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// A simple doubly linked list example using slotmap. | |
extern crate slotmap; | |
use slotmap::{SlotMap, Key}; | |
struct Node<T> { | |
value: T, | |
prev: Key, | |
next: Key, | |
} | |
struct List<T> { | |
sm: SlotMap<Node<T>>, | |
head: Key, | |
tail: Key, | |
} | |
impl<T> List<T> { | |
fn new() -> Self { | |
Self { | |
sm: SlotMap::new(), | |
head: Key::null(), | |
tail: Key::null(), | |
} | |
} | |
fn len(&self) -> usize { | |
self.sm.len() | |
} | |
fn push_head(&mut self, value: T) { | |
let k = self.sm.insert(Node { | |
value, | |
prev: Key::null(), | |
next: self.head, | |
}); | |
if !self.head.is_null() { | |
self.sm[self.head].prev = k; | |
} else { | |
self.tail = k; | |
} | |
self.head = k; | |
} | |
fn push_tail(&mut self, value: T) { | |
let k = self.sm.insert(Node { | |
value, | |
prev: self.tail, | |
next: Key::null(), | |
}); | |
if !self.tail.is_null() { | |
self.sm[self.tail].next = k; | |
} else { | |
self.head = k; | |
} | |
self.tail = k; | |
} | |
fn pop_head(&mut self) -> Option<T> { | |
if self.head.is_null() { | |
return None; | |
} | |
let old_head = self.head; | |
self.head = self.sm[old_head].next; | |
if self.len() == 1 { | |
self.tail = Key::null(); | |
} | |
Some(self.sm.remove(old_head).unwrap().value) | |
} | |
fn pop_tail(&mut self) -> Option<T> { | |
if self.tail.is_null() { | |
return None; | |
} | |
let old_tail = self.tail; | |
self.tail = self.sm[old_tail].prev; | |
if self.len() == 1 { | |
self.head = Key::null(); | |
} | |
Some(self.sm.remove(old_tail).unwrap().value) | |
} | |
} | |
fn main() { | |
let mut dll = List::new(); | |
dll.push_head(5); | |
dll.push_tail(6); | |
dll.push_tail(7); | |
dll.push_head(4); | |
assert_eq!(dll.len(), 4); | |
assert_eq!(dll.pop_head(), Some(4)); | |
assert_eq!(dll.pop_head(), Some(5)); | |
assert_eq!(dll.pop_tail(), Some(7)); | |
assert_eq!(dll.pop_tail(), Some(6)); | |
assert_eq!(dll.pop_head(), None); | |
} |
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