Row splitting and joining

src/document.rs

@@ -37,6 +37,11 @@ impl Document {
     }
 
     pub fn insert(&mut self, at: &Position, c: char) {
+        if c == '\n' {
+            self.insert_newline(at);
+            return;
+        }
+
         if at.y == self.len() {
             let mut row = Row::default();
             row.insert(0, c);
@@ -48,11 +53,32 @@ impl Document {
     }
 
     pub fn delete(&mut self, at: &Position) {
-        if at.y >= self.len() {
+        let len = self.len();
+        if at.y >= len {
             return
         }
 
-        let row = self.rows.get_mut(at.y).unwrap();
+        if at.x == self.rows.get_mut(at.y).unwrap().len() && at.y < len - 1 {
-        row.delete(at.x);
+            let next_row = self.rows.remove(at.y + 1);
+            let row = self.rows.get_mut(at.y).unwrap();
+            row.append(&next_row);
+        } else {
+            let row = self.rows.get_mut(at.y).unwrap();
+            row.delete(at.x);
+        }
+    }
+
+    fn insert_newline(&mut self, at: &Position) {
+        if at.y > self.len() {
+            return;
+        }
+
+        if at.y == self.len() {
+            self.rows.push(Row::default());
+            return;
+        }
+
+        let new_row = self.rows.get_mut(at.y).unwrap().split(at.x);
+        self.rows.insert(at.y + 1, new_row);
     }
 }

src/row.rs

@@ -83,4 +83,19 @@ impl Row {
 
         self.update_len();
     }
+
+    pub fn append(&mut self, new: &Self) {
+        self.string = format!("{}{}", self.string, new.string);
+        self.update_len();
+    }
+
+    pub fn split(&mut self, at: usize) -> Self {
+        let beginning: String = self.string[..].graphemes(true).take(at).collect();
+        let remainder: String = self.string[..].graphemes(true).skip(at).collect();
+
+        self.string = beginning;
+        self.update_len();
+
+        Self::from(&remainder[..])
+    }
 }