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use super::ExtNode as Node;
use super::{Error, Result};
use std::cell::RefCell;
use std::clone::Clone;
use std::fmt::Debug;
use std::rc::Rc;
/// `Double` is a double linked list referencing the head, the tail node node and the length of the list.
#[derive(Debug)]
pub struct Double<T> {
head: Option<Rc<RefCell<Node<T>>>>,
tail: Option<Rc<RefCell<Node<T>>>>,
len: usize,
}
impl<T> Default for Double<T>
where
T: Debug + PartialEq + Clone,
{
fn default() -> Self {
Self::new()
}
}
impl<T> Double<T>
where
T: Debug + PartialEq + Clone,
{
/// Create a new instance of the `Double` linked list.
pub fn new() -> Self {
Double {
head: None,
tail: None,
len: 0,
}
}
/// Append a new value to the end of the list.
pub fn append(&mut self, value: T) {
let new_node = Rc::new(RefCell::new(Node::new(value)));
match self.head.as_mut() {
None => {
self.tail = Some(new_node.clone());
self.head = Some(new_node);
}
Some(current) => {
let mut current = current.clone();
while current.borrow().get_next().is_some() {
current = unsafe {
current
.as_ptr()
.as_ref()
.unwrap()
.get_next()
.clone()
.unwrap()
};
}
new_node
.borrow_mut()
.set_previous(Some(Rc::downgrade(¤t)));
self.tail = Some(new_node.clone());
current.borrow_mut().set_next(Some(new_node));
}
}
self.len += 1;
}
/// Remove a node from the list.
/// Returns true if the value is found and removed.
/// If the value is not found, it returns an error.
pub fn remove(&mut self, value: T) -> Result<bool> {
if self.is_empty() {
return Err(Error::EmptyList);
}
match self.head.as_mut() {
None => return Err(Error::EmptyList),
Some(current) => {
let mut current = current.clone();
if *current.borrow().get_value() == value {
let next = current.borrow_mut().get_next_mut().take();
self.head = std::mem::replace(&mut self.head, next);
if let Some(next) = self.head.as_mut() {
next.borrow_mut().set_previous(None);
}
self.len -= 1;
return Ok(true);
}
while current.borrow().get_next().is_some() {
if let Some(next) = current.borrow_mut().get_next_mut().take() {
if *next.borrow().get_value() == value {
if let Some(next_next) = next.borrow().get_next() {
next_next
.borrow_mut()
.set_previous(Some(Rc::downgrade(¤t)));
unsafe {
current
.as_ptr()
.as_mut()
.unwrap()
.get_next_mut()
.replace(next_next.clone());
}
}
self.len -= 1;
return Ok(true);
}
}
current = unsafe {
current
.as_ptr()
.as_ref()
.unwrap()
.get_next()
.clone()
.unwrap()
};
}
if current.borrow().get_next().is_none() && *current.borrow().get_value() == value {
let previous = current
.borrow()
.get_previous()
.clone()
.unwrap()
.upgrade()
.unwrap();
previous.borrow_mut().set_next(None);
self.tail = Some(previous);
self.len -= 1;
return Ok(true);
}
}
}
Err(Error::ValueNotFound)
}
/// Search for a value in the list, returns true if the value is found.
/// If the value is not found, it returns an error.
pub fn search(&self, value: T) -> Result<bool> {
match self.head.as_ref() {
None => return Err(Error::EmptyList),
Some(current) => {
let mut current = current;
if current.borrow().get_next().is_none() {
return Ok(*current.borrow().get_value() == value);
}
while current.borrow().get_next().is_some() {
if *current.borrow().get_value() == value {
return Ok(true);
}
current = unsafe {
current
.as_ptr()
.as_ref()
.unwrap()
.get_next()
.as_ref()
.unwrap()
};
}
if current.borrow().get_next().is_none() {
return Ok(*current.borrow().get_value() == value);
}
}
}
Err(Error::ValueNotFound)
}
/// Update a value in the list, returns true if the value is found and updated.
/// If the value is not found, it returns an error.
pub fn update(&mut self, old_value: T, new_value: T) -> Result<bool> {
match self.head.as_ref() {
None => return Err(Error::EmptyList),
Some(current) => {
let mut current = current;
if current.borrow().get_next().is_none() {
return Ok(*current.borrow().get_value() == old_value);
}
while current.borrow().get_next().is_some() {
if *current.borrow().get_value() == old_value {
current.borrow_mut().set_value(new_value);
return Ok(true);
}
current = unsafe {
current
.as_ptr()
.as_ref()
.unwrap()
.get_next()
.as_ref()
.unwrap()
};
}
if current.borrow().get_next().is_none() {
current.borrow_mut().set_value(new_value);
return Ok(true);
}
}
}
Err(Error::ValueNotFound)
}
/// Create a new instance of the double linked list from a vector.
pub fn from_vec(values: Vec<T>) -> Self {
let mut list = Self::new();
for value in values {
list.append(value);
}
list
}
/// Remove the last node from the list.
/// Returns the value of the removed node.
/// If the list is empty, it returns an error.
pub fn pop(&mut self) -> Result<Option<T>> {
if self.is_empty() {
return Err(Error::EmptyList);
}
match self.tail.as_ref() {
None => Err(Error::EmptyList),
Some(tail) => {
let tail = tail.clone();
let previous = tail
.borrow_mut()
.get_previous_mut()
.clone()
.unwrap()
.upgrade()
.unwrap();
previous.borrow_mut().set_next(None);
self.tail = Some(previous);
self.len -= 1;
return Ok(Some(tail.borrow().get_value().clone()));
}
}
}
pub fn print(&self) {
if self.is_empty() {
println!("{}", Error::EmptyList);
}
let mut index = 0;
while index < self.len {
let _ = self.get(index).map(|value| {
println!("{:?}", value.unwrap());
index += 1;
});
}
}
/// Check if the list is empty.
pub fn is_empty(&self) -> bool {
self.head.is_none()
}
/// Get an element from the list by index.
/// Returns an error if the list is empty or the index is out of bounds.
/// If the index is valid, it returns the value of the node.
pub fn get(&self, index: usize) -> Result<Option<T>> {
if self.is_empty() {
return Err(Error::EmptyList);
}
let mut current = &self.head;
let mut current_index = 0;
while current_index <= index {
let current_ref = current.as_ref().unwrap();
if current_index == index {
return Ok(Some(current_ref.borrow().get_value().clone()));
}
current = unsafe { current_ref.as_ptr().as_ref().unwrap().get_next() };
current_index += 1;
}
Err(Error::IndexOutOfBounds)
}
}
// region: --- Tests
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_double_linked_list_ops() {
let mut list = Double::new();
list.append(1);
list.append(2);
assert!(!list.is_empty());
let value = list.pop().unwrap().unwrap();
assert_eq!(value, 2);
assert_eq!(list.len, 1);
let mut list2 = Double::from_vec(vec!["hello", "world", "rust"]);
assert_eq!(list2.get(1).unwrap().unwrap(), "world");
assert!(!list2.is_empty());
assert!(list2.search("rust").unwrap());
assert!(list2.update("world", "earth").unwrap());
assert_eq!(list2.get(1).unwrap().unwrap(), "earth");
assert!(list2.remove("earth").unwrap());
list2.print();
}
#[test]
fn test_double_linked_list_errors() {
let mut list: Double<i32> = Double::new();
assert!(list.is_empty());
assert!(list.search(6).is_err());
assert!(list.update(6, 7).is_err());
assert!(list.pop().is_err());
assert!(list.remove(6).is_err());
}
}
// endregion: --- Tests