1 files changed, 54 insertions, 0 deletions
diff --git a/src/rope.rs b/src/rope.rs
index 3162e44..7d5ee28 100644
--- a/src/rope.rs
+++ b/src/rope.rs
@@ -132,6 +132,55 @@ impl Node {
             }
         }
     }
+
+    fn insert(&self, pos: usize, c: u8) -> Node {
+        match self {
+            Node::Leaf(v) => {
+                if v.len() < MAX_NODE_SIZE {
+                    let mut new_buf = vec![0; v.len() + 1];
+                    new_buf[..pos].copy_from_slice(&v[..pos]);
+                    new_buf[pos] = c;
+                    new_buf[pos + 1..].copy_from_slice(&v[pos..]);
+                    return Node::Leaf(new_buf);
+                }
+                let mut buf_left = vec![0; pos + 1];
+                buf_left[..pos].copy_from_slice(&v[..pos]);
+                buf_left[pos] = c;
+                let mut buf_right = Vec::new();
+                buf_right.extend_from_slice(&v[pos..]);
+                let mut lines = self.lines();
+                if c == b'\n' {
+                    lines += 1;
+                }
+                return Node::Branch(Branch {
+                    left: Rc::new(Node::Leaf(buf_left)),
+                    right: Rc::new(Node::Leaf(buf_right)),
+                    len: v.len() + 1,
+                    lines: lines,
+                });
+            }
+            Node::Branch(b) => {
+                let mut lines = self.lines();
+                if c == b'\n' {
+                    lines += 1;
+                }
+                if pos < b.left.len() {
+                    return Node::Branch(Branch {
+                        left: Rc::new(b.left.insert(pos, c)),
+                        right: b.right.clone(),
+                        len: b.len + 1,
+                        lines: lines,
+                    });
+                }
+                return Node::Branch(Branch {
+                    left: b.left.clone(),
+                    right: Rc::new(b.right.insert(pos - b.left.len(), c)),
+                    len: b.len + 1,
+                    lines: lines,
+                });
+            }
+        }
+    }
 }
 
 impl Display for Node {
@@ -251,4 +300,9 @@ impl Slice {
     pub fn len(&self) -> usize {
         return self.end - self.start;
     }
+
+    pub fn insert(&self, pos: usize, c: u8) -> Rope {
+        let Rope(buf) = &self.buf;
+        return Rope(Rc::new(buf.insert(self.start + pos, c)));
+    }
 }