Use mattermost v5 module (#1192)

vendor/github.com/mattermost/go-i18n/i18n/language/language.go

@@ -0,0 +1,99 @@
+// Package language defines languages that implement CLDR pluralization.
+package language
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Language is a written human language.
+type Language struct {
+	// Tag uniquely identifies the language as defined by RFC 5646.
+	//
+	// Most language tags are a two character language code (ISO 639-1)
+	// optionally followed by a dash and a two character country code (ISO 3166-1).
+	// (e.g. en, pt-br)
+	Tag string
+	*PluralSpec
+}
+
+func (l *Language) String() string {
+	return l.Tag
+}
+
+// MatchingTags returns the set of language tags that map to this Language.
+// e.g. "zh-hans-cn" yields {"zh", "zh-hans", "zh-hans-cn"}
+// BUG: This should be computed once and stored as a field on Language for efficiency,
+//      but this would require changing how Languages are constructed.
+func (l *Language) MatchingTags() []string {
+	parts := strings.Split(l.Tag, "-")
+	var prefix, matches []string
+	for _, part := range parts {
+		prefix = append(prefix, part)
+		match := strings.Join(prefix, "-")
+		matches = append(matches, match)
+	}
+	return matches
+}
+
+// Parse returns a slice of supported languages found in src or nil if none are found.
+// It can parse language tags and Accept-Language headers.
+func Parse(src string) []*Language {
+	var langs []*Language
+	start := 0
+	for end, chr := range src {
+		switch chr {
+		case ',', ';', '.':
+			tag := strings.TrimSpace(src[start:end])
+			if spec := GetPluralSpec(tag); spec != nil {
+				langs = append(langs, &Language{NormalizeTag(tag), spec})
+			}
+			start = end + 1
+		}
+	}
+	if start > 0 {
+		tag := strings.TrimSpace(src[start:])
+		if spec := GetPluralSpec(tag); spec != nil {
+			langs = append(langs, &Language{NormalizeTag(tag), spec})
+		}
+		return dedupe(langs)
+	}
+	if spec := GetPluralSpec(src); spec != nil {
+		langs = append(langs, &Language{NormalizeTag(src), spec})
+	}
+	return langs
+}
+
+func dedupe(langs []*Language) []*Language {
+	found := make(map[string]struct{}, len(langs))
+	deduped := make([]*Language, 0, len(langs))
+	for _, lang := range langs {
+		if _, ok := found[lang.Tag]; !ok {
+			found[lang.Tag] = struct{}{}
+			deduped = append(deduped, lang)
+		}
+	}
+	return deduped
+}
+
+// MustParse is similar to Parse except it panics instead of retuning a nil Language.
+func MustParse(src string) []*Language {
+	langs := Parse(src)
+	if len(langs) == 0 {
+		panic(fmt.Errorf("unable to parse language from %q", src))
+	}
+	return langs
+}
+
+// Add adds support for a new language.
+func Add(l *Language) {
+	tag := NormalizeTag(l.Tag)
+	pluralSpecs[tag] = l.PluralSpec
+}
+
+// NormalizeTag returns a language tag with all lower-case characters
+// and dashes "-" instead of underscores "_"
+func NormalizeTag(tag string) string {
+	tag = strings.ToLower(tag)
+	return strings.Replace(tag, "_", "-", -1)
+}