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|
use crate::widget::Element;
use std::any::{self, Any};
pub struct Tree {
pub tag: any::TypeId,
pub state: State,
pub children: Vec<Tree>,
}
impl Tree {
pub fn empty() -> Self {
Self {
tag: any::TypeId::of::<()>(),
state: State(Box::new(())),
children: Vec::new(),
}
}
pub fn new<Message, Renderer>(
element: &Element<'_, Message, Renderer>,
) -> Self {
Self {
tag: element.as_widget().tag(),
state: State(element.as_widget().state()),
children: element.as_widget().children_state(),
}
}
pub fn diff<Message, Renderer>(
&mut self,
new: &Element<'_, Message, Renderer>,
) {
if self.tag == new.as_widget().tag() {
new.as_widget().diff(self)
} else {
*self = Self::new(new);
}
}
pub fn diff_children<Message, Renderer>(
&mut self,
new_children: &[Element<'_, Message, Renderer>],
) {
if self.children.len() > new_children.len() {
self.children.truncate(new_children.len());
}
for (child_state, new) in
self.children.iter_mut().zip(new_children.iter())
{
child_state.diff(new);
}
if self.children.len() < new_children.len() {
self.children.extend(
new_children[self.children.len()..].iter().map(Self::new),
);
}
}
}
pub struct State(Box<dyn Any>);
impl State {
pub fn downcast_ref<T>(&self) -> &T
where
T: 'static,
{
self.0.downcast_ref().expect("Downcast widget state")
}
pub fn downcast_mut<T>(&mut self) -> &mut T
where
T: 'static,
{
self.0.downcast_mut().expect("Downcast widget state")
}
}
|
