add deletion

src/document.rs

@@ -39,4 +39,19 @@ impl Document {
             row.insert(at.x, c);
         }
     }
+    pub fn delete(&mut self, at: &Position) {
+        let len = self.len();
+        if at.y >= len {
+            return;
+        }
+
+        if at.x == self.rows.get_mut(at.y).unwrap().len() && at.y < len - 1 {
+            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);
+        }
+    }
 }

src/editor.rs

@@ -107,6 +107,13 @@ impl Editor {
                 self.document.insert(&self.cursor_position, c);
                 self.move_cursor(Key::Right);
             }
+            Key::Delete => self.document.delete(&self.cursor_position),
+            Key::Backspace => {
+                if self.cursor_position.x > 0 || self.cursor_position.y > 0 {
+                    self.move_cursor(Key::Left);
+                    self.document.delete(&self.cursor_position);
+                }
+            }
             Key::Up
             | Key::Down
             | Key::Left

src/row.rs

@@ -53,4 +53,19 @@ impl Row {
         }
         self.update_len();
     }
+    pub fn delete(&mut self, at: usize) {
+        if at >= self.len() {
+            return;
+        } else {
+            let mut result: String = self.string[..].graphemes(true).take(at).collect();
+            let remainder: String = self.string[..].graphemes(true).skip(at + 1).collect();
+            result.push_str(&remainder);
+            self.string = result;
+        }
+        self.update_len();
+    }
+    pub fn append(&mut self, new: &Self) {
+        self.string = format!("{}{}", self.string, new.string);
+        self.update_len();
+    }
 }