iterator

Iterator

Iterator is a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc.).

Example

We will create a travel guide with entries on the routes. And we will get information about each route.

1. First, we will create our Iterator interface. This interface will check if the next element exists and receive the element.

   // route/route.go
   
   type Iterator interface {
     HasNext() bool
     GetNext() *Route
   }

2. Now we need our structure with information about a route.

   // route/route.go
   
   type Route struct {
     Name       string
     TravelTime int
   }

3. And now, we will use our interface to iterate to the routes.

   // route/route.go
   
   type Routes struct {
     Routes []Route
     index  int
   }
   
   func (r *Routes) HasNext() bool {
     return r.index < len(r.Routes)
   }
   
   func (r *Routes) GetNext() *Route {
     if r.HasNext() {
       val := &r.Routes[r.index]
       r.index++
   
       return val
     }
   
     return nil
   }