r3bl_tui 0.7.2

TUI library to build modern apps inspired by React, Elm, with Flexbox, CSS, editor component, emoji support, and more
Documentation 
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/*
 *   Copyright (c) 2022-2025 R3BL LLC
 *   All rights reserved.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

//! Using [`crossterm::event::poll`] is non-blocking, but also inefficient. The following
//! code will generate some CPU utilization while idling.
//!
//! ```
//! use std::time::Duration;
//! use std::io;
//! use crossterm::event::{read, poll};
//!
//! fn print_events() -> io::Result<bool> {
//!     loop {
//!         if poll(Duration::from_millis(100))? {
//!             // It's guaranteed that `read` won't block, because `poll` returned
//!             // `Ok(true)`.
//!             println!("{:?}", read()?);
//!         } else {
//!             // Timeout expired, no `Event` is available
//!         }
//!     }
//! }
//! ```
//!
//! The following code uses [`crossterm::event::read`] and blocks the thread that its
//! running on.
//!
//! ```
//! use crossterm::event::read;
//! use std::io;
//!
//! fn print_events() -> io::Result<bool> {
//!     loop {
//!         // Blocks until an `Event` is available
//!         println!("{:?}", read()?);
//!     }
//! }
//! ```
//!
//! - tokio crate docs:
//!     - [Async in depth, futures, polling, efficient wakers](https://tokio.rs/tokio/tutorial/async)
//!     - [Example of delay (setTimeout) w/out waker, inefficient](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=7a43cdf047cc17047c3c8b3f137293f0)
//!     - [Example of delay (setTimeout) w/ waker, efficient](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6633717db032ffe7af809e9131d7462f)
//!     - [Per task concurrency w/ `select!`, vs parallelism w/ `tokio::spawn`](https://tokio.rs/tokio/tutorial/select#per-task-concurrency)
//! - std docs:
//!     - <https://doc.rust-lang.org/std/future/trait.Future.html>
//!     - <https://doc.rust-lang.org/std/task/struct.Waker.html>
//!     - <https://doc.rust-lang.org/std/pin/index.html>
//! - polling crate docs:
//!     - <https://docs.rs/polling/latest/polling/index.html>
//!     - <https://en.wikipedia.org/wiki/Epoll>
//! - crossterm crate docs:
//!     - <https://github.com/crossterm-rs/crossterm/wiki/Upgrade-from-0.13-to-0.14#115-event-polling>
//!     - <https://github.com/crossterm-rs/crossterm/wiki/Upgrade-from-0.13-to-0.14#111-new-event-api>
//!     - <https://github.com/crossterm-rs/crossterm/blob/master/examples/event-stream-tokio.rs>

use futures_util::FutureExt;

use super::InputEvent;
use crate::{DEBUG_TUI_SHOW_TERMINAL_BACKEND, InputDevice};

pub trait InputDeviceExt {
    #[allow(async_fn_in_trait)]
    async fn next_input_event(&mut self) -> Option<InputEvent>;
}

impl InputDeviceExt for InputDevice {
    async fn next_input_event(&mut self) -> Option<InputEvent> {
        loop {
            let maybe_result_event = self.next().fuse().await;
            match maybe_result_event {
                Ok(event) => {
                    let input_event = InputEvent::try_from(event);
                    if let Ok(input_event) = input_event {
                        return Some(input_event);
                    }
                    // Conversion errors are expected in the following cases:
                    // 1. Key Release/Repeat events (filtered in
                    //    InputEvent::try_from)
                    // 2. Paste events (not supported)
                    //
                    // These are normal occurrences, not bugs. We simply continue
                    // reading the next event. The TryFrom implementations handle
                    // all expected cases by returning Err(()), so we don't need
                    // to panic or log errors here.
                    //
                    // Continue reading the next event in the loop.
                }
                Err(e) => {
                    DEBUG_TUI_SHOW_TERMINAL_BACKEND.then(|| {
                        // % is Display, ? is Debug.
                        tracing::error!(
                            message = "Error reading input event.",
                            error = ?e,
                        );
                    });
                    return None;
                }
            }
        }
    }
}