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#![forbid(unsafe_code, missing_debug_implementations)]
#![feature(futures_api)]
use futures::prelude::*;
use futures::sync::oneshot;
use wasm_bindgen::prelude::Closure;
use wasm_bindgen::JsCast;
struct DocumentReady {
receiver: oneshot::Receiver<()>,
_cb: Closure<FnMut()>,
}
impl Future for DocumentReady {
type Item = ();
type Error = ();
fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
match self.receiver.poll() {
Ok(Async::Ready(_)) => Ok(Async::Ready(())),
Ok(Async::NotReady) => Ok(Async::NotReady),
Err(_) => {
if cfg!(debug_assertions) {
unreachable!("This future keeps the closure alive. The closure keeps the sender alive. Therefor it can't be cancelled.")
}
Err(())
}
}
}
}
pub fn ready() -> impl Future<Item = (), Error = ()> {
let doc = window()
.document()
.expect("should have a document on window");
let (sender, receiver) = oneshot::channel();
let mut sender = Some(sender);
let cb = move || {
sender.take().unwrap().send(()).unwrap();
};
let cb = Closure::wrap(Box::new(cb) as Box<FnMut()>);
match doc.ready_state().as_str() {
"complete" | "interactive" => {
window()
.set_timeout_with_callback(cb.as_ref().unchecked_ref())
.unwrap();
}
_ => {
doc
.add_event_listener_with_callback(
"DOMContentLoaded",
cb.as_ref().unchecked_ref(),
)
.unwrap();
}
};
DocumentReady { _cb: cb, receiver }
}
fn window() -> web_sys::Window {
web_sys::window().expect("no global `window` exists")
}