如何使用Rust nom来获取字符串的最后一个匹配项？

use nom::{
    bytes::complete::{tag, take_while},
    combinator::map_res,
    sequence::tuple,
    IResult,
};

// 定义一个解析器，用于匹配字符串中的最后一个特定模式
fn last_match(input: &str) -> IResult<&str, &str> {
    // 这里假设我们要匹配的模式是 "abc"
    let pattern = "abc";
    let len = pattern.len();

    // 从输入字符串的末尾开始向前搜索
    let (input, _) = take_while(|c| c != pattern.chars().next().unwrap())(input)?;
    let (input, matched) = tag(pattern)(input)?;

    Ok((input, matched))
}

fn main() {
    let input = "xyzabc123abc";
    match last_match(input) {
        Ok((remaining, matched)) => println!("Last match: '{}' (remaining: '{}')", matched, remaining),
        Err(e) => println!("Error: {:?}", e),
    }
}