add downcasting example

examples/downcast.rs

@@ -0,0 +1,48 @@
+extern crate skim;
+use skim::prelude::*;
+
+/// This example illustrates downcasting custom structs that implement
+/// `SkimItem` after calling `Skim::run_with`.
+
+#[derive(Debug, Clone)]
+struct Item {
+    text: String,
+}
+
+impl SkimItem for Item {
+    fn text(&self) -> Cow<str> {
+        Cow::Borrowed(&self.text)
+    }
+
+    fn preview(&self, _context: PreviewContext) -> ItemPreview {
+        ItemPreview::Text(self.text.to_owned())
+    }
+}
+
+pub fn main() {
+    let options = SkimOptionsBuilder::default()
+        .height(Some("50%"))
+        .multi(true)
+        .preview(Some(""))
+        .build()
+        .unwrap();
+
+    let (tx, rx): (SkimItemSender, SkimItemReceiver) = unbounded();
+
+    tx.send(Arc::new(Item { text: "a".to_string() })).unwrap();
+    tx.send(Arc::new(Item { text: "b".to_string() })).unwrap();
+    tx.send(Arc::new(Item { text: "c".to_string() })).unwrap();
+
+    drop(tx);
+
+    let selected_items = Skim::run_with(&options, Some(rx))
+        .map(|out| out.selected_items)
+        .unwrap_or_else(|| Vec::new())
+        .iter()
+        .map(|selected_item| (**selected_item).as_any().downcast_ref::<Item>().unwrap().to_owned())
+        .collect::<Vec<Item>>();
+
+    for item in selected_items {
+        println!("{:?}", item);
+    }
+}