New: i18n pluralization and variables support and more...

fixes: #1649, #1648, #1641, #1650

relative to: #1597

_examples/i18n/template/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"strings"
+	"text/template"
+
+	"github.com/kataras/iris/v12"
+
+	// go get -u golang.org/x/text/message
+
+	"golang.org/x/text/feature/plural"
+	"golang.org/x/text/language"
+	"golang.org/x/text/message"
+)
+
+/*
+ Iris I18n supports text/template inside the translation values.
+ Follow this example to learn how to use that feature.
+
+ This is just an example on how to use template functions.
+ See the "plurals" example for a more comprehensive pluralization support instead.
+*/
+
+func main() {
+	app := newApp()
+	app.Listen(":8080")
+}
+
+func newApp() *iris.Application {
+	app := iris.New()
+
+	// set the printers after load, so they can be done by loop of available languages.
+	printers := make(map[string]*message.Printer)
+
+	message.Set(language.Greek, "Hello %d dog",
+		plural.Selectf(1, "%d",
+			"one", "Γεια σου σκυλί",
+			"other", "Γεια σας %[1]d σκυλιά",
+		))
+
+	/* by variable, single word:
+	message.Set(language.Greek, "Hi %d dog(s)",
+		catalog.Var("dogs", plural.Selectf(1, "%d", "one", "σκυλί", "other", "σκυλιά")),
+		catalog.String("Γεια %[1]d ${dogs}"))
+	*/
+
+	// Set custom functions per locale!
+	app.I18n.Loader.Funcs = func(current iris.Locale) template.FuncMap {
+		return template.FuncMap{
+			"plural": func(word string, count int) string {
+				// Your own implementation or use a 3rd-party package
+				// like we do here.
+				return printers[current.Language()].Sprintf(word, count)
+			},
+			"uppercase": func(word string) string {
+				return strings.ToUpper(word)
+			},
+			"concat": func(words ...string) string {
+				return strings.Join(words, " ")
+			},
+		}
+	}
+
+	err := app.I18n.Load("./locales/*/*", "en-US", "el-GR")
+	if err != nil {
+		panic(err)
+	}
+
+	for _, tag := range app.I18n.Tags() {
+		printers[tag.String()] = message.NewPrinter(tag)
+	}
+
+	message.NewPrinter(language.Greek).Printf("Hello %d dog", 2)
+
+	app.Get("/", func(ctx iris.Context) {
+		text := ctx.Tr("HiDogs", iris.Map{
+			"count": 2,
+		}) // en-US: prints "Hi 2 dogs".
+		ctx.WriteString(text)
+	})
+
+	app.Get("/singular", func(ctx iris.Context) {
+		text := ctx.Tr("HiDogs", iris.Map{
+			"count": 1,
+		}) // en-US: prints "Hi 1 dog".
+		ctx.WriteString(text)
+	})
+
+	app.Get("/members", func(ctx iris.Context) {
+		text := ctx.Tr("forms.registered_members", iris.Map{
+			"count": 42,
+		}) // en-US: prints "There are 42 members registered".
+		ctx.WriteString(text)
+	})
+
+	// showcases the other.ini translation file.
+	app.Get("/other", func(ctx iris.Context) {
+		ctx.Writef(`AccessLogClear: %s
+Title: %s`, ctx.Tr("debug.AccessLogClear"), ctx.Tr("user.connections.Title"))
+	})
+
+	return app
+}