Crate key_node_list

Expand description

Doubly-linked list that stores key-node pairs.

KeyNodeList is a doubly-linked list, it uses a hash map to maintain correspondence between keys and nodes, and records the previous key and the next key of the current node in the node itself. There is no pointer operations during this process, so key_node_list is all implemented in safe Rust.

You can complete key lookups, key-node pair updates, key-node pair deletions and other operations of KeyNodeList in O(1)~ time. You can also use cursor-based interface to traverse or edit the linked list.

Examples

Organizing key-value pairs using `KeyValueList`

use key_node_list::KeyValueList;

// construct key-value list from tuple array
let mut list = KeyValueList::from([(1, "Reimu"), (2, "Marisa")]);

// or pushing other key-value pairs to the front/back of list
list.push_front(0, "Alice").unwrap();
list.push_back(3, "Patchouli").unwrap();

// query nodes by key
assert_eq!(list[&1].value(), &"Reimu");
assert_eq!(list[&0].value(), &"Alice");

// also you can update nodes by key
*list.node_mut(&3).unwrap().value_mut() = "Youmu";
*list.front_node_mut().unwrap().value_mut() = "Mokou";
assert_eq!(list[&3].value(), &"Youmu");
assert_eq!(list[&0].value(), &"Mokou");
assert_eq!(list.front_node().unwrap().value(), &"Mokou");

// remove some key-node pairs
assert!(list.pop_front().is_some());
assert!(list.remove(&2).is_some());

// all key-node pairs are in order
list.push_back(5, "Yuyuko");
let vec: Vec<_> = list.into_iter().map(|(k, n)| (k, n.into_value())).collect();
assert_eq!(vec, [(1, "Reimu"), (3, "Youmu"), (5, "Yuyuko")]);

Editing list using cursors

use key_node_list::KeyValueList;

let mut first_name = KeyValueList::from([
  (1, "Reimu".to_string()),
  (2, "Marisa".to_string()),
]);

let last_name = KeyValueList::from([(1, "Hakurei"), (2, "Kirisame")]);

// append last names after first names
let mut first_cur = first_name.cursor_front_mut();
let mut last_cur = last_name.cursor_front();
while let Some(node) = first_cur.node_mut() {
  node.value_mut().push(' ');
  node.value_mut().push_str(last_cur.node().unwrap().value());
  first_cur.move_next();
  last_cur.move_next();
}

let vec: Vec<_> = first_name.iter().map(|(k, n)| (k, n.value().as_str())).collect();
assert_eq!(vec, [(&1, "Reimu Hakurei"), (&2, "Marisa Kirisame")]);

Customizing your own nodes

use key_node_list::{Node, impl_node};
use key_node_list::KeyNodeList;

struct NameNode<'a> {
  first: &'a str,
  last: &'a str,
  prev: Option<i32>,
  next: Option<i32>,
}

impl<'a> From<(&'a str, &'a str)> for NameNode<'a> {
  fn from(name: (&'a str, &'a str)) -> Self {
    let (first, last) = name;
    Self {
      first,
      last,
      prev: None,
      next: None,
    }
  }
}

// implements `Node` trait for `NameNode`
impl_node!(NameNode<'a> { Key = i32, prev = prev, next = next });

// create a `KeyNodeList` with node type `NameNode`
let mut names: KeyNodeList<_, NameNode> = KeyNodeList::new();
names.push_back(1, ("Reimu", "Hakurei"));
names.push_back(2, ("Marisa", "Kirisame"));
assert_eq!(names[&1].first, "Reimu");
assert_eq!(names[&2].last, "Kirisame");