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// ! 这是itor的例子
// ! 
// ! itor工具集
// ! 


#[derive(PartialEq, Debug)]

pub struct Shoe {
    pub size: u32,
    pub style: String,
}


/// 显示我的鞋子的尺寸
/// 
/// #Example
/// 
/// ```
/// 
/// let shoes = vec![
///     learn_itor::Shoe { size: 10, style: String::from("sneaker") },
///     learn_itor::Shoe { size: 13, style: String::from("sandal") },
///     learn_itor::Shoe { size: 10, style: String::from("boot") },
/// ];
/// let in_my_size = learn_itor::shoes_in_my_size(shoes, 10);
/// assert_eq!(
///     in_my_size,
///     vec![
///         learn_itor::Shoe { size: 10, style: String::from("sneaker")},
///         learn_itor::Shoe { size: 10, style: String::from("boot") },
///     ],
/// ); 
/// ```
/// 
pub fn shoes_in_my_size(shoes: Vec<Shoe>, show_size: u32) -> Vec<Shoe> {
    shoes.into_iter().filter(
        |s| s.size == show_size 
    ).collect()
}

#[test]
fn filters_by_size(){
    let shoes = vec![
        Shoe { size: 10, style: String::from("sneaker") },
        Shoe { size: 13, style: String::from("sandal") },
        Shoe { size: 10, style: String::from("boot") },
    ];

    let in_my_size = shoes_in_my_size(shoes, 13);

    assert_eq!(
        in_my_size,
        vec![
            Shoe { size: 13, style: String::from("sandal") },
            //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!(Some(1), counter.next());
    assert_eq!(Some(2), counter.next());
    assert_eq!(Some(3), counter.next());
    assert_eq!(Some(4), counter.next());
    assert_eq!(Some(5), counter.next());
    assert_eq!(None, counter.next());
    assert_eq!(None, counter.next());
}