Rust Match模式：绑定特定情况的文字值[重复]

Question

此问题已经在这里有了答案：

• Is there a way to match two enum variants and also bind the matched variant to a variable?1个答案

我有以下匹配项

match it.peek() {
     Some('0') | Some('1') | Some('2') | Some('3')
   | Some('4') | Some('5') | Some('6') | Some('7')
   | Some('8') | Some('9') => { list.push(...) }
     _ => {...}
}

现在，我想在Some的情况下编写一个简单的get元素，我确定这是行不通的，但是您会从中得到想法的：

match it.peek() {
     Some('0' as digit) | Some('1' as digit) | Some('2' as digit) | Some('3' as digit)
   | Some('4' as digit) | Some('5' as digit) | Some('6' as digit) | Some('7'  as digit)
   | Some('8' as digit) | Some('9' as digit) => { list.push(digit) }
     _ => {...}
}

这可能吗？我知道我可以嵌套第二个匹配项，从数字中解包字符，但是然后我需要两次实现_大小写，这是我想避免的。

Answer 1

您可以对char::is_digit使用条件匹配：

fn main() {
    let c = Some('2');
    match c {
        Some(c) if c.is_digit(10) => println!("Found a digit: {}", c),
        _ => println!("Found another thing"),
    }
}

Answer 2

我想出了这个

match it.peek() {
    Some(c)
        if *c == '0'
            || *c == '1'
            || *c == '2'
            || *c == '3'
            || *c == '4'
            || *c == '5'
            || *c == '6'
            || *c == '7'
            || *c == '8'
            || *c == '9' => {}
}

这似乎可以解决问题。仍然对更好的方式感兴趣