feat: AttributeInterceptor component to allow passing attributes to…

… other elements (#3340)

leptos/src/attribute_interceptor.rs

@@ -0,0 +1,150 @@
+use crate::attr::{
+    any_attribute::{AnyAttribute, IntoAnyAttribute},
+    Attribute, NextAttribute,
+};
+use leptos::prelude::*;
+
+/// Function stored to build/rebuild the wrapped children when attributes are added.
+type ChildBuilder<T> = dyn Fn(AnyAttribute) -> T + Send + Sync + 'static;
+
+/// Intercepts attributes passed to your component, allowing passing them to any element.
+///
+/// By default, Leptos passes any attributes passed to your component (e.g. `<MyComponent
+/// attr:class="some-class"/>`) to the top-level element in the view returned by your component.
+/// [`AttributeInterceptor`] allows you to intercept this behavior and pass it onto any element in
+/// your component instead.
+///
+/// Must be the top level element in your component's view.
+///
+/// ## Example
+///
+/// Any attributes passed to MyComponent will be passed to the #inner element.
+///
+/// ```
+/// # use leptos::prelude::*;
+/// use leptos::attribute_interceptor::AttributeInterceptor;
+///
+/// #[component]
+/// pub fn MyComponent() -> impl IntoView {
+///     view! {
+///         <AttributeInterceptor let:attrs>
+///             <div id="wrapper">
+///                 <div id="inner" {..attrs} />
+///             </div>
+///         </AttributeInterceptor>
+///     }
+/// }
+/// ```
+#[component]
+pub fn AttributeInterceptor<Chil, T>(
+    /// The elements that will be rendered, with the attributes this component received as a
+    /// parameter.
+    children: Chil,
+) -> impl IntoView
+where
+    Chil: Fn(AnyAttribute) -> T + Send + Sync + 'static,
+    T: IntoView,
+{
+    AttributeInterceptorInner::new(children)
+}
+
+/// Wrapper to intercept attributes passed to a component so you can apply them to a different
+/// element.
+struct AttributeInterceptorInner<T: IntoView, A> {
+    children_builder: Box<ChildBuilder<T>>,
+    children: T,
+    attributes: A,
+}
+
+impl<T: IntoView> AttributeInterceptorInner<T, ()> {
+    /// Use this as the returned view from your component to collect the attributes that are passed
+    /// to your component so you can manually handle them.
+    pub fn new<F>(children: F) -> Self
+    where
+        F: Fn(AnyAttribute) -> T + Send + Sync + 'static,
+    {
+        let children_builder = Box::new(children);
+        let children = children_builder(().into_any_attr());
+
+        Self {
+            children_builder,
+            children,
+            attributes: (),
+        }
+    }
+}
+
+impl<T: IntoView, A: Attribute> Render for AttributeInterceptorInner<T, A> {
+    type State = <T as Render>::State;
+
+    fn build(self) -> Self::State {
+        self.children.build()
+    }
+
+    fn rebuild(self, state: &mut Self::State) {
+        self.children.rebuild(state);
+    }
+}
+
+impl<T: IntoView, A> AddAnyAttr for AttributeInterceptorInner<T, A>
+where
+    A: Attribute,
+{
+    type Output<SomeNewAttr: leptos::attr::Attribute> =
+        AttributeInterceptorInner<T, <<A as NextAttribute>::Output<SomeNewAttr> as Attribute>::CloneableOwned>;
+
+    fn add_any_attr<NewAttr: leptos::attr::Attribute>(
+        self,
+        attr: NewAttr,
+    ) -> Self::Output<NewAttr>
+    where
+        Self::Output<NewAttr>: RenderHtml,
+    {
+        let attributes =
+            self.attributes.add_any_attr(attr).into_cloneable_owned();
+
+        let children =
+            (self.children_builder)(attributes.clone().into_any_attr());
+
+        AttributeInterceptorInner {
+            children_builder: self.children_builder,
+            children,
+            attributes,
+        }
+    }
+}
+
+impl<T: IntoView, A: Attribute> RenderHtml for AttributeInterceptorInner<T, A> {
+    type AsyncOutput = T::AsyncOutput;
+
+    const MIN_LENGTH: usize = T::MIN_LENGTH;
+
+    fn dry_resolve(&mut self) {
+        self.children.dry_resolve()
+    }
+
+    fn resolve(
+        self,
+    ) -> impl std::future::Future<Output = Self::AsyncOutput> + Send {
+        self.children.resolve()
+    }
+
+    fn to_html_with_buf(
+        self,
+        buf: &mut String,
+        position: &mut leptos::tachys::view::Position,
+        escape: bool,
+        mark_branches: bool,
+    ) {
+        self.children
+            .to_html_with_buf(buf, position, escape, mark_branches)
+    }
+
+    fn hydrate<const FROM_SERVER: bool>(
+        self,
+        cursor: &leptos::tachys::hydration::Cursor,
+        position: &leptos::tachys::view::PositionState,
+    ) -> Self::State {
+        self.children.hydrate::<FROM_SERVER>(cursor, position)
+    }
+}

leptos/src/lib.rs

@@ -192,6 +192,9 @@ pub mod callback;
 /// Types that can be passed as the `children` prop of a component.
 pub mod children;
 
+/// Wrapper for intercepting component attributes.
+pub mod attribute_interceptor;
+
 #[doc(hidden)]
 /// Traits used to implement component constructors.
 pub mod component;