Create `iced_widget` subcrate and re-organize the whole codebase

1 files changed, 409 insertions, 0 deletions

diff --git a/widget/src/lazy.rs b/widget/src/lazy.rs
new file mode 100644
index 00000000..b08ed8cb
--- /dev/null
+++ b/widget/src/lazy.rs
@@ -0,0 +1,409 @@
+#![allow(clippy::await_holding_refcell_ref, clippy::type_complexity)]
+pub(crate) mod helpers;
+
+pub mod component;
+pub mod responsive;
+
+pub use component::Component;
+pub use responsive::Responsive;
+
+mod cache;
+
+use crate::core::event::{self, Event};
+use crate::core::layout::{self, Layout};
+use crate::core::mouse;
+use crate::core::overlay;
+use crate::core::renderer;
+use crate::core::widget::tree::{self, Tree};
+use crate::core::widget::{self, Widget};
+use crate::core::Element;
+use crate::core::{
+    self, Clipboard, Hasher, Length, Point, Rectangle, Shell, Size,
+};
+
+use ouroboros::self_referencing;
+use std::cell::RefCell;
+use std::hash::{Hash, Hasher as H};
+use std::rc::Rc;
+
+#[allow(missing_debug_implementations)]
+pub struct Lazy<'a, Message, Renderer, Dependency, View> {
+    dependency: Dependency,
+    view: Box<dyn Fn(&Dependency) -> View + 'a>,
+    element: RefCell<
+        Option<Rc<RefCell<Option<Element<'static, Message, Renderer>>>>>,
+    >,
+}
+
+impl<'a, Message, Renderer, Dependency, View>
+    Lazy<'a, Message, Renderer, Dependency, View>
+where
+    Dependency: Hash + 'a,
+    View: Into<Element<'static, Message, Renderer>>,
+{
+    pub fn new(
+        dependency: Dependency,
+        view: impl Fn(&Dependency) -> View + 'a,
+    ) -> Self {
+        Self {
+            dependency,
+            view: Box::new(view),
+            element: RefCell::new(None),
+        }
+    }
+
+    fn with_element<T>(
+        &self,
+        f: impl FnOnce(&Element<'_, Message, Renderer>) -> T,
+    ) -> T {
+        f(self
+            .element
+            .borrow()
+            .as_ref()
+            .unwrap()
+            .borrow()
+            .as_ref()
+            .unwrap())
+    }
+
+    fn with_element_mut<T>(
+        &self,
+        f: impl FnOnce(&mut Element<'_, Message, Renderer>) -> T,
+    ) -> T {
+        f(self
+            .element
+            .borrow()
+            .as_ref()
+            .unwrap()
+            .borrow_mut()
+            .as_mut()
+            .unwrap())
+    }
+}
+
+struct Internal<Message, Renderer> {
+    element: Rc<RefCell<Option<Element<'static, Message, Renderer>>>>,
+    hash: u64,
+}
+
+impl<'a, Message, Renderer, Dependency, View> Widget<Message, Renderer>
+    for Lazy<'a, Message, Renderer, Dependency, View>
+where
+    View: Into<Element<'static, Message, Renderer>> + 'static,
+    Dependency: Hash + 'a,
+    Message: 'static,
+    Renderer: core::Renderer + 'static,
+{
+    fn tag(&self) -> tree::Tag {
+        struct Tag<T>(T);
+        tree::Tag::of::<Tag<View>>()
+    }
+
+    fn state(&self) -> tree::State {
+        let mut hasher = Hasher::default();
+        self.dependency.hash(&mut hasher);
+        let hash = hasher.finish();
+
+        let element =
+            Rc::new(RefCell::new(Some((self.view)(&self.dependency).into())));
+
+        (*self.element.borrow_mut()) = Some(element.clone());
+
+        tree::State::new(Internal { element, hash })
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        self.with_element(|element| vec![Tree::new(element.as_widget())])
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        let current = tree.state.downcast_mut::<Internal<Message, Renderer>>();
+
+        let mut hasher = Hasher::default();
+        self.dependency.hash(&mut hasher);
+        let new_hash = hasher.finish();
+
+        if current.hash != new_hash {
+            current.hash = new_hash;
+
+            let element = (self.view)(&self.dependency).into();
+            current.element = Rc::new(RefCell::new(Some(element)));
+
+            (*self.element.borrow_mut()) = Some(current.element.clone());
+            self.with_element(|element| {
+                tree.diff_children(std::slice::from_ref(&element.as_widget()))
+            });
+        } else {
+            (*self.element.borrow_mut()) = Some(current.element.clone());
+        }
+    }
+
+    fn width(&self) -> Length {
+        self.with_element(|element| element.as_widget().width())
+    }
+
+    fn height(&self) -> Length {
+        self.with_element(|element| element.as_widget().height())
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        self.with_element(|element| {
+            element.as_widget().layout(renderer, limits)
+        })
+    }
+
+    fn operate(
+        &self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+        operation: &mut dyn widget::Operation<Message>,
+    ) {
+        self.with_element(|element| {
+            element.as_widget().operate(
+                &mut tree.children[0],
+                layout,
+                renderer,
+                operation,
+            );
+        });
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        self.with_element_mut(|element| {
+            element.as_widget_mut().on_event(
+                &mut tree.children[0],
+                event,
+                layout,
+                cursor_position,
+                renderer,
+                clipboard,
+                shell,
+            )
+        })
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.with_element(|element| {
+            element.as_widget().mouse_interaction(
+                &tree.children[0],
+                layout,
+                cursor_position,
+                viewport,
+                renderer,
+            )
+        })
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        self.with_element(|element| {
+            element.as_widget().draw(
+                &tree.children[0],
+                renderer,
+                theme,
+                style,
+                layout,
+                cursor_position,
+                viewport,
+            )
+        })
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'_, Message, Renderer>> {
+        let overlay = Overlay(Some(
+            InnerBuilder {
+                cell: self.element.borrow().as_ref().unwrap().clone(),
+                element: self
+                    .element
+                    .borrow()
+                    .as_ref()
+                    .unwrap()
+                    .borrow_mut()
+                    .take()
+                    .unwrap(),
+                tree: &mut tree.children[0],
+                overlay_builder: |element, tree| {
+                    element.as_widget_mut().overlay(tree, layout, renderer)
+                },
+            }
+            .build(),
+        ));
+
+        let has_overlay = overlay
+            .with_overlay_maybe(|overlay| overlay::Element::position(overlay));
+
+        has_overlay
+            .map(|position| overlay::Element::new(position, Box::new(overlay)))
+    }
+}
+
+#[self_referencing]
+struct Inner<'a, Message, Renderer>
+where
+    Message: 'a,
+    Renderer: 'a,
+{
+    cell: Rc<RefCell<Option<Element<'static, Message, Renderer>>>>,
+    element: Element<'static, Message, Renderer>,
+    tree: &'a mut Tree,
+
+    #[borrows(mut element, mut tree)]
+    #[covariant]
+    overlay: Option<overlay::Element<'this, Message, Renderer>>,
+}
+
+struct Overlay<'a, Message, Renderer>(Option<Inner<'a, Message, Renderer>>);
+
+impl<'a, Message, Renderer> Drop for Overlay<'a, Message, Renderer> {
+    fn drop(&mut self) {
+        let heads = self.0.take().unwrap().into_heads();
+        (*heads.cell.borrow_mut()) = Some(heads.element);
+    }
+}
+
+impl<'a, Message, Renderer> Overlay<'a, Message, Renderer> {
+    fn with_overlay_maybe<T>(
+        &self,
+        f: impl FnOnce(&overlay::Element<'_, Message, Renderer>) -> T,
+    ) -> Option<T> {
+        self.0.as_ref().unwrap().borrow_overlay().as_ref().map(f)
+    }
+
+    fn with_overlay_mut_maybe<T>(
+        &mut self,
+        f: impl FnOnce(&mut overlay::Element<'_, Message, Renderer>) -> T,
+    ) -> Option<T> {
+        self.0
+            .as_mut()
+            .unwrap()
+            .with_overlay_mut(|overlay| overlay.as_mut().map(f))
+    }
+}
+
+impl<'a, Message, Renderer> overlay::Overlay<Message, Renderer>
+    for Overlay<'a, Message, Renderer>
+where
+    Renderer: core::Renderer,
+{
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        bounds: Size,
+        position: Point,
+    ) -> layout::Node {
+        self.with_overlay_maybe(|overlay| {
+            let translation = position - overlay.position();
+
+            overlay.layout(renderer, bounds, translation)
+        })
+        .unwrap_or_default()
+    }
+
+    fn draw(
+        &self,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+    ) {
+        let _ = self.with_overlay_maybe(|overlay| {
+            overlay.draw(renderer, theme, style, layout, cursor_position);
+        });
+    }
+
+    fn mouse_interaction(
+        &self,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.with_overlay_maybe(|overlay| {
+            overlay.mouse_interaction(
+                layout,
+                cursor_position,
+                viewport,
+                renderer,
+            )
+        })
+        .unwrap_or_default()
+    }
+
+    fn on_event(
+        &mut self,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        self.with_overlay_mut_maybe(|overlay| {
+            overlay.on_event(
+                event,
+                layout,
+                cursor_position,
+                renderer,
+                clipboard,
+                shell,
+            )
+        })
+        .unwrap_or(event::Status::Ignored)
+    }
+
+    fn is_over(&self, layout: Layout<'_>, cursor_position: Point) -> bool {
+        self.with_overlay_maybe(|overlay| {
+            overlay.is_over(layout, cursor_position)
+        })
+        .unwrap_or_default()
+    }
+}
+
+impl<'a, Message, Renderer, Dependency, View>
+    From<Lazy<'a, Message, Renderer, Dependency, View>>
+    for Element<'a, Message, Renderer>
+where
+    View: Into<Element<'static, Message, Renderer>> + 'static,
+    Renderer: core::Renderer + 'static,
+    Message: 'static,
+    Dependency: Hash + 'a,
+{
+    fn from(lazy: Lazy<'a, Message, Renderer, Dependency, View>) -> Self {
+        Self::new(lazy)
+    }
+}