Feat: overall API updates

packages/core/src/hooks.rs

@@ -0,0 +1,116 @@
+//! Useful, foundational hooks that 3rd parties can implement.
+//! Currently implemented:
+//! - use_ref
+//! - use_state
+
+pub use use_ref_def::use_ref;
+pub use use_state_def::use_state;
+
+mod use_state_def {
+    use crate::inner::*;
+    use std::{borrow::BorrowMut, cell::RefCell, ops::DerefMut, rc::Rc};
+
+    struct UseState<T: 'static> {
+        new_val: Rc<RefCell<Option<T>>>,
+        current_val: T,
+        caller: Box<dyn Fn(T) + 'static>,
+    }
+
+    /// Store state between component renders!
+    /// When called, this hook retrives a stored value and provides a setter to update that value.
+    /// When the setter is called, the component is re-ran with the new value.
+    ///
+    /// This is behaves almost exactly the same way as React's "use_state".
+    ///
+    /// Usage:
+    /// ```ignore
+    /// static Example: FC<()> = |ctx| {
+    ///     let (counter, set_counter) = use_state(ctx, || 0);
+    ///     let increment = || set_couter(counter + 1);
+    ///     let decrement = || set_couter(counter + 1);
+    ///
+    ///     html! {
+    ///         <div>
+    ///             <h1>"Counter: {counter}" </h1>
+    ///             <button onclick={increment}> "Increment" </button>
+    ///             <button onclick={decrement}> "Decrement" </button>
+    ///         </div>  
+    ///     }
+    /// }
+    /// ```
+    pub fn use_state<'a, T: 'static, F: FnOnce() -> T + 'static>(
+        ctx: &'_ Context<'a>,
+        initial_state_fn: F,
+    ) -> (&'a T, &'a impl Fn(T)) {
+        ctx.use_hook(
+            move || UseState {
+                new_val: Rc::new(RefCell::new(None)),
+                current_val: initial_state_fn(),
+                caller: Box::new(|_| println!("setter called!")),
+            },
+            move |hook| {
+                let inner = hook.new_val.clone();
+                let scheduled_update = ctx.schedule_update();
+
+                // get ownership of the new val and replace the current with the new
+                // -> as_ref -> borrow_mut -> deref_mut -> take
+                // -> rc     -> &RefCell   -> RefMut    -> &Option<T> -> T
+                if let Some(new_val) = hook.new_val.as_ref().borrow_mut().deref_mut().take() {
+                    hook.current_val = new_val;
+                }
+
+                // todo: swap out the caller with a subscription call and an internal update
+                hook.caller = Box::new(move |new_val| {
+                    // update the setter with the new value
+                    let mut new_inner = inner.as_ref().borrow_mut();
+                    *new_inner = Some(new_val);
+
+                    // Ensure the component gets updated
+                    scheduled_update();
+                });
+
+                // box gets derefed into a ref which is then taken as ref with the hook
+                (&hook.current_val, &hook.caller)
+            },
+            |_| {},
+        )
+    }
+}
+
+mod use_ref_def {
+    use crate::inner::*;
+    use std::{borrow::BorrowMut, cell::RefCell, ops::DerefMut, rc::Rc};
+
+    pub struct UseRef<T: 'static> {
+        _current: RefCell<T>,
+    }
+    impl<T: 'static> UseRef<T> {
+        fn new(val: T) -> Self {
+            Self {
+                _current: RefCell::new(val),
+            }
+        }
+
+        fn modify(&self, modifier: impl FnOnce(&mut T)) {
+            let mut val = self._current.borrow_mut();
+            let val_as_ref = val.deref_mut();
+            modifier(val_as_ref);
+        }
+
+        pub fn current(&self) -> std::cell::Ref<'_, T> {
+            self._current.borrow()
+        }
+    }
+
+    /// Store a mutable value between renders!
+    /// To read the value, borrow the ref.
+    /// To change it, use modify.
+    /// Modifications to this value do not cause updates to the component
+    /// Attach to inner context reference, so context can be consumed
+    pub fn use_ref<'a, T: 'static>(
+        ctx: &'_ Context<'a>,
+        initial_state_fn: impl FnOnce() -> T + 'static,
+    ) -> &'a UseRef<T> {
+        ctx.use_hook(|| UseRef::new(initial_state_fn()), |state| &*state, |_| {})
+    }
+}