New Function: LanguageNameByCode (#31)

* New Function: LanguageNameByCode

* Test added

humanize/example_test.go

@@ -322,3 +322,30 @@ func ExampleWithNow() {
 	// 1 周，1 日
 	// 1 Woche, 1 Tag
 }
+
+func ExampleHumanizer_LanguageNameByCode() {
+	collection := humanize.MustNew(humanize.WithLocale(es.New(), zhHans.New(), de.New()))
+	for _, tag := range []language.Tag{language.English, language.SimplifiedChinese, language.Spanish} {
+		h := collection.CreateHumanizer(tag)
+		fmt.Println("Current language: ", h.Language())
+
+		for _, code := range []string{"de", "en"} {
+			fmt.Printf("%s: %s\n", code, h.LanguageNameByCode(code))
+		}
+
+		fmt.Println(strings.Repeat(" -", 20))
+	}
+	// Output:
+	// Current language:  en
+	// de: German
+	// en: English
+	//  - - - - - - - - - - - - - - - - - - - -
+	// Current language:  zh-Hans
+	// de: 德语
+	// en: 英语
+	//  - - - - - - - - - - - - - - - - - - - -
+	// Current language:  es
+	// de: Alemán
+	// en: Inglés
+	//  - - - - - - - - - - - - - - - - - - - -
+}

humanize/helper.go

@@ -12,10 +12,28 @@ import (
 )
 
 // LanguageName returns the name of the spoken language as called by the languages used.
+//
+// If no translation exists for the name of the language, the input is returned.
 func (h *Humanizer) LanguageName(lang string) string {
 	return h.loc.Get(lang)
 }
 
+// LanguageNameByCode returns the name of a language for a language code
+// in the national language of the Humanizer.
+//
+// If no language is known for the code, an empty string is returned.
+// If a language is known, but no translations are available, the English name is returned.
+//
+// For example, if a Humanizer was created for French, 'Anglais' is returned for the code 'en'
+// and the value 'Allemand' for the code 'de'.
+func (h *Humanizer) LanguageNameByCode(code string) string {
+	info, ok := LocaleInfos[code]
+	if !ok {
+		return ""
+	}
+	return h.loc.Get(info.Name)
+}
+
 // Language returns the currently used language.
 func (h *Humanizer) Language() language.Tag {
 	return h.loc.Language()