Method new

publication/code/chapter06/hashmap.rs:12–22

(cap: usize)

impl<T: Clone + PartialEq + Default> HashMap<T> {
    fn new(cap: usize) -> Self {
        // 初始化 slot 和 data
        let mut slot = Vec::with_capacity(cap);
        let mut data = Vec::with_capacity(cap);
        for _i in 0..cap{
            slot.push(0);
            data.push(Default::default());
        }

        HashMap { cap, slot, data }
    }

    fn len(&self) -> usize {
        let mut len = 0;