窥视迭代器内部

Question

我试图窥视我当前位置的char段，同时迭代＆amp; str。

let myStr = "12345";
let mut iter = myStr.chars().peekable();
for c in iter {
    let current: char = c;
    let next: char = *iter.peek().unwrap_or(&'∅');
}

我将把这个字符传递到沿线的方法中。但是，即使是此MRE也会产生一个借用的移动错误，我不确定如何过去。

error[E0382]: borrow of moved value: `iter`
   --> src/lib.rs:7:27
    |
4   |     let mut iter = myStr.chars().peekable();
    |         -------- move occurs because `iter` has type `Peekable<Chars<'_>>`, which does not implement the `Copy` trait
5   |     for c in iter {
    |              ---- `iter` moved due to this implicit call to `.into_iter()`
6   |         let current: char = c;
7   |         let next: char = *iter.peek().unwrap_or(&'∅');
    |                           ^^^^^^^^^^^ value borrowed here after move
    |
note: this function takes ownership of the receiver `self`, which moves `iter`
   --> /home/james/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/collect.rs:267:18
    |
267 |     fn into_iter(self) -> Self::IntoIter;

知道这里发生了什么事吗？我已经尝试了参考和删除的各种组合，但我尝试过任何尝试似乎没有用。

Answer 1

迭代器移至循环的中。您无法在循环的内手动操纵迭代器。但是，循环的可以用替换：

while let Some(c) = iter.next() {
    let current: char = c;
    let next: char = *iter.peek().unwrap_or(&'∅');
}

Playground 。

Answer 2

如果您可以使用切片，则使用windows（）：

let slice = ['1', '2', '3', '4', '5'];
let iter = slice.windows(2);
for arr in iter {
    let current = arr[0];
    let next = arr[1];
}

Playground