From f650ce0cb6db913b86e91150ee10270b36b344d5 Mon Sep 17 00:00:00 2001
From: Michael Davis <mcarsondavis@gmail.com>
Date: Tue, 22 Nov 2022 20:37:37 -0600
Subject: [PATCH] Apply transactions to all views on history changes

This ensures that jumplist selections follow changes in documents, even
when there are multiple views (for example a split where both windows
edit the same document).
---
 helix-core/src/history.rs   | 18 ++++++++++++++++++
 helix-term/src/ui/editor.rs | 26 +++++++++++++++++++++++---
 helix-view/src/macros.rs    |  2 +-
 3 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/helix-core/src/history.rs b/helix-core/src/history.rs
index 51174c02475e..8a8702b9cc6a 100644
--- a/helix-core/src/history.rs
+++ b/helix-core/src/history.rs
@@ -119,6 +119,24 @@ impl History {
         self.current == 0
     }
 
+    /// Returns the changes since the given revision composed into a transaction.
+    /// Returns None if there are no changes between the current and given revisions.
+    pub fn changes_since(&self, revision: usize) -> Option<Transaction> {
+        if self.at_root() || self.current >= revision {
+            return None;
+        }
+
+        let mut transaction = self.revisions[revision].transaction.clone();
+
+        // The bounds are checked in the if condition above:
+        // `revision + 1` is known to be `<= self.current`.
+        for revision in &self.revisions[revision + 1..self.current] {
+            transaction = transaction.compose(revision.transaction.clone());
+        }
+
+        Some(transaction)
+    }
+
     /// Undo the last edit.
     pub fn undo(&mut self) -> Option<&Transaction> {
         if self.at_root() {
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 6c8ee2d95e9c..44f89b77ed15 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -1337,7 +1337,9 @@ impl Component for EditorView {
                 cx.editor.status_msg = None;
 
                 let mode = cx.editor.mode();
-                let (view, _) = current!(cx.editor);
+                let (view, doc) = current!(cx.editor);
+                let original_doc_id = doc.id();
+                let original_doc_revision = doc.get_current_revision();
                 let focus = view.id;
 
                 if let Some(on_next_key) = self.on_next_key.take() {
@@ -1413,13 +1415,31 @@ impl Component for EditorView {
                     let view = view_mut!(cx.editor, focus);
                     let doc = doc_mut!(cx.editor, &view.doc);
 
-                    view.ensure_cursor_in_view(doc, config.scrolloff);
-
                     // Store a history state if not in insert mode. This also takes care of
                     // committing changes when leaving insert mode.
                     if mode != Mode::Insert {
                         doc.append_changes_to_history(view.id);
                     }
+
+                    // If the current document has been changed, apply the changes to all views.
+                    // This ensures that selections in jumplists follow changes.
+                    if doc.id() == original_doc_id
+                        && doc.get_current_revision() > original_doc_revision
+                    {
+                        if let Some(transaction) =
+                            doc.history.get_mut().changes_since(original_doc_revision)
+                        {
+                            let doc = doc!(cx.editor, &original_doc_id);
+                            for (view, _focused) in cx.editor.tree.views_mut() {
+                                view.apply(&transaction, doc);
+                            }
+                        }
+                    }
+
+                    let view = view_mut!(cx.editor, focus);
+                    let doc = doc_mut!(cx.editor, &view.doc);
+
+                    view.ensure_cursor_in_view(doc, config.scrolloff);
                 }
 
                 EventResult::Consumed(callback)
diff --git a/helix-view/src/macros.rs b/helix-view/src/macros.rs
index 53ab434622d4..ee9cd4111795 100644
--- a/helix-view/src/macros.rs
+++ b/helix-view/src/macros.rs
@@ -67,7 +67,7 @@ macro_rules! view {
 #[macro_export]
 macro_rules! doc {
     ($editor:expr, $id:expr) => {{
-        $editor.documents[$id]
+        &$editor.documents[$id]
     }};
     ($editor:expr) => {{
         $crate::current_ref!($editor).1