Add Either widget

src/widgets/either.rs

@@ -0,0 +1,59 @@
+use async_trait::async_trait;
+
+use crate::{AsyncWidget, Frame, Size, Widget};
+
+pub enum Either<I1, I2> {
+    First(I1),
+    Second(I2),
+}
+
+impl<E, I1, I2> Widget<E> for Either<I1, I2>
+where
+    I1: Widget<E>,
+    I2: Widget<E>,
+{
+    fn size(
+        &self,
+        frame: &mut Frame,
+        max_width: Option<u16>,
+        max_height: Option<u16>,
+    ) -> Result<Size, E> {
+        match self {
+            Self::First(l) => l.size(frame, max_width, max_height),
+            Self::Second(r) => r.size(frame, max_width, max_height),
+        }
+    }
+
+    fn draw(self, frame: &mut Frame) -> Result<(), E> {
+        match self {
+            Self::First(l) => l.draw(frame),
+            Self::Second(r) => r.draw(frame),
+        }
+    }
+}
+
+#[async_trait]
+impl<E, I1, I2> AsyncWidget<E> for Either<I1, I2>
+where
+    I1: AsyncWidget<E> + Send + Sync,
+    I2: AsyncWidget<E> + Send + Sync,
+{
+    async fn size(
+        &self,
+        frame: &mut Frame,
+        max_width: Option<u16>,
+        max_height: Option<u16>,
+    ) -> Result<Size, E> {
+        match self {
+            Self::First(l) => l.size(frame, max_width, max_height).await,
+            Self::Second(r) => r.size(frame, max_width, max_height).await,
+        }
+    }
+
+    async fn draw(self, frame: &mut Frame) -> Result<(), E> {
+        match self {
+            Self::First(l) => l.draw(frame).await,
+            Self::Second(r) => r.draw(frame).await,
+        }
+    }
+}