Merge branch 'master' into debug-signals

packages/signals/src/signal.rs

@@ -1,5 +1,6 @@
 use std::{
     cell::RefCell,
+    mem::MaybeUninit,
     ops::{Deref, DerefMut},
     rc::Rc,
     sync::Arc,
@@ -11,7 +12,7 @@ use dioxus_core::{
 };
 use generational_box::{GenerationalRef, GenerationalRefMut};
 
-use crate::{CopyValue, Effect};
+use crate::{get_effect_stack, CopyValue, Effect, EffectStack};
 
 /// Creates a new Signal. Signals are a Copy state management solution with automatic dependency tracking.
 ///
@@ -45,6 +46,7 @@ use crate::{CopyValue, Effect};
 /// }
 /// ```
 #[track_caller]
+#[must_use]
 pub fn use_signal<T: 'static>(cx: &ScopeState, f: impl FnOnce() -> T) -> Signal<T> {
     #[cfg(debug_assertions)]
     let caller = std::panic::Location::caller();
@@ -91,6 +93,7 @@ pub(crate) struct SignalData<T> {
     pub(crate) subscribers: Rc<RefCell<Vec<ScopeId>>>,
     pub(crate) effect_subscribers: Rc<RefCell<Vec<Effect>>>,
     pub(crate) update_any: Arc<dyn Fn(ScopeId)>,
+    pub(crate) effect_stack: EffectStack,
     pub(crate) value: T,
 }
 
@@ -154,6 +157,7 @@ impl<T: 'static> Signal<T> {
                 effect_subscribers: Default::default(),
                 update_any: schedule_update_any().expect("in a virtual dom"),
                 value,
+                effect_stack: get_effect_stack(),
             }),
         }
     }
@@ -170,6 +174,7 @@ impl<T: 'static> Signal<T> {
                     effect_subscribers: Default::default(),
                     update_any: schedule_update_any().expect("in a virtual dom"),
                     value,
+                    effect_stack: get_effect_stack(),
                 },
                 #[cfg(debug_assertions)]
                 caller,
@@ -186,6 +191,7 @@ impl<T: 'static> Signal<T> {
                     effect_subscribers: Default::default(),
                     update_any: schedule_update_any().expect("in a virtual dom"),
                     value,
+                    effect_stack: get_effect_stack(),
                 },
                 owner,
             ),
@@ -202,7 +208,7 @@ impl<T: 'static> Signal<T> {
     #[track_caller]
     pub fn read(&self) -> GenerationalRef<T> {
         let inner = self.inner.read();
-        if let Some(effect) = Effect::current() {
+        if let Some(effect) = inner.effect_stack.current() {
             let mut effect_subscribers = inner.effect_subscribers.borrow_mut();
             if !effect_subscribers.contains(&effect) {
                 effect_subscribers.push(effect);
@@ -230,7 +236,7 @@ impl<T: 'static> Signal<T> {
     /// Get a mutable reference to the signal's value.
     /// If the signal has been dropped, this will panic.
     #[track_caller]
-    pub fn write(&self) -> Write<'_, T> {
+    pub fn write(&self) -> Write<T> {
         let inner = self.inner.write();
         let borrow = GenerationalRefMut::map(inner, |v| &mut v.value);
         Write {
@@ -299,12 +305,52 @@ impl<T: Clone + 'static> Signal<T> {
     }
 }
 
+impl Signal<bool> {
+    /// Invert the boolean value of the signal. This will trigger an update on all subscribers.
+    pub fn toggle(&self) {
+        self.set(!self.value());
+    }
+}
+
 impl<T: 'static> PartialEq for Signal<T> {
     fn eq(&self, other: &Self) -> bool {
         self.inner == other.inner
     }
 }
 
+impl<T> Deref for Signal<T> {
+    type Target = dyn Fn() -> GenerationalRef<T>;
+
+    fn deref(&self) -> &Self::Target {
+        // https://github.com/dtolnay/case-studies/tree/master/callable-types
+
+        // First we create a closure that captures something with the Same in memory layout as Self (MaybeUninit<Self>).
+        let uninit_callable = MaybeUninit::<Self>::uninit();
+        // Then move that value into the closure. We assume that the closure now has a in memory layout of Self.
+        let uninit_closure = move || Self::read(unsafe { &*uninit_callable.as_ptr() });
+
+        // Check that the size of the closure is the same as the size of Self in case the compiler changed the layout of the closure.
+        let size_of_closure = std::mem::size_of_val(&uninit_closure);
+        assert_eq!(size_of_closure, std::mem::size_of::<Self>());
+
+        // Then cast the lifetime of the closure to the lifetime of &self.
+        fn cast_lifetime<'a, T>(_a: &T, b: &'a T) -> &'a T {
+            b
+        }
+        let reference_to_closure = cast_lifetime(
+            {
+                // The real closure that we will never use.
+                &uninit_closure
+            },
+            // We transmute self into a reference to the closure. This is safe because we know that the closure has the same memory layout as Self so &Closure == &Self.
+            unsafe { std::mem::transmute(self) },
+        );
+
+        // Cast the closure to a trait object.
+        reference_to_closure as &Self::Target
+    }
+}
+
 struct SignalSubscriberDrop<T: 'static> {
     signal: Signal<T>,
 }
@@ -316,14 +362,14 @@ impl<T: 'static> Drop for SignalSubscriberDrop<T> {
 }
 
 /// A mutable reference to a signal's value.
-pub struct Write<'a, T: 'static, I: 'static = T> {
-    write: GenerationalRefMut<'a, T>,
+pub struct Write<T: 'static, I: 'static = T> {
+    write: GenerationalRefMut<T>,
     signal: SignalSubscriberDrop<I>,
 }
 
-impl<'a, T: 'static, I: 'static> Write<'a, T, I> {
+impl<T: 'static, I: 'static> Write<T, I> {
     /// Map the mutable reference to the signal's value to a new type.
-    pub fn map<O>(myself: Self, f: impl FnOnce(&mut T) -> &mut O) -> Write<'a, O, I> {
+    pub fn map<O>(myself: Self, f: impl FnOnce(&mut T) -> &mut O) -> Write<O, I> {
         let Self { write, signal } = myself;
         Write {
             write: GenerationalRefMut::map(write, f),
@@ -335,14 +381,14 @@ impl<'a, T: 'static, I: 'static> Write<'a, T, I> {
     pub fn filter_map<O>(
         myself: Self,
         f: impl FnOnce(&mut T) -> Option<&mut O>,
-    ) -> Option<Write<'a, O, I>> {
+    ) -> Option<Write<O, I>> {
         let Self { write, signal } = myself;
         let write = GenerationalRefMut::filter_map(write, f);
         write.map(|write| Write { write, signal })
     }
 }
 
-impl<'a, T: 'static> Deref for Write<'a, T> {
+impl<T: 'static, I: 'static> Deref for Write<T, I> {
     type Target = T;
 
     fn deref(&self) -> &Self::Target {
@@ -350,7 +396,7 @@ impl<'a, T: 'static> Deref for Write<'a, T> {
     }
 }
 
-impl<T> DerefMut for Write<'_, T> {
+impl<T, I> DerefMut for Write<T, I> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.write
     }
@@ -397,3 +443,36 @@ impl<T: 'static> PartialEq for ReadOnlySignal<T> {
         self.inner == other.inner
     }
 }
+
+impl<T> Deref for ReadOnlySignal<T> {
+    type Target = dyn Fn() -> GenerationalRef<T>;
+
+    fn deref(&self) -> &Self::Target {
+        // https://github.com/dtolnay/case-studies/tree/master/callable-types
+
+        // First we create a closure that captures something with the Same in memory layout as Self (MaybeUninit<Self>).
+        let uninit_callable = MaybeUninit::<Self>::uninit();
+        // Then move that value into the closure. We assume that the closure now has a in memory layout of Self.
+        let uninit_closure = move || Self::read(unsafe { &*uninit_callable.as_ptr() });
+
+        // Check that the size of the closure is the same as the size of Self in case the compiler changed the layout of the closure.
+        let size_of_closure = std::mem::size_of_val(&uninit_closure);
+        assert_eq!(size_of_closure, std::mem::size_of::<Self>());
+
+        // Then cast the lifetime of the closure to the lifetime of &self.
+        fn cast_lifetime<'a, T>(_a: &T, b: &'a T) -> &'a T {
+            b
+        }
+        let reference_to_closure = cast_lifetime(
+            {
+                // The real closure that we will never use.
+                &uninit_closure
+            },
+            // We transmute self into a reference to the closure. This is safe because we know that the closure has the same memory layout as Self so &Closure == &Self.
+            unsafe { std::mem::transmute(self) },
+        );
+
+        // Cast the closure to a trait object.
+        reference_to_closure as &Self::Target
+    }
+}