keep jump/file history when using :split (#3031)

* keep jump/file history when using :split

* move history cloning into the switch function

Co-authored-by: Robin <robinvandijk@klippa.com>

helix-term/src/commands.rs

@@ -4083,13 +4083,11 @@ fn split(cx: &mut Context, action: Action) {
     let (view, doc) = current!(cx.editor);
     let id = doc.id();
     let selection = doc.selection(view.id).clone();
-    let offset = view.offset;
 
     cx.editor.switch(id, action);
 
     // match the selection in the previous view
     let (view, doc) = current!(cx.editor);
-    view.offset = offset;
     doc.set_selection(view.id, selection);
 }
 

helix-view/src/editor.rs

@@ -874,7 +874,12 @@ impl Editor {
                 return;
             }
             Action::HorizontalSplit | Action::VerticalSplit => {
-                let view = View::new(id, self.config().gutters.clone());
+                // copy the current view, unless there is no view yet
+                let view = self
+                    .tree
+                    .try_get(self.tree.focus)
+                    .cloned()
+                    .unwrap_or_else(|| View::new(id, self.config().gutters.clone()));
                 let view_id = self.tree.split(
                     view,
                     match action {

helix-view/src/tree.rs

@@ -271,12 +271,16 @@ impl Tree {
     }
 
     pub fn get(&self, index: ViewId) -> &View {
+        self.try_get(index).unwrap()
+    }
+
+    pub fn try_get(&self, index: ViewId) -> Option<&View> {
         match &self.nodes[index] {
             Node {
                 content: Content::View(view),
                 ..
-            } => view,
-            _ => unreachable!(),
+            } => Some(view),
+            _ => None,
         }
     }
 

helix-view/src/view.rs

@@ -64,6 +64,7 @@ impl JumpList {
     }
 }
 
+#[derive(Clone)]
 pub struct View {
     pub id: ViewId,
     pub offset: Position,