Rust题目解答

main.rs

use regex::Regex;
use std::collections::HashMap;
use std::fs;

fn main() {
    let content = read();
    let re = Regex::new(r#"^(?P<ip>\S+) \S+ \S+ \[(?P<timestamp>[^\]]+)\] "(?P<method>\S+) (?P<path>[^\s]+) \S+" (?P<status>\d+) \d+ "(?P<referrer>[^"]*)" "(?P<user_agent>[^"]*)"$"#).unwrap();
    let mut mac = HashMap::new();
    let mut linux = HashMap::new();
    let mut win = HashMap::new();
    let mut other = HashMap::new();
    for line in content.lines() {
        let caps = re.captures(line);
        let caps = match caps {
            Some(c) => c,
            None => {
                // 中文的请求默认不解析
                continue;
            }
        };
        let user_agent = &caps["user_agent"];
        let user_agent = user_agent.to_string();
        // 获得了操作系统和浏览器的信息
        let lparen = user_agent.find('(');
        let rparen = user_agent.find(')');
        if rparen.is_none() || rparen.unwrap() + 1 >= user_agent.len() {
            continue;
        }
        if !lparen.is_none() && !rparen.is_none() {
            let os = &user_agent[lparen.unwrap() + 1..rparen.unwrap()];
            let browser = &user_agent[rparen.unwrap() + 2..];
            match os {
                c if c.contains("Mac") => {
                    *mac.entry(browser.to_string()).or_insert(0) += 1;
                }
                c if c.contains("Windows") => {
                    *win.entry(browser.to_string()).or_insert(0) += 1;
                }
                c if c.contains("Linux") => {
                    *linux.entry(browser.to_string()).or_insert(0) += 1;
                }
                _ => {
                    *other.entry(browser.to_string()).or_insert(0) += 1;
                }
            }
        }
    }

    let (k, v) = mac
        .iter()
        .max_by_key(|(_, &value)| value)
        .expect("hashmap is empty");
    println!("mac {}", k);
    let (k, v) = win
        .iter()
        .max_by_key(|(_, &value)| value)
        .expect("hashmap is empty");
    println!("win {}", k);
    let (k, v) = linux
        .iter()
        .max_by_key(|(_, &value)| value)
        .expect("hashmap is empty");
    println!("linux {}", k);
    let (k, v) = other
        .iter()
        .max_by_key(|(_, &value)| value)
        .expect("hashmap is empty");
    println!("other {}", k);
}

//
// regex提取信息
// 考虑map-reduce进行优化
fn read() -> String {
    fs::read_to_string("access.log").unwrap()
}