#pragma once
#include <folly/Traits.h>
+#include <folly/functional/Invoke.h>
#include <cstddef>
#include <cstdlib>
#include <limits>
#include <memory>
#include <stdexcept>
+#include <type_traits>
#include <utility>
namespace folly {
#else
-template<typename T, typename... Args>
+template <typename T, typename... Args>
typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
make_unique(Args&&... args) {
return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}
// Allows 'make_unique<T[]>(10)'. (N3690 s20.9.1.4 p3-4)
-template<typename T>
+template <typename T>
typename std::enable_if<std::is_array<T>::value, std::unique_ptr<T>>::type
make_unique(const size_t n) {
return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
}
// Disallows 'make_unique<T[10]>()'. (N3690 s20.9.1.4 p5)
-template<typename T, typename... Args>
+template <typename T, typename... Args>
typename std::enable_if<
std::extent<T>::value != 0, std::unique_ptr<T>>::type
make_unique(Args&&...) = delete;
return std::weak_ptr<T>(ptr);
}
-using SysBufferDeleter = static_function_deleter<void, ::free>;
+struct SysBufferDeleter {
+ void operator()(void* p) const {
+ ::free(p);
+ }
+};
+
using SysBufferUniquePtr = std::unique_ptr<void, SysBufferDeleter>;
inline SysBufferUniquePtr allocate_sys_buffer(size_t size) {
return SysBufferUniquePtr(::malloc(size));
public:
void* allocate(size_t size) {
void* p = ::malloc(size);
- if (!p) throw std::bad_alloc();
+ if (!p) {
+ throw std::bad_alloc();
+ }
return p;
}
void deallocate(void* p) {
{
typedef typename std::remove_reference<Allocator>::type allocator_type;
-public:
+ public:
typedef typename Allocator::pointer pointer;
allocator_delete() = default;
}
void operator()(pointer p) const {
- if (!p) return;
+ if (!p) {
+ return;
+ }
const_cast<allocator_delete*>(this)->destroy(p);
const_cast<allocator_delete*>(this)->deallocate(p, 1);
}
};
-template <typename T, typename Allocator>
-class is_simple_allocator {
- FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(has_destroy, destroy);
+namespace detail {
- typedef typename std::remove_const<
- typename std::remove_reference<Allocator>::type
- >::type allocator;
- typedef typename std::remove_reference<T>::type value_type;
- typedef value_type* pointer;
+FOLLY_CREATE_MEMBER_INVOKE_TRAITS(destroy_invoke_traits, destroy);
-public:
- constexpr static bool value = !has_destroy<allocator, void(pointer)>::value
- && !has_destroy<allocator, void(void*)>::value;
-};
+} // namespace detail
+
+template <typename Allocator, typename Value>
+using is_simple_allocator =
+ Negation<detail::destroy_invoke_traits::is_invocable<Allocator, Value*>>;
template <typename T, typename Allocator>
struct as_stl_allocator {
typedef typename std::conditional<
- is_simple_allocator<T, Allocator>::value,
+ is_simple_allocator<
+ typename std::remove_reference<Allocator>::type,
+ typename std::remove_reference<T>::type
+ >::value,
folly::StlAllocator<
typename std::remove_reference<Allocator>::type,
typename std::remove_reference<T>::type
template <typename T, typename Allocator>
typename std::enable_if<
- is_simple_allocator<T, Allocator>::value,
+ is_simple_allocator<
+ typename std::remove_reference<Allocator>::type,
+ typename std::remove_reference<T>::type
+ >::value,
folly::StlAllocator<
typename std::remove_reference<Allocator>::type,
typename std::remove_reference<T>::type
template <typename T, typename Allocator>
typename std::enable_if<
- !is_simple_allocator<T, Allocator>::value,
+ !is_simple_allocator<
+ typename std::remove_reference<Allocator>::type,
+ typename std::remove_reference<T>::type
+ >::value,
typename std::remove_reference<Allocator>::type
>::type make_stl_allocator(Allocator&& allocator) {
return std::move(allocator);
typedef std::unique_ptr<T,
folly::allocator_delete<
typename std::conditional<
- is_simple_allocator<T, Allocator>::value,
+ is_simple_allocator<
+ typename std::remove_reference<Allocator>::type,
+ typename std::remove_reference<T>::type
+ >::value,
folly::StlAllocator<typename std::remove_reference<Allocator>::type, T>,
typename std::remove_reference<Allocator>::type
>::type
*/
template <class T> struct IsArenaAllocator : std::false_type { };
-} // namespace folly
+/*
+ * folly::enable_shared_from_this
+ *
+ * To be removed once C++17 becomes a minimum requirement for folly.
+ */
+#if __cplusplus >= 201700L || \
+ __cpp_lib_enable_shared_from_this >= 201603L
+
+// Guaranteed to have std::enable_shared_from_this::weak_from_this(). Prefer
+// type alias over our own class.
+/* using override */ using std::enable_shared_from_this;
+
+#else
+
+/**
+ * Extends std::enabled_shared_from_this. Offers weak_from_this() to pre-C++17
+ * code. Use as drop-in replacement for std::enable_shared_from_this.
+ *
+ * C++14 has no direct means of creating a std::weak_ptr, one must always
+ * create a (temporary) std::shared_ptr first. C++17 adds weak_from_this() to
+ * std::enable_shared_from_this to avoid that overhead. Alas code that must
+ * compile under different language versions cannot call
+ * std::enable_shared_from_this::weak_from_this() directly. Hence this class.
+ *
+ * @example
+ * class MyClass : public folly::enable_shared_from_this<MyClass> {};
+ *
+ * int main() {
+ * std::shared_ptr<MyClass> sp = std::make_shared<MyClass>();
+ * std::weak_ptr<MyClass> wp = sp->weak_from_this();
+ * }
+ */
+template <typename T>
+class enable_shared_from_this : public std::enable_shared_from_this<T> {
+ public:
+ constexpr enable_shared_from_this() noexcept = default;
+
+ std::weak_ptr<T> weak_from_this() noexcept {
+ return weak_from_this_<T>(this);
+ }
+
+ std::weak_ptr<T const> weak_from_this() const noexcept {
+ return weak_from_this_<T>(this);
+ }
+
+ private:
+ // Uses SFINAE to detect and call
+ // std::enable_shared_from_this<T>::weak_from_this() if available. Falls
+ // back to std::enable_shared_from_this<T>::shared_from_this() otherwise.
+ template <typename U>
+ auto weak_from_this_(std::enable_shared_from_this<U>* base_ptr)
+ noexcept -> decltype(base_ptr->weak_from_this()) {
+ return base_ptr->weak_from_this();
+ }
+
+ template <typename U>
+ auto weak_from_this_(std::enable_shared_from_this<U> const* base_ptr)
+ const noexcept -> decltype(base_ptr->weak_from_this()) {
+ return base_ptr->weak_from_this();
+ }
+
+ template <typename U>
+ std::weak_ptr<U> weak_from_this_(...) noexcept {
+ try {
+ return this->shared_from_this();
+ } catch (std::bad_weak_ptr const&) {
+ // C++17 requires that weak_from_this() on an object not owned by a
+ // shared_ptr returns an empty weak_ptr. Sadly, in C++14,
+ // shared_from_this() on such an object is undefined behavior, and there
+ // is nothing we can do to detect and handle the situation in a portable
+ // manner. But in case a compiler is nice enough to implement C++17
+ // semantics of shared_from_this() and throws a bad_weak_ptr, we catch it
+ // and return an empty weak_ptr.
+ return std::weak_ptr<U>{};
+ }
+ }
+
+ template <typename U>
+ std::weak_ptr<U const> weak_from_this_(...) const noexcept {
+ try {
+ return this->shared_from_this();
+ } catch (std::bad_weak_ptr const&) {
+ return std::weak_ptr<U const>{};
+ }
+ }
+};
+
+#endif
+
+} // namespace folly
projects / folly.git / blobdiff