prompt: make the callback a FnOnce.

helix-term/src/commands.rs

@@ -262,7 +262,6 @@ pub fn split_selection(cx: &mut Context) {
     //  # update state
     // }
 
-    cx.callback = Some(Box::new(|compositor: &mut Compositor| {
     let prompt = Prompt::new(
         "split:".to_string(),
         |input: &str| Vec::new(), // this is fine because Vec::new() doesn't allocate
@@ -271,8 +270,7 @@ pub fn split_selection(cx: &mut Context) {
                 Ok(regex) => {
                     let view = editor.view_mut().unwrap();
                     let text = &view.doc.text().slice(..);
-                        let selection =
-                            selection::split_on_matches(text, view.doc.selection(), &regex);
+                    let selection = selection::split_on_matches(text, view.doc.selection(), &regex);
                     view.doc.set_selection(selection);
                 }
                 Err(_) => (), // TODO: mark command line as error
@@ -280,6 +278,7 @@ pub fn split_selection(cx: &mut Context) {
         },
     );
 
+    cx.callback = Some(Box::new(move |compositor: &mut Compositor| {
         compositor.push(Box::new(prompt));
     }));
 }

helix-term/src/compositor.rs

@@ -19,7 +19,7 @@ use smol::Executor;
 use tui::buffer::Buffer as Surface;
 use tui::layout::Rect;
 
-pub type Callback = Box<dyn Fn(&mut Compositor)>;
+pub type Callback = Box<dyn FnOnce(&mut Compositor)>;
 
 // --> EventResult should have a callback that takes a context with methods like .popup(),
 // .prompt() etc. That way we can abstract it from the renderer.