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#![deny(missing_docs)]
use std::iter::FromIterator;
use std::mem;
#[derive(Default, Debug, Eq, PartialEq)]
pub struct Queue<T>(Vec<T>, Vec<T>);
impl<T> Queue<T> {
pub fn new() -> Self {
Queue(vec![], vec![])
}
pub fn push(&mut self, item: T) {
self.0.push(item);
}
pub fn pop(&mut self) -> Option<T> {
self.move_to_second_stack();
self.1.pop()
}
fn move_to_second_stack(&mut self) {
let v = mem::take(&mut self.0);
let iter = v.into_iter().rev();
self.1.extend(iter);
}
}
impl<T> FromIterator<T> for Queue<T> {
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Queue<T> {
let mut queue = Queue::new();
for i in iter {
queue.push(i);
}
queue
}
}
impl<T> IntoIterator for Queue<T> {
type Item = T;
type IntoIter = std::iter::Chain<std::vec::IntoIter<T>, std::vec::IntoIter<T>>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter().chain(self.1.into_iter())
}
}
#[macro_export]
macro_rules! queue [
($($e:expr),*) => ({
let mut _temp = Queue::new();
$(_temp.push($e);)*
_temp
})
];
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn new_test() {
let queue: Queue<i32> = Queue::new();
assert_eq!(Queue::new(), queue);
}
#[test]
fn push_test() {
let mut queue = queue![];
queue.push(10);
assert_eq!(queue, Queue(vec![10], vec![]));
}
#[test]
fn pop_test() {
let mut queue = queue![10];
assert_eq!(queue.pop(), Some(10));
}
#[test]
fn push_then_pop_loop() {
let mut queue = queue![];
for i in 1..10 {
queue.push(i);
}
for i in 1..10 {
assert_eq!(queue.pop(), Some(i));
}
}
#[test]
fn from_iter_test() {
let iter = 1..5;
let mut queue = Queue::from_iter(iter);
for i in 1..5 {
assert_eq!(queue.pop(), Some(i));
}
}
#[test]
fn into_iter_test() {
let queue = queue![1, 2, 3];
let mut iter = queue.into_iter();
for i in 1..3 {
assert_eq!(Some(i), iter.next());
}
}
}