简单匹配和搜索

regex crate 提供正规表达支持 tust，将它添加到你的 Cargo.toml：

[dependencies]
regex = "0.1"

regex 箱子的主要界面是 regex::Regex：

extern crate regex;
use regex::Regex;

fn main() {
    //"r" stands for "raw" strings, you probably
    // need them because rustc checks escape sequences,
    // although you can always use "\\" withour "r"
    let num_regex = Regex::new(r"\d+").unwrap();
    // is_match checks if string matches the pattern
    assert!(num_regex.is_match("some string with number 1"));

    let example_string = "some 123 numbers";
    // Regex::find searches for pattern and returns Option<(usize,usize)>,
    // which is either indexes of first and last bytes of match
    // or "None" if nothing matched
    match num_regex.find(example_string) {
        // Get the match slice from string, prints "123"
        Some(x) => println!("{}", &example_string[x.0 .. x.1]),
        None    => unreachable!()
    }
}