copy_to_unique_ptr, copy_to_shared_ptr

Summary: [Folly] `copy_to_unique_ptr`, `copy_to_shared_ptr` - type-deducing wrappers around `make_unique` and `make_shared`.

Reviewed By: vitaut

Differential Revision: D21332222

fbshipit-source-id: f41dac0fcfa972118d3a721194c941e14511a80c

folly/Memory.h

@@ -348,6 +348,30 @@ std::weak_ptr<T> to_weak_ptr(const std::shared_ptr<T>& ptr) {
   return std::weak_ptr<T>(ptr);
 }
 
+/**
+ *  copy_to_unique_ptr
+ *
+ *  Move or copy the argument to the heap and return it owned by a unique_ptr.
+ *
+ *  Like make_unique, but deduces the type of the owned object.
+ */
+template <typename T>
+std::unique_ptr<remove_cvref_t<T>> copy_to_unique_ptr(T&& t) {
+  return make_unique<remove_cvref_t<T>>(static_cast<T&&>(t));
+}
+
+/**
+ *  copy_to_shared_ptr
+ *
+ *  Move or copy the argument to the heap and return it owned by a shared_ptr.
+ *
+ *  Like make_shared, but deduces the type of the owned object.
+ */
+template <typename T>
+std::shared_ptr<remove_cvref_t<T>> copy_to_shared_ptr(T&& t) {
+  return std::make_shared<remove_cvref_t<T>>(static_cast<T&&>(t));
+}
+
 namespace detail {
 template <typename T>
 struct lift_void_to_char {

folly/test/MemoryTest.cpp

@@ -91,6 +91,16 @@ TEST(to_weak_ptr, example) {
   EXPECT_EQ(3, (to_weak_ptr(decltype(s)(s)).lock(), s.use_count())) << "rvalue";
 }
 
+TEST(copy_to_unique_ptr, example) {
+  std::unique_ptr<int> s = copy_to_unique_ptr(17);
+  EXPECT_EQ(17, *s);
+}
+
+TEST(copy_to_shared_ptr, example) {
+  std::shared_ptr<int> s = copy_to_shared_ptr(17);
+  EXPECT_EQ(17, *s);
+}
+
 TEST(SysAllocator, equality) {
   using Alloc = SysAllocator<float>;
   Alloc const a, b;