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Diffstat (limited to 'Firestore/third_party/abseil-cpp/absl/utility/utility.h')
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diff --git a/Firestore/third_party/abseil-cpp/absl/utility/utility.h b/Firestore/third_party/abseil-cpp/absl/utility/utility.h new file mode 100644 index 0000000..1943c4a --- /dev/null +++ b/Firestore/third_party/abseil-cpp/absl/utility/utility.h @@ -0,0 +1,264 @@ +// 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 +// +// http://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. +// +// This header file contains C++11 versions of standard <utility> header +// abstractions available within C++14 and C++17, and are designed to be drop-in +// replacement for code compliant with C++14 and C++17. +// +// The following abstractions are defined: +// +// * integer_sequence<T, Ints...> == std::integer_sequence<T, Ints...> +// * index_sequence<Ints...> == std::index_sequence<Ints...> +// * make_integer_sequence<T, N> == std::make_integer_sequence<T, N> +// * 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> +// +// 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 +// `constexpr` `std::move()` and `std::forward()` implementations in C++11. +// +// References: +// +// http://en.cppreference.com/w/cpp/utility/integer_sequence +// http://en.cppreference.com/w/cpp/utility/apply +// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3658.html +// + +#ifndef ABSL_UTILITY_UTILITY_H_ +#define ABSL_UTILITY_UTILITY_H_ + +#include <cstddef> +#include <cstdlib> +#include <tuple> +#include <utility> + +#include "absl/base/config.h" +#include "absl/base/internal/inline_variable.h" +#include "absl/base/internal/invoke.h" +#include "absl/meta/type_traits.h" + +namespace absl { + +// integer_sequence +// +// Class template representing a compile-time integer sequence. An instantiation +// of `integer_sequence<T, Ints...>` has a sequence of integers encoded in its +// type through its template arguments (which is a common need when +// working with C++11 variadic templates). `absl::integer_sequence` is designed +// to be a drop-in replacement for C++14's `std::integer_sequence`. +// +// Example: +// +// template< class T, T... Ints > +// void user_function(integer_sequence<T, Ints...>); +// +// int main() +// { +// // user_function's `T` will be deduced to `int` and `Ints...` +// // will be deduced to `0, 1, 2, 3, 4`. +// user_function(make_integer_sequence<int, 5>()); +// } +template <typename T, T... Ints> +struct integer_sequence { + using value_type = T; + static constexpr size_t size() noexcept { return sizeof...(Ints); } +}; + +// index_sequence +// +// A helper template for an `integer_sequence` of `size_t`, +// `absl::index_sequence` is designed to be a drop-in replacement for C++14's +// `std::index_sequence`. +template <size_t... Ints> +using index_sequence = integer_sequence<size_t, Ints...>; + +namespace utility_internal { + +template <typename Seq, size_t SeqSize, size_t Rem> +struct Extend; + +// Note that SeqSize == sizeof...(Ints). It's passed explicitly for efficiency. +template <typename T, T... Ints, size_t SeqSize> +struct Extend<integer_sequence<T, Ints...>, SeqSize, 0> { + using type = integer_sequence<T, Ints..., (Ints + SeqSize)...>; +}; + +template <typename T, T... Ints, size_t SeqSize> +struct Extend<integer_sequence<T, Ints...>, SeqSize, 1> { + using type = integer_sequence<T, Ints..., (Ints + SeqSize)..., 2 * SeqSize>; +}; + +// Recursion helper for 'make_integer_sequence<T, N>'. +// 'Gen<T, N>::type' is an alias for 'integer_sequence<T, 0, 1, ... N-1>'. +template <typename T, size_t N> +struct Gen { + using type = + typename Extend<typename Gen<T, N / 2>::type, N / 2, N % 2>::type; +}; + +template <typename T> +struct Gen<T, 0> { + using type = integer_sequence<T>; +}; + +} // namespace utility_internal + +// Compile-time sequences of integers + +// make_integer_sequence +// +// This template alias is equivalent to +// `integer_sequence<int, 0, 1, ..., N-1>`, and is designed to be a drop-in +// replacement for C++14's `std::make_integer_sequence`. +template <typename T, T N> +using make_integer_sequence = typename utility_internal::Gen<T, N>::type; + +// make_index_sequence +// +// This template alias is equivalent to `index_sequence<0, 1, ..., N-1>`, +// and is designed to be a drop-in replacement for C++14's +// `std::make_index_sequence`. +template <size_t N> +using make_index_sequence = make_integer_sequence<size_t, N>; + +// index_sequence_for +// +// Converts a typename pack into an index sequence of the same length, and +// is designed to be a drop-in replacement for C++14's +// `std::index_sequence_for()` +template <typename... Ts> +using index_sequence_for = make_index_sequence<sizeof...(Ts)>; + +// Tag types + +#ifdef ABSL_HAVE_STD_OPTIONAL + +using std::in_place_t; +using std::in_place; + +#else // ABSL_HAVE_STD_OPTIONAL + +// in_place_t +// +// Tag type used to specify in-place construction, such as with +// `absl::optional`, designed to be a drop-in replacement for C++17's +// `std::in_place_t`. +struct in_place_t {}; + +ABSL_INTERNAL_INLINE_CONSTEXPR(in_place_t, in_place, {}); + +#endif // ABSL_HAVE_STD_OPTIONAL + +#ifdef ABSL_HAVE_STD_ANY +using std::in_place_type_t; +#else + +// in_place_type_t +// +// Tag type used for in-place construction when the type to construct needs to +// be specified, such as with `absl::any`, designed to be a drop-in replacement +// for C++17's `std::in_place_type_t`. +template <typename T> +struct in_place_type_t {}; +#endif // ABSL_HAVE_STD_ANY + +// in_place_index_t +// +// Tag type used for in-place construction when the type to construct needs to +// be specified, such as with `absl::any`, designed to be a drop-in replacement +// for C++17's `std::in_place_index_t`. +template <size_t I> +struct in_place_index_t {}; + +// Constexpr move and forward + +// move() +// +// A constexpr version of `std::move()`, designed to be a drop-in replacement +// for C++14's `std::move()`. +template <typename T> +constexpr absl::remove_reference_t<T>&& move(T&& t) noexcept { + return static_cast<absl::remove_reference_t<T>&&>(t); +} + +// forward() +// +// A constexpr version of `std::forward()`, designed to be a drop-in replacement +// for C++14's `std::forward()`. +template <typename T> +constexpr T&& forward( + absl::remove_reference_t<T>& t) noexcept { // NOLINT(runtime/references) + return static_cast<T&&>(t); +} + +namespace utility_internal { +// Helper method for expanding tuple into a called method. +template <typename Functor, typename Tuple, std::size_t... Indexes> +auto apply_helper(Functor&& functor, Tuple&& t, index_sequence<Indexes...>) + -> decltype(absl::base_internal::Invoke( + absl::forward<Functor>(functor), + std::get<Indexes>(absl::forward<Tuple>(t))...)) { + return absl::base_internal::Invoke( + absl::forward<Functor>(functor), + std::get<Indexes>(absl::forward<Tuple>(t))...); +} + +} // namespace utility_internal + +// apply +// +// Invokes a Callable using elements of a tuple as its arguments. +// Each element of the tuple corresponds to an argument of the call (in order). +// Both the Callable argument and the tuple argument are perfect-forwarded. +// For member-function Callables, the first tuple element acts as the `this` +// pointer. `absl::apply` is designed to be a drop-in replacement for C++17's +// `std::apply`. Unlike C++17's `std::apply`, this is not currently `constexpr`. +// +// Example: +// +// class Foo{void Bar(int);}; +// void user_function(int, std::string); +// void user_function(std::unique_ptr<Foo>); +// +// int main() +// { +// std::tuple<int, std::string> tuple1(42, "bar"); +// // Invokes the user function overload on int, std::string. +// absl::apply(&user_function, tuple1); +// +// auto foo = absl::make_unique<Foo>(); +// std::tuple<Foo*, int> tuple2(foo.get(), 42); +// // Invokes the method Bar on foo with one argument 42. +// absl::apply(&Foo::Bar, foo.get(), 42); +// +// std::tuple<std::unique_ptr<Foo>> tuple3(absl::make_unique<Foo>()); +// // Invokes the user function that takes ownership of the unique +// // pointer. +// absl::apply(&user_function, std::move(tuple)); +// } +template <typename Functor, typename Tuple> +auto apply(Functor&& functor, Tuple&& t) + -> decltype(utility_internal::apply_helper( + absl::forward<Functor>(functor), absl::forward<Tuple>(t), + absl::make_index_sequence<std::tuple_size< + typename std::remove_reference<Tuple>::type>::value>{})) { + return utility_internal::apply_helper( + absl::forward<Functor>(functor), absl::forward<Tuple>(t), + absl::make_index_sequence<std::tuple_size< + typename std::remove_reference<Tuple>::type>::value>{}); +} +} // namespace absl + +#endif // ABSL_UTILITY_UTILITY_H_ |