feat(lsp): LSP preselected items appear first in completion menu (#4480)

* feat(lsp): LSP preselected items appear first in completion menu

* fix: shorter diff

helix-term/src/ui/completion.rs

@@ -92,11 +92,15 @@ impl Completion {
 
     pub fn new(
         editor: &Editor,
-        items: Vec<CompletionItem>,
+        mut items: Vec<CompletionItem>,
         offset_encoding: helix_lsp::OffsetEncoding,
         start_offset: usize,
         trigger_offset: usize,
     ) -> Self {
+        // Sort completion items according to their preselect status (given by the LSP server)
+        items.sort_by_key(|item| !item.preselect.unwrap_or(false));
+
+        // Then create the menu
         let menu = Menu::new(items, (), move |editor: &mut Editor, item, event| {
             fn item_to_transaction(
                 doc: &Document,

helix-term/src/ui/menu.rs

@@ -108,7 +108,8 @@ impl<T: Item> Menu<T> {
                         .map(|score| (index, score))
                 }),
         );
-        self.matches.sort_unstable_by_key(|(_, score)| -score);
+        // Order of equal elements needs to be preserved as LSP preselected items come in order of high to low priority
+        self.matches.sort_by_key(|(_, score)| -score);
 
         // reset cursor position
         self.cursor = None;