zng_app/handler.rs
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//! Handler types and macros.
use std::any::Any;
use std::future::Future;
use std::marker::PhantomData;
use std::time::Duration;
use std::{mem, thread};
#[doc(hidden)]
pub use zng_clone_move::*;
use zng_handle::{Handle, WeakHandle};
use zng_task::{self as task, UiTask};
use crate::INSTANT;
/// Represents a handler in a widget context.
///
/// There are different flavors of handlers, you can use macros to declare then.
/// See [`hn!`], [`hn_once!`] or [`async_hn!`], [`async_hn_once!`] to start.
#[diagnostic::on_unimplemented(
note = "use `hn!(|args: &{A}| {{ }})` to declare a widget handler from a `FnMut` closure",
note = "use `hn_once!`, `async_hn!` or `async_hn_once!` for other closure types"
)]
pub trait WidgetHandler<A: Clone + 'static>: Any + Send {
/// Called every time the handler's event happens in the widget context.
///
/// Returns `true` when the event handler is async and it has not finished handling the event.
///
/// [`update`]: WidgetHandler::update
/// [`info`]: crate::widget::node::UiNode::info
/// [`subscribe`]: WidgetHandler::subscribe
fn event(&mut self, args: &A) -> bool;
/// Called every widget update.
///
/// Returns `false` when all pending async tasks are completed. Note that event properties
/// will call this method every update even if it is returning `false`.
///
/// [`update`]: WidgetHandler::update
fn update(&mut self) -> bool {
false
}
/// Box the handler.
///
/// The type `Box<dyn WidgetHandler<A>>` implements `WidgetHandler<A>` and just returns itself
/// in this method, avoiding double boxing.
fn boxed(self) -> Box<dyn WidgetHandler<A>>
where
Self: Sized,
{
Box::new(self)
}
/// Boxes the handler if the `feature = "dyn_closure"` is active, otherwise retains the same handler type.
#[cfg(feature = "dyn_closure")]
fn cfg_boxed(self) -> Box<dyn WidgetHandler<A>>
where
Self: Sized,
{
self.boxed()
}
/// Boxes the handler if the `feature = "dyn_closure"` is active, otherwise retains the same handler type.
#[cfg(not(feature = "dyn_closure"))]
fn cfg_boxed(self) -> Self
where
Self: Sized,
{
self
}
}
impl<A: Clone + 'static> WidgetHandler<A> for Box<dyn WidgetHandler<A>> {
fn event(&mut self, args: &A) -> bool {
self.as_mut().event(args)
}
fn update(&mut self) -> bool {
self.as_mut().update()
}
fn boxed(self) -> Box<dyn WidgetHandler<A>>
where
Self: Sized,
{
self
}
}
#[doc(hidden)]
pub struct FnMutWidgetHandler<H> {
handler: H,
}
impl<A, H> WidgetHandler<A> for FnMutWidgetHandler<H>
where
A: Clone + 'static,
H: FnMut(&A) + Send + 'static,
{
fn event(&mut self, args: &A) -> bool {
(self.handler)(args);
false
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn hn<A, H>(handler: H) -> FnMutWidgetHandler<H>
where
A: Clone + 'static,
H: FnMut(&A) + Send + 'static,
{
FnMutWidgetHandler { handler }
}
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn hn<A, H>(handler: H) -> FnMutWidgetHandler<Box<dyn FnMut(&A) + Send>>
where
A: Clone + 'static,
H: FnMut(&A) + Send + 'static,
{
FnMutWidgetHandler {
handler: Box::new(handler),
}
}
///<span data-del-macro-root></span> Declare a mutable *clone-move* event handler.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`clmv!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example declares an event handler for the `on_click` property.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// # let
/// on_click = hn!(|_| {
/// println!("Clicked!");
/// });
/// # on_click }
/// ```
///
/// The closure input is `&ClickArgs` for this property. Note that
/// if you want to use the event args you must annotate the input type, the context type is inferred.
///
/// ```
/// # #[derive(Clone)] pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize }
/// # use zng_app::handler::hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// # let
/// on_click = hn!(|args: &ClickArgs| {
/// println!("Clicked {}!", args.click_count);
/// });
/// # on_click }
/// ```
///
/// Internally the [`clmv!`] macro is used so you can *clone-move* variables into the handler.
///
/// ```
/// # #[derive(Clone)] pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize }
/// # use zng_txt::formatx;
/// # use zng_var::{var, Var};
/// # use zng_app::handler::hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let foo = var(0);
///
/// // ..
///
/// # let
/// on_click = hn!(foo, |args: &ClickArgs| {
/// foo.set(args.click_count);
/// });
///
/// // can still use after:
/// let bar = foo.map(|c| formatx!("click_count: {c}"));
///
/// # on_click }
/// ```
///
/// In the example above only a clone of `foo` is moved into the handler. Note that handlers always capture by move, if `foo` was not
/// listed in the *clone-move* section it would not be available after the handler is created. See [`clmv!`] for details.
///
/// [`clmv!`]: zng_clone_move::clmv
#[macro_export]
macro_rules! hn {
($($tt:tt)+) => {
$crate::handler::hn($crate::handler::clmv!{ $($tt)+ })
}
}
#[doc(inline)]
pub use crate::hn;
use crate::{AppControlFlow, HeadlessApp};
#[doc(hidden)]
pub struct FnOnceWidgetHandler<H> {
handler: Option<H>,
}
impl<A, H> WidgetHandler<A> for FnOnceWidgetHandler<H>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
fn event(&mut self, args: &A) -> bool {
if let Some(handler) = self.handler.take() {
handler(args);
}
false
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn hn_once<A, H>(handler: H) -> FnOnceWidgetHandler<H>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
FnOnceWidgetHandler { handler: Some(handler) }
}
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn hn_once<A, H>(handler: H) -> FnOnceWidgetHandler<Box<dyn FnOnce(&A) + Send>>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
FnOnceWidgetHandler {
handler: Some(Box::new(handler)),
}
}
///<span data-del-macro-root></span> Declare a *clone-move* event handler that is only called once.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`clmv!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example captures `data` by move and then destroys it in the first call, this cannot be done using [`hn!`] because
/// the `data` needs to be available for all event calls. In this case the closure is only called once, subsequent events
/// are ignored by the handler.
///
/// ```
/// # use zng_app::handler::hn_once;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<()> {
/// let data = vec![1, 2, 3];
/// # let
/// on_click = hn_once!(|_| {
/// for i in data {
/// print!("{i}, ");
/// }
/// });
/// # on_click }
/// ```
///
/// Other then declaring a `FnOnce` this macro behaves like [`hn!`], so the same considerations apply. You can *clone-move* variables,
/// the type of the input is the event arguments and must be annotated.
///
/// ```
/// # use zng_app::handler::hn_once;
/// # let _scope = zng_app::APP.minimal();
/// # #[derive(Clone)]
/// # pub struct ClickArgs { click_count: usize }
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let data = vec![1, 2, 3];
/// # let
/// on_click = hn_once!(data, |args: &ClickArgs| {
/// drop(data);
/// });
///
/// println!("{data:?}");
/// # on_click }
/// ```
///
/// [`clmv!`]: zng_clone_move::clmv
#[macro_export]
macro_rules! hn_once {
($($tt:tt)+) => {
$crate::handler::hn_once($crate::handler::clmv! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::hn_once;
#[doc(hidden)]
pub struct AsyncFnMutWidgetHandler<H> {
handler: H,
tasks: Vec<UiTask<()>>,
}
impl<A, F, H> WidgetHandler<A> for AsyncFnMutWidgetHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A) -> F + Send + 'static,
{
fn event(&mut self, args: &A) -> bool {
let handler = &mut self.handler;
let mut task = UiTask::new(Some(WIDGET.id()), handler(args.clone()));
let need_update = task.update().is_none();
if need_update {
self.tasks.push(task);
}
need_update
}
fn update(&mut self) -> bool {
self.tasks.retain_mut(|t| t.update().is_none());
!self.tasks.is_empty()
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn async_hn<A, F, H>(handler: H) -> AsyncFnMutWidgetHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A) -> F + Send + 'static,
{
AsyncFnMutWidgetHandler { handler, tasks: vec![] }
}
#[cfg(feature = "dyn_closure")]
type BoxedAsyncHn<A> = Box<dyn FnMut(A) -> std::pin::Pin<Box<dyn Future<Output = ()> + Send>> + Send>;
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn async_hn<A, F, H>(mut handler: H) -> AsyncFnMutWidgetHandler<BoxedAsyncHn<A>>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A) -> F + Send + 'static,
{
AsyncFnMutWidgetHandler {
handler: Box::new(move |args| Box::pin(handler(args))),
tasks: vec![],
}
}
///<span data-del-macro-root></span> Declare an async *clone-move* event handler.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`async_clmv_fn!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example declares an async event handler for the `on_click` property.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// # let
/// on_click = async_hn!(|_| {
/// println!("Clicked!");
///
/// task::run(async {
/// println!("In other thread!");
/// }).await;
///
/// println!("Back in UI thread, in a widget update.");
/// });
/// # on_click }
/// ```
///
/// The closure input is `ClickArgs` for this property. Note that
/// if you want to use the event args you must annotate the input type.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn;
/// # use zng_app::widget::WIDGET;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// # let
/// on_click = async_hn!(|args: ClickArgs| {
/// println!("Clicked {} {} times!", WIDGET.id(), args.click_count);
///
/// });
/// # on_click }
/// ```
///
/// Internally the [`async_clmv_fn!`] macro is used so you can *clone-move* variables into the handler.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn;
/// # use zng_var::{var, Var};
/// # use zng_task as task;
/// # use zng_txt::formatx;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let enabled = var(true);
///
/// // ..
///
/// # let
/// on_click = async_hn!(enabled, |args: ClickArgs| {
/// enabled.set(false);
///
/// task::run(async move {
/// println!("do something {}", args.click_count);
/// }).await;
///
/// enabled.set(true);
/// });
///
/// // can still use after:
/// # let
/// text = enabled.map(|&e| if e { "Click Me!" } else { "Busy.." });
/// enabled;
///
/// # on_click }
/// ```
///
/// In the example above only a clone of `enabled` is moved into the handler. Note that handlers always capture by move, if `enabled` was not
/// listed in the *clone-move* section it would not be available after the handler is created. See [`async_clmv_fn!`] for details.
///
/// The example also demonstrates a common pattern with async handlers, most events are only raised when the widget is enabled, so you can
/// disable the widget while the async task is running. This way you don't block the UI running a task but the user cannot spawn a second
/// task while the first is still running.
///
/// ## Futures and Clone-Move
///
/// You may want to always *clone-move* captures for async handlers, because they then automatically get cloned again for each event. This
/// needs to happen because you can have more then one *handler task* running at the same type, and both want access to the captured variables.
///
/// This second cloning can be avoided by using the [`async_hn_once!`] macro instead, but only if you expect a single event.
///
/// [`async_clmv_fn!`]: zng_clone_move::async_clmv_fn
#[macro_export]
macro_rules! async_hn {
($($tt:tt)+) => {
$crate::handler::async_hn($crate::handler::async_clmv_fn! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::async_hn;
enum AsyncFnOnceWhState<H> {
NotCalled(H),
Pending(UiTask<()>),
Done,
}
#[doc(hidden)]
pub struct AsyncFnOnceWidgetHandler<H> {
state: AsyncFnOnceWhState<H>,
}
impl<A, F, H> WidgetHandler<A> for AsyncFnOnceWidgetHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
fn event(&mut self, args: &A) -> bool {
match mem::replace(&mut self.state, AsyncFnOnceWhState::Done) {
AsyncFnOnceWhState::NotCalled(handler) => {
let mut task = UiTask::new(Some(WIDGET.id()), handler(args.clone()));
let is_pending = task.update().is_none();
if is_pending {
self.state = AsyncFnOnceWhState::Pending(task);
}
is_pending
}
AsyncFnOnceWhState::Pending(t) => {
self.state = AsyncFnOnceWhState::Pending(t);
false
}
AsyncFnOnceWhState::Done => false,
}
}
fn update(&mut self) -> bool {
let mut is_pending = false;
if let AsyncFnOnceWhState::Pending(t) = &mut self.state {
is_pending = t.update().is_none();
if !is_pending {
self.state = AsyncFnOnceWhState::Done;
}
}
is_pending
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn async_hn_once<A, F, H>(handler: H) -> AsyncFnOnceWidgetHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
AsyncFnOnceWidgetHandler {
state: AsyncFnOnceWhState::NotCalled(handler),
}
}
#[cfg(feature = "dyn_closure")]
type BoxedAsyncHnOnce<A> = Box<dyn FnOnce(A) -> std::pin::Pin<Box<dyn Future<Output = ()> + Send>> + Send>;
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn async_hn_once<A, F, H>(handler: H) -> AsyncFnOnceWidgetHandler<BoxedAsyncHnOnce<A>>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
AsyncFnOnceWidgetHandler {
state: AsyncFnOnceWhState::NotCalled(Box::new(move |args| Box::pin(handler(args)))),
}
}
///<span data-del-macro-root></span> Declare an async *clone-move* event handler that is only called once.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`async_clmv_fn_once!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example captures `data` by move and then moves it again to another thread. This is not something you can do using [`async_hn!`]
/// because that handler expects to be called many times. We expect `on_open` to only be called once, so we can don't need to capture by
/// *clone-move* here just to use `data`.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn_once;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let data = vec![1, 2, 3];
/// # let
/// on_open = async_hn_once!(|_| {
/// task::run(async move {
/// for i in data {
/// print!("{i}, ");
/// }
/// }).await;
///
/// println!("Done!");
/// });
/// # on_open }
/// ```
///
/// You can still *clone-move* to have access to the variable after creating the handler, in this case the `data` will be cloned into the handler
/// but will just be moved to the other thread, avoiding a needless clone.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn_once;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let data = vec![1, 2, 3];
/// # let
/// on_open = async_hn_once!(data, |_| {
/// task::run(async move {
/// for i in data {
/// print!("{i}, ");
/// }
/// }).await;
///
/// println!("Done!");
/// });
/// println!("{data:?}");
/// # on_open }
/// ```
///
/// [`async_clmv_fn_once!`]: zng_clone_move::async_clmv_fn_once
#[macro_export]
macro_rules! async_hn_once {
($($tt:tt)+) => {
$crate::handler::async_hn_once($crate::handler::async_clmv_fn_once! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::async_hn_once;
/// Represents a weak handle to an [`AppHandler`] subscription.
pub trait AppWeakHandle: Send {
/// Dynamic clone.
fn clone_boxed(&self) -> Box<dyn AppWeakHandle>;
/// Unsubscribes the [`AppHandler`].
///
/// This stops the handler from being called again and causes it to be dropped in a future app update.
fn unsubscribe(&self);
}
impl<D: Send + Sync + 'static> AppWeakHandle for WeakHandle<D> {
fn clone_boxed(&self) -> Box<dyn AppWeakHandle> {
Box::new(self.clone())
}
fn unsubscribe(&self) {
if let Some(handle) = self.upgrade() {
handle.force_drop();
}
}
}
/// Arguments for a call of [`AppHandler::event`].
pub struct AppHandlerArgs<'a> {
/// Handle to the [`AppHandler`] subscription.
pub handle: &'a dyn AppWeakHandle,
/// If the handler is invoked in a *preview* context.
pub is_preview: bool,
}
/// Represents an event handler in the app context.
///
/// There are different flavors of handlers, you can use macros to declare then.
/// See [`app_hn!`], [`app_hn_once!`] or [`async_app_hn!`], [`async_app_hn_once!`] to start.
#[diagnostic::on_unimplemented(
note = "use `app_hn!(|args: &{A}, _| {{ }})` to declare an app handler closure",
note = "use `app_hn_once!`, `async_app_hn!` or `async_app_hn_once!` for other closure types"
)]
pub trait AppHandler<A: Clone + 'static>: Any + Send {
/// Called every time the event happens.
///
/// The `handler_args` can be used to unsubscribe the handler. Async handlers are expected to schedule
/// their tasks to run somewhere in the app, usually in the [`UPDATES.on_update`]. The `handle` is
/// **not** expected to cancel running async tasks, only to drop `self` before the next event happens.
///
/// [`UPDATES.on_update`]: crate::update::UPDATES::on_update
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs);
/// Boxes the handler.
///
/// The type `Box<dyn AppHandler<A>>` implements `AppHandler<A>` and just returns itself
/// in this method, avoiding double boxing.
fn boxed(self) -> Box<dyn AppHandler<A>>
where
Self: Sized,
{
Box::new(self)
}
/// Boxes the handler if the `feature = "dyn_closure"` is enabled, otherwise maintain the same type.
#[cfg(feature = "dyn_closure")]
fn cfg_boxed(self) -> Box<dyn AppHandler<A>>
where
Self: Sized,
{
self.boxed()
}
/// Boxes the handler if the `feature = "dyn_closure"` is enabled, otherwise maintain the same type.
#[cfg(not(feature = "dyn_closure"))]
fn cfg_boxed(self) -> Self
where
Self: Sized,
{
self
}
}
impl<A: Clone + 'static> AppHandler<A> for Box<dyn AppHandler<A>> {
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
self.as_mut().event(args, handler_args)
}
fn boxed(self) -> Box<dyn AppHandler<A>> {
self
}
}
#[doc(hidden)]
pub struct FnMutAppHandler<H> {
handler: H,
}
impl<A, H> AppHandler<A> for FnMutAppHandler<H>
where
A: Clone + 'static,
H: FnMut(&A, &dyn AppWeakHandle) + Send + 'static,
{
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
(self.handler)(args, handler_args.handle);
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn app_hn<A, H>(handler: H) -> FnMutAppHandler<H>
where
A: Clone + 'static,
H: FnMut(&A, &dyn AppWeakHandle) + Send + 'static,
{
FnMutAppHandler { handler }
}
#[cfg(feature = "dyn_closure")]
type BoxedAppHn<A> = Box<dyn FnMut(&A, &dyn AppWeakHandle) + Send>;
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn app_hn<A, H>(handler: H) -> FnMutAppHandler<BoxedAppHn<A>>
where
A: Clone + 'static,
H: FnMut(&A, &dyn AppWeakHandle) + Send + 'static,
{
FnMutAppHandler {
handler: Box::new(handler),
}
}
///<span data-del-macro-root></span> Declare a mutable *clone-move* app event handler.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`clmv!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example declares an event handler for the `CLICK_EVENT`.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::app_hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// CLICK_EVENT.on_event(app_hn!(|_, _| {
/// println!("Clicked Somewhere!");
/// })).perm();
/// # }
/// ```
///
/// The closure input is `&A, &dyn AppWeakHandle` with `&A` equaling `&ClickArgs` for this event. Note that
/// if you want to use the event args you must annotate the input type, the context and handle type is inferred.
///
/// The handle can be used to unsubscribe the event handler, if [`unsubscribe`](AppWeakHandle::unsubscribe) is called the handler
/// will be dropped some time before the next event update.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::app_hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// CLICK_EVENT.on_event(app_hn!(|args: &ClickArgs, handle| {
/// println!("Clicked {}!", args.target);
/// handle.unsubscribe();
/// })).perm();
/// # }
/// ```
///
/// Internally the [`clmv!`] macro is used so you can *clone-move* variables into the handler.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_txt::{formatx, ToTxt};
/// # use zng_var::{var, Var};
/// # use zng_app::handler::app_hn;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// let foo = var("".to_txt());
///
/// CLICK_EVENT.on_event(app_hn!(foo, |args: &ClickArgs, _| {
/// foo.set(args.target.to_txt());
/// })).perm();
///
/// // can still use after:
/// let bar = foo.map(|c| formatx!("last click: {c}"));
///
/// # }
/// ```
///
/// In the example above only a clone of `foo` is moved into the handler. Note that handlers always capture by move, if `foo` was not
/// listed in the *clone-move* section it would not be available after the handler is created. See [`clmv!`] for details.
///
/// [`clmv!`]: zng_clone_move::clmv
#[macro_export]
macro_rules! app_hn {
($($tt:tt)+) => {
$crate::handler::app_hn($crate::handler::clmv!{ $($tt)+ })
}
}
#[doc(inline)]
pub use crate::app_hn;
#[doc(hidden)]
pub struct FnOnceAppHandler<H> {
handler: Option<H>,
}
impl<A, H> AppHandler<A> for FnOnceAppHandler<H>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
if let Some(handler) = self.handler.take() {
handler(args);
handler_args.handle.unsubscribe();
} else {
tracing::error!("`app_hn_once!` called after requesting unsubscribe");
}
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn app_hn_once<A, H>(handler: H) -> FnOnceAppHandler<H>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
FnOnceAppHandler { handler: Some(handler) }
}
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn app_hn_once<A, H>(handler: H) -> FnOnceAppHandler<Box<dyn FnOnce(&A) + Send>>
where
A: Clone + 'static,
H: FnOnce(&A) + Send + 'static,
{
FnOnceAppHandler {
handler: Some(Box::new(handler)),
}
}
///<span data-del-macro-root></span> Declare a *clone-move* app event handler that is only called once.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`clmv!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example captures `data` by move and then destroys it in the first call, this cannot be done using [`app_hn!`] because
/// the `data` needs to be available for all event calls. In this case the closure is only called once, subsequent events
/// are ignored by the handler and it automatically requests unsubscribe.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::app_hn_once;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// let data = vec![1, 2, 3];
///
/// CLICK_EVENT.on_event(app_hn_once!(|_| {
/// for i in data {
/// print!("{i}, ");
/// }
/// })).perm();
/// # }
/// ```
///
/// Other then declaring a `FnOnce` this macro behaves like [`app_hn!`], so the same considerations apply. You can *clone-move* variables,
/// the type of the input is the event arguments and must be annotated.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::app_hn_once;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// let data = vec![1, 2, 3];
///
/// CLICK_EVENT.on_event(app_hn_once!(data, |args: &ClickArgs| {
/// drop(data);
/// })).perm();
///
/// println!("{data:?}");
/// # }
/// ```
///
/// [`clmv!`]: zng_clone_move::clmv
#[macro_export]
macro_rules! app_hn_once {
($($tt:tt)+) => {
$crate::handler::app_hn_once($crate::handler::clmv! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::app_hn_once;
#[doc(hidden)]
pub struct AsyncFnMutAppHandler<H> {
handler: H,
}
impl<A, F, H> AppHandler<A> for AsyncFnMutAppHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A, Box<dyn AppWeakHandle>) -> F + Send + 'static,
{
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
let handler = &mut self.handler;
let mut task = UiTask::new(None, handler(args.clone(), handler_args.handle.clone_boxed()));
if task.update().is_none() {
if handler_args.is_preview {
UPDATES
.on_pre_update(app_hn!(|_, handle| {
if task.update().is_some() {
handle.unsubscribe();
}
}))
.perm();
} else {
UPDATES
.on_update(app_hn!(|_, handle| {
if task.update().is_some() {
handle.unsubscribe();
}
}))
.perm();
}
}
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn async_app_hn<A, F, H>(handler: H) -> AsyncFnMutAppHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A, Box<dyn AppWeakHandle>) -> F + Send + 'static,
{
AsyncFnMutAppHandler { handler }
}
#[cfg(feature = "dyn_closure")]
type BoxedAsyncAppHn<A> = Box<dyn FnMut(A, Box<dyn AppWeakHandle>) -> std::pin::Pin<Box<dyn Future<Output = ()> + Send>> + Send>;
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn async_app_hn<A, F, H>(mut handler: H) -> AsyncFnMutAppHandler<BoxedAsyncAppHn<A>>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnMut(A, Box<dyn AppWeakHandle>) -> F + Send + 'static,
{
AsyncFnMutAppHandler {
handler: Box::new(move |args, handle| Box::pin(handler(args, handle))),
}
}
///<span data-del-macro-root></span> Declare an async *clone-move* app event handler.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`async_clmv_fn!`] so
/// the input is the same syntax.
///
/// The handler generates a future for each event, the future is polled immediately if it does not finish it is scheduled
/// to update in [`on_pre_update`](crate::update::UPDATES::on_pre_update) or [`on_update`](crate::update::UPDATES::on_update) depending
/// on if the handler was assigned to a *preview* event or not.
///
/// Note that this means [`propagation`](crate::event::AnyEventArgs::propagation) can only be meaningfully stopped before the
/// first `.await`, after, the event has already propagated.
///
/// # Examples
///
/// The example declares an async event handler for the `CLICK_EVENT`.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::async_app_hn;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// CLICK_EVENT.on_event(async_app_hn!(|_, _| {
/// println!("Clicked Somewhere!");
///
/// task::run(async {
/// println!("In other thread!");
/// }).await;
///
/// println!("Back in UI thread, in an app update.");
/// })).perm();
/// # }
/// ```
///
/// The closure input is `A, Box<dyn AppWeakHandle>` for all handlers and `A` is `ClickArgs` for this example. Note that
/// if you want to use the event args you must annotate the input type, the context and handle types are inferred.
///
/// The handle can be used to unsubscribe the event handler, if [`unsubscribe`](AppWeakHandle::unsubscribe) is called the handler
/// will be dropped some time before the next event update. Running tasks are not canceled by unsubscribing, the only way to *cancel*
/// then is by returning early inside the async blocks.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::async_app_hn;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// CLICK_EVENT.on_event(async_app_hn!(|args: ClickArgs, handle| {
/// println!("Clicked {}!", args.target);
/// task::run(async move {
/// handle.unsubscribe();
/// });
/// })).perm();
/// # }
/// ```
///
/// Internally the [`async_clmv_fn!`] macro is used so you can *clone-move* variables into the handler.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # zng_app::event::event! { pub static CLICK_EVENT: ClickArgs; }
/// # use zng_app::handler::async_app_hn;
/// # use zng_var::{var, Var};
/// # use zng_task as task;
/// # use zng_txt::{formatx, ToTxt};
/// #
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() {
/// let status = var("pending..".to_txt());
///
/// CLICK_EVENT.on_event(async_app_hn!(status, |args: ClickArgs, _| {
/// status.set(formatx!("processing {}..", args.target));
///
/// task::run(async move {
/// println!("do something slow");
/// }).await;
///
/// status.set(formatx!("finished {}", args.target));
/// })).perm();
///
/// // can still use after:
/// let text = status;
///
/// # }
/// ```
///
/// In the example above only a clone of `status` is moved into the handler. Note that handlers always capture by move, if `status` was not
/// listed in the *clone-move* section it would not be available after the handler is created. See [`async_clmv_fn!`] for details.
///
/// ## Futures and Clone-Move
///
/// You may want to always *clone-move* captures for async handlers, because they then automatically get cloned again for each event. This
/// needs to happen because you can have more then one *handler task* running at the same type, and both want access to the captured variables.
///
/// This second cloning can be avoided by using the [`async_hn_once!`] macro instead, but only if you expect a single event.
///
/// [`async_clmv_fn!`]: zng_clone_move::async_clmv_fn
#[macro_export]
macro_rules! async_app_hn {
($($tt:tt)+) => {
$crate::handler::async_app_hn($crate::handler::async_clmv_fn! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::async_app_hn;
#[doc(hidden)]
pub struct AsyncFnOnceAppHandler<H> {
handler: Option<H>,
}
impl<A, F, H> AppHandler<A> for AsyncFnOnceAppHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
if let Some(handler) = self.handler.take() {
handler_args.handle.unsubscribe();
let mut task = UiTask::new(None, handler(args.clone()));
if task.update().is_none() {
if handler_args.is_preview {
UPDATES
.on_pre_update(app_hn!(|_, handle| {
if task.update().is_some() {
handle.unsubscribe();
}
}))
.perm();
} else {
UPDATES
.on_update(app_hn!(|_, handle| {
if task.update().is_some() {
handle.unsubscribe();
}
}))
.perm();
}
}
} else {
tracing::error!("`async_app_hn_once!` called after requesting unsubscribe");
}
}
}
#[doc(hidden)]
#[cfg(not(feature = "dyn_closure"))]
pub fn async_app_hn_once<A, F, H>(handler: H) -> AsyncFnOnceAppHandler<H>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
AsyncFnOnceAppHandler { handler: Some(handler) }
}
#[cfg(feature = "dyn_closure")]
type BoxedAsyncAppHnOnce<A> = Box<dyn FnOnce(A) -> std::pin::Pin<Box<dyn Future<Output = ()> + Send>> + Send>;
#[doc(hidden)]
#[cfg(feature = "dyn_closure")]
pub fn async_app_hn_once<A, F, H>(handler: H) -> AsyncFnOnceAppHandler<BoxedAsyncAppHnOnce<A>>
where
A: Clone + 'static,
F: Future<Output = ()> + Send + 'static,
H: FnOnce(A) -> F + Send + 'static,
{
AsyncFnOnceAppHandler {
handler: Some(Box::new(move |args| Box::pin(handler(args)))),
}
}
///<span data-del-macro-root></span> Declare an async *clone-move* app event handler that is only called once.
///
/// The macro input is a closure with optional *clone-move* variables, internally it uses [`async_clmv_fn_once!`] so
/// the input is the same syntax.
///
/// # Examples
///
/// The example captures `data` by move and then moves it again to another thread. This is not something you can do using [`async_app_hn!`]
/// because that handler expects to be called many times. We want to handle `CLICK_EVENT` once in this example, so we can don't need
/// to capture by *clone-move* just to use `data`.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn_once;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let data = vec![1, 2, 3];
/// # let
/// on_open = async_hn_once!(|_| {
/// task::run(async move {
/// for i in data {
/// print!("{i}, ");
/// }
/// }).await;
///
/// println!("Done!");
/// });
/// # on_open }
/// ```
///
/// You can still *clone-move* to have access to the variable after creating the handler, in this case the `data` will be cloned into the handler
/// but will just be moved to the other thread, avoiding a needless clone.
///
/// ```
/// # zng_app::event::event_args! { pub struct ClickArgs { pub target: zng_txt::Txt, pub click_count: usize, .. fn delivery_list(&self, _l: &mut UpdateDeliveryList) { } } }
/// # use zng_app::handler::async_hn_once;
/// # use zng_task as task;
/// # let _scope = zng_app::APP.minimal();
/// # fn assert_type() -> impl zng_app::handler::WidgetHandler<ClickArgs> {
/// let data = vec![1, 2, 3];
/// # let
/// on_open = async_hn_once!(data, |_| {
/// task::run(async move {
/// for i in data {
/// print!("{i}, ");
/// }
/// }).await;
///
/// println!("Done!");
/// });
/// println!("{data:?}");
/// # on_open }
/// ```
///
/// [`async_clmv_fn_once!`]: zng_clone_move::async_clmv_fn_once
#[macro_export]
macro_rules! async_app_hn_once {
($($tt:tt)+) => {
$crate::handler::async_app_hn_once($crate::handler::async_clmv_fn_once! { $($tt)+ })
}
}
#[doc(inline)]
pub use crate::async_app_hn_once;
use crate::update::UPDATES;
use crate::widget::{UiTaskWidget, WIDGET};
/// Widget handler wrapper that filters the events, only delegating to `self` when `filter` returns `true`.
pub struct FilterWidgetHandler<A, H, F> {
_args: PhantomData<fn() -> A>,
handler: H,
filter: F,
}
impl<A, H, F> FilterWidgetHandler<A, H, F>
where
A: Clone + 'static,
H: WidgetHandler<A>,
F: FnMut(&A) -> bool + Send + 'static,
{
/// New filter handler.
pub fn new(handler: H, filter: F) -> Self {
Self {
handler,
filter,
_args: PhantomData,
}
}
}
impl<A, H, F> WidgetHandler<A> for FilterWidgetHandler<A, H, F>
where
A: Clone + 'static,
H: WidgetHandler<A>,
F: FnMut(&A) -> bool + Send + 'static,
{
fn event(&mut self, args: &A) -> bool {
if (self.filter)(args) {
self.handler.event(args)
} else {
false
}
}
fn update(&mut self) -> bool {
self.handler.update()
}
}
/// App handler wrapper that filters the events, only delegating to `self` when `filter` returns `true`.
pub struct FilterAppHandler<A, H, F> {
_args: PhantomData<fn() -> A>,
handler: H,
filter: F,
}
impl<A, H, F> FilterAppHandler<A, H, F>
where
A: Clone + 'static,
H: AppHandler<A>,
F: FnMut(&A) -> bool + Send + 'static,
{
/// New filter handler.
pub fn new(handler: H, filter: F) -> Self {
Self {
handler,
filter,
_args: PhantomData,
}
}
}
impl<A, H, F> AppHandler<A> for FilterAppHandler<A, H, F>
where
A: Clone + 'static,
H: AppHandler<A>,
F: FnMut(&A) -> bool + Send + 'static,
{
fn event(&mut self, args: &A, handler_args: &AppHandlerArgs) {
if (self.filter)(args) {
self.handler.event(args, handler_args);
}
}
}
impl HeadlessApp {
/// Calls an [`AppHandler<A>`] once and blocks until the update tasks started during the call complete.
///
/// This function *spins* until all update tasks are completed. Timers or send events can
/// be received during execution but the loop does not sleep, it just spins requesting an update
/// for each pass.
pub fn block_on<A>(&mut self, handler: &mut dyn AppHandler<A>, args: &A, timeout: Duration) -> Result<(), String>
where
A: Clone + 'static,
{
self.block_on_multi(vec![handler], args, timeout)
}
/// Calls multiple [`AppHandler<A>`] once each and blocks until all update tasks are complete.
///
/// This function *spins* until all update tasks are completed. Timers or send events can
/// be received during execution but the loop does not sleep, it just spins requesting an update
/// for each pass.
pub fn block_on_multi<A>(&mut self, handlers: Vec<&mut dyn AppHandler<A>>, args: &A, timeout: Duration) -> Result<(), String>
where
A: Clone + 'static,
{
let (pre_len, pos_len) = UPDATES.handler_lens();
let handler_args = AppHandlerArgs {
handle: &Handle::dummy(()).downgrade(),
is_preview: false,
};
for handler in handlers {
handler.event(args, &handler_args);
}
let mut pending = UPDATES.new_update_handlers(pre_len, pos_len);
if !pending.is_empty() {
let start_time = INSTANT.now();
while {
pending.retain(|h| h());
!pending.is_empty()
} {
UPDATES.update(None);
let flow = self.update(false);
if INSTANT.now().duration_since(start_time) >= timeout {
return Err(format!(
"block_on reached timeout of {timeout:?} before the handler task could finish",
));
}
match flow {
AppControlFlow::Poll => continue,
AppControlFlow::Wait => {
thread::yield_now();
continue;
}
AppControlFlow::Exit => return Ok(()),
}
}
}
Ok(())
}
/// Polls a `future` and updates the app repeatedly until it completes or the `timeout` is reached.
pub fn block_on_fut<F: Future>(&mut self, future: F, timeout: Duration) -> Result<F::Output, String> {
let future = task::with_deadline(future, timeout);
let mut future = std::pin::pin!(future);
let waker = UPDATES.waker(None);
let mut cx = std::task::Context::from_waker(&waker);
loop {
let mut fut_poll = future.as_mut().poll(&mut cx);
let flow = self.update_observe(
|| {
if fut_poll.is_pending() {
fut_poll = future.as_mut().poll(&mut cx);
}
},
true,
);
match fut_poll {
std::task::Poll::Ready(r) => match r {
Ok(r) => return Ok(r),
Err(e) => return Err(e.to_string()),
},
std::task::Poll::Pending => {}
}
match flow {
AppControlFlow::Poll => continue,
AppControlFlow::Wait => {
thread::yield_now();
continue;
}
AppControlFlow::Exit => return Err("app exited".to_owned()),
}
}
}
/// Calls the `handler` once and [`block_on`] it with a 60 seconds timeout using the minimal headless app.
///
/// [`block_on`]: Self::block_on
#[track_caller]
#[cfg(any(test, doc, feature = "test_util"))]
pub fn doc_test<A, H>(args: A, mut handler: H)
where
A: Clone + 'static,
H: AppHandler<A>,
{
let mut app = crate::APP.minimal().run_headless(false);
app.block_on(&mut handler, &args, DOC_TEST_BLOCK_ON_TIMEOUT).unwrap();
}
/// Calls the `handlers` once each and [`block_on_multi`] with a 60 seconds timeout.
///
/// [`block_on_multi`]: Self::block_on_multi
#[track_caller]
#[cfg(any(test, doc, feature = "test_util"))]
pub fn doc_test_multi<A>(args: A, mut handlers: Vec<Box<dyn AppHandler<A>>>)
where
A: Clone + 'static,
{
let mut app = crate::APP.minimal().run_headless(false);
app.block_on_multi(handlers.iter_mut().map(|h| h.as_mut()).collect(), &args, DOC_TEST_BLOCK_ON_TIMEOUT)
.unwrap()
}
}
#[cfg(any(test, doc, feature = "test_util"))]
const DOC_TEST_BLOCK_ON_TIMEOUT: Duration = Duration::from_secs(60);