Fix initial selection of Document in new view

When a new View of a Document is created, a default cursor of 0, 0 is
created, and it does not get normalized to a single width cursor until
at least one movement of the cursor happens. This appears to have no
practical negative effect that I could find, but it makes tests difficult
to work with, since the initial selection is not what you expect it to be.

This changes the initial selection of a new View to be the width of the
first grapheme in the text.

2 files changed, 40 insertions, 18 deletions

diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index a2d2af77..00adaa1a 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -1,5 +1,6 @@
 use anyhow::{anyhow, bail, Context, Error};
 use helix_core::auto_pairs::AutoPairs;
+use helix_core::Range;
 use serde::de::{self, Deserialize, Deserializer};
 use serde::Serialize;
 use std::cell::Cell;
@@ -83,7 +84,7 @@ impl Serialize for Mode {
 pub struct Document {
     pub(crate) id: DocumentId,
     text: Rope,
-    pub(crate) selections: HashMap<ViewId, Selection>,
+    selections: HashMap<ViewId, Selection>,
 
     path: Option<PathBuf>,
     encoding: &'static encoding::Encoding,
@@ -637,6 +638,37 @@ impl Document {
             .insert(view_id, selection.ensure_invariants(self.text().slice(..)));
     }
 
+    /// Find the origin selection of the text in a document, i.e. where
+    /// a single cursor would go if it were on the first grapheme. If
+    /// the text is empty, returns (0, 0).
+    pub fn origin(&self) -> Range {
+        if self.text().len_chars() == 0 {
+            return Range::new(0, 0);
+        }
+
+        Range::new(0, 1).grapheme_aligned(self.text().slice(..))
+    }
+
+    /// Reset the view's selection on this document to the
+    /// [origin](Document::origin) cursor.
+    pub fn reset_selection(&mut self, view_id: ViewId) {
+        let origin = self.origin();
+        self.set_selection(view_id, Selection::single(origin.anchor, origin.head));
+    }
+
+    /// Initializes a new selection for the given view if it does not
+    /// already have one.
+    pub fn ensure_view_init(&mut self, view_id: ViewId) {
+        if self.selections.get(&view_id).is_none() {
+            self.reset_selection(view_id);
+        }
+    }
+
+    /// Remove a view's selection from this document.
+    pub fn remove_view(&mut self, view_id: ViewId) {
+        self.selections.remove(&view_id);
+    }
+
     /// Apply a [`Transaction`] to the [`Document`] to change its text.
     fn apply_impl(&mut self, transaction: &Transaction, view_id: ViewId) -> bool {
         let old_doc = self.text().clone();
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index 76ac0b51..8607c65a 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -32,12 +32,12 @@ use anyhow::{bail, Error};
 
 pub use helix_core::diagnostic::Severity;
 pub use helix_core::register::Registers;
+use helix_core::Position;
 use helix_core::{
     auto_pairs::AutoPairs,
     syntax::{self, AutoPairConfig},
     Change,
 };
-use helix_core::{Position, Selection};
 use helix_dap as dap;
 
 use serde::{ser::SerializeMap, Deserialize, Deserializer, Serialize, Serializer};
@@ -645,11 +645,8 @@ impl Editor {
         view.offset = Position::default();
 
         let doc = self.documents.get_mut(&doc_id).unwrap();
+        doc.ensure_view_init(view.id);
 
-        // initialize selection for view
-        doc.selections
-            .entry(view.id)
-            .or_insert_with(|| Selection::point(0));
         // TODO: reuse align_view
         let pos = doc
             .selection(view.id)
@@ -719,9 +716,7 @@ impl Editor {
             Action::Load => {
                 let view_id = view!(self).id;
                 let doc = self.documents.get_mut(&id).unwrap();
-                if doc.selections().is_empty() {
-                    doc.set_selection(view_id, Selection::point(0));
-                }
+                doc.ensure_view_init(view_id);
                 return;
             }
             Action::HorizontalSplit | Action::VerticalSplit => {
@@ -736,7 +731,7 @@ impl Editor {
                 );
                 // initialize selection for view
                 let doc = self.documents.get_mut(&id).unwrap();
-                doc.set_selection(view_id, Selection::point(0));
+                doc.ensure_view_init(view_id);
             }
         }
 
@@ -769,7 +764,7 @@ impl Editor {
         Ok(self.new_file_from_document(action, Document::from(rope, Some(encoding))))
     }
 
-    // ???
+    // ??? possible use for integration tests
     pub fn open(&mut self, path: PathBuf, action: Action) -> Result<DocumentId, Error> {
         let path = helix_core::path::get_canonicalized_path(&path)?;
         let id = self.document_by_path(&path).map(|doc| doc.id);
@@ -791,12 +786,7 @@ impl Editor {
     pub fn close(&mut self, id: ViewId) {
         let view = self.tree.get(self.tree.focus);
         // remove selection
-        self.documents
-            .get_mut(&view.doc)
-            .unwrap()
-            .selections
-            .remove(&id);
-
+        self.documents.get_mut(&view.doc).unwrap().remove_view(id);
         self.tree.remove(id);
         self._refresh();
     }
@@ -871,7 +861,7 @@ impl Editor {
             let view = View::new(doc_id, self.config().gutters.clone());
             let view_id = self.tree.insert(view);
             let doc = self.documents.get_mut(&doc_id).unwrap();
-            doc.set_selection(view_id, Selection::point(0));
+            doc.ensure_view_init(view_id);
         }
 
         self._refresh();