rust学习 day1

边读rust程序设计这本书边写代码。
今天主要和cargo（换源，包提速），以及actix-web这个库（版本不兼容）鏖战。
清华的源也太慢了，换了中科大的才搞定。
书里的actix-web版本太落后了，编译通过不了，换了actix-web 4.0然后参考官方指南：https://actix.rs/docs/getting-started/，才编译成功。

use actix_web::{web, App, HttpResponse, HttpServer};
use serde::Deserialize;


#[actix_web::main]
async fn main() {

    println!("Serving on http://127.0.0.1:3000");

    HttpServer::new(|| {
        App::new()
            .route("/", web::get().to(get_index))
            .route("/gcd", web::post().to(post_gcd))
    })
        .bind(("127.0.0.1", 3000)).expect("bind error!!")
        .run()
        .await.expect("run error!!");
}

async fn get_index() -> HttpResponse {
    HttpResponse::Ok()
        .content_type("text/html")
        .body(
            r#"
                <title>GCD Calculator2.0</title>
                <form action="/gcd" method="post">
                    <input type="text" name="n"/>
                    <input type="text" name="m"/>
                    <button type="submit">Compute GCD</button>
                </form>
            "#,
        )
}

#[derive(Deserialize)]
struct GcdParameters {
    n: u64,
    m: u64,
}

async fn post_gcd(form: web::Form<GcdParameters>) -> HttpResponse {
    if form.n==0 || form.m == 0 {
        return HttpResponse::BadRequest()
            .content_type("text/html")
            .body("do not input 0!");
    }

    let response =
        format!("the gcd of {} and {} is <b>{}</b>",
                form.n, form.m, gcd(form.n, form.m));

    return HttpResponse::Ok()
        .content_type("text/html")
        .body(response);
}

#[test]
fn test_gcd() {
    assert_eq!(gcd(14, 15), 1);
    assert_eq!(gcd(2*3*5*11*17, 3*7*11*13*19), 3*11);
}

fn gcd(mut n:u64, mut m:u64) -> u64 {
    assert!(n != 0 && m != 0);
    while m != 0 {
        if m < n {
            let t = m;
            m = n;
            n = t;
        }
        m = m % n;
    }
    return n;
}