ensure safety of std::move

vector/src/vector.hpp

@@ -276,6 +276,24 @@ class vector {
     }
     return *this;
   }
+  vector &operator=(vector &&other) noexcept {
+    if (this == &other) return *this;
+    if (raw_beg != nullptr) {
+      for (size_t i = 0; i < current_length; ++i) {
+        std::allocator_traits<decltype(alloc)>::destroy(alloc, raw_beg + i);
+      }
+      alloc.deallocate(raw_beg, allocated_length);
+    }
+    raw_beg = other.raw_beg;
+    raw_end = other.raw_end;
+    allocated_length = other.allocated_length;
+    current_length = other.current_length;
+    other.raw_beg = nullptr;
+    other.raw_end = nullptr;
+    other.allocated_length = 0;
+    other.current_length = 0;
+    return *this;
+  }
   /**
    * assigns specified element with bounds checking
    * throw index_out_of_bound if pos is not in [0, size)
@@ -340,11 +358,13 @@ class vector {
    * clears the contents
    */
   void clear() {
+    if (raw_beg != nullptr) {
       for (size_t i = 0; i < current_length; ++i) {
         alloc.destroy(raw_beg + i);
       }
       current_length = 0;
       alloc.deallocate(raw_beg, allocated_length);
+    }
     raw_beg = alloc.allocate(1);
     raw_end = raw_beg;
     allocated_length = 1;
@@ -504,7 +524,7 @@ class vector {
     }
   }
 };
-template<typename T>
+template <typename T>
 std::allocator<T> vector<T>::alloc;
 
 }  // namespace sjtu