add alternate file (#223)

* add alternate file

inspired by vim ctrl-6/kak ga commands. the alternate file is kept per view

* apply feedback from #223

* rename to last_accessed

* add ga doc

* add fail message for ga

2 files changed, 10 insertions, 0 deletions

diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index bd53c53b..ef0d8213 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -88,6 +88,12 @@ impl Editor {
     pub fn switch(&mut self, id: DocumentId, action: Action) {
         use crate::tree::Layout;
         use helix_core::Selection;
+
+        if !self.documents.contains_key(id) {
+            log::error!("cannot switch to document that does not exist (anymore)");
+            return;
+        }
+
         match action {
             Action::Replace => {
                 let view = self.view();
@@ -98,6 +104,7 @@ impl Editor {
 
                 let view = self.view_mut();
                 view.jumps.push(jump);
+                view.last_accessed_doc = Some(view.doc);
                 view.doc = id;
                 view.first_line = 0;
 
diff --git a/helix-view/src/view.rs b/helix-view/src/view.rs
index 5d2d27fd..c0a72c78 100644
--- a/helix-view/src/view.rs
+++ b/helix-view/src/view.rs
@@ -67,6 +67,8 @@ pub struct View {
     pub first_col: usize,
     pub area: Rect,
     pub jumps: JumpList,
+    /// the last accessed file before the current one
+    pub last_accessed_doc: Option<DocumentId>,
 }
 
 impl View {
@@ -78,6 +80,7 @@ impl View {
             first_col: 0,
             area: Rect::default(), // will get calculated upon inserting into tree
             jumps: JumpList::new((doc, Selection::point(0))), // TODO: use actual sel
+            last_accessed_doc: None,
         }
     }