Update jet parser to v4.0.0 as requested at: #1551

Former-commit-id: 1ad89532d11716af7a49fe9aafca59e943d98ebe

_examples/view/template_jet_0/main.go

@@ -49,6 +49,9 @@ func (dt *doneTODOs) Range() (reflect.Value, reflect.Value, bool) {
 	return reflect.Value{}, reflect.Value{}, true
 }
 
+// Note: jet version 4 requires this.
+func (dt *doneTODOs) ProvidesIndex() bool { return true }
+
 func (dt *doneTODOs) Render(r *view.JetRuntime) {
 	r.Write([]byte(fmt.Sprintf("custom renderer")))
 }
@@ -73,11 +76,6 @@ func main() {
 	// from middlewares as well, by:
 	// view.AddJetRuntimeVars(ctx, vars)
 	// or tmpl.AddRuntimeVars(ctx, vars)
-	//
-	// The Iris Jet fixes the issue when custom jet.Ranger and custom jet.Renderer are not actually work at all,
-	// hope that this is a temp issue on the jet parser itself and authors will fix it soon
-	// so we can remove the "hacks" we've putted for those to work as expected.
-
 	app := iris.New()
 	tmpl := iris.Jet("./views", ".jet") // <--
 	tmpl.Reload(true)                   // remove in production.

_examples/view/template_jet_0/views/todos/index.jet

@@ -1,4 +1,4 @@
-{{extends "layouts/application.jet"}}
+{{extends "../layouts/application.jet"}}
 
 {{block button(label, href="javascript:void(0)")}}
   <a href="{{ href }}">{{ label }}</a>

_examples/view/template_jet_0/views/todos/show.jet

@@ -1,8 +1,8 @@
-{{extends "layouts/application.jet"}}
+{{extends "../layouts/application.jet"}}
 
 {{block documentBody()}}
   <h1>Show TODO</h1>
-  <p>This uses a custom renderer by implementing the jet.Renderer (or view.JetRenderer) interface.
+  <p>This uses a custom renderer by implementing the Renderer interface.
   <p>
     {{.}}
   </p>