refactor project structure (start of redoing atomic branch without atomics)

core/src/layout/widget/mod.rs

@@ -0,0 +1,64 @@
+use crate::layout::{Len, Painter, SizeCtx, Ui};
+use std::{any::Any, marker::PhantomData};
+
+mod id;
+mod like;
+mod tag;
+mod widgets;
+
+pub use id::*;
+pub use like::*;
+pub use tag::*;
+pub use widgets::*;
+
+pub trait Widget: Any {
+    fn draw(&mut self, painter: &mut Painter);
+    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len;
+    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len;
+}
+
+impl Widget for () {
+    fn draw(&mut self, _: &mut Painter) {}
+    fn desired_width(&mut self, _: &mut SizeCtx) -> Len {
+        Len::ZERO
+    }
+    fn desired_height(&mut self, _: &mut SizeCtx) -> Len {
+        Len::ZERO
+    }
+}
+
+/// A function that returns a widget given a UI.
+/// Useful for defining trait functions on widgets that create a parent widget so that the children
+/// don't need to be IDs yet
+pub trait WidgetFn<W: Widget>: FnOnce(&mut Ui) -> W {}
+impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetFn<W> for F {}
+
+pub struct WidgetArr<const LEN: usize, Ws> {
+    pub arr: [WidgetId; LEN],
+    _pd: PhantomData<Ws>,
+}
+
+impl<const LEN: usize, Ws> WidgetArr<LEN, Ws> {
+    pub fn new(arr: [WidgetId; LEN]) -> Self {
+        Self {
+            arr,
+            _pd: PhantomData,
+        }
+    }
+}
+
+pub trait WidgetOption {
+    fn get(self, ui: &mut Ui) -> Option<WidgetId>;
+}
+
+impl WidgetOption for () {
+    fn get(self, _: &mut Ui) -> Option<WidgetId> {
+        None
+    }
+}
+
+impl<F: FnOnce(&mut Ui) -> Option<WidgetId>> WidgetOption for F {
+    fn get(self, ui: &mut Ui) -> Option<WidgetId> {
+        self(ui)
+    }
+}