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Accepted
Pioneer_11
Asked: 2024-07-15 09:31:55 +0800 CST

rust`split` 在模式匹配之前分裂

  • 772

我正在尝试拆分String保留每个模式匹配，但将匹配的部分保留为下一个子字符串的开头而不是最后一个子字符串的终止符。

当前实施：

let s = String::from("AaaBbCc");
for block in s.split_inclusive(|c: char| c.is_uppercase()) {
    println!("{block}")
}

电流输出

A
aaB
bC
c

期望输出

Aaa
Bb
Cc

如何实现这一点？

rust

2 个回答

  1. Best Answer

    我不认为标准库能帮到你（尽管 上有上百万种方法String，但我可能错了）。但如果你真的需要懒惰的话，这是一个足够简单的迭代器，你可以自己编写：

    struct CamelCaseSplit<'a> {
    char_indices: std::str::CharIndices<'a>,
    chunk_start: usize,
    s: &'a str
}

impl<'a> CamelCaseSplit<'a> {
    pub fn new(s: &'a str) -> Self {
        let mut char_indices = s.char_indices();
        // We'll never want to split before the first char, so skip it.
        char_indices.next();
        Self {
            char_indices,
            chunk_start: 0,
            s,
        }
    }
}

impl<'a> Iterator for CamelCaseSplit<'a> {
    type Item = &'a str;
    
    fn next(&mut self) -> Option<Self::Item> {
        // The input is exhausted
        if self.chunk_start == self.s.len() {
            return None;
        }
        // Find the next uppercase letter position OR the end of the string
        let chunk_end = if let Some((chunk_end, _)) = self.char_indices.by_ref().skip_while(|(_, c)| !c.is_uppercase()).next() {
            chunk_end
        } else {
            self.s.len()
        };
        let chunk = &self.s[self.chunk_start..chunk_end];
        self.chunk_start = chunk_end;
        return Some(chunk);
    }
}

fn main() {
    let split = CamelCaseSplit::new("AaaBbCc");
    for c in split {
        println!("{c}");
        // Aaa
        // Bb
        // Cc
    }
}
    • 2

  2. 我相信这无法通过任何单一方法实现String。但有一个解决方法如下：

    let s = String::from("AaaBbCc");
let s_reversed = s.chars().rev().collect::<String>();
let blocks = s_reversed
    .split_inclusive(|c: char| c.is_uppercase())
    // reverse each block in the iterator...
    .map(|block| block.chars().rev().collect::<String>())
    // and then reverse the whole iterator
    .rev();
for block in blocks {
    println!("{}", block)
}
    • 1

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