Package ring implements operations on circular lists.
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.
type Ring struct {
Value interface{} // for use by client; untouched by this library
// contains filtered or unexported fields
}
func New(n int) *Ring
New creates a ring of n elements.
func (r *Ring) Do(f func(interface{})) Do calls function f on each element of the ring, in forward order. The behavior of Do is undefined if f changes *r.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 5
r := ring.New(5)
// Get the length of the ring
n := r.Len()
// Initialize the ring with some integer values
for i := 0; i < n; i++ {
r.Value = i
r = r.Next()
}
// Iterate through the ring and print its contents
r.Do(func(p interface{}) {
fmt.Println(p.(int))
})
}
func (r *Ring) Len() int
Len computes the number of elements in ring r. It executes in time proportional to the number of elements.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 4
r := ring.New(4)
// Print out its length
fmt.Println(r.Len())
}
func (r *Ring) Link(s *Ring) *Ring
Link connects ring r with ring s such that r.Next() becomes s and returns the original value for r.Next(). r must not be empty.
If r and s point to the same ring, linking them removes the elements between r and s from the ring. The removed elements form a subring and the result is a reference to that subring (if no elements were removed, the result is still the original value for r.Next(), and not nil).
If r and s point to different rings, linking them creates a single ring with the elements of s inserted after r. The result points to the element following the last element of s after insertion.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create two rings, r and s, of size 2
r := ring.New(2)
s := ring.New(2)
// Get the length of the ring
lr := r.Len()
ls := s.Len()
// Initialize r with 0s
for i := 0; i < lr; i++ {
r.Value = 0
r = r.Next()
}
// Initialize s with 1s
for j := 0; j < ls; j++ {
s.Value = 1
s = s.Next()
}
// Link ring r and ring s
rs := r.Link(s)
// Iterate through the combined ring and print its contents
rs.Do(func(p interface{}) {
fmt.Println(p.(int))
})
}
func (r *Ring) Move(n int) *Ring
Move moves n % r.Len() elements backward (n < 0) or forward (n >= 0) in the ring and returns that ring element. r must not be empty.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 5
r := ring.New(5)
// Get the length of the ring
n := r.Len()
// Initialize the ring with some integer values
for i := 0; i < n; i++ {
r.Value = i
r = r.Next()
}
// Move the pointer forward by three steps
r = r.Move(3)
// Iterate through the ring and print its contents
r.Do(func(p interface{}) {
fmt.Println(p.(int))
})
}
func (r *Ring) Next() *Ring
Next returns the next ring element. r must not be empty.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 5
r := ring.New(5)
// Get the length of the ring
n := r.Len()
// Initialize the ring with some integer values
for i := 0; i < n; i++ {
r.Value = i
r = r.Next()
}
// Iterate through the ring and print its contents
for j := 0; j < n; j++ {
fmt.Println(r.Value)
r = r.Next()
}
}
func (r *Ring) Prev() *Ring
Prev returns the previous ring element. r must not be empty.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 5
r := ring.New(5)
// Get the length of the ring
n := r.Len()
// Initialize the ring with some integer values
for i := 0; i < n; i++ {
r.Value = i
r = r.Next()
}
// Iterate through the ring backwards and print its contents
for j := 0; j < n; j++ {
r = r.Prev()
fmt.Println(r.Value)
}
}
func (r *Ring) Unlink(n int) *Ring
Unlink removes n % r.Len() elements from the ring r, starting at r.Next(). If n % r.Len() == 0, r remains unchanged. The result is the removed subring. r must not be empty.
package main
import (
"container/ring"
"fmt"
)
func main() {
// Create a new ring of size 6
r := ring.New(6)
// Get the length of the ring
n := r.Len()
// Initialize the ring with some integer values
for i := 0; i < n; i++ {
r.Value = i
r = r.Next()
}
// Unlink three elements from r, starting from r.Next()
r.Unlink(3)
// Iterate through the remaining ring and print its contents
r.Do(func(p interface{}) {
fmt.Println(p.(int))
})
}
© Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
https://golang.org/pkg/container/ring/