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|
use crate::widget::Element;
use std::any::Any;
use std::marker::PhantomData;
pub struct Tree<Message, Renderer> {
pub state: Box<dyn Any>,
pub children: Vec<Tree<Message, Renderer>>,
types_: PhantomData<(Message, Renderer)>,
}
impl<Message, Renderer> Tree<Message, Renderer> {
pub fn new(element: &Element<Message, Renderer>) -> Self {
Self {
state: element.as_widget().state(),
children: element
.as_widget()
.children()
.iter()
.map(Self::new)
.collect(),
types_: PhantomData,
}
}
pub fn diff(
&mut self,
current: &Element<Message, Renderer>,
new: &Element<Message, Renderer>,
) {
if current.as_widget().tag() == new.as_widget().tag() {
let current_children = current.as_widget().children();
let new_children = new.as_widget().children();
if current_children.len() > new_children.len() {
self.children.truncate(new_children.len());
}
for (child_state, (current, new)) in self
.children
.iter_mut()
.zip(current_children.iter().zip(new_children.iter()))
{
child_state.diff(current, new);
}
if current_children.len() < new_children.len() {
self.children.extend(
new_children[current_children.len()..]
.iter()
.map(Self::new),
);
}
} else {
*self = Self::new(new);
}
}
}
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