its
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// base language. For example, for English, passing "nl-BE" would return Flemish
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// whereas passing "nl" returns "Dutch".
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func (d *Dictionary) Languages() Namer {
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return dictLanguages{d}
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}
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type dictLanguages struct {
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d *Dictionary
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}
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func (n dictLanguages) name(i int) string {
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for d := n.d; d != nil; d = d.parent {
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if s := d.lang.name(i); s != "" {
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return s
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}
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}
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return ""
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}
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// Name implements the Namer interface for language names.
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func (n dictLanguages) Name(x interface{}) string {
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return nameLanguage(n, x)
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}
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// Scripts returns a Namer for naming scripts. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either a
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// language.Script or a language.Tag. It will not attempt to infer a script for
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// tags with an unspecified script.
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func (d *Dictionary) Scripts() Namer {
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return dictScripts{d}
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}
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type dictScripts struct {
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d *Dictionary
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}
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func (n dictScripts) name(i int) string {
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for d := n.d; d != nil; d = d.parent {
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if s := d.script.name(i); s != "" {
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return s
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}
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}
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return ""
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}
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// Name implements the Namer interface for script names.
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func (n dictScripts) Name(x interface{}) string {
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return nameScript(n, x)
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}
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// Regions returns a Namer for naming regions. It returns nil if there is no
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// data for the given tag. The type passed to Name must be either a
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// language.Region or a language.Tag. It will not attempt to infer a region for
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// tags with an unspecified region.
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func (d *Dictionary) Regions() Namer {
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return dictRegions{d}
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}
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type dictRegions struct {
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d *Dictionary
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}
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func (n dictRegions) name(i int) string {
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for d := n.d; d != nil; d = d.parent {
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if s := d.region.name(i); s != "" {
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return s
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}
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}
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return ""
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}
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// Name implements the Namer interface for region names.
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func (n dictRegions) Name(x interface{}) string {
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return nameRegion(n, x)
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}
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// A SelfNamer implements a Namer that returns the name of language in this same
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// language. It provides a very compact mechanism to provide a comprehensive
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// list of languages to users in their native language.
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type SelfNamer struct {
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// Supported defines the values supported by this Namer.
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Supported language.Coverage
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}
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var (
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// Self is a shared instance of a SelfNamer.
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Self *SelfNamer = &self
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self = SelfNamer{language.NewCoverage(selfTagSet.Tags)}
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)
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// Name returns the name of a given language tag in the language identified by
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// this tag. It supports both the language.Base and language.Tag types.
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func (n SelfNamer) Name(x interface{}) string {
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t, _ := language.All.Compose(x)
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base, scr, reg := t.Raw()
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baseScript := language.Script{}
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if (scr == language.Script{} && reg != language.Region{}) {
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// For looking up in the self dictionary, we need to select the
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// maximized script. This is even the case if the script isn't
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// specified.
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s1, _ := t.Script()
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if baseScript = getScript(base); baseScript != s1 {
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scr = s1
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}
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}
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i, scr, reg := selfTagSet.index(base, scr, reg)
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if i == -1 {
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return ""
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}
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// Only return the display name if the script matches the expected script.
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if (scr != language.Script{}) {
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if (baseScript == language.Script{}) {
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baseScript = getScript(base)
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}
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if baseScript != scr {
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return ""
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}
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}
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return selfHeaders[0].name(i)
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}
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// getScript returns the maximized script for a base language.
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func getScript(b language.Base) language.Script {
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tag, _ := language.Raw.Compose(b)
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scr, _ := tag.Script()
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return scr
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}
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