Fix cursor position bugs related to o and O

- `O` at the beginning of file didn't move cursor
- `o` and `O` messed up cursor position with multiple cursors

Fixes #127

helix-term/src/commands.rs

@@ -1495,13 +1495,13 @@ fn open(cx: &mut Context, open: Open) {
     enter_insert_mode(doc);
 
     let text = doc.text().slice(..);
+    let contents = doc.text();
     let selection = doc.selection(view.id);
 
     let mut ranges = SmallVec::with_capacity(selection.len());
+    let mut offs = 0;
 
-    let changes: Vec<Change> = selection
+    let mut transaction = Transaction::change_by_selection(contents, selection, |range| {
-        .iter()
-        .map(|range| {
         let line = text.char_to_line(range.head);
 
         let line = match open {
@@ -1528,20 +1528,22 @@ fn open(cx: &mut Context, open: Open) {
         let text = text.repeat(count);
 
         // calculate new selection range
-            let pos = index + text.chars().count();
+        let pos = if line == 0 {
+            0 // Required since text will have a min len of 1 (\n)
+        } else {
+            index + offs + text.chars().count()
+        };
         ranges.push(Range::new(pos, pos));
 
+        offs += text.chars().count();
+
         (index, index, Some(text.into()))
-        })
+    });
-        .collect();
 
     // TODO: count actually inserts "n" new lines and starts editing on all of them.
     // TODO: append "count" newlines and modify cursors to those lines
 
-    let selection = Selection::new(ranges, 0);
+    transaction = transaction.with_selection(Selection::new(ranges, selection.primary_index()));
-
-    let transaction =
-        Transaction::change(doc.text(), changes.into_iter()).with_selection(selection);
 
     doc.apply(&transaction, view.id);
 }