Rust 如何使用字符串迭代器执行查找

发布于03月09日

我想试着熟悉铁 rust ，所以我try Crafting Interpreters分.在Longer Lexemes部分中，它有一个peek函数，用于获取当前索引前面的一个字符.

我不知道在铁 rust 里该怎么做.由于语言的设计和Unicode的复杂性，似乎不鼓励对字符串进行索引.

如果我做chars.next()，那么它就会消耗这个值.我认为原始字符串上的.as_bytes()可以工作，但它只支持ASCII值.从互联网上看，.chars().nth().unwrap()是解决方案，但它似乎非常慢.

推荐答案

@BallPointtBen关于使用peekable的 comments 的一个实际例子是:

fn main() {
    let data = "Hello, world!";
    let mut iter = data.chars().peekable();
    
    while let Some(&current) = iter.peek() {
        // Do something with the current character without consuming it
        println!("Current character: {}", current);

        // Now consume the character
        iter.next();
        
        // You can also peek the next character without consuming it
        if let Some(&next) = iter.peek() {
            println!("Next character: {}", next);
        } else {
            println!("This was the last character.");
        }
    }
}

Rust Playground Example个

输出:

Current character: H
Next character: e
Current character: e
Next character: l
Current character: l
Next character: l
Current character: l
Next character: o
Current character: o
Next character: ,
Current character: ,
Next character:  
Current character:  
Next character: w
Current character: w
Next character: o
Current character: o
Next character: r
Current character: r
Next character: l
Current character: l
Next character: d
Current character: d
Next character: !