Switch document list to use indexmap::IndexMap (added dependency)

Cargo.lock

@@ -1433,6 +1433,7 @@ dependencies = [
  "helix-stdx",
  "helix-tui",
  "helix-vcs",
+ "indexmap",
  "libc",
  "log",
  "once_cell",

helix-view/Cargo.toml

@@ -51,6 +51,7 @@ log = "~0.4"
 
 parking_lot = "0.12.3"
 thiserror.workspace = true
+indexmap = "2.5.0"
 
 [target.'cfg(windows)'.dependencies]
 clipboard-win = { version = "5.4", features = ["std"] }

helix-view/src/editor.rs

@@ -18,6 +18,7 @@ use helix_vcs::DiffProviderRegistry;
 use futures_util::stream::select_all::SelectAll;
 use futures_util::{future, StreamExt};
 use helix_lsp::{Call, LanguageServerId};
+use indexmap::IndexMap;
 use tokio_stream::wrappers::UnboundedReceiverStream;
 
 use std::{
@@ -1015,7 +1016,7 @@ pub struct Editor {
     pub mode: Mode,
     pub tree: Tree,
     pub next_document_id: DocumentId,
-    pub documents: BTreeMap<DocumentId, Document>,
+    pub documents: IndexMap<DocumentId, Document>,
 
     // We Flatten<> to resolve the inner DocumentSavedEventFuture. For that we need a stream of streams, hence the Once<>.
     // https://stackoverflow.com/a/66875668
@@ -1164,7 +1165,7 @@ impl Editor {
             mode: Mode::Normal,
             tree: Tree::new(area),
             next_document_id: DocumentId::default(),
-            documents: BTreeMap::new(),
+            documents: IndexMap::new(),
             saves: HashMap::new(),
             save_queue: SelectAll::new(),
             write_count: 0,
@@ -1595,7 +1596,7 @@ impl Editor {
                     // Copy `doc.id` into a variable before calling `self.documents.remove`, which requires a mutable
                     // borrow, invalidating direct access to `doc.id`.
                     let id = doc.id;
-                    self.documents.remove(&id);
+                    self.documents.shift_remove(&id);
 
                     // Remove the scratch buffer from any jumplists
                     for (view, _) in self.tree.views_mut() {
@@ -1796,7 +1797,7 @@ impl Editor {
             }
         }
 
-        self.documents.remove(&doc_id);
+        self.documents.shift_remove(&doc_id);
 
         // If the document we removed was visible in all views, we will have no more views. We don't
         // want to close the editor just for a simple buffer close, so we need to create a new view