study_rust_example/iterator_closure/
iterator_process_study.rs

1fn iterator_vector(v: &Vec<i32>) {
2    let v_iter = v.iter();
3    for val in v_iter {
4        println!("iterator_vector:: val = {val}");
5    }
6    // 等同于如下的测试函数test_iterator_demo
7    // 测试拥有vector所有权的vector
8    let mut v_iter_into = v.into_iter();
9    assert_eq!(v_iter_into.next(), Some(&1));
10    assert_eq!(v_iter_into.next(), Some(&2));
11    assert_eq!(v_iter_into.next(), Some(&3));
12    assert_eq!(v_iter_into.next(), Some(&4));
13    assert_eq!(v_iter_into.next(), Some(&5));
14    assert_eq!(v_iter_into.next(), Some(&6));
15    assert_eq!(v_iter_into.next(), None);
16}
17
18fn iterator_mute_vector(v: &mut Vec<i32>) {
19    let v_mute_iter = v.iter_mut();
20    for value in v_mute_iter {
21        *value = *value * 2;
22    }
23    println!("value_vector {:?}", v);
24}
25
26fn iterator_consume_method(v: &Vec<i32>) {
27    let v_iter = v.iter();
28    let total: i32 = v_iter.sum();
29    assert_eq!(total, 42);
30    println!("total {total}");
31}
32
33fn produce_iterator_method(v: &Vec<i32>) {
34    let v2: Vec<_> = v.iter().map(|x| x + 1).collect();
35    println!("produce_iterator_method vec: {:?}", v2);
36}
37
38pub fn iterator_usage() {
39    let mut v1 = vec![1, 2, 3, 4, 5, 6];
40    iterator_vector(&v1);
41    iterator_mute_vector(&mut v1);
42    println!("iterator_usage {:?}", v1);
43    iterator_consume_method(&v1);
44    produce_iterator_method(&v1);
45}
46
47#[derive(Debug, PartialEq)]
48struct Shoe {
49    size: u32,
50    style: String,
51}
52
53fn shoe_in_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
54    shoes.into_iter().filter(|s| s.size == shoe_size).collect()
55}
56
57#[cfg(test)]
58mod tests {
59    #[test]
60    fn test_iterator_demo() {
61        let v1 = vec![1, 2, 3];
62        // 需要使 v1_iter 可变：在迭代器上调用 next 方法会更改迭代器用来跟踪其在序列中位置的内部状态。
63        // 换句话说，此代码消耗或用完迭代器。每次调用 next 都会消耗迭代器中的一个项目。
64        // 当我们使用 for 循环时，我们不需要使 v1_iter 可变，因为循环获取了 v1_iter 的所有权并使其在幕后可变
65        let mut v1_iter = v1.iter();
66        assert_eq!(v1_iter.next(), Some(&1));
67        assert_eq!(v1_iter.next(), Some(&2));
68        assert_eq!(v1_iter.next(), Some(&3));
69        assert_eq!(v1_iter.next(), None);
70    }
71
72    #[test]
73    fn test_shoe_in_size() {
74        use super::*;
75        let shoes = vec![
76            Shoe {
77                size: 10,
78                style: String::from("sneaker"),
79            },
80            Shoe {
81                size: 13,
82                style: String::from("sandal"),
83            },
84            Shoe {
85                size: 10,
86                style: String::from("boot"),
87            },
88        ];
89        let in_my_size = shoe_in_size(shoes, 10);
90        assert_eq!(
91            in_my_size,
92            vec![
93                Shoe {
94                    size: 10,
95                    style: String::from("sneaker"),
96                },
97                Shoe {
98                    size: 10,
99                    style: String::from("boot"),
100                },
101            ]
102        )
103    }
104}
study_rust_example/iterator_closure/iterator_process_study.rs

study_rust_example/iterator_closure/
iterator_process_study.rs
