diff options
Diffstat (limited to 'absl/utility/utility.h')
| -rw-r--r-- | absl/utility/utility.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/absl/utility/utility.h b/absl/utility/utility.h index 5b9b84e05d84..d73602c47d3b 100644 --- a/absl/utility/utility.h +++ b/absl/utility/utility.h @@ -24,6 +24,7 @@ // * make_index_sequence<N> == std::make_index_sequence<N> // * index_sequence_for<Ts...> == std::index_sequence_for<Ts...> // * apply<Functor, Tuple> == std::apply<Functor, Tuple> +// * exchange<T> == std::exchange<T> // // This header file also provides the tag types `in_place_t`, `in_place_type_t`, // and `in_place_index_t`, as well as the constant `in_place`, and @@ -264,6 +265,27 @@ auto apply(Functor&& functor, Tuple&& t) absl::make_index_sequence<std::tuple_size< typename std::remove_reference<Tuple>::type>::value>{}); } + +// exchange +// +// Replaces the value of `obj` with `new_value` and returns the old value of +// `obj`. `absl::exchange` is designed to be a drop-in replacement for C++14's +// `std::exchange`. +// +// Example: +// +// Foo& operator=(Foo&& other) { +// ptr1_ = absl::exchange(other.ptr1_, nullptr); +// int1_ = absl::exchange(other.int1_, -1); +// return *this; +// } +template <typename T, typename U = T> +T exchange(T& obj, U&& new_value) { + T old_value = absl::move(obj); + obj = absl::forward<U>(new_value); + return old_value; +} + } // namespace absl #endif // ABSL_UTILITY_UTILITY_H_ |