Implement move assignment operator for Array.

format-test.cc

@@ -226,12 +226,13 @@ TEST(ArrayTest, MoveCtor) {
   // dynamic allocation.
   array.push_back('a');
   CheckMoveArray("testa", array);
+  const char *inline_buffer_ptr = &array[0];
   // Adding one more character causes the content to move from the inline to
   // a dynamically allocated buffer.
   array.push_back('b');
   Array<char, 5> array2(std::move(array));
   // Move should rip the guts of the first array.
-  EXPECT_TRUE(!&array[0]);
+  EXPECT_EQ(inline_buffer_ptr, &array[0]);
   EXPECT_EQ("testab", std::string(&array2[0], array2.size()));
   EXPECT_GT(array2.capacity(), 5);
 }
@@ -335,12 +336,13 @@ TEST(WriterTest, MoveCtor) {
   w.Clear();
   w << s;
   CheckMoveWriter(s, w);
+  const char *inline_buffer_ptr = w.data();
   // Adding one more character causes the content to move from the inline to
   // a dynamically allocated buffer.
   w << '*';
   Writer w2(std::move(w));
   // Move should rip the guts of the first writer.
-  EXPECT_TRUE(!w.data());
+  EXPECT_EQ(inline_buffer_ptr, w.data());
   EXPECT_EQ(s + '*', w2.str());
 }
 

format.cc

@@ -33,7 +33,6 @@
 
 #include "format.h"
 
-#include <cassert>
 #include <cctype>
 #include <climits>
 #include <cmath>

format.h

@@ -30,6 +30,7 @@
 
 #include <stdint.h>
 
+#include <cassert>
 #include <cstddef>  // for std::ptrdiff_t
 #include <cstdio>
 #include <algorithm>
@@ -143,30 +144,47 @@ class Array {
 
   void Grow(std::size_t size);
 
-  // Do not implement!
-  Array(const Array &);
-  void operator=(const Array &);
-
- public:
-  Array() : size_(0), capacity_(SIZE), ptr_(data_) {}
-  ~Array() {
+  // Free memory allocated by the array.
+  void Free() {
     if (ptr_ != data_) delete [] ptr_;
   }
 
-#if FMT_USE_RVALUE_REFERENCES
-  Array(Array &&other)
-  : size_(other.size_),
-    capacity_(other.capacity_) {
+  // Move data from other to this array.
+  void Move(Array &other) {
+    size_ = other.size_;
+    capacity_ = other.capacity_;
     if (other.ptr_ == other.data_) {
       ptr_ = data_;
       std::copy(other.data_, other.data_ + size_, CheckPtr(data_, capacity_));
     } else {
       ptr_ = other.ptr_;
-      other.ptr_ = 0;
+      // Set pointer to the inline array so that delete is not called
+      // when freeing.
+      other.ptr_ = other.data_;
     }
   }
 
-  // TODO: move assignment operator
+  // Do not implement!
+  Array(const Array &);
+  void operator=(const Array &);
+
+ public:
+  Array() : size_(0), capacity_(SIZE), ptr_(data_) {}
+  ~Array() { Free(); }
+
+#if FMT_USE_RVALUE_REFERENCES
+
+  Array(Array &&other) {
+    Move(other);
+  }
+
+  Array& operator=(Array&& other) {
+    assert(this != &other);
+    Free();
+    Move(other);
+    return *this;
+  }
+
 #endif
 
   // Returns the size of this array.