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@mattgathu

mattgathu/main.rs

Last active Jan 15, 2021
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Simple Event Hooks in Rust, Observer pattern in Rust
use std::io;
use std::str;
use std::error::Error;
use std::io::{Read, Write};
use std::net::TcpStream;
#[allow(unused_variables)]
pub trait Events {
fn on_connect(&self, host: &str, port: i32) {}
fn on_error(&self, err: &str) {}
fn on_read(&self, resp: &[u8]) {}
fn on_shutdown(&self) {}
fn on_pre_read(&self) {}
fn on_post_read(&self) {}
}
struct Logger;
impl Events for Logger {
fn on_connect(&self, host: &str, port: i32) {
println!("Connected to {} on port {}", host, port);
}
fn on_error(&self, err: &str) {
println!("error: {}", err);
}
fn on_read(&self, resp: &[u8]) {
print!("{}", str::from_utf8(resp).unwrap());
}
fn on_shutdown(&self) {
println!("Connection closed.");
}
fn on_pre_read(&self) {
println!("Receiving content:\n");
}
fn on_post_read(&self) {
println!("\nFinished receiving content.")
}
}
struct HttpClient {
host: String,
port: i32,
hooks: Vec<Box<Events>>,
}
impl HttpClient {
pub fn new(host: &str, port: i32) -> Self {
Self {
host: host.to_owned(),
port: port,
hooks: Vec::new(),
}
}
pub fn add_events_hook<E: Events + 'static>(&mut self, hook: E) {
self.hooks.push(Box::new(hook));
}
pub fn get(&self, endpoint: &str) {
let cmd = format!("GET {} HTTP/1.1\r\nHost: {}\r\n\r\n", endpoint, self.host).into_bytes();
let mut socket = self.connect().unwrap();
socket.write(cmd.as_slice()).unwrap();
socket.flush().unwrap();
for hook in &self.hooks {
hook.on_pre_read();
}
loop {
let mut buf = vec![0; 512usize];
let cnt = socket.read(&mut buf[..]).unwrap();
buf.truncate(cnt);
if !buf.is_empty() {
for hook in &self.hooks {
hook.on_read(buf.as_slice());
}
} else {
for hook in &self.hooks {
hook.on_post_read();
}
break;
}
}
for hook in &self.hooks {
hook.on_shutdown();
}
}
pub fn connect(&self) -> io::Result<TcpStream>{
let addr = format!("{}:{}", self.host, self.port);
match TcpStream::connect(addr) {
Ok(stream) => {
for hook in &self.hooks {
hook.on_connect(&self.host, self.port);
}
Ok(stream)
},
Err(error) => {
for hook in &self.hooks {
hook.on_error(error.description());
}
Err(error)
},
}
}
}
fn main() {
let mut http_stream = HttpClient::new("httpbin.org", 80);
http_stream.add_events_hook(Logger);
http_stream.get("/ip");
}
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