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use std::fmt;
#[derive(Debug, Default)]
pub struct Stack<T>(Vec<T>);
impl<T: fmt::Debug> Stack<T> {
pub fn new() -> Stack<T> {
Stack(vec![])
}
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
pub fn push(&mut self, value: T) {
self.0.push(value);
}
pub fn pop(&mut self) -> T {
self.0.pop().expect("Unable to pop from empty stack!")
}
pub fn peek(&self) -> &T {
let len = self.0.len();
if len == 0 {
panic!("Cannot peek into empty stack!")
}
&self.0[len - 1]
}
pub fn peek_mut(&mut self) -> &mut T {
let len = self.0.len();
if len == 0 {
panic!("Cannot peek into empty stack!")
}
&mut self.0[len - 1]
}
pub fn as_slice(&self) -> &[T] {
self.0.as_slice()
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn new() {
let stack: Stack<usize> = Stack::new();
assert!(stack.is_empty());
}
#[test]
fn push() {
let mut stack: Stack<usize> = Stack::new();
stack.push(13);
assert!(!stack.is_empty());
}
#[test]
fn pop() {
let mut stack: Stack<usize> = Stack::new();
stack.push(13);
let value = stack.pop();
assert_eq!(value, 13);
}
#[test]
#[should_panic(expected = "empty stack")]
fn empty_pop() {
let mut stack: Stack<usize> = Stack::new();
stack.pop();
}
#[test]
fn peek() {
let mut stack: Stack<usize> = Stack::new();
stack.push(13);
assert_eq!(*stack.peek(), 13)
}
#[test]
#[should_panic(expected = "empty stack")]
fn empty_peek() {
let stack: Stack<usize> = Stack::new();
stack.peek();
}
}