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|
//use std::thread;
//use std::time::Duration;
//
//struct Cacher<T>
// where T: Fn(u32) -> u32
//{
// calculation: T,
// value: Option<u32>,
//}
//
//impl<T> Cacher<T>
// where T: Fn(u32) -> u32
//{
// fn new (calculation: T) -> Cacher<T> {
// Cacher {
// calculation,
// value: None,
// }
// }
//
// fn value(&mut self, arg: u32) -> u32 {
// match self.value {
// Some(v) => v,
// None => {
// let v = (self.calculation)(arg);
// self.value = Some(v);
// v
// },
// }
// }
//}
//
//fn main() {
// let simulated_user_specified_value = 26;
// let simulated_random_number = 3;
//
// generate_workout(
// simulated_user_specified_value,
// simulated_random_number
// );
//}
//
//fn generate_workout(intensity: u32, random_number: u32) {
// let mut expensive_result = Cacher::new(|num| {
// println!("calculating slowly...");
// thread::sleep(Duration::from_secs(2));
// num
// });
//
// if intensity < 25 {
// println!(
// "Today, do {} pushups!",
// expensive_result.value(intensity)
// );
// println!(
// "Next, do {} situps!",
// expensive_result.value(intensity)
// );
// }
// else {
// if random_number == 3 {
// println!("Take a break today! Remember to stay hydrated!");
// }
// else {
// println!(
// "Today, run for {} minutes!",
// expensive_result.value(intensity)
// );
// }
// }
//}
//
fn main() {
let v1 = vec![1, 2, 3];
let v1_iter = v1.iter();
for val in v1_iter {
dbg!(val);
}
}
#[test]
fn iterator_demonstration() {
let v1 = vec![1, 2, 3];
let mut v1_iter = v1.iter();
assert_eq!(v1_iter.next(), Some(&1));
assert_eq!(v1_iter.next(), Some(&2));
assert_eq!(v1_iter.next(), Some(&3));
assert_eq!(v1_iter.next(), None);
}
#[test]
fn iterator_sum() {
let v1 = vec![1, 2, 3];
let v1_iter = v1.iter();
let total: i32 = v1_iter.sum();
assert_eq!(total, 6);
}
#[test]
fn iterator_map() {
let v1: Vec<i32> = vec![1, 2, 3];
let v2: Vec<_> = v1.iter().map(|x| x + 1).collect();
assert_eq!(v2, vec![2, 3, 4]);
}
#[derive(PartialEq, Debug)]
struct Shoe {
size: i32,
style: String,
}
fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: i32) -> Vec<Shoe> {
shoes.into_iter()
.filter(|s| s.size == shoe_size)
.collect()
}
#[test]
fn filters_by_size() {
let shoes = vec![
Shoe { size: 10, style: String::from("sneaker") },
Shoe { size: 10, style: String::from("boot") },
Shoe { size: 13, style: String::from("sandal") },
];
let in_my_size = shoes_in_my_size(shoes, 10);
assert_eq!(
in_my_size,
vec![
Shoe { size: 10, style: String::from("sneaker") },
Shoe { size: 10, style: String::from("boot") },
]
);
}
struct Counter {
count: u32,
}
impl Counter {
fn new() -> Counter {
Counter { count: 0 }
}
}
impl Iterator for Counter {
type Item = u32;
fn next(&mut self) -> Option<Self::Item> {
self.count += 1;
if self.count < 6 {
Some(self.count)
}
else {
None
}
}
}
#[test]
fn calling_next_directly() {
let mut counter = Counter::new();
assert_eq!(counter.next(), Some(1));
assert_eq!(counter.next(), Some(2));
assert_eq!(counter.next(), Some(3));
assert_eq!(counter.next(), Some(4));
assert_eq!(counter.next(), Some(5));
assert_eq!(counter.next(), None);
}
#[test]
fn using_other_iterator_trait_methods() {
let sum: u32 = Counter::new().zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.filter(|x| x % 3 == 0)
.sum();
assert_eq!(18, sum);
}
|
