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v/vlib/adt/linked_list.v
2021-12-23 18:23:04 +02:00

139 lines
2.8 KiB
V

module adt
pub struct ListNode<T> {
mut:
data T
next &ListNode<T> = 0
}
pub struct LinkedList<T> {
mut:
head &ListNode<T> = 0
len int
}
// is_empty checks if the linked list is empty
pub fn (list LinkedList<T>) is_empty() bool {
return list.len == 0
}
// len returns the length of the linked list
pub fn (list LinkedList<T>) len() int {
return list.len
}
// first returns the first element of the linked list
pub fn (list LinkedList<T>) first() ?T {
return if !list.is_empty() { list.head.data } else { error('Linked list is empty') }
}
// last returns the last element of the linked list
pub fn (list LinkedList<T>) last() ?T {
if list.head == 0 {
return error('Linked list is empty')
} else {
mut node := list.head
for node.next != 0 {
node = node.next
}
return node.data
}
}
// push adds an element to the end of the linked list
pub fn (mut list LinkedList<T>) push(item T) {
new_node := &ListNode{
data: item
}
if list.head == 0 {
// first node case
list.head = new_node
} else {
mut node := list.head
for node.next != 0 {
node = node.next
}
node.next = new_node
}
list.len += 1
}
// pop removes the last element of the linked list
pub fn (mut list LinkedList<T>) pop() ?T {
if list.head == 0 {
return error('Linked list is empty')
}
mut node := list.head
mut to_return := node.data
if node.next == 0 {
// first node case
// set to null
list.head = voidptr(0)
} else {
for node.next.next != 0 {
node = node.next
}
to_return = node.next.data
// set to null
node.next = voidptr(0)
}
list.len -= 1
return to_return
}
// shift removes the first element of the linked list
pub fn (mut list LinkedList<T>) shift() ?T {
if list.head == 0 {
return error('Linked list is empty')
} else {
list.len -= 1
node := list.head
list.head = node.next
return node.data
}
}
// insert adds an element to the linked list at the given index
pub fn (mut list LinkedList<T>) insert(idx int, item T) ? {
if idx < 0 || idx > list.len {
return error('Index out of bounds')
} else if list.len == 0 {
list.push(item)
} else {
list.len += 1
mut node := list.head
if idx == 0 {
// first node case
list.head = &ListNode{
data: item
next: node
}
} else {
for i := 0; i < idx - 1; i++ {
node = node.next
}
node.next = &ListNode{
data: item
next: node.next
}
}
}
}
// prepend adds an element to the beginning of the linked list (equivalent to insert(0, item))
pub fn (mut list LinkedList<T>) prepend(item T) {
list.insert(0, item) or {}
}
// str returns a string representation of the linked list
pub fn (list LinkedList<T>) str() string {
mut result_array := []T{}
mut node := list.head
for node != 0 {
result_array << node.data
node = node.next
}
return result_array.str()
}