76 lines
1.7 KiB
Rust
76 lines
1.7 KiB
Rust
#[derive(PartialEq, Debug)]
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struct Shoe {
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size: u32,
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style: String,
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}
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fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
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shoes.into_iter() // into_iter takes ownership of the original vector
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.filter(|s| s.size == shoe_size) // Filter is lazy!
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.collect() // Tell the iterator to run, and give me a collection
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}
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struct Counter {
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count: u32,
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}
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impl Counter {
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fn new() -> Counter {
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Counter { count: 0 }
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}
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}
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impl Iterator for Counter {
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type Item = u32;
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fn next(&mut self) -> Option<Self::Item> {
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self.count += 1;
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if self.count < 6 {
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Some(self.count)
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} else {
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None
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}
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}
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}
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#[test]
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fn filters_by_size() {
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let shoes = vec![
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Shoe { size: 10, style: String::from("sneaker") },
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Shoe { size: 13, style: String::from("sandal") },
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Shoe { size: 10, style: String::from("boot") },
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];
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let in_my_size = shoes_in_my_size(shoes, 10);
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assert_eq!(
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in_my_size,
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vec![
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Shoe { size: 10, style: String::from("sneaker") },
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Shoe { size: 10, style: String::from("boot") },
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]
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);
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}
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#[test]
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fn calling_next_directly() {
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let mut counter = Counter::new();
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assert_eq!(counter.next(), Some(1));
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assert_eq!(counter.next(), Some(2));
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assert_eq!(counter.next(), Some(3));
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assert_eq!(counter.next(), Some(4));
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assert_eq!(counter.next(), Some(5));
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assert_eq!(counter.next(), None);
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}
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#[test]
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fn using_other_iterator_trait_methods() {
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let sum: u32 = Counter::new().zip(Counter::new().skip(1))
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.map(|(a, b)| a * b)
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.filter(|x| x % 3 == 0)
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.sum();
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assert_eq!(18, sum);
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}
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