... notably, this includes Abseil's own StatusOr type, which conflicted with our implementation (that was taken from TensorFlow). Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f
		
			
				
	
	
		
			699 lines
		
	
	
	
		
			25 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			699 lines
		
	
	
	
		
			25 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// -----------------------------------------------------------------------------
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// File: memory.h
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// -----------------------------------------------------------------------------
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//
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// This header file contains utility functions for managing the creation and
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// conversion of smart pointers. This file is an extension to the C++
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// standard <memory> library header file.
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#ifndef ABSL_MEMORY_MEMORY_H_
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#define ABSL_MEMORY_MEMORY_H_
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#include <cstddef>
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#include <limits>
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#include <memory>
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#include <new>
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#include <type_traits>
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#include <utility>
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#include "absl/base/macros.h"
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#include "absl/meta/type_traits.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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// -----------------------------------------------------------------------------
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// Function Template: WrapUnique()
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// -----------------------------------------------------------------------------
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//
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// Adopts ownership from a raw pointer and transfers it to the returned
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// `std::unique_ptr`, whose type is deduced. Because of this deduction, *do not*
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// specify the template type `T` when calling `WrapUnique`.
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//
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// Example:
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//   X* NewX(int, int);
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//   auto x = WrapUnique(NewX(1, 2));  // 'x' is std::unique_ptr<X>.
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//
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// Do not call WrapUnique with an explicit type, as in
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// `WrapUnique<X>(NewX(1, 2))`.  The purpose of WrapUnique is to automatically
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// deduce the pointer type. If you wish to make the type explicit, just use
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// `std::unique_ptr` directly.
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//
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//   auto x = std::unique_ptr<X>(NewX(1, 2));
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//                  - or -
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//   std::unique_ptr<X> x(NewX(1, 2));
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//
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// While `absl::WrapUnique` is useful for capturing the output of a raw
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// pointer factory, prefer 'absl::make_unique<T>(args...)' over
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// 'absl::WrapUnique(new T(args...))'.
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//
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//   auto x = WrapUnique(new X(1, 2));  // works, but nonideal.
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//   auto x = make_unique<X>(1, 2);     // safer, standard, avoids raw 'new'.
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//
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// Note that `absl::WrapUnique(p)` is valid only if `delete p` is a valid
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// expression. In particular, `absl::WrapUnique()` cannot wrap pointers to
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// arrays, functions or void, and it must not be used to capture pointers
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// obtained from array-new expressions (even though that would compile!).
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template <typename T>
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std::unique_ptr<T> WrapUnique(T* ptr) {
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  static_assert(!std::is_array<T>::value, "array types are unsupported");
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  static_assert(std::is_object<T>::value, "non-object types are unsupported");
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  return std::unique_ptr<T>(ptr);
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}
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namespace memory_internal {
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// Traits to select proper overload and return type for `absl::make_unique<>`.
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template <typename T>
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struct MakeUniqueResult {
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  using scalar = std::unique_ptr<T>;
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};
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template <typename T>
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struct MakeUniqueResult<T[]> {
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  using array = std::unique_ptr<T[]>;
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};
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template <typename T, size_t N>
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struct MakeUniqueResult<T[N]> {
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  using invalid = void;
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};
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}  // namespace memory_internal
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// gcc 4.8 has __cplusplus at 201301 but the libstdc++ shipped with it doesn't
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// define make_unique.  Other supported compilers either just define __cplusplus
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// as 201103 but have make_unique (msvc), or have make_unique whenever
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// __cplusplus > 201103 (clang).
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#if (__cplusplus > 201103L || defined(_MSC_VER)) && \
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    !(defined(__GLIBCXX__) && !defined(__cpp_lib_make_unique))
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using std::make_unique;
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#else
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// -----------------------------------------------------------------------------
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// Function Template: make_unique<T>()
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// -----------------------------------------------------------------------------
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//
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// Creates a `std::unique_ptr<>`, while avoiding issues creating temporaries
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// during the construction process. `absl::make_unique<>` also avoids redundant
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// type declarations, by avoiding the need to explicitly use the `new` operator.
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//
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// This implementation of `absl::make_unique<>` is designed for C++11 code and
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// will be replaced in C++14 by the equivalent `std::make_unique<>` abstraction.
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// `absl::make_unique<>` is designed to be 100% compatible with
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// `std::make_unique<>` so that the eventual migration will involve a simple
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// rename operation.
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//
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// For more background on why `std::unique_ptr<T>(new T(a,b))` is problematic,
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// see Herb Sutter's explanation on
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// (Exception-Safe Function Calls)[https://herbsutter.com/gotw/_102/].
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// (In general, reviewers should treat `new T(a,b)` with scrutiny.)
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//
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// Example usage:
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//
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//    auto p = make_unique<X>(args...);  // 'p'  is a std::unique_ptr<X>
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//    auto pa = make_unique<X[]>(5);     // 'pa' is a std::unique_ptr<X[]>
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//
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// Three overloads of `absl::make_unique` are required:
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//
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//   - For non-array T:
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//
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//       Allocates a T with `new T(std::forward<Args> args...)`,
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//       forwarding all `args` to T's constructor.
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//       Returns a `std::unique_ptr<T>` owning that object.
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//
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//   - For an array of unknown bounds T[]:
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//
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//       `absl::make_unique<>` will allocate an array T of type U[] with
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//       `new U[n]()` and return a `std::unique_ptr<U[]>` owning that array.
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//
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//       Note that 'U[n]()' is different from 'U[n]', and elements will be
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//       value-initialized. Note as well that `std::unique_ptr` will perform its
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//       own destruction of the array elements upon leaving scope, even though
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//       the array [] does not have a default destructor.
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//
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//       NOTE: an array of unknown bounds T[] may still be (and often will be)
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//       initialized to have a size, and will still use this overload. E.g:
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//
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//         auto my_array = absl::make_unique<int[]>(10);
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//
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//   - For an array of known bounds T[N]:
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//
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//       `absl::make_unique<>` is deleted (like with `std::make_unique<>`) as
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//       this overload is not useful.
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//
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//       NOTE: an array of known bounds T[N] is not considered a useful
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//       construction, and may cause undefined behavior in templates. E.g:
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//
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//         auto my_array = absl::make_unique<int[10]>();
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//
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//       In those cases, of course, you can still use the overload above and
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//       simply initialize it to its desired size:
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//
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//         auto my_array = absl::make_unique<int[]>(10);
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// `absl::make_unique` overload for non-array types.
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template <typename T, typename... Args>
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typename memory_internal::MakeUniqueResult<T>::scalar make_unique(
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    Args&&... args) {
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  return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
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}
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// `absl::make_unique` overload for an array T[] of unknown bounds.
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// The array allocation needs to use the `new T[size]` form and cannot take
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// element constructor arguments. The `std::unique_ptr` will manage destructing
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// these array elements.
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template <typename T>
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typename memory_internal::MakeUniqueResult<T>::array make_unique(size_t n) {
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  return std::unique_ptr<T>(new typename absl::remove_extent_t<T>[n]());
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}
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// `absl::make_unique` overload for an array T[N] of known bounds.
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// This construction will be rejected.
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template <typename T, typename... Args>
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typename memory_internal::MakeUniqueResult<T>::invalid make_unique(
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    Args&&... /* args */) = delete;
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#endif
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// -----------------------------------------------------------------------------
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// Function Template: RawPtr()
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// -----------------------------------------------------------------------------
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//
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// Extracts the raw pointer from a pointer-like value `ptr`. `absl::RawPtr` is
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// useful within templates that need to handle a complement of raw pointers,
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// `std::nullptr_t`, and smart pointers.
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template <typename T>
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auto RawPtr(T&& ptr) -> decltype(std::addressof(*ptr)) {
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  // ptr is a forwarding reference to support Ts with non-const operators.
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  return (ptr != nullptr) ? std::addressof(*ptr) : nullptr;
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}
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inline std::nullptr_t RawPtr(std::nullptr_t) { return nullptr; }
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// -----------------------------------------------------------------------------
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// Function Template: ShareUniquePtr()
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// -----------------------------------------------------------------------------
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//
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// Adopts a `std::unique_ptr` rvalue and returns a `std::shared_ptr` of deduced
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// type. Ownership (if any) of the held value is transferred to the returned
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// shared pointer.
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//
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// Example:
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//
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//     auto up = absl::make_unique<int>(10);
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//     auto sp = absl::ShareUniquePtr(std::move(up));  // shared_ptr<int>
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//     CHECK_EQ(*sp, 10);
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//     CHECK(up == nullptr);
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//
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// Note that this conversion is correct even when T is an array type, and more
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// generally it works for *any* deleter of the `unique_ptr` (single-object
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// deleter, array deleter, or any custom deleter), since the deleter is adopted
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// by the shared pointer as well. The deleter is copied (unless it is a
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// reference).
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//
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// Implements the resolution of [LWG 2415](http://wg21.link/lwg2415), by which a
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// null shared pointer does not attempt to call the deleter.
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template <typename T, typename D>
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std::shared_ptr<T> ShareUniquePtr(std::unique_ptr<T, D>&& ptr) {
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  return ptr ? std::shared_ptr<T>(std::move(ptr)) : std::shared_ptr<T>();
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}
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// -----------------------------------------------------------------------------
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// Function Template: WeakenPtr()
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// -----------------------------------------------------------------------------
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//
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// Creates a weak pointer associated with a given shared pointer. The returned
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// value is a `std::weak_ptr` of deduced type.
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//
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// Example:
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//
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//    auto sp = std::make_shared<int>(10);
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//    auto wp = absl::WeakenPtr(sp);
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//    CHECK_EQ(sp.get(), wp.lock().get());
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//    sp.reset();
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//    CHECK(wp.lock() == nullptr);
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//
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template <typename T>
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std::weak_ptr<T> WeakenPtr(const std::shared_ptr<T>& ptr) {
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  return std::weak_ptr<T>(ptr);
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}
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namespace memory_internal {
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// ExtractOr<E, O, D>::type evaluates to E<O> if possible. Otherwise, D.
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template <template <typename> class Extract, typename Obj, typename Default,
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          typename>
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struct ExtractOr {
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  using type = Default;
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};
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template <template <typename> class Extract, typename Obj, typename Default>
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struct ExtractOr<Extract, Obj, Default, void_t<Extract<Obj>>> {
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  using type = Extract<Obj>;
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};
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template <template <typename> class Extract, typename Obj, typename Default>
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using ExtractOrT = typename ExtractOr<Extract, Obj, Default, void>::type;
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// Extractors for the features of allocators.
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template <typename T>
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using GetPointer = typename T::pointer;
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template <typename T>
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using GetConstPointer = typename T::const_pointer;
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template <typename T>
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using GetVoidPointer = typename T::void_pointer;
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template <typename T>
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using GetConstVoidPointer = typename T::const_void_pointer;
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template <typename T>
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using GetDifferenceType = typename T::difference_type;
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template <typename T>
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using GetSizeType = typename T::size_type;
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template <typename T>
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using GetPropagateOnContainerCopyAssignment =
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    typename T::propagate_on_container_copy_assignment;
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template <typename T>
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using GetPropagateOnContainerMoveAssignment =
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    typename T::propagate_on_container_move_assignment;
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template <typename T>
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using GetPropagateOnContainerSwap = typename T::propagate_on_container_swap;
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template <typename T>
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using GetIsAlwaysEqual = typename T::is_always_equal;
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template <typename T>
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struct GetFirstArg;
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template <template <typename...> class Class, typename T, typename... Args>
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struct GetFirstArg<Class<T, Args...>> {
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  using type = T;
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};
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template <typename Ptr, typename = void>
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struct ElementType {
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  using type = typename GetFirstArg<Ptr>::type;
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};
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template <typename T>
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struct ElementType<T, void_t<typename T::element_type>> {
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  using type = typename T::element_type;
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};
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template <typename T, typename U>
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struct RebindFirstArg;
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template <template <typename...> class Class, typename T, typename... Args,
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          typename U>
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struct RebindFirstArg<Class<T, Args...>, U> {
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  using type = Class<U, Args...>;
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};
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template <typename T, typename U, typename = void>
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struct RebindPtr {
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  using type = typename RebindFirstArg<T, U>::type;
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};
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template <typename T, typename U>
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struct RebindPtr<T, U, void_t<typename T::template rebind<U>>> {
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  using type = typename T::template rebind<U>;
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};
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template <typename T, typename U>
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constexpr bool HasRebindAlloc(...) {
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  return false;
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}
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template <typename T, typename U>
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constexpr bool HasRebindAlloc(typename T::template rebind<U>::other*) {
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  return true;
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}
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template <typename T, typename U, bool = HasRebindAlloc<T, U>(nullptr)>
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struct RebindAlloc {
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  using type = typename RebindFirstArg<T, U>::type;
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};
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template <typename T, typename U>
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struct RebindAlloc<T, U, true> {
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  using type = typename T::template rebind<U>::other;
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};
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}  // namespace memory_internal
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// -----------------------------------------------------------------------------
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// Class Template: pointer_traits
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// -----------------------------------------------------------------------------
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//
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// An implementation of C++11's std::pointer_traits.
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//
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// Provided for portability on toolchains that have a working C++11 compiler,
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// but the standard library is lacking in C++11 support. For example, some
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// version of the Android NDK.
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//
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template <typename Ptr>
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struct pointer_traits {
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  using pointer = Ptr;
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  // element_type:
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  // Ptr::element_type if present. Otherwise T if Ptr is a template
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  // instantiation Template<T, Args...>
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  using element_type = typename memory_internal::ElementType<Ptr>::type;
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  // difference_type:
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  // Ptr::difference_type if present, otherwise std::ptrdiff_t
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  using difference_type =
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      memory_internal::ExtractOrT<memory_internal::GetDifferenceType, Ptr,
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                                  std::ptrdiff_t>;
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  // rebind:
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  // Ptr::rebind<U> if exists, otherwise Template<U, Args...> if Ptr is a
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  // template instantiation Template<T, Args...>
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  template <typename U>
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  using rebind = typename memory_internal::RebindPtr<Ptr, U>::type;
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  // pointer_to:
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  // Calls Ptr::pointer_to(r)
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  static pointer pointer_to(element_type& r) {  // NOLINT(runtime/references)
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    return Ptr::pointer_to(r);
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  }
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};
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// Specialization for T*.
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template <typename T>
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struct pointer_traits<T*> {
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  using pointer = T*;
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  using element_type = T;
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  using difference_type = std::ptrdiff_t;
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  template <typename U>
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  using rebind = U*;
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  // pointer_to:
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  // Calls std::addressof(r)
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  static pointer pointer_to(
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      element_type& r) noexcept {  // NOLINT(runtime/references)
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    return std::addressof(r);
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  }
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};
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// -----------------------------------------------------------------------------
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// Class Template: allocator_traits
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// -----------------------------------------------------------------------------
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//
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// A C++11 compatible implementation of C++17's std::allocator_traits.
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//
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#if __cplusplus >= 201703L
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using std::allocator_traits;
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#else  // __cplusplus >= 201703L
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template <typename Alloc>
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struct allocator_traits {
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  using allocator_type = Alloc;
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						|
 | 
						|
  // 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
 | 
						|
  // absl::pointer_traits<pointer>::rebind<const value_type>
 | 
						|
  using const_pointer =
 | 
						|
      memory_internal::ExtractOrT<memory_internal::GetConstPointer, Alloc,
 | 
						|
                                  typename absl::pointer_traits<pointer>::
 | 
						|
                                      template rebind<const value_type>>;
 | 
						|
 | 
						|
  // void_pointer:
 | 
						|
  // Alloc::void_pointer if present, otherwise
 | 
						|
  // absl::pointer_traits<pointer>::rebind<void>
 | 
						|
  using void_pointer = memory_internal::ExtractOrT<
 | 
						|
      memory_internal::GetVoidPointer, Alloc,
 | 
						|
      typename absl::pointer_traits<pointer>::template rebind<void>>;
 | 
						|
 | 
						|
  // const_void_pointer:
 | 
						|
  // Alloc::const_void_pointer if present, otherwise
 | 
						|
  // absl::pointer_traits<pointer>::rebind<const void>
 | 
						|
  using const_void_pointer = memory_internal::ExtractOrT<
 | 
						|
      memory_internal::GetConstVoidPointer, Alloc,
 | 
						|
      typename absl::pointer_traits<pointer>::template rebind<const void>>;
 | 
						|
 | 
						|
  // difference_type:
 | 
						|
  // Alloc::difference_type if present, otherwise
 | 
						|
  // absl::pointer_traits<pointer>::difference_type
 | 
						|
  using difference_type = memory_internal::ExtractOrT<
 | 
						|
      memory_internal::GetDifferenceType, Alloc,
 | 
						|
      typename 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:
 | 
						|
  // absl::allocator_traits<rebind_alloc<T>>
 | 
						|
  template <typename T>
 | 
						|
  using rebind_traits = 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
 | 
						|
 | 
						|
// 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
 | 
						|
// 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(ABSL_ALLOCATOR_NOTHROW) && 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) {
 | 
						|
    ABSL_INTERNAL_TRY {
 | 
						|
      std::allocator_traits<Allocator>::construct(alloc, std::addressof(*cur),
 | 
						|
                                                  args...);
 | 
						|
    }
 | 
						|
    ABSL_INTERNAL_CATCH_ANY {
 | 
						|
      while (cur != first) {
 | 
						|
        --cur;
 | 
						|
        std::allocator_traits<Allocator>::destroy(alloc, std::addressof(*cur));
 | 
						|
      }
 | 
						|
      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)) {
 | 
						|
    ABSL_INTERNAL_TRY {
 | 
						|
      std::allocator_traits<Allocator>::construct(alloc, std::addressof(*cur),
 | 
						|
                                                  *first);
 | 
						|
    }
 | 
						|
    ABSL_INTERNAL_CATCH_ANY {
 | 
						|
      while (cur != destination) {
 | 
						|
        --cur;
 | 
						|
        std::allocator_traits<Allocator>::destroy(alloc, std::addressof(*cur));
 | 
						|
      }
 | 
						|
      ABSL_INTERNAL_RETHROW;
 | 
						|
    }
 | 
						|
  }
 | 
						|
}
 | 
						|
}  // namespace memory_internal
 | 
						|
ABSL_NAMESPACE_END
 | 
						|
}  // namespace absl
 | 
						|
 | 
						|
#endif  // ABSL_MEMORY_MEMORY_H_
 |