Implement exiting

src/main.rs

@@ -1,11 +1,33 @@
 use gntag::agent::{Agent, SimpleAgent};
 use gntag::view::TerminalView;
 use gntag::world::ActualWorld;
+use std::io;
+use std::io::Read;
+use std::process::exit;
+use std::sync::{Arc, Mutex};
+use std::thread;
 
 fn main() {
-  let mut view = TerminalView::try_new().unwrap();
+  let view = Arc::new(Mutex::new(Some(TerminalView::try_new().unwrap())));
+  let view2 = view.clone();
+  thread::spawn(move || {
+    let stdin = io::stdin();
+    for byte in stdin.bytes().flatten() {
+      if byte == b'q' || byte == 0x1b || byte == 0x03 {
+        if let Ok(mut view) = view2.lock() {
+          *view = None; // drop view
+          println!("\n");
+        }
+        exit(0);
+      }
+    }
+  });
   loop {
-    let (width, height) = view.content_size().unwrap();
+    let (width, height) = (*view.lock().unwrap())
+      .as_mut()
+      .unwrap()
+      .content_size()
+      .unwrap();
     let mut agents: Vec<(_, Box<dyn Agent>)> = vec![];
     for x in (0..width).step_by(10) {
       for y in (0..height).step_by(10) {
@@ -16,7 +38,9 @@ fn main() {
 
     let mut gen = 0;
     loop {
-      let resized = view
+      let resized = (*view.lock().unwrap())
+        .as_mut()
+        .unwrap()
         .draw(
           gen,
           world