Package 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.

type Ring struct {
		Value interface{} // for use by client; untouched by this library
		// contains filtered or unexported fields
}

func New ¶

func New(n int) *Ring

New creates a ring of n elements.

func (*Ring) Do ¶

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.

Example

Code:

// 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))
})

Output:

func (*Ring) Len ¶

func (r *Ring) Len() int

Len computes the number of elements in ring r. It executes in time proportional to the number of elements.

Example

Code:

// Create a new ring of size 4
r := ring.New(4)

// Print out its length
fmt.Println(r.Len())

Output:

func (*Ring) Link ¶

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.

Example

Code:

// 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))
})

Output:

func (*Ring) Move ¶

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.

Example

Code:

// 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))
})

Output:

func (*Ring) Next ¶

func (r *Ring) Next() *Ring

Next returns the next ring element. r must not be empty.

Example

Code:

// 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()
}

Output:

func (*Ring) Prev ¶

func (r *Ring) Prev() *Ring

Prev returns the previous ring element. r must not be empty.

Example

Code:

// 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)
}

Output:

func (*Ring) Unlink ¶

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.

Example

Code:

// 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))
})

Output:

0
4
5