Fixing Multiple Panics (#121)

* init

* wip

* wip

3 files changed, 24 insertions, 3 deletions

diff --git a/helix-core/src/movement.rs b/helix-core/src/movement.rs
index 387b59b1..d6745fff 100644
--- a/helix-core/src/movement.rs
+++ b/helix-core/src/movement.rs
@@ -45,7 +45,10 @@ pub fn move_vertically(
 
     let new_line = match dir {
         Direction::Backward => row.saturating_sub(count),
-        Direction::Forward => std::cmp::min(row.saturating_add(count), text.len_lines() - 2),
+        Direction::Forward => std::cmp::min(
+            row.saturating_add(count),
+            text.len_lines().saturating_sub(2),
+        ),
     };
 
     // convert to 0-indexed, subtract another 1 because len_chars() counts \n
diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs
index 67a20934..7dafc97a 100644
--- a/helix-core/src/selection.rs
+++ b/helix-core/src/selection.rs
@@ -383,7 +383,7 @@ pub fn split_on_matches(
             // TODO: retain range direction
 
             let end = text.byte_to_char(start_byte + mat.start());
-            result.push(Range::new(start, end - 1));
+            result.push(Range::new(start, end.saturating_sub(1)));
             start = text.byte_to_char(start_byte + mat.end());
         }
 
diff --git a/helix-core/src/transaction.rs b/helix-core/src/transaction.rs
index e61063f0..085f40b7 100644
--- a/helix-core/src/transaction.rs
+++ b/helix-core/src/transaction.rs
@@ -90,7 +90,8 @@ impl ChangeSet {
             return;
         }
 
-        self.len_after += fragment.len();
+        // Avoiding std::str::len() to account for UTF-8 characters.
+        self.len_after += fragment.chars().count();
 
         let new_last = match self.changes.as_mut_slice() {
             [.., Insert(prev)] | [.., Insert(prev), Delete(_)] => {
@@ -754,4 +755,21 @@ mod test {
         use Operation::*;
         assert_eq!(changes.changes, &[Insert("a".into())]);
     }
+
+    #[test]
+    fn combine_with_utf8() {
+        const TEST_CASE: &'static str = "Hello, これはヒレクスエディターです！";
+
+        let empty = Rope::from("");
+        let mut a = ChangeSet::new(&empty);
+
+        let mut b = ChangeSet::new(&empty);
+        b.insert(TEST_CASE.into());
+
+        let changes = a.compose(b);
+
+        use Operation::*;
+        assert_eq!(changes.changes, &[Insert(TEST_CASE.into())]);
+        assert_eq!(changes.len_after, TEST_CASE.chars().count());
+    }
 }