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use crate::{
    event::Event,
    event_loop::{ControlFlow, EventLoop, EventLoopWindowTarget},
};

/// Additional methods on [`EventLoop`] to return control flow to the caller.
pub trait EventLoopExtRunReturn {
    /// A type provided by the user that can be passed through [`Event::UserEvent`].
    type UserEvent;

    /// Initializes the `winit` event loop.
    ///
    /// Unlike [`EventLoop::run`], this function accepts non-`'static` (i.e. non-`move`) closures
    /// and returns control flow to the caller when `control_flow` is set to [`ControlFlow::Exit`].
    ///
    /// # Caveats
    ///
    /// Despite its appearance at first glance, this is *not* a perfect replacement for
    /// `poll_events`. For example, this function will not return on Windows or macOS while a
    /// window is getting resized, resulting in all application logic outside of the
    /// `event_handler` closure not running until the resize operation ends. Other OS operations
    /// may also result in such freezes. This behavior is caused by fundamental limitations in the
    /// underlying OS APIs, which cannot be hidden by `winit` without severe stability repercussions.
    ///
    /// You are strongly encouraged to use `run`, unless the use of this is absolutely necessary.
    ///
    /// ## Platform-specific
    ///
    /// - **X11 / Wayland:** This function returns `1` upon disconnection from
    ///   the display server.
    fn run_return<F>(&mut self, event_handler: F) -> i32
    where
        F: FnMut(
            Event<'_, Self::UserEvent>,
            &EventLoopWindowTarget<Self::UserEvent>,
            &mut ControlFlow,
        );
}

impl<T> EventLoopExtRunReturn for EventLoop<T> {
    type UserEvent = T;

    fn run_return<F>(&mut self, event_handler: F) -> i32
    where
        F: FnMut(
            Event<'_, Self::UserEvent>,
            &EventLoopWindowTarget<Self::UserEvent>,
            &mut ControlFlow,
        ),
    {
        self.event_loop.run_return(event_handler)
    }
}