| //! Support for long-lived closures in `wasm-bindgen` |
| //! |
| //! This module defines the `Closure` type which is used to pass "owned |
| //! closures" from Rust to JS. Some more details can be found on the `Closure` |
| //! type itself. |
| |
| use std::fmt; |
| #[cfg(feature = "nightly")] |
| use std::marker::Unsize; |
| use std::mem::{self, ManuallyDrop}; |
| use std::prelude::v1::*; |
| |
| use crate::convert::*; |
| use crate::describe::*; |
| use crate::throw_str; |
| use crate::JsValue; |
| use crate::UnwrapThrowExt; |
| |
| /// A handle to both a closure in Rust as well as JS closure which will invoke |
| /// the Rust closure. |
| /// |
| /// A `Closure` is the primary way that a `'static` lifetime closure is |
| /// transferred from Rust to JS. `Closure` currently requires that the closures |
| /// it's created with have the `'static` lifetime in Rust for soundness reasons. |
| /// |
| /// This type is a "handle" in the sense that whenever it is dropped it will |
| /// invalidate the JS closure that it refers to. Any usage of the closure in JS |
| /// after the `Closure` has been dropped will raise an exception. It's then up |
| /// to you to arrange for `Closure` to be properly deallocate at an appropriate |
| /// location in your program. |
| /// |
| /// The type parameter on `Closure` is the type of closure that this represents. |
| /// Currently this can only be the `Fn` and `FnMut` traits with up to 7 |
| /// arguments (and an optional return value). The arguments/return value of the |
| /// trait must be numbers like `u32` for now, although this restriction may be |
| /// lifted in the future! |
| /// |
| /// # Examples |
| /// |
| /// Here are a number of examples of using `Closure`. |
| /// |
| /// ## Using the `setInterval` API |
| /// |
| /// Sample usage of `Closure` to invoke the `setInterval` API. |
| /// |
| /// ```rust,no_run |
| /// use wasm_bindgen::prelude::*; |
| /// |
| /// #[wasm_bindgen] |
| /// extern "C" { |
| /// fn setInterval(closure: &Closure<FnMut()>, time: u32) -> i32; |
| /// fn clearInterval(id: i32); |
| /// |
| /// #[wasm_bindgen(js_namespace = console)] |
| /// fn log(s: &str); |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub struct IntervalHandle { |
| /// interval_id: i32, |
| /// _closure: Closure<FnMut()>, |
| /// } |
| /// |
| /// impl Drop for IntervalHandle { |
| /// fn drop(&mut self) { |
| /// clearInterval(self.interval_id); |
| /// } |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub fn run() -> IntervalHandle { |
| /// // First up we use `Closure::wrap` to wrap up a Rust closure and create |
| /// // a JS closure. |
| /// let cb = Closure::wrap(Box::new(|| { |
| /// log("interval elapsed!"); |
| /// }) as Box<FnMut()>); |
| /// |
| /// // Next we pass this via reference to the `setInterval` function, and |
| /// // `setInterval` gets a handle to the corresponding JS closure. |
| /// let interval_id = setInterval(&cb, 1_000); |
| /// |
| /// // If we were to drop `cb` here it would cause an exception to be raised |
| /// // whenever the interval elapses. Instead we *return* our handle back to JS |
| /// // so JS can decide when to cancel the interval and deallocate the closure. |
| /// IntervalHandle { |
| /// interval_id, |
| /// _closure: cb, |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// ## Casting a `Closure` to a `js_sys::Function` |
| /// |
| /// This is the same `setInterval` example as above, except it is using |
| /// `web_sys` (which uses `js_sys::Function` for callbacks) instead of manually |
| /// writing bindings to `setInterval` and other Web APIs. |
| /// |
| /// ```rust,ignore |
| /// use wasm_bindgen::JsCast; |
| /// |
| /// #[wasm_bindgen] |
| /// pub struct IntervalHandle { |
| /// interval_id: i32, |
| /// _closure: Closure<FnMut()>, |
| /// } |
| /// |
| /// impl Drop for IntervalHandle { |
| /// fn drop(&mut self) { |
| /// let window = web_sys::window().unwrap(); |
| /// window.clear_interval_with_handle(self.interval_id); |
| /// } |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub fn run() -> Result<IntervalHandle, JsValue> { |
| /// let cb = Closure::wrap(Box::new(|| { |
| /// web_sys::console::log_1(&"inverval elapsed!".into()); |
| /// }) as Box<FnMut()>); |
| /// |
| /// let window = web_sys::window().unwrap(); |
| /// let interval_id = window.set_interval_with_callback_and_timeout_and_arguments_0( |
| /// // Note this method call, which uses `as_ref()` to get a `JsValue` |
| /// // from our `Closure` which is then converted to a `&Function` |
| /// // using the `JsCast::unchecked_ref` function. |
| /// cb.as_ref().unchecked_ref(), |
| /// 1_000, |
| /// )?; |
| /// |
| /// // Same as above. |
| /// Ok(IntervalHandle { |
| /// interval_id, |
| /// _closure: cb, |
| /// }) |
| /// } |
| /// ``` |
| /// |
| /// ## Using `FnOnce` and `Closure::once` with `requestAnimationFrame` |
| /// |
| /// Because `requestAnimationFrame` only calls its callback once, we can use |
| /// `FnOnce` and `Closure::once` with it. |
| /// |
| /// ```rust,no_run |
| /// use wasm_bindgen::prelude::*; |
| /// |
| /// #[wasm_bindgen] |
| /// extern "C" { |
| /// fn requestAnimationFrame(closure: &Closure<FnMut()>) -> u32; |
| /// fn cancelAnimationFrame(id: u32); |
| /// |
| /// #[wasm_bindgen(js_namespace = console)] |
| /// fn log(s: &str); |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub struct AnimationFrameHandle { |
| /// animation_id: u32, |
| /// _closure: Closure<FnMut()>, |
| /// } |
| /// |
| /// impl Drop for AnimationFrameHandle { |
| /// fn drop(&mut self) { |
| /// cancelAnimationFrame(self.animation_id); |
| /// } |
| /// } |
| /// |
| /// // A type that will log a message when it is dropped. |
| /// struct LogOnDrop(&'static str); |
| /// impl Drop for LogOnDrop { |
| /// fn drop(&mut self) { |
| /// log(self.0); |
| /// } |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub fn run() -> AnimationFrameHandle { |
| /// // We are using `Closure::once` which takes a `FnOnce`, so the function |
| /// // can drop and/or move things that it closes over. |
| /// let fired = LogOnDrop("animation frame fired or canceled"); |
| /// let cb = Closure::once(move || drop(fired)); |
| /// |
| /// // Schedule the animation frame! |
| /// let animation_id = requestAnimationFrame(&cb); |
| /// |
| /// // Again, return a handle to JS, so that the closure is not dropped |
| /// // immediately and JS can decide whether to cancel the animation frame. |
| /// AnimationFrameHandle { |
| /// animation_id, |
| /// _closure: cb, |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// ## Converting `FnOnce`s directly into JavaScript Functions with `Closure::once_into_js` |
| /// |
| /// If we don't want to allow a `FnOnce` to be eagerly dropped (maybe because we |
| /// just want it to drop after it is called and don't care about cancellation) |
| /// then we can use the `Closure::once_into_js` function. |
| /// |
| /// This is the same `requestAnimationFrame` example as above, but without |
| /// supporting early cancellation. |
| /// |
| /// ``` |
| /// use wasm_bindgen::prelude::*; |
| /// |
| /// #[wasm_bindgen] |
| /// extern "C" { |
| /// // We modify the binding to take an untyped `JsValue` since that is what |
| /// // is returned by `Closure::once_into_js`. |
| /// // |
| /// // If we were using the `web_sys` binding for `requestAnimationFrame`, |
| /// // then the call sites would cast the `JsValue` into a `&js_sys::Function` |
| /// // using `f.unchecked_ref::<js_sys::Function>()`. See the `web_sys` |
| /// // example above for details. |
| /// fn requestAnimationFrame(callback: JsValue); |
| /// |
| /// #[wasm_bindgen(js_namespace = console)] |
| /// fn log(s: &str); |
| /// } |
| /// |
| /// // A type that will log a message when it is dropped. |
| /// struct LogOnDrop(&'static str); |
| /// impl Drop for LogOnDrop { |
| /// fn drop(&mut self) { |
| /// log(self.0); |
| /// } |
| /// } |
| /// |
| /// #[wasm_bindgen] |
| /// pub fn run() { |
| /// // We are using `Closure::once_into_js` which takes a `FnOnce` and |
| /// // converts it into a JavaScript function, which is returned as a |
| /// // `JsValue`. |
| /// let fired = LogOnDrop("animation frame fired"); |
| /// let cb = Closure::once_into_js(move || drop(fired)); |
| /// |
| /// // Schedule the animation frame! |
| /// requestAnimationFrame(cb); |
| /// |
| /// // No need to worry about whether or not we drop a `Closure` |
| /// // here or return some sort of handle to JS! |
| /// } |
| /// ``` |
| pub struct Closure<T: ?Sized> { |
| js: ManuallyDrop<JsValue>, |
| data: ManuallyDrop<Box<T>>, |
| } |
| |
| union FatPtr<T: ?Sized> { |
| ptr: *mut T, |
| fields: (usize, usize), |
| } |
| |
| impl<T> Closure<T> |
| where |
| T: ?Sized + WasmClosure, |
| { |
| /// A more ergonomic version of `Closure::wrap` that does the boxing and |
| /// cast to trait object for you. |
| /// |
| /// *This method requires the `nightly` feature of the `wasm-bindgen` crate |
| /// to be enabled, meaning this is a nightly-only API. Users on stable |
| /// should use `Closure::wrap`.* |
| #[cfg(feature = "nightly")] |
| pub fn new<F>(t: F) -> Closure<T> |
| where |
| F: Unsize<T> + 'static, |
| { |
| Closure::wrap(Box::new(t) as Box<T>) |
| } |
| |
| /// Creates a new instance of `Closure` from the provided boxed Rust |
| /// function. |
| /// |
| /// Note that the closure provided here, `Box<T>`, has a few requirements |
| /// associated with it: |
| /// |
| /// * It must implement `Fn` or `FnMut` (for `FnOnce` functions see |
| /// `Closure::once` and `Closure::once_into_js`). |
| /// |
| /// * It must be `'static`, aka no stack references (use the `move` |
| /// keyword). |
| /// |
| /// * It can have at most 7 arguments. |
| /// |
| /// * Its arguments and return values are all types that can be shared with |
| /// JS (i.e. have `#[wasm_bindgen]` annotations or are simple numbers, |
| /// etc.) |
| pub fn wrap(mut data: Box<T>) -> Closure<T> { |
| assert_eq!(mem::size_of::<*const T>(), mem::size_of::<FatPtr<T>>()); |
| let (a, b) = unsafe { |
| FatPtr { |
| ptr: &mut *data as *mut T, |
| } |
| .fields |
| }; |
| |
| // Here we need to create a `JsValue` with the data and `T::invoke()` |
| // function pointer. To do that we... take a few unconventional turns. |
| // In essence what happens here is this: |
| // |
| // 1. First up, below we call a function, `breaks_if_inlined`. This |
| // function, as the name implies, does not work if it's inlined. |
| // More on that in a moment. |
| // 2. This function internally calls a special import recognized by the |
| // `wasm-bindgen` CLI tool, `__wbindgen_describe_closure`. This |
| // imported symbol is similar to `__wbindgen_describe` in that it's |
| // not intended to show up in the final binary but it's an |
| // intermediate state for a `wasm-bindgen` binary. |
| // 3. The `__wbindgen_describe_closure` import is namely passed a |
| // descriptor function, monomorphized for each invocation. |
| // |
| // Most of this doesn't actually make sense to happen at runtime! The |
| // real magic happens when `wasm-bindgen` comes along and updates our |
| // generated code. When `wasm-bindgen` runs it performs a few tasks: |
| // |
| // * First, it finds all functions that call |
| // `__wbindgen_describe_closure`. These are all `breaks_if_inlined` |
| // defined below as the symbol isn't called anywhere else. |
| // * Next, `wasm-bindgen` executes the `breaks_if_inlined` |
| // monomorphized functions, passing it dummy arguments. This will |
| // execute the function just enough to invoke the special import, |
| // namely telling us about the function pointer that is the describe |
| // shim. |
| // * This knowledge is then used to actually find the descriptor in the |
| // function table which is then executed to figure out the signature |
| // of the closure. |
| // * Finally, and probably most heinously, the call to |
| // `breaks_if_inlined` is rewritten to call an otherwise globally |
| // imported function. This globally imported function will generate |
| // the `JsValue` for this closure specialized for the signature in |
| // question. |
| // |
| // Later on `wasm-gc` will clean up all the dead code and ensure that |
| // we don't actually call `__wbindgen_describe_closure` at runtime. This |
| // means we will end up not actually calling `breaks_if_inlined` in the |
| // final binary, all calls to that function should be pruned. |
| // |
| // See crates/cli-support/src/js/closures.rs for a more information |
| // about what's going on here. |
| |
| extern "C" fn describe<T: WasmClosure + ?Sized>() { |
| inform(CLOSURE); |
| T::describe() |
| } |
| |
| #[inline(never)] |
| unsafe fn breaks_if_inlined<T: WasmClosure + ?Sized>(a: usize, b: usize) -> u32 { |
| super::__wbindgen_describe_closure(a as u32, b as u32, describe::<T> as u32) |
| } |
| |
| let idx = unsafe { breaks_if_inlined::<T>(a, b) }; |
| |
| Closure { |
| js: ManuallyDrop::new(JsValue::_new(idx)), |
| data: ManuallyDrop::new(data), |
| } |
| } |
| |
| /// Leaks this `Closure` to ensure it remains valid for the duration of the |
| /// entire program. |
| /// |
| /// > **Note**: this function will leak memory. It should be used sparingly |
| /// > to ensure the memory leak doesn't affect the program too much. |
| /// |
| /// When a `Closure` is dropped it will invalidate the associated JS |
| /// closure, but this isn't always desired. Some callbacks are alive for |
| /// the entire duration of the program, so this can be used to conveniently |
| /// leak this instance of `Closure` while performing as much internal |
| /// cleanup as it can. |
| pub fn forget(self) { |
| unsafe { |
| super::__wbindgen_cb_forget(self.js.idx); |
| mem::forget(self); |
| } |
| } |
| } |
| |
| // NB: we use a specific `T` for this `Closure<T>` impl block to avoid every |
| // call site having to provide an explicit, turbo-fished type like |
| // `Closure::<FnOnce()>::once(...)`. |
| impl Closure<dyn FnOnce()> { |
| /// Create a `Closure` from a function that can only be called once. |
| /// |
| /// Since we have no way of enforcing that JS cannot attempt to call this |
| /// `FnOne(A...) -> R` more than once, this produces a `Closure<FnMut(A...) |
| /// -> R>` that will dynamically throw a JavaScript error if called more |
| /// than once. |
| /// |
| /// # Example |
| /// |
| /// ```rust,no_run |
| /// use wasm_bindgen::prelude::*; |
| /// |
| /// // Create an non-`Copy`, owned `String`. |
| /// let mut s = String::from("Hello"); |
| /// |
| /// // Close over `s`. Since `f` returns `s`, it is `FnOnce` and can only be |
| /// // called once. If it was called a second time, it wouldn't have any `s` |
| /// // to work with anymore! |
| /// let f = move || { |
| /// s += ", World!"; |
| /// s |
| /// }; |
| /// |
| /// // Create a `Closure` from `f`. Note that the `Closure`'s type parameter |
| /// // is `FnMut`, even though `f` is `FnOnce`. |
| /// let closure: Closure<FnMut() -> String> = Closure::once(f); |
| /// ``` |
| pub fn once<F, A, R>(fn_once: F) -> Closure<F::FnMut> |
| where |
| F: 'static + WasmClosureFnOnce<A, R>, |
| { |
| Closure::wrap(fn_once.into_fn_mut()) |
| } |
| |
| /// Convert a `FnOnce(A...) -> R` into a JavaScript `Function` object. |
| /// |
| /// If the JavaScript function is invoked more than once, it will throw an |
| /// exception. |
| /// |
| /// Unlike `Closure::once`, this does *not* return a `Closure` that can be |
| /// dropped before the function is invoked to deallocate the closure. The |
| /// only way the `FnOnce` is deallocated is by calling the JavaScript |
| /// function. If the JavaScript function is never called then the `FnOnce` |
| /// and everything it closes over will leak. |
| /// |
| /// ```rust,ignore |
| /// use js_sys; |
| /// use wasm_bindgen::{prelude::*, JsCast}; |
| /// |
| /// let f = Closure::once_into_js(move || { |
| /// // ... |
| /// }); |
| /// |
| /// assert!(f.is_instance_of::<js_sys::Function>()); |
| /// ``` |
| pub fn once_into_js<F, A, R>(fn_once: F) -> JsValue |
| where |
| F: 'static + WasmClosureFnOnce<A, R>, |
| { |
| fn_once.into_js_function() |
| } |
| } |
| |
| /// A trait for converting an `FnOnce(A...) -> R` into a `FnMut(A...) -> R` that |
| /// will throw if ever called more than once. |
| #[doc(hidden)] |
| pub trait WasmClosureFnOnce<A, R>: 'static { |
| type FnMut: ?Sized + 'static + WasmClosure; |
| |
| fn into_fn_mut(self) -> Box<Self::FnMut>; |
| |
| fn into_js_function(self) -> JsValue; |
| } |
| |
| impl<T: ?Sized> AsRef<JsValue> for Closure<T> { |
| fn as_ref(&self) -> &JsValue { |
| &self.js |
| } |
| } |
| |
| impl<T> WasmDescribe for Closure<T> |
| where |
| T: WasmClosure + ?Sized, |
| { |
| fn describe() { |
| inform(ANYREF); |
| } |
| } |
| |
| // `Closure` can only be passed by reference to imports. |
| impl<'a, T> IntoWasmAbi for &'a Closure<T> |
| where |
| T: WasmClosure + ?Sized, |
| { |
| type Abi = u32; |
| |
| fn into_abi(self) -> u32 { |
| (&*self.js).into_abi() |
| } |
| } |
| |
| fn _check() { |
| fn _assert<T: IntoWasmAbi>() {} |
| _assert::<&Closure<dyn Fn()>>(); |
| _assert::<&Closure<dyn Fn(String)>>(); |
| _assert::<&Closure<dyn Fn() -> String>>(); |
| _assert::<&Closure<dyn FnMut()>>(); |
| _assert::<&Closure<dyn FnMut(String)>>(); |
| _assert::<&Closure<dyn FnMut() -> String>>(); |
| } |
| |
| impl<T> fmt::Debug for Closure<T> |
| where |
| T: ?Sized, |
| { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| write!(f, "Closure {{ ... }}") |
| } |
| } |
| |
| impl<T> Drop for Closure<T> |
| where |
| T: ?Sized, |
| { |
| fn drop(&mut self) { |
| unsafe { |
| // this will implicitly drop our strong reference in addition to |
| // invalidating all future invocations of the closure |
| if super::__wbindgen_cb_drop(self.js.idx) != 0 { |
| ManuallyDrop::drop(&mut self.data); |
| } |
| } |
| } |
| } |
| |
| /// An internal trait for the `Closure` type. |
| /// |
| /// This trait is not stable and it's not recommended to use this in bounds or |
| /// implement yourself. |
| #[doc(hidden)] |
| pub unsafe trait WasmClosure { |
| fn describe(); |
| } |
| |
| // The memory safety here in these implementations below is a bit tricky. We |
| // want to be able to drop the `Closure` object from within the invocation of a |
| // `Closure` for cases like promises. That means that while it's running we |
| // might drop the `Closure`, but that shouldn't invalidate the environment yet. |
| // |
| // Instead what we do is to wrap closures in `Rc` variables. The main `Closure` |
| // has a strong reference count which keeps the trait object alive. Each |
| // invocation of a closure then *also* clones this and gets a new reference |
| // count. When the closure returns it will release the reference count. |
| // |
| // This means that if the main `Closure` is dropped while it's being invoked |
| // then destruction is deferred until execution returns. Otherwise it'll |
| // deallocate data immediately. |
| |
| macro_rules! doit { |
| ($( |
| ($($var:ident)*) |
| )*) => ($( |
| unsafe impl<$($var,)* R> WasmClosure for dyn Fn($($var),*) -> R + 'static |
| where $($var: FromWasmAbi + 'static,)* |
| R: ReturnWasmAbi + 'static, |
| { |
| fn describe() { |
| #[allow(non_snake_case)] |
| unsafe extern "C" fn invoke<$($var: FromWasmAbi,)* R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| $($var: <$var as FromWasmAbi>::Abi),* |
| ) -> <R as ReturnWasmAbi>::Abi { |
| if a == 0 { |
| throw_str("closure invoked recursively or destroyed already"); |
| } |
| // Make sure all stack variables are converted before we |
| // convert `ret` as it may throw (for `Result`, for |
| // example) |
| let ret = { |
| let f: *const dyn Fn($($var),*) -> R = |
| FatPtr { fields: (a, b) }.ptr; |
| $( |
| let $var = <$var as FromWasmAbi>::from_abi($var); |
| )* |
| (*f)($($var),*) |
| }; |
| ret.return_abi() |
| } |
| |
| inform(invoke::<$($var,)* R> as u32); |
| |
| unsafe extern fn destroy<$($var: FromWasmAbi,)* R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| ) { |
| // This can be called by the JS glue in erroneous situations |
| // such as when the closure has already been destroyed. If |
| // that's the case let's not make things worse by |
| // segfaulting and/or asserting, so just ignore null |
| // pointers. |
| if a == 0 { |
| return; |
| } |
| drop(Box::from_raw(FatPtr::<dyn Fn($($var,)*) -> R> { |
| fields: (a, b) |
| }.ptr)); |
| } |
| inform(destroy::<$($var,)* R> as u32); |
| |
| <&Self>::describe(); |
| } |
| } |
| |
| unsafe impl<$($var,)* R> WasmClosure for dyn FnMut($($var),*) -> R + 'static |
| where $($var: FromWasmAbi + 'static,)* |
| R: ReturnWasmAbi + 'static, |
| { |
| fn describe() { |
| #[allow(non_snake_case)] |
| unsafe extern "C" fn invoke<$($var: FromWasmAbi,)* R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| $($var: <$var as FromWasmAbi>::Abi),* |
| ) -> <R as ReturnWasmAbi>::Abi { |
| if a == 0 { |
| throw_str("closure invoked recursively or destroyed already"); |
| } |
| // Make sure all stack variables are converted before we |
| // convert `ret` as it may throw (for `Result`, for |
| // example) |
| let ret = { |
| let f: *const dyn FnMut($($var),*) -> R = |
| FatPtr { fields: (a, b) }.ptr; |
| let f = f as *mut dyn FnMut($($var),*) -> R; |
| $( |
| let $var = <$var as FromWasmAbi>::from_abi($var); |
| )* |
| (*f)($($var),*) |
| }; |
| ret.return_abi() |
| } |
| |
| inform(invoke::<$($var,)* R> as u32); |
| |
| unsafe extern fn destroy<$($var: FromWasmAbi,)* R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| ) { |
| // See `Fn()` above for why we simply return |
| if a == 0 { |
| return; |
| } |
| drop(Box::from_raw(FatPtr::<dyn FnMut($($var,)*) -> R> { |
| fields: (a, b) |
| }.ptr)); |
| } |
| inform(destroy::<$($var,)* R> as u32); |
| |
| <&mut Self>::describe(); |
| } |
| } |
| |
| #[allow(non_snake_case, unused_parens)] |
| impl<T, $($var,)* R> WasmClosureFnOnce<($($var),*), R> for T |
| where T: 'static + FnOnce($($var),*) -> R, |
| $($var: FromWasmAbi + 'static,)* |
| R: ReturnWasmAbi + 'static |
| { |
| type FnMut = dyn FnMut($($var),*) -> R; |
| |
| fn into_fn_mut(self) -> Box<Self::FnMut> { |
| let mut me = Some(self); |
| Box::new(move |$($var),*| { |
| let me = me.take().expect_throw("FnOnce called more than once"); |
| me($($var),*) |
| }) |
| } |
| |
| fn into_js_function(self) -> JsValue { |
| use std::rc::Rc; |
| use crate::__rt::WasmRefCell; |
| |
| let mut me = Some(self); |
| |
| let rc1 = Rc::new(WasmRefCell::new(None)); |
| let rc2 = rc1.clone(); |
| |
| let closure = Closure::wrap(Box::new(move |$($var),*| { |
| // Invoke ourself and get the result. |
| let me = me.take().expect_throw("FnOnce called more than once"); |
| let result = me($($var),*); |
| |
| // And then drop the `Rc` holding this function's `Closure` |
| // alive. |
| debug_assert_eq!(Rc::strong_count(&rc2), 1); |
| let option_closure = rc2.borrow_mut().take(); |
| debug_assert!(option_closure.is_some()); |
| drop(option_closure); |
| |
| result |
| }) as Box<dyn FnMut($($var),*) -> R>); |
| |
| let js_val = closure.as_ref().clone(); |
| |
| *rc1.borrow_mut() = Some(closure); |
| debug_assert_eq!(Rc::strong_count(&rc1), 2); |
| drop(rc1); |
| |
| js_val |
| } |
| } |
| )*) |
| } |
| |
| doit! { |
| () |
| (A) |
| (A B) |
| (A B C) |
| (A B C D) |
| (A B C D E) |
| (A B C D E F) |
| (A B C D E F G) |
| (A B C D E F G H) |
| } |
| |
| // Copy the above impls down here for where there's only one argument and it's a |
| // reference. We could add more impls for more kinds of references, but it |
| // becomes a combinatorial explosion quickly. Let's see how far we can get with |
| // just this one! Maybe someone else can figure out voodoo so we don't have to |
| // duplicate. |
| |
| unsafe impl<A, R> WasmClosure for dyn Fn(&A) -> R |
| where A: RefFromWasmAbi, |
| R: ReturnWasmAbi + 'static, |
| { |
| fn describe() { |
| #[allow(non_snake_case)] |
| unsafe extern "C" fn invoke<A: RefFromWasmAbi, R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| arg: <A as RefFromWasmAbi>::Abi, |
| ) -> <R as ReturnWasmAbi>::Abi { |
| if a == 0 { |
| throw_str("closure invoked recursively or destroyed already"); |
| } |
| // Make sure all stack variables are converted before we |
| // convert `ret` as it may throw (for `Result`, for |
| // example) |
| let ret = { |
| let f: *const dyn Fn(&A) -> R = |
| FatPtr { fields: (a, b) }.ptr; |
| let arg = <A as RefFromWasmAbi>::ref_from_abi(arg); |
| (*f)(&*arg) |
| }; |
| ret.return_abi() |
| } |
| |
| inform(invoke::<A, R> as u32); |
| |
| unsafe extern fn destroy<A: RefFromWasmAbi, R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| ) { |
| // See `Fn()` above for why we simply return |
| if a == 0 { |
| return; |
| } |
| drop(Box::from_raw(FatPtr::<dyn Fn(&A) -> R> { |
| fields: (a, b) |
| }.ptr)); |
| } |
| inform(destroy::<A, R> as u32); |
| |
| <&Self>::describe(); |
| } |
| } |
| |
| unsafe impl<A, R> WasmClosure for dyn FnMut(&A) -> R |
| where A: RefFromWasmAbi, |
| R: ReturnWasmAbi + 'static, |
| { |
| fn describe() { |
| #[allow(non_snake_case)] |
| unsafe extern "C" fn invoke<A: RefFromWasmAbi, R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| arg: <A as RefFromWasmAbi>::Abi, |
| ) -> <R as ReturnWasmAbi>::Abi { |
| if a == 0 { |
| throw_str("closure invoked recursively or destroyed already"); |
| } |
| // Make sure all stack variables are converted before we |
| // convert `ret` as it may throw (for `Result`, for |
| // example) |
| let ret = { |
| let f: *const dyn FnMut(&A) -> R = |
| FatPtr { fields: (a, b) }.ptr; |
| let f = f as *mut dyn FnMut(&A) -> R; |
| let arg = <A as RefFromWasmAbi>::ref_from_abi(arg); |
| (*f)(&*arg) |
| }; |
| ret.return_abi() |
| } |
| |
| inform(invoke::<A, R> as u32); |
| |
| unsafe extern fn destroy<A: RefFromWasmAbi, R: ReturnWasmAbi>( |
| a: usize, |
| b: usize, |
| ) { |
| // See `Fn()` above for why we simply return |
| if a == 0 { |
| return; |
| } |
| drop(Box::from_raw(FatPtr::<dyn FnMut(&A) -> R> { |
| fields: (a, b) |
| }.ptr)); |
| } |
| inform(destroy::<A, R> as u32); |
| |
| <&mut Self>::describe(); |
| } |
| } |
| |
| #[allow(non_snake_case)] |
| impl<T, A, R> WasmClosureFnOnce<(&A,), R> for T |
| where T: 'static + FnOnce(&A) -> R, |
| A: RefFromWasmAbi + 'static, |
| R: ReturnWasmAbi + 'static |
| { |
| type FnMut = dyn FnMut(&A) -> R; |
| |
| fn into_fn_mut(self) -> Box<Self::FnMut> { |
| let mut me = Some(self); |
| Box::new(move |arg| { |
| let me = me.take().expect_throw("FnOnce called more than once"); |
| me(arg) |
| }) |
| } |
| |
| fn into_js_function(self) -> JsValue { |
| use std::rc::Rc; |
| use crate::__rt::WasmRefCell; |
| |
| let mut me = Some(self); |
| |
| let rc1 = Rc::new(WasmRefCell::new(None)); |
| let rc2 = rc1.clone(); |
| |
| let closure = Closure::wrap(Box::new(move |arg: &A| { |
| // Invoke ourself and get the result. |
| let me = me.take().expect_throw("FnOnce called more than once"); |
| let result = me(arg); |
| |
| // And then drop the `Rc` holding this function's `Closure` |
| // alive. |
| debug_assert_eq!(Rc::strong_count(&rc2), 1); |
| let option_closure = rc2.borrow_mut().take(); |
| debug_assert!(option_closure.is_some()); |
| drop(option_closure); |
| |
| result |
| }) as Box<dyn FnMut(&A) -> R>); |
| |
| let js_val = closure.as_ref().clone(); |
| |
| *rc1.borrow_mut() = Some(closure); |
| debug_assert_eq!(Rc::strong_count(&rc1), 2); |
| drop(rc1); |
| |
| js_val |
| } |
| } |
