Support inserting newline.

1 files changed, 18 insertions, 5 deletions

diff --git a/src/rope.rs b/src/rope.rs
index 11a030b..5454557 100644
--- a/src/rope.rs
+++ b/src/rope.rs
@@ -152,11 +152,24 @@ impl Rope {
                     new_buf[pos + 1..].copy_from_slice(&l.bytes()[pos..]);
                     return Rope::leaf(new_buf);
                 }
-                let mut buf_left = vec![0; pos + 1];
-                buf_left[..pos].copy_from_slice(&l.bytes()[..pos]);
-                buf_left[pos] = c;
-                let mut buf_right = Vec::new();
-                buf_right.extend_from_slice(&l.bytes()[pos..]);
+                let half = MAX_NODE_SIZE / 2;
+                let mut buf_left;
+                let mut buf_right;
+                if pos <= half {
+                    buf_left = vec![0; half+1];
+                    buf_right = vec![0; half];
+                    buf_left[..pos].copy_from_slice(&l.bytes()[..pos]);
+                    buf_left[pos] = c;
+                    buf_left[pos+1..].copy_from_slice(&l.bytes()[pos..half]);
+                    buf_right.copy_from_slice(&l.bytes()[half..]);
+                } else {
+                    buf_left = vec![0; half];
+                    buf_right = vec![0; half+1];
+                    buf_left.copy_from_slice(&l.bytes()[..half]);
+                    buf_right[..pos-half].copy_from_slice(&l.bytes()[half..pos]);
+                    buf_right[pos-half] = c;
+                    buf_right[pos-half+1..].copy_from_slice(&l.bytes()[pos..]);
+                }
                 return Rope::leaf(buf_left).concat(&Rope::leaf(buf_right));
             }
             Rope(Node::Branch(b)) => {