rust_ds/linked_lists/double/mod.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303
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.
pub struct Double<T: Clone> {
head: Option<Rc<RefCell<Node<T>>>>,
tail: Option<Rc<RefCell<Node<T>>>>,
len: usize,
}
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()
.take()
.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()
.get_previous()
.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()));
}
}
}
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().clone().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