Container in Go: ring

Ring:

A Ring is an element of a circular list, or ring. Rings do not have a beginning or end; a pointer to any ring element serves as reference to the entire ring. Empty rings are represented as nil Ring pointers. The zero value for a Ring is a one-element ring with a nil Value.

package main

import (
  . "fmt";
  "container/ring";
  "strings";
  "bytes";
)

// print the elements of the ring 
func PrintRing(r *ring.Ring) {
  Println("------------------------------");
  for value := range r.Iter() {
    Println("value: ", value);
  }
  Println("------------------------------");
}

func main() {
  // create a new ring with 10 items
  r := ring.New(10);

  Println("len of ring: ", r.Len());
  PrintRing(r);

  // set some value
  r.Value = "value 1";
  // take the next
  
  r = r.Next();
  r.Value = "value 2";

  r = r.Next();
  r.Value = "value 3";

  r = r.Next();
  r.Value = "value 4";

  PrintRing(r);


  // create a second ring with 3 item and set his value
  r2 := ring.New(3);
  r2.Value = "r2 value 1";
  r2 = r2.Next();
  r2.Value = "r2 value 2";
  r2 = r2.Next();
  r2.Value = "r2 value 3";
  PrintRing(r2);

  // merge ring2 into ring 1
  r = r.Link(r2);
  PrintRing(r);

  // remove a value in ring
  for p:=r.Next(); p!=r; p=p.Next() {
    if p.Value != nil {
      value := p.Value.(string);
      if bytes.Equal(strings.Bytes(value),strings.Bytes("r2 value 2")) {
        p.Value=nil;
      }
    }
  }

  PrintRing(r);
}

output:

len of ring:  10
------------------------------
value:  
value:  
value:  
value:  
value:  
value:  
value:  
value:  
value:  
value:  
------------------------------
------------------------------
value:  value 4
value:  
value:  
value:  
value:  
value:  
value:  
value:  value 1
value:  value 2
value:  value 3
------------------------------
------------------------------
value:  r2 value 3
value:  r2 value 1
value:  r2 value 2
------------------------------
------------------------------
value:  
value:  
value:  
value:  
value:  
value:  
value:  value 1
value:  value 2
value:  value 3
value:  value 4
value:  r2 value 3
value:  r2 value 1
value:  r2 value 2
------------------------------
------------------------------
value:  
value:  
value:  
value:  
value:  
value:  
value:  value 1
value:  value 2
value:  value 3
value:  value 4
value:  r2 value 3
value:  r2 value 1
value:  
------------------------------