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

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

relative to: #1597

_examples/i18n/template/locales/el-GR/other.ini

@@ -0,0 +1,10 @@
+[nav]
+User = Λογαριασμός
+
+[debug]
+Title = Μενού προγραμματιστή
+AccessLog = Πρόσβαση στο αρχείο καταγραφής
+AccessLogClear = Καθαρισμός {{tr "debug.AccessLog"}}
+
+[user.connections]
+Title = {{tr "nav.User"}} Συνδέσεις

_examples/i18n/template/locales/el-GR/user.ini

@@ -0,0 +1,5 @@
+[forms]
+member = μέλος
+register = Γίνε {{tr "forms.member" }}
+registered = εγγεγραμμένοι
+registered_members = Υπάρχουν {{ concat (plural (tr "forms.member") .count) (tr "forms.registered") }}

_examples/i18n/template/locales/el-GR/welcome.yml

@@ -0,0 +1 @@
+HiDogs: Hi %d {{plural (tr "Dog") .count }}

_examples/i18n/template/locales/en-US/other.ini

@@ -0,0 +1,12 @@
+# just an example of some more nested keys,
+# see /other endpoint.
+[nav]
+User = Account
+
+[debug]
+Title = Developer Menu
+AccessLog = Access Log
+AccessLogClear = Clear {{tr "debug.AccessLog"}}
+
+[user.connections]
+Title = {{tr "nav.User"}} Connections

_examples/i18n/template/locales/en-US/user.ini

@@ -0,0 +1,5 @@
+[forms]
+member = member
+register = Become a {{tr "forms.member" }}
+registered = registered
+registered_members = There are {{ concat (plural (tr "forms.member") .count) (tr "forms.registered") }}

_examples/i18n/template/locales/en-US/welcome.yml

@@ -0,0 +1,2 @@
+Dog: "dog"
+HiDogs: Hi %d {{plural (tr "Dog") .count }}

_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
+}

_examples/i18n/template/main_test.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/kataras/iris/v12/httptest"
+)
+
+func TestI18nLoaderFuncMap(t *testing.T) {
+	app := newApp()
+
+	e := httptest.New(t, app)
+	e.GET("/").Expect().Status(httptest.StatusOK).
+		Body().Equal("Hi 2 dogs")
+	e.GET("/singular").Expect().Status(httptest.StatusOK).
+		Body().Equal("Hi 1 dog")
+	e.GET("/members").Expect().Status(httptest.StatusOK).
+		Body().Equal("There are 42 members registered")
+	e.GET("/").WithHeader("Accept-Language", "el").Expect().Status(httptest.StatusOK).
+		Body().Equal("Γειά 2 σκυλί")
+
+	e.GET("/other").Expect().Status(httptest.StatusOK).
+		Body().Equal("AccessLogClear: Clear Access Log\nTitle: Account Connections")
+	e.GET("/other").WithHeader("Accept-Language", "el").Expect().Status(httptest.StatusOK).
+		Body().Equal("AccessLogClear: Καθαρισμός Πρόσβαση στο αρχείο καταγραφής\nTitle: Λογαριασμός Συνδέσεις")
+}