pattern-matching - Rust的比赛早破

Question

我想切换x的许多可能情况，并且有一种情况(这里是x == 0)，我想检查一些其他代码的结果以确定下一步要做什么。一种可能性是比赛早退。
我会使用break在C中进行此早期返回，但是Rust不允许这样做。 return从父函数返回(在本例中为main())，而不是仅从匹配项返回(即，末尾的println!没有运行!)。
我可以否定子条件(此处为y == 0)并缩进下面的所有代码-但我发现这很丑陋且难以理解。
对于我来说，将子条件放入比赛后卫是没有选择的，因为它太大了。
在Rust中这是否可行，或者有更好的选择(除了创建另一个子功能或其他解决方法)？
最小示例:

fn main() {
    let x = 1;

    match x {
        1 => {
            let y = 0;
            /*
             * do ev1l stuff to y that I don't want to put into the match-guard
             * as it's simply too much.
             */

            /* break early ... */
            if y == 0 {break;} // > error: `break` outside of loop [E0268]

            assert!(y != 0, "y was 0!");
            /* do other stuff in here. */
        }
        _ => {}
    }

    println!("done matching");
}

我找到了 Mixing matching, mutation, and moves in Rust-是吗？

match embraces both imperative and functional styles of programming: you can continue using break statements, assignments, et cetera, rather than being forced to adopt an expression-oriented mindset.

我仍在学习Rust并且来自C语言，所以请多多包涵;-)

Answer 1

您可以将match包装为仅运行一次并退出循环的loop

fn main() {
    let x = 1;

    loop { match x {
        1 => {
            let y = 0;
            /*
             * do ev1l stuff to y that I don't want to put into the match-guard
             * as it's simply too much.
             */

            /* break early ... */
            if y == 0 { break; }

            assert!(y != 0, "y was 0!");
            /* do other stuff in here. */
        }
        _ => {}
    } break; }

    println!("done matching");
}