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use crate::view::{View, ViewPath, ViewWrapper};
use crate::views::{NamedView, ViewRef};
use std::any::Any;
/// Provides `call_on<V: View>` to views.
///
/// This trait is mostly a wrapper around [`View::call_on_any`].
///
/// It provides a nicer interface to find a view when you know its type.
pub trait Finder {
/// Runs a callback on the view identified by `sel`.
///
/// If the view is found, return the result of `callback`.
///
/// If the view is not found, or if it is not of the asked type,
/// it returns `None`.
fn call_on<V, F, R>(
&mut self,
sel: &Selector<'_>,
callback: F,
) -> Option<R>
where
V: View + Any,
F: FnOnce(&mut V) -> R;
/// Convenient method to use `call_on` with a `view::Selector::Name`.
fn call_on_name<V, F, R>(&mut self, name: &str, callback: F) -> Option<R>
where
V: View + Any,
F: FnOnce(&mut V) -> R,
{
self.call_on(&Selector::Name(name), callback)
}
/// Same as [`call_on_name`](Finder::call_on_name).
#[deprecated(note = "`call_on_id` is being renamed to `call_on_name`")]
fn call_on_id<V, F, R>(&mut self, id: &str, callback: F) -> Option<R>
where
V: View + Any,
F: FnOnce(&mut V) -> R,
{
self.call_on_name(id, callback)
}
/// Convenient method to find a view wrapped in an [`NamedView`].
fn find_name<V>(&mut self, name: &str) -> Option<ViewRef<V>>
where
V: View + Any,
{
self.call_on_name(name, NamedView::<V>::get_mut)
}
/// Same as [`find_name`](Finder::find_name()).
#[deprecated(note = "`find_id` is being renamed to `find_name`")]
fn find_id<V>(&mut self, id: &str) -> Option<ViewRef<V>>
where
V: View + Any,
{
self.find_name(id)
}
}
impl<T: View> Finder for T {
fn call_on<V, F, R>(
&mut self,
sel: &Selector<'_>,
callback: F,
) -> Option<R>
where
V: View + Any,
F: FnOnce(&mut V) -> R,
{
let mut result = None;
{
let result_ref = &mut result;
let mut callback = Some(callback);
let mut callback = |v: &mut dyn Any| {
if let Some(callback) = callback.take() {
if v.is::<V>() {
*result_ref =
v.downcast_mut::<V>().map(|v| callback(v));
} else if v.is::<NamedView<V>>() {
*result_ref = v
.downcast_mut::<NamedView<V>>()
.and_then(|v| v.with_view_mut(callback));
}
}
};
self.call_on_any(sel, &mut callback);
}
result
}
}
/// Selects a single view (if any) in the tree.
pub enum Selector<'a> {
/// Same as [`Selector::Name`].
#[deprecated(
note = "`Selector::Id` is being renamed to `Selector::Name`"
)]
Id(&'a str),
/// Selects a view from its name.
Name(&'a str),
/// Selects a view from its path.
Path(&'a ViewPath),
}