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use std::fmt;
use std::collections::VecDeque;
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct Connection {
id: usize,
generation: usize,
}
impl Connection {
pub(crate) fn new(id: usize, generation: usize) -> Self {
Self {
id,
generation,
}
}
}
impl fmt::Display for Connection {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Connection({},{})", self.id, self.generation)
}
}
pub struct ConnectionList {
connections: Vec<Connection>,
empty: VecDeque<usize>,
}
impl ConnectionList {
pub fn new(size: usize) -> Self {
let mut connections = Vec::with_capacity(size);
let mut empty = VecDeque::with_capacity(size);
for i in 0..size {
connections.push(Connection::new(i, 0));
empty.push_back(i);
}
Self {
connections,
empty,
}
}
pub fn is_alive(&self, connection: Connection) -> bool {
let id = connection.id;
if self.connections[id].generation != connection.generation {
return false;
}
connection.generation % 2 == 1
}
pub fn create_connection(&mut self) -> Option<Connection> {
let id = self.empty.pop_front()?;
let old_connection = self.connections[id];
let new_connection = Connection::new(id, old_connection.generation + 1);
self.connections[id] = new_connection;
Some(new_connection)
}
pub fn delete_connection(&mut self, connection: Connection) -> Result<(), ()> {
let id = connection.id;
let old_connection = self.connections[id];
if connection.generation != old_connection.generation {
return Err(())
}
let new_connection = Connection::new(id, old_connection.generation + 1);
self.connections[id] = new_connection;
self.empty.push_back(id);
Ok(())
}
}
pub struct ConnectionIterator<'a> {
list: &'a ConnectionList,
index: usize,
}
impl<'a> Iterator for ConnectionIterator<'a> {
type Item = Connection;
fn next(&mut self) -> Option<Self::Item> {
while self.index < self.list.connections.len() {
let connection = self.list.connections[self.index];
self.index += 1;
if self.list.is_alive(connection) {
return Some(connection);
}
}
None
}
}
impl<'a> IntoIterator for &'a ConnectionList {
type Item = Connection;
type IntoIter = ConnectionIterator<'a>;
fn into_iter(self) -> Self::IntoIter {
ConnectionIterator {
list: self,
index: 0,
}
}
}
pub struct ConnectionDataList<T> {
items: Vec<Option<T>>,
generations: Vec<usize>,
}
impl<T> ConnectionDataList<T> {
pub fn new(size: usize) -> Self {
let mut items = Vec::with_capacity(size);
let mut generations = Vec::with_capacity(size);
for _ in 0..size {
items.push(None);
generations.push(0);
}
Self {
items,
generations,
}
}
pub fn get(&self, connection: Connection) -> Option<&T> {
let id = connection.id;
if connection.generation != self.generations[id] {
return None;
}
match self.items[id] {
Some(ref item) => Some(item),
None => None,
}
}
pub fn get_mut(&mut self, connection: Connection) -> Option<&mut T> {
let id = connection.id;
if connection.generation != self.generations[id] {
return None;
}
match self.items[id] {
Some(ref mut item) => Some(item),
None => None,
}
}
pub fn set(&mut self, connection: Connection, item: T) {
let id = connection.id;
if connection.generation < self.generations[id] {
panic!("connection no longer alive")
}
self.generations[id] = connection.generation;
self.items[id] = Some(item);
}
pub fn remove(&mut self, connection: Connection) -> Option<T> {
let id = connection.id;
if connection.generation != self.generations[id] {
return None;
}
self.items[id].take()
}
}