use std::cell::RefCell;use std::rc::Rc; use calloop::{EventLoop, LoopHandle}; use util::ResultExt; use crate::platform::linux::LinuxClient;use crate::platform::{LinuxCommon, PlatformWindow};use crate::{AnyWindowHandle, CursorStyle, DisplayId, PlatformDisplay, WindowParams}; pub struct HeadlessClientState {    pub(crate) _loop_handle: LoopHandle<'static, HeadlessClient>,    pub(crate) event_loop: Option<calloop::EventLoop<'static, HeadlessClient>>,    pub(crate) common: LinuxCommon,} #[derive(Clone)]pub(crate) struct HeadlessClient(Rc<RefCell<HeadlessClientState>>); impl HeadlessClient {    pub(crate) fn new() -> Self {        let event_loop = EventLoop::try_new().unwrap();         let (common, main_receiver) = LinuxCommon::new(event_loop.get_signal());         let handle = event_loop.handle();         handle            .insert_source(main_receiver, |event, _, _: &mut HeadlessClient| {                if let calloop::channel::Event::Msg(runnable) = event {                    runnable.run();                }            })            .ok();         HeadlessClient(Rc::new(RefCell::new(HeadlessClientState {            event_loop: Some(event_loop),            _loop_handle: handle,            common,        })))    }} impl LinuxClient for HeadlessClient {    fn with_common<R>(&self, f: impl FnOnce(&mut LinuxCommon) -> R) -> R {        f(&mut self.0.borrow_mut().common)    }     fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {        vec![]    }     fn primary_display(&self) -> Option<Rc<dyn PlatformDisplay>> {        None    }     fn display(&self, _id: DisplayId) -> Option<Rc<dyn PlatformDisplay>> {        None    }     fn active_window(&self) -> Option<AnyWindowHandle> {        None    }     fn window_stack(&self) -> Option<Vec<AnyWindowHandle>> {        None    }     fn open_window(        &self,        _handle: AnyWindowHandle,        _params: WindowParams,    ) -> anyhow::Result<Box<dyn PlatformWindow>> {        Err(anyhow::anyhow!(            "neither DISPLAY nor WAYLAND_DISPLAY is set. You can run in headless mode"        ))    }     fn compositor_name(&self) -> &'static str {        "headless"    }     fn set_cursor_style(&self, _style: CursorStyle) {}     fn open_uri(&self, _uri: &str) {}     fn reveal_path(&self, _path: std::path::PathBuf) {}     fn write_to_primary(&self, _item: crate::ClipboardItem) {}     fn write_to_clipboard(&self, _item: crate::ClipboardItem) {}     fn read_from_primary(&self) -> Option<crate::ClipboardItem> {        None    }     fn read_from_clipboard(&self) -> Option<crate::ClipboardItem> {        None    }     fn run(&self) {        let mut event_loop = self            .0            .borrow_mut()            .event_loop            .take()            .expect("App is already running");         event_loop.run(None, &mut self.clone(), |_| {}).log_err();    }}