Improve the custom hooks chapter

docs/guide/examples/hooks_custom_logic.rs

@@ -0,0 +1,57 @@
+#![allow(unused)]
+
+use dioxus::prelude::*;
+
+fn main() {}
+
+// ANCHOR: use_state
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::sync::Arc;
+
+#[derive(Clone)]
+struct UseState<T> {
+    value: Rc<RefCell<T>>,
+    update: Arc<dyn Fn()>,
+}
+
+fn my_use_state<T: 'static>(cx: &ScopeState, init: impl FnOnce() -> T) -> &UseState<T> {
+    cx.use_hook(|| {
+        // The update function will trigger a re-render in the component cx is attached to
+        let update = cx.schedule_update();
+        // Create the initial state
+        let value = Rc::new(RefCell::new(init()));
+
+        UseState { value, update }
+    })
+}
+
+impl<T: Clone> UseState<T> {
+    fn get(&self) -> T {
+        self.value.borrow().clone()
+    }
+
+    fn set(&self, value: T) {
+        // Update the state
+        *self.value.borrow_mut() = value;
+        // Trigger a re-render on the component the state is from
+        (self.update)();
+    }
+}
+// ANCHOR_END: use_state
+
+// ANCHOR: use_context
+pub fn use_context<T: 'static + Clone>(cx: &ScopeState) -> Option<&T> {
+    cx.use_hook(|| cx.consume_context::<T>()).as_ref()
+}
+
+pub fn use_context_provider<T: 'static + Clone>(cx: &ScopeState, f: impl FnOnce() -> T) -> &T {
+    cx.use_hook(|| {
+        let val = f();
+        // Provide the context state to the scope
+        cx.provide_context(val.clone());
+        val
+    })
+}
+
+// ANCHOR_END: use_context