123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698 |
- // Copyright 2017 The Abseil Authors.
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // https://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
- //
- // -----------------------------------------------------------------------------
- // File: memory.h
- // -----------------------------------------------------------------------------
- //
- // This header file contains utility functions for managing the creation and
- // conversion of smart pointers. This file is an extension to the C++
- // standard <memory> library header file.
- #ifndef Y_ABSL_MEMORY_MEMORY_H_
- #define Y_ABSL_MEMORY_MEMORY_H_
- #include <cstddef>
- #include <limits>
- #include <memory>
- #include <new>
- #include <type_traits>
- #include <utility>
- #include "y_absl/base/macros.h"
- #include "y_absl/meta/type_traits.h"
- namespace y_absl {
- Y_ABSL_NAMESPACE_BEGIN
- // -----------------------------------------------------------------------------
- // Function Template: WrapUnique()
- // -----------------------------------------------------------------------------
- //
- // Adopts ownership from a raw pointer and transfers it to the returned
- // `std::unique_ptr`, whose type is deduced. Because of this deduction, *do not*
- // specify the template type `T` when calling `WrapUnique`.
- //
- // Example:
- // X* NewX(int, int);
- // auto x = WrapUnique(NewX(1, 2)); // 'x' is std::unique_ptr<X>.
- //
- // Do not call WrapUnique with an explicit type, as in
- // `WrapUnique<X>(NewX(1, 2))`. The purpose of WrapUnique is to automatically
- // deduce the pointer type. If you wish to make the type explicit, just use
- // `std::unique_ptr` directly.
- //
- // auto x = std::unique_ptr<X>(NewX(1, 2));
- // - or -
- // std::unique_ptr<X> x(NewX(1, 2));
- //
- // While `y_absl::WrapUnique` is useful for capturing the output of a raw
- // pointer factory, prefer 'y_absl::make_unique<T>(args...)' over
- // 'y_absl::WrapUnique(new T(args...))'.
- //
- // auto x = WrapUnique(new X(1, 2)); // works, but nonideal.
- // auto x = make_unique<X>(1, 2); // safer, standard, avoids raw 'new'.
- //
- // Note that `y_absl::WrapUnique(p)` is valid only if `delete p` is a valid
- // expression. In particular, `y_absl::WrapUnique()` cannot wrap pointers to
- // arrays, functions or void, and it must not be used to capture pointers
- // obtained from array-new expressions (even though that would compile!).
- template <typename T>
- std::unique_ptr<T> WrapUnique(T* ptr) {
- static_assert(!std::is_array<T>::value, "array types are unsupported");
- static_assert(std::is_object<T>::value, "non-object types are unsupported");
- return std::unique_ptr<T>(ptr);
- }
- namespace memory_internal {
- // Traits to select proper overload and return type for `y_absl::make_unique<>`.
- template <typename T>
- struct MakeUniqueResult {
- using scalar = std::unique_ptr<T>;
- };
- template <typename T>
- struct MakeUniqueResult<T[]> {
- using array = std::unique_ptr<T[]>;
- };
- template <typename T, size_t N>
- struct MakeUniqueResult<T[N]> {
- using invalid = void;
- };
- } // namespace memory_internal
- // gcc 4.8 has __cplusplus at 201301 but the libstdc++ shipped with it doesn't
- // define make_unique. Other supported compilers either just define __cplusplus
- // as 201103 but have make_unique (msvc), or have make_unique whenever
- // __cplusplus > 201103 (clang).
- #if defined(__cpp_lib_make_unique)
- using std::make_unique;
- #else
- // -----------------------------------------------------------------------------
- // Function Template: make_unique<T>()
- // -----------------------------------------------------------------------------
- //
- // Creates a `std::unique_ptr<>`, while avoiding issues creating temporaries
- // during the construction process. `y_absl::make_unique<>` also avoids redundant
- // type declarations, by avoiding the need to explicitly use the `new` operator.
- //
- // This implementation of `y_absl::make_unique<>` is designed for C++11 code and
- // will be replaced in C++14 by the equivalent `std::make_unique<>` abstraction.
- // `y_absl::make_unique<>` is designed to be 100% compatible with
- // `std::make_unique<>` so that the eventual migration will involve a simple
- // rename operation.
- //
- // For more background on why `std::unique_ptr<T>(new T(a,b))` is problematic,
- // see Herb Sutter's explanation on
- // (Exception-Safe Function Calls)[https://herbsutter.com/gotw/_102/].
- // (In general, reviewers should treat `new T(a,b)` with scrutiny.)
- //
- // Example usage:
- //
- // auto p = make_unique<X>(args...); // 'p' is a std::unique_ptr<X>
- // auto pa = make_unique<X[]>(5); // 'pa' is a std::unique_ptr<X[]>
- //
- // Three overloads of `y_absl::make_unique` are required:
- //
- // - For non-array T:
- //
- // Allocates a T with `new T(std::forward<Args> args...)`,
- // forwarding all `args` to T's constructor.
- // Returns a `std::unique_ptr<T>` owning that object.
- //
- // - For an array of unknown bounds T[]:
- //
- // `y_absl::make_unique<>` will allocate an array T of type U[] with
- // `new U[n]()` and return a `std::unique_ptr<U[]>` owning that array.
- //
- // Note that 'U[n]()' is different from 'U[n]', and elements will be
- // value-initialized. Note as well that `std::unique_ptr` will perform its
- // own destruction of the array elements upon leaving scope, even though
- // the array [] does not have a default destructor.
- //
- // NOTE: an array of unknown bounds T[] may still be (and often will be)
- // initialized to have a size, and will still use this overload. E.g:
- //
- // auto my_array = y_absl::make_unique<int[]>(10);
- //
- // - For an array of known bounds T[N]:
- //
- // `y_absl::make_unique<>` is deleted (like with `std::make_unique<>`) as
- // this overload is not useful.
- //
- // NOTE: an array of known bounds T[N] is not considered a useful
- // construction, and may cause undefined behavior in templates. E.g:
- //
- // auto my_array = y_absl::make_unique<int[10]>();
- //
- // In those cases, of course, you can still use the overload above and
- // simply initialize it to its desired size:
- //
- // auto my_array = y_absl::make_unique<int[]>(10);
- // `y_absl::make_unique` overload for non-array types.
- template <typename T, typename... Args>
- typename memory_internal::MakeUniqueResult<T>::scalar make_unique(
- Args&&... args) {
- return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
- }
- // `y_absl::make_unique` overload for an array T[] of unknown bounds.
- // The array allocation needs to use the `new T[size]` form and cannot take
- // element constructor arguments. The `std::unique_ptr` will manage destructing
- // these array elements.
- template <typename T>
- typename memory_internal::MakeUniqueResult<T>::array make_unique(size_t n) {
- return std::unique_ptr<T>(new typename y_absl::remove_extent_t<T>[n]());
- }
- // `y_absl::make_unique` overload for an array T[N] of known bounds.
- // This construction will be rejected.
- template <typename T, typename... Args>
- typename memory_internal::MakeUniqueResult<T>::invalid make_unique(
- Args&&... /* args */) = delete;
- #endif
- // -----------------------------------------------------------------------------
- // Function Template: RawPtr()
- // -----------------------------------------------------------------------------
- //
- // Extracts the raw pointer from a pointer-like value `ptr`. `y_absl::RawPtr` is
- // useful within templates that need to handle a complement of raw pointers,
- // `std::nullptr_t`, and smart pointers.
- template <typename T>
- auto RawPtr(T&& ptr) -> decltype(std::addressof(*ptr)) {
- // ptr is a forwarding reference to support Ts with non-const operators.
- return (ptr != nullptr) ? std::addressof(*ptr) : nullptr;
- }
- inline std::nullptr_t RawPtr(std::nullptr_t) { return nullptr; }
- // -----------------------------------------------------------------------------
- // Function Template: ShareUniquePtr()
- // -----------------------------------------------------------------------------
- //
- // Adopts a `std::unique_ptr` rvalue and returns a `std::shared_ptr` of deduced
- // type. Ownership (if any) of the held value is transferred to the returned
- // shared pointer.
- //
- // Example:
- //
- // auto up = y_absl::make_unique<int>(10);
- // auto sp = y_absl::ShareUniquePtr(std::move(up)); // shared_ptr<int>
- // CHECK_EQ(*sp, 10);
- // CHECK(up == nullptr);
- //
- // Note that this conversion is correct even when T is an array type, and more
- // generally it works for *any* deleter of the `unique_ptr` (single-object
- // deleter, array deleter, or any custom deleter), since the deleter is adopted
- // by the shared pointer as well. The deleter is copied (unless it is a
- // reference).
- //
- // Implements the resolution of [LWG 2415](http://wg21.link/lwg2415), by which a
- // null shared pointer does not attempt to call the deleter.
- template <typename T, typename D>
- std::shared_ptr<T> ShareUniquePtr(std::unique_ptr<T, D>&& ptr) {
- return ptr ? std::shared_ptr<T>(std::move(ptr)) : std::shared_ptr<T>();
- }
- // -----------------------------------------------------------------------------
- // Function Template: WeakenPtr()
- // -----------------------------------------------------------------------------
- //
- // Creates a weak pointer associated with a given shared pointer. The returned
- // value is a `std::weak_ptr` of deduced type.
- //
- // Example:
- //
- // auto sp = std::make_shared<int>(10);
- // auto wp = y_absl::WeakenPtr(sp);
- // CHECK_EQ(sp.get(), wp.lock().get());
- // sp.reset();
- // CHECK(wp.lock() == nullptr);
- //
- template <typename T>
- std::weak_ptr<T> WeakenPtr(const std::shared_ptr<T>& ptr) {
- return std::weak_ptr<T>(ptr);
- }
- namespace memory_internal {
- // ExtractOr<E, O, D>::type evaluates to E<O> if possible. Otherwise, D.
- template <template <typename> class Extract, typename Obj, typename Default,
- typename>
- struct ExtractOr {
- using type = Default;
- };
- template <template <typename> class Extract, typename Obj, typename Default>
- struct ExtractOr<Extract, Obj, Default, void_t<Extract<Obj>>> {
- using type = Extract<Obj>;
- };
- template <template <typename> class Extract, typename Obj, typename Default>
- using ExtractOrT = typename ExtractOr<Extract, Obj, Default, void>::type;
- // Extractors for the features of allocators.
- template <typename T>
- using GetPointer = typename T::pointer;
- template <typename T>
- using GetConstPointer = typename T::const_pointer;
- template <typename T>
- using GetVoidPointer = typename T::void_pointer;
- template <typename T>
- using GetConstVoidPointer = typename T::const_void_pointer;
- template <typename T>
- using GetDifferenceType = typename T::difference_type;
- template <typename T>
- using GetSizeType = typename T::size_type;
- template <typename T>
- using GetPropagateOnContainerCopyAssignment =
- typename T::propagate_on_container_copy_assignment;
- template <typename T>
- using GetPropagateOnContainerMoveAssignment =
- typename T::propagate_on_container_move_assignment;
- template <typename T>
- using GetPropagateOnContainerSwap = typename T::propagate_on_container_swap;
- template <typename T>
- using GetIsAlwaysEqual = typename T::is_always_equal;
- template <typename T>
- struct GetFirstArg;
- template <template <typename...> class Class, typename T, typename... Args>
- struct GetFirstArg<Class<T, Args...>> {
- using type = T;
- };
- template <typename Ptr, typename = void>
- struct ElementType {
- using type = typename GetFirstArg<Ptr>::type;
- };
- template <typename T>
- struct ElementType<T, void_t<typename T::element_type>> {
- using type = typename T::element_type;
- };
- template <typename T, typename U>
- struct RebindFirstArg;
- template <template <typename...> class Class, typename T, typename... Args,
- typename U>
- struct RebindFirstArg<Class<T, Args...>, U> {
- using type = Class<U, Args...>;
- };
- template <typename T, typename U, typename = void>
- struct RebindPtr {
- using type = typename RebindFirstArg<T, U>::type;
- };
- template <typename T, typename U>
- struct RebindPtr<T, U, void_t<typename T::template rebind<U>>> {
- using type = typename T::template rebind<U>;
- };
- template <typename T, typename U>
- constexpr bool HasRebindAlloc(...) {
- return false;
- }
- template <typename T, typename U>
- constexpr bool HasRebindAlloc(typename T::template rebind<U>::other*) {
- return true;
- }
- template <typename T, typename U, bool = HasRebindAlloc<T, U>(nullptr)>
- struct RebindAlloc {
- using type = typename RebindFirstArg<T, U>::type;
- };
- template <typename T, typename U>
- struct RebindAlloc<T, U, true> {
- using type = typename T::template rebind<U>::other;
- };
- } // namespace memory_internal
- // -----------------------------------------------------------------------------
- // Class Template: pointer_traits
- // -----------------------------------------------------------------------------
- //
- // An implementation of C++11's std::pointer_traits.
- //
- // Provided for portability on toolchains that have a working C++11 compiler,
- // but the standard library is lacking in C++11 support. For example, some
- // version of the Android NDK.
- //
- template <typename Ptr>
- struct pointer_traits {
- using pointer = Ptr;
- // element_type:
- // Ptr::element_type if present. Otherwise T if Ptr is a template
- // instantiation Template<T, Args...>
- using element_type = typename memory_internal::ElementType<Ptr>::type;
- // difference_type:
- // Ptr::difference_type if present, otherwise std::ptrdiff_t
- using difference_type =
- memory_internal::ExtractOrT<memory_internal::GetDifferenceType, Ptr,
- std::ptrdiff_t>;
- // rebind:
- // Ptr::rebind<U> if exists, otherwise Template<U, Args...> if Ptr is a
- // template instantiation Template<T, Args...>
- template <typename U>
- using rebind = typename memory_internal::RebindPtr<Ptr, U>::type;
- // pointer_to:
- // Calls Ptr::pointer_to(r)
- static pointer pointer_to(element_type& r) { // NOLINT(runtime/references)
- return Ptr::pointer_to(r);
- }
- };
- // Specialization for T*.
- template <typename T>
- struct pointer_traits<T*> {
- using pointer = T*;
- using element_type = T;
- using difference_type = std::ptrdiff_t;
- template <typename U>
- using rebind = U*;
- // pointer_to:
- // Calls std::addressof(r)
- static pointer pointer_to(
- element_type& r) noexcept { // NOLINT(runtime/references)
- return std::addressof(r);
- }
- };
- // -----------------------------------------------------------------------------
- // Class Template: allocator_traits
- // -----------------------------------------------------------------------------
- //
- // A C++11 compatible implementation of C++17's std::allocator_traits.
- //
- #if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
- using std::allocator_traits;
- #else // __cplusplus >= 201703L
- template <typename Alloc>
- struct allocator_traits {
- using allocator_type = Alloc;
- // value_type:
- // Alloc::value_type
- using value_type = typename Alloc::value_type;
- // pointer:
- // Alloc::pointer if present, otherwise value_type*
- using pointer = memory_internal::ExtractOrT<memory_internal::GetPointer,
- Alloc, value_type*>;
- // const_pointer:
- // Alloc::const_pointer if present, otherwise
- // y_absl::pointer_traits<pointer>::rebind<const value_type>
- using const_pointer =
- memory_internal::ExtractOrT<memory_internal::GetConstPointer, Alloc,
- typename y_absl::pointer_traits<pointer>::
- template rebind<const value_type>>;
- // void_pointer:
- // Alloc::void_pointer if present, otherwise
- // y_absl::pointer_traits<pointer>::rebind<void>
- using void_pointer = memory_internal::ExtractOrT<
- memory_internal::GetVoidPointer, Alloc,
- typename y_absl::pointer_traits<pointer>::template rebind<void>>;
- // const_void_pointer:
- // Alloc::const_void_pointer if present, otherwise
- // y_absl::pointer_traits<pointer>::rebind<const void>
- using const_void_pointer = memory_internal::ExtractOrT<
- memory_internal::GetConstVoidPointer, Alloc,
- typename y_absl::pointer_traits<pointer>::template rebind<const void>>;
- // difference_type:
- // Alloc::difference_type if present, otherwise
- // y_absl::pointer_traits<pointer>::difference_type
- using difference_type = memory_internal::ExtractOrT<
- memory_internal::GetDifferenceType, Alloc,
- typename y_absl::pointer_traits<pointer>::difference_type>;
- // size_type:
- // Alloc::size_type if present, otherwise
- // std::make_unsigned<difference_type>::type
- using size_type = memory_internal::ExtractOrT<
- memory_internal::GetSizeType, Alloc,
- typename std::make_unsigned<difference_type>::type>;
- // propagate_on_container_copy_assignment:
- // Alloc::propagate_on_container_copy_assignment if present, otherwise
- // std::false_type
- using propagate_on_container_copy_assignment = memory_internal::ExtractOrT<
- memory_internal::GetPropagateOnContainerCopyAssignment, Alloc,
- std::false_type>;
- // propagate_on_container_move_assignment:
- // Alloc::propagate_on_container_move_assignment if present, otherwise
- // std::false_type
- using propagate_on_container_move_assignment = memory_internal::ExtractOrT<
- memory_internal::GetPropagateOnContainerMoveAssignment, Alloc,
- std::false_type>;
- // propagate_on_container_swap:
- // Alloc::propagate_on_container_swap if present, otherwise std::false_type
- using propagate_on_container_swap =
- memory_internal::ExtractOrT<memory_internal::GetPropagateOnContainerSwap,
- Alloc, std::false_type>;
- // is_always_equal:
- // Alloc::is_always_equal if present, otherwise std::is_empty<Alloc>::type
- using is_always_equal =
- memory_internal::ExtractOrT<memory_internal::GetIsAlwaysEqual, Alloc,
- typename std::is_empty<Alloc>::type>;
- // rebind_alloc:
- // Alloc::rebind<T>::other if present, otherwise Alloc<T, Args> if this Alloc
- // is Alloc<U, Args>
- template <typename T>
- using rebind_alloc = typename memory_internal::RebindAlloc<Alloc, T>::type;
- // rebind_traits:
- // y_absl::allocator_traits<rebind_alloc<T>>
- template <typename T>
- using rebind_traits = y_absl::allocator_traits<rebind_alloc<T>>;
- // allocate(Alloc& a, size_type n):
- // Calls a.allocate(n)
- static pointer allocate(Alloc& a, // NOLINT(runtime/references)
- size_type n) {
- return a.allocate(n);
- }
- // allocate(Alloc& a, size_type n, const_void_pointer hint):
- // Calls a.allocate(n, hint) if possible.
- // If not possible, calls a.allocate(n)
- static pointer allocate(Alloc& a, size_type n, // NOLINT(runtime/references)
- const_void_pointer hint) {
- return allocate_impl(0, a, n, hint);
- }
- // deallocate(Alloc& a, pointer p, size_type n):
- // Calls a.deallocate(p, n)
- static void deallocate(Alloc& a, pointer p, // NOLINT(runtime/references)
- size_type n) {
- a.deallocate(p, n);
- }
- // construct(Alloc& a, T* p, Args&&... args):
- // Calls a.construct(p, std::forward<Args>(args)...) if possible.
- // If not possible, calls
- // ::new (static_cast<void*>(p)) T(std::forward<Args>(args)...)
- template <typename T, typename... Args>
- static void construct(Alloc& a, T* p, // NOLINT(runtime/references)
- Args&&... args) {
- construct_impl(0, a, p, std::forward<Args>(args)...);
- }
- // destroy(Alloc& a, T* p):
- // Calls a.destroy(p) if possible. If not possible, calls p->~T().
- template <typename T>
- static void destroy(Alloc& a, T* p) { // NOLINT(runtime/references)
- destroy_impl(0, a, p);
- }
- // max_size(const Alloc& a):
- // Returns a.max_size() if possible. If not possible, returns
- // std::numeric_limits<size_type>::max() / sizeof(value_type)
- static size_type max_size(const Alloc& a) { return max_size_impl(0, a); }
- // select_on_container_copy_construction(const Alloc& a):
- // Returns a.select_on_container_copy_construction() if possible.
- // If not possible, returns a.
- static Alloc select_on_container_copy_construction(const Alloc& a) {
- return select_on_container_copy_construction_impl(0, a);
- }
- private:
- template <typename A>
- static auto allocate_impl(int, A& a, // NOLINT(runtime/references)
- size_type n, const_void_pointer hint)
- -> decltype(a.allocate(n, hint)) {
- return a.allocate(n, hint);
- }
- static pointer allocate_impl(char, Alloc& a, // NOLINT(runtime/references)
- size_type n, const_void_pointer) {
- return a.allocate(n);
- }
- template <typename A, typename... Args>
- static auto construct_impl(int, A& a, // NOLINT(runtime/references)
- Args&&... args)
- -> decltype(a.construct(std::forward<Args>(args)...)) {
- a.construct(std::forward<Args>(args)...);
- }
- template <typename T, typename... Args>
- static void construct_impl(char, Alloc&, T* p, Args&&... args) {
- ::new (static_cast<void*>(p)) T(std::forward<Args>(args)...);
- }
- template <typename A, typename T>
- static auto destroy_impl(int, A& a, // NOLINT(runtime/references)
- T* p) -> decltype(a.destroy(p)) {
- a.destroy(p);
- }
- template <typename T>
- static void destroy_impl(char, Alloc&, T* p) {
- p->~T();
- }
- template <typename A>
- static auto max_size_impl(int, const A& a) -> decltype(a.max_size()) {
- return a.max_size();
- }
- static size_type max_size_impl(char, const Alloc&) {
- return (std::numeric_limits<size_type>::max)() / sizeof(value_type);
- }
- template <typename A>
- static auto select_on_container_copy_construction_impl(int, const A& a)
- -> decltype(a.select_on_container_copy_construction()) {
- return a.select_on_container_copy_construction();
- }
- static Alloc select_on_container_copy_construction_impl(char,
- const Alloc& a) {
- return a;
- }
- };
- #endif // __cplusplus >= 201703L
- namespace memory_internal {
- // This template alias transforms Alloc::is_nothrow into a metafunction with
- // Alloc as a parameter so it can be used with ExtractOrT<>.
- template <typename Alloc>
- using GetIsNothrow = typename Alloc::is_nothrow;
- } // namespace memory_internal
- // Y_ABSL_ALLOCATOR_NOTHROW is a build time configuration macro for user to
- // specify whether the default allocation function can throw or never throws.
- // If the allocation function never throws, user should define it to a non-zero
- // value (e.g. via `-DABSL_ALLOCATOR_NOTHROW`).
- // If the allocation function can throw, user should leave it undefined or
- // define it to zero.
- //
- // allocator_is_nothrow<Alloc> is a traits class that derives from
- // Alloc::is_nothrow if present, otherwise std::false_type. It's specialized
- // for Alloc = std::allocator<T> for any type T according to the state of
- // Y_ABSL_ALLOCATOR_NOTHROW.
- //
- // default_allocator_is_nothrow is a class that derives from std::true_type
- // when the default allocator (global operator new) never throws, and
- // std::false_type when it can throw. It is a convenience shorthand for writing
- // allocator_is_nothrow<std::allocator<T>> (T can be any type).
- // NOTE: allocator_is_nothrow<std::allocator<T>> is guaranteed to derive from
- // the same type for all T, because users should specialize neither
- // allocator_is_nothrow nor std::allocator.
- template <typename Alloc>
- struct allocator_is_nothrow
- : memory_internal::ExtractOrT<memory_internal::GetIsNothrow, Alloc,
- std::false_type> {};
- #if defined(Y_ABSL_ALLOCATOR_NOTHROW) && Y_ABSL_ALLOCATOR_NOTHROW
- template <typename T>
- struct allocator_is_nothrow<std::allocator<T>> : std::true_type {};
- struct default_allocator_is_nothrow : std::true_type {};
- #else
- struct default_allocator_is_nothrow : std::false_type {};
- #endif
- namespace memory_internal {
- template <typename Allocator, typename Iterator, typename... Args>
- void ConstructRange(Allocator& alloc, Iterator first, Iterator last,
- const Args&... args) {
- for (Iterator cur = first; cur != last; ++cur) {
- Y_ABSL_INTERNAL_TRY {
- std::allocator_traits<Allocator>::construct(alloc, std::addressof(*cur),
- args...);
- }
- Y_ABSL_INTERNAL_CATCH_ANY {
- while (cur != first) {
- --cur;
- std::allocator_traits<Allocator>::destroy(alloc, std::addressof(*cur));
- }
- Y_ABSL_INTERNAL_RETHROW;
- }
- }
- }
- template <typename Allocator, typename Iterator, typename InputIterator>
- void CopyRange(Allocator& alloc, Iterator destination, InputIterator first,
- InputIterator last) {
- for (Iterator cur = destination; first != last;
- static_cast<void>(++cur), static_cast<void>(++first)) {
- Y_ABSL_INTERNAL_TRY {
- std::allocator_traits<Allocator>::construct(alloc, std::addressof(*cur),
- *first);
- }
- Y_ABSL_INTERNAL_CATCH_ANY {
- while (cur != destination) {
- --cur;
- std::allocator_traits<Allocator>::destroy(alloc, std::addressof(*cur));
- }
- Y_ABSL_INTERNAL_RETHROW;
- }
- }
- }
- } // namespace memory_internal
- Y_ABSL_NAMESPACE_END
- } // namespace y_absl
- #endif // Y_ABSL_MEMORY_MEMORY_H_
|