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|
use crate::Element;
use std::any::{self, Any};
pub struct Tree {
pub tag: Tag,
pub state: State,
pub children: Vec<Tree>,
}
impl Tree {
pub fn empty() -> Self {
Self {
tag: Tag::stateless(),
state: State::None,
children: Vec::new(),
}
}
pub fn new<Message, Renderer>(
element: &Element<'_, Message, Renderer>,
) -> Self {
Self {
tag: element.as_widget().tag(),
state: element.as_widget().state(),
children: element.as_widget().children(),
}
}
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>],
) {
self.diff_children_custom(
new_children,
|new, child_state| child_state.diff(new),
Self::new,
)
}
pub fn diff_children_custom<T>(
&mut self,
new_children: &[T],
diff: impl Fn(&T, &mut Tree),
new_state: impl Fn(&T) -> Self,
) {
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())
{
diff(new, child_state);
}
if self.children.len() < new_children.len() {
self.children.extend(
new_children[self.children.len()..].iter().map(new_state),
);
}
}
}
#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)]
pub struct Tag(any::TypeId);
impl Tag {
pub fn of<T>() -> Self
where
T: 'static,
{
Self(any::TypeId::of::<T>())
}
pub fn stateless() -> Self {
Self::of::<()>()
}
}
pub enum State {
None,
Some(Box<dyn Any>),
}
impl State {
pub fn new<T>(state: T) -> Self
where
T: 'static,
{
State::Some(Box::new(state))
}
pub fn downcast_ref<T>(&self) -> &T
where
T: 'static,
{
match self {
State::None => panic!("Downcast on stateless state"),
State::Some(state) => {
state.downcast_ref().expect("Downcast widget state")
}
}
}
pub fn downcast_mut<T>(&mut self) -> &mut T
where
T: 'static,
{
match self {
State::None => panic!("Downcast on stateless state"),
State::Some(state) => {
state.downcast_mut().expect("Downcast widget state")
}
}
}
}
|
