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//! Timing module for frame-based applications //! //! Contains methods for slowing down to a fixed framerate, as well as //! measuring actual frames per second. //! //! An example game loop: //! //! ```ignore //! use std::time; //! use ticktock::{Clock, Timer}; //! //! let now = time::Instant::now(); //! //! // initialize game //! // ... //! //! // show some fps measurements every 5 seconds //! let mut fps_counter = Timer::apply(|delta_t, prev_tick| (delta_t, *prev_tick), 0) //! .every(time::Duration::from_secs(5)) //! .start(now); //! //! // run with a constant framerate of 30 fps //! for (tick, now) in Clock::framerate(30.0).iter() { //! // this loop will run approx. every 33.3333 ms //! //! // update, render, etc //! // ... //! //! // update or display fps count //! if let Some((delta_t, prev_tick)) = fps_counter.update(now) { //! fps_counter.set_value(tick); //! //! let fps = (tick - prev_tick) as f64 / delta_t.as_secs_f64(); //! println!("FPS: {}", fps); //! } //! break; // ignore, for doctests //! } //! ``` pub mod clock; pub mod delay; pub mod throttled_io; pub mod timer; pub use crate::clock::Clock; pub use crate::timer::Timer; /// Iterator attempt /// /// Given an iterator of outcomes, iterates returning either /// /// * the first successful outcome /// * the last unsuccessful outcome /// * `None` if the iterator was empty /// /// `Result` is often used as an outcome, e.g. when trying to reconnect multiple times: /// /// ```rust /// use std::net::TcpStream; /// use std::time::Duration; /// use ticktock::delay::Delay; /// use ticktock::Attempt; /// /// const RETRY_DELAY: Duration = Duration::from_millis(250); /// /// // attempt to connect to localhost:12348 three times, before giving up. /// // in total, 500 ms of delay will be inserted /// let conn = Delay::new(RETRY_DELAY) /// .map(|_| TcpStream::connect("localhost:12348")) /// .take(3) /// .attempt() /// .unwrap(); /// /// # // our test will fail, because there is noting listening at 12348 /// # assert!(conn.is_err()); /// ``` /// /// `Option` is also a valid outcome: /// /// ```ignore /// let credentials = vec![("Bob", "secret"), ("Jeff", "hunter2"), ("John", "swordfish")]; /// /// fn try_login(username: &str, password: &str) -> Option<(String, String)> { ... } /// /// // brute-force our way in /// let valid_credentials: Option<(String, String)> = credentials /// .map(|(u, p)| try_login(u, p)) /// .attempt() /// .unwrap(); /// ``` // note: this could probably be expressed more cleanly by using associated types // (i.e. `type Outcome = ...`), but a bug in the rust compiler at the time of this writing // did not allow for it https://github.com/rust-lang/rust/issues/20400 pub trait Attempt<O> { /// Consumes until the successful outcome is encountered. In case of failure, returns the last /// unsuccessful outcome. fn attempt(self) -> Option<O>; } impl<T, E, I> Attempt<Result<T, E>> for I where I: Iterator<Item = Result<T, E>>, { fn attempt(self) -> Option<Result<T, E>> { let mut rv = None; for res in self { rv = Some(res); // do not keep going if we got an Ok if let Some(Ok(_)) = rv { break; } } rv } } impl<T, I> Attempt<Option<T>> for I where I: Iterator<Item = Option<T>>, { fn attempt(self) -> Option<Option<T>> { let mut rv = None; for res in self { rv = Some(res); // do not keep going if we got an Ok if let Some(Some(_)) = rv { break; } } rv } } #[cfg(test)] mod test { use super::Attempt; #[test] fn attempt_works_on_ok_results() { let rs = vec![Err(1), Err(2), Err(3), Ok(4), Ok(5)]; assert_eq!(Some(Ok(4)), rs.into_iter().attempt()); } #[test] fn attempt_works_on_err_results() { let rs: Vec<Result<(), _>> = vec![Err(1), Err(2), Err(3)]; assert_eq!(Some(Err(3)), rs.into_iter().attempt()); } #[test] fn attempt_works_on_empty_result_vecs() { let rs: Vec<Result<(), ()>> = Vec::new(); assert_eq!(None, rs.into_iter().attempt()); } #[test] fn attempt_works_on_some_options() { let rs = vec![None, None, None, Some(4), Some(5)]; assert_eq!(Some(Some(4)), rs.into_iter().attempt()); } #[test] fn attempt_works_on_none_options() { let rs: Vec<Option<()>> = vec![None, None, None]; assert_eq!(Some(None), rs.into_iter().attempt()); } #[test] fn attempt_works_on_empty_option_vecs() { let rs: Vec<Option<()>> = Vec::new(); assert_eq!(None, rs.into_iter().attempt()); } }