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100 lines
2.7 KiB
Go
100 lines
2.7 KiB
Go
// Package language defines languages that implement CLDR pluralization.
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package language
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import (
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"fmt"
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"strings"
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)
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// Language is a written human language.
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type Language struct {
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// Tag uniquely identifies the language as defined by RFC 5646.
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//
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// Most language tags are a two character language code (ISO 639-1)
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// optionally followed by a dash and a two character country code (ISO 3166-1).
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// (e.g. en, pt-br)
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Tag string
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*PluralSpec
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}
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func (l *Language) String() string {
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return l.Tag
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}
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// MatchingTags returns the set of language tags that map to this Language.
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// e.g. "zh-hans-cn" yields {"zh", "zh-hans", "zh-hans-cn"}
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// BUG: This should be computed once and stored as a field on Language for efficiency,
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// but this would require changing how Languages are constructed.
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func (l *Language) MatchingTags() []string {
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parts := strings.Split(l.Tag, "-")
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var prefix, matches []string
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for _, part := range parts {
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prefix = append(prefix, part)
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match := strings.Join(prefix, "-")
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matches = append(matches, match)
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}
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return matches
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}
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// Parse returns a slice of supported languages found in src or nil if none are found.
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// It can parse language tags and Accept-Language headers.
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func Parse(src string) []*Language {
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var langs []*Language
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start := 0
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for end, chr := range src {
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switch chr {
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case ',', ';', '.':
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tag := strings.TrimSpace(src[start:end])
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if spec := getPluralSpec(tag); spec != nil {
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langs = append(langs, &Language{NormalizeTag(tag), spec})
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}
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start = end + 1
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}
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}
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if start > 0 {
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tag := strings.TrimSpace(src[start:])
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if spec := getPluralSpec(tag); spec != nil {
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langs = append(langs, &Language{NormalizeTag(tag), spec})
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}
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return dedupe(langs)
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}
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if spec := getPluralSpec(src); spec != nil {
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langs = append(langs, &Language{NormalizeTag(src), spec})
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}
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return langs
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}
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func dedupe(langs []*Language) []*Language {
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found := make(map[string]struct{}, len(langs))
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deduped := make([]*Language, 0, len(langs))
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for _, lang := range langs {
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if _, ok := found[lang.Tag]; !ok {
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found[lang.Tag] = struct{}{}
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deduped = append(deduped, lang)
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}
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}
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return deduped
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}
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// MustParse is similar to Parse except it panics instead of retuning a nil Language.
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func MustParse(src string) []*Language {
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langs := Parse(src)
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if len(langs) == 0 {
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panic(fmt.Errorf("unable to parse language from %q", src))
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}
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return langs
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}
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// Add adds support for a new language.
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func Add(l *Language) {
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tag := NormalizeTag(l.Tag)
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pluralSpecs[tag] = l.PluralSpec
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}
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// NormalizeTag returns a language tag with all lower-case characters
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// and dashes "-" instead of underscores "_"
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func NormalizeTag(tag string) string {
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tag = strings.ToLower(tag)
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return strings.Replace(tag, "_", "-", -1)
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}
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