833 lines
27 KiB
C++
833 lines
27 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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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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* http://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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// @author: Andrei Alexandrescu
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#pragma once
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#include <functional>
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#include <limits>
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#include <memory>
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#include <tuple>
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#include <type_traits>
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#include <folly/Portability.h>
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#define FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(classname, type_name) \
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template <typename TTheClass_> \
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struct classname##__folly_traits_impl__ { \
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template <typename UTheClass_> \
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static constexpr bool test(typename UTheClass_::type_name*) { \
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return true; \
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} \
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template <typename> \
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static constexpr bool test(...) { \
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return false; \
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} \
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}; \
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template <typename TTheClass_> \
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using classname = typename std::conditional< \
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classname##__folly_traits_impl__<TTheClass_>::template test<TTheClass_>( \
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nullptr), \
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std::true_type, \
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std::false_type>::type
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#define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, cv_qual) \
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template <typename TTheClass_, typename RTheReturn_, typename... TTheArgs_> \
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struct classname##__folly_traits_impl__< \
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TTheClass_, \
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RTheReturn_(TTheArgs_...) cv_qual> { \
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template < \
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typename UTheClass_, \
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RTheReturn_ (UTheClass_::*)(TTheArgs_...) cv_qual> \
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struct sfinae {}; \
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template <typename UTheClass_> \
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static std::true_type test(sfinae<UTheClass_, &UTheClass_::func_name>*); \
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template <typename> \
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static std::false_type test(...); \
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}
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/*
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* The FOLLY_CREATE_HAS_MEMBER_FN_TRAITS is used to create traits
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* classes that check for the existence of a member function with
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* a given name and signature. It currently does not support
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* checking for inherited members.
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*
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* Such classes receive two template parameters: the class to be checked
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* and the signature of the member function. A static boolean field
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* named `value` (which is also constexpr) tells whether such member
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* function exists.
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*
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* Each traits class created is bound only to the member name, not to
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* its signature nor to the type of the class containing it.
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*
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* Say you need to know if a given class has a member function named
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* `test` with the following signature:
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*
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* int test() const;
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*
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* You'd need this macro to create a traits class to check for a member
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* named `test`, and then use this traits class to check for the signature:
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*
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* namespace {
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*
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* FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(has_test_traits, test);
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*
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* } // unnamed-namespace
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*
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* void some_func() {
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* cout << "Does class Foo have a member int test() const? "
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* << boolalpha << has_test_traits<Foo, int() const>::value;
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* }
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*
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* You can use the same traits class to test for a completely different
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* signature, on a completely different class, as long as the member name
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* is the same:
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*
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* void some_func() {
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* cout << "Does class Foo have a member int test()? "
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* << boolalpha << has_test_traits<Foo, int()>::value;
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* cout << "Does class Foo have a member int test() const? "
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* << boolalpha << has_test_traits<Foo, int() const>::value;
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* cout << "Does class Bar have a member double test(const string&, long)? "
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* << boolalpha << has_test_traits<Bar, double(const string&, long)>::value;
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* }
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*
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* @author: Marcelo Juchem <marcelo@fb.com>
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*/
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#define FOLLY_CREATE_HAS_MEMBER_FN_TRAITS(classname, func_name) \
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template <typename, typename> \
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struct classname##__folly_traits_impl__; \
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FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, ); \
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FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL(classname, func_name, const); \
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FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
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classname, func_name, /* nolint */ volatile); \
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FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
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classname, func_name, /* nolint */ volatile const); \
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template <typename TTheClass_, typename TTheSignature_> \
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using classname = \
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decltype(classname##__folly_traits_impl__<TTheClass_, TTheSignature_>:: \
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template test<TTheClass_>(nullptr))
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namespace folly {
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template <typename...>
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struct tag_t {};
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#if __cplusplus >= 201703L
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template <typename... T>
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inline constexpr tag_t<T...> tag;
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#endif
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#if __cpp_lib_bool_constant || _MSC_VER
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using std::bool_constant;
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#else
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// mimic: std::bool_constant, C++17
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template <bool B>
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using bool_constant = std::integral_constant<bool, B>;
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#endif
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template <std::size_t I>
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using index_constant = std::integral_constant<std::size_t, I>;
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namespace detail {
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/**
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* A type trait to check if a given type is an instantiation of a class
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* template.
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*
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* Note that this only works with template type parameters. It does not work
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* with non-type template parameters, template template parameters, or alias
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* templates.
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*/
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template <template <typename...> class, typename>
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struct is_instantiation_of : std::false_type {};
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template <template <typename...> class C, typename... T>
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struct is_instantiation_of<C, C<T...>> : std::true_type {};
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template <template <typename...> class C, typename T>
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constexpr bool is_instantiation_of_v = is_instantiation_of<C, T>::value;
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} // namespace detail
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namespace detail {
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template <bool, typename T>
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struct is_constexpr_default_constructible_;
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template <typename T>
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struct is_constexpr_default_constructible_<false, T> {
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using type = std::false_type;
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};
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template <typename T>
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struct is_constexpr_default_constructible_<true, T> {
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static constexpr int take(T) {
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return 0;
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}
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template <int = take(T{})>
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static std::true_type sfinae(int);
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static std::false_type sfinae(...);
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using type = decltype(sfinae(0));
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};
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} // namespace detail
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// is_constexpr_default_constructible
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// is_constexpr_default_constructible_v
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//
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// A type trait, with associated variable template, which determines whether
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// its type parameter is constexpr default-constructible, that is, default-
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// constructible in a constexpr context.
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//
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// Instantiations of is_constexpr_default_constructible unambiguously inherit
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// std::integral_constant<bool, V> for some bool V.
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template <typename T>
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struct is_constexpr_default_constructible
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: detail::is_constexpr_default_constructible_<
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std::is_default_constructible<T>::value,
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T>::type {};
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template <typename T>
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FOLLY_INLINE_VARIABLE constexpr bool is_constexpr_default_constructible_v =
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is_constexpr_default_constructible<T>::value;
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/***
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* _t
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*
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* Instead of:
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*
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* using decayed = typename std::decay<T>::type;
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*
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* With the C++14 standard trait aliases, we could use:
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*
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* using decayed = std::decay_t<T>;
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*
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* Without them, we could use:
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*
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* using decayed = _t<std::decay<T>>;
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*
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* Also useful for any other library with template types having dependent
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* member types named `type`, like the standard trait types.
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*/
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template <typename T>
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using _t = typename T::type;
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/**
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* A type trait to remove all const volatile and reference qualifiers on a
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* type T
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*/
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template <typename T>
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struct remove_cvref {
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using type =
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typename std::remove_cv<typename std::remove_reference<T>::type>::type;
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};
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template <typename T>
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using remove_cvref_t = typename remove_cvref<T>::type;
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namespace detail {
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template <typename Src>
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struct like_ {
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template <typename Dst>
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using apply = Dst;
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};
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template <typename Src>
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struct like_<Src const> {
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template <typename Dst>
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using apply = Dst const;
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};
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template <typename Src>
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struct like_<Src volatile> {
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template <typename Dst>
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using apply = Dst volatile;
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};
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template <typename Src>
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struct like_<Src const volatile> {
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template <typename Dst>
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using apply = Dst const volatile;
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};
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template <typename Src>
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struct like_<Src&> {
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template <typename Dst>
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using apply = typename like_<Src>::template apply<Dst>&;
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};
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template <typename Src>
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struct like_<Src&&> {
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template <typename Dst>
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using apply = typename like_<Src>::template apply<Dst>&&;
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};
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} // namespace detail
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// mimic: like_t, p0847r0
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template <typename Src, typename Dst>
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using like_t = typename detail::like_<Src>::template apply<remove_cvref_t<Dst>>;
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// mimic: like, p0847r0
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template <typename Src, typename Dst>
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struct like {
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using type = like_t<Src, Dst>;
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};
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/**
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* type_t
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*
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* A type alias for the first template type argument. `type_t` is useful for
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* controlling class-template and function-template partial specialization.
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*
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* Example:
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*
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* template <typename Value>
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* class Container {
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* public:
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* template <typename... Args>
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* Container(
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* type_t<in_place_t, decltype(Value(std::declval<Args>()...))>,
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* Args&&...);
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* };
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*
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* void_t
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*
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* A type alias for `void`. `void_t` is useful for controling class-template
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* and function-template partial specialization.
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*
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* Example:
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*
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* // has_value_type<T>::value is true if T has a nested type `value_type`
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* template <class T, class = void>
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* struct has_value_type
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* : std::false_type {};
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*
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* template <class T>
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* struct has_value_type<T, folly::void_t<typename T::value_type>>
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* : std::true_type {};
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*/
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/**
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* There is a bug in libstdc++, libc++, and MSVC's STL that causes it to
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* ignore unused template parameter arguments in template aliases and does not
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* cause substitution failures. This defect has been recorded here:
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* http://open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#1558.
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*
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* This causes the implementation of std::void_t to be buggy, as it is likely
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* defined as something like the following:
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*
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* template <typename...>
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* using void_t = void;
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*
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* This causes the compiler to ignore all the template arguments and does not
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* help when one wants to cause substitution failures. Rather declarations
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* which have void_t in orthogonal specializations are treated as the same.
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* For example, assuming the possible `T` types are only allowed to have
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* either the alias `one` or `two` and never both or none:
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*
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* template <typename T,
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* typename std::void_t<std::decay_t<T>::one>* = nullptr>
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* void foo(T&&) {}
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* template <typename T,
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* typename std::void_t<std::decay_t<T>::two>* = nullptr>
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* void foo(T&&) {}
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*
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* The second foo() will be a redefinition because it conflicts with the first
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* one; void_t does not cause substitution failures - the template types are
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* just ignored.
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*/
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namespace traits_detail {
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template <class T, class...>
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struct type_t_ {
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using type = T;
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};
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} // namespace traits_detail
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template <class T, class... Ts>
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using type_t = typename traits_detail::type_t_<T, Ts...>::type;
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template <class... Ts>
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using void_t = type_t<void, Ts...>;
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template <typename T>
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using aligned_storage_for_t =
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typename std::aligned_storage<sizeof(T), alignof(T)>::type;
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// Older versions of libstdc++ do not provide std::is_trivially_copyable
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#if defined(__clang__) && !defined(_LIBCPP_VERSION)
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template <class T>
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struct is_trivially_copyable : bool_constant<__is_trivially_copyable(T)> {};
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#else
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template <class T>
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using is_trivially_copyable = std::is_trivially_copyable<T>;
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#endif
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template <class T>
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FOLLY_INLINE_VARIABLE constexpr bool is_trivially_copyable_v =
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is_trivially_copyable<T>::value;
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/**
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* IsRelocatable<T>::value describes the ability of moving around
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* memory a value of type T by using memcpy (as opposed to the
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* conservative approach of calling the copy constructor and then
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* destroying the old temporary. Essentially for a relocatable type,
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* the following two sequences of code should be semantically
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* equivalent:
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*
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* void move1(T * from, T * to) {
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* new(to) T(from);
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* (*from).~T();
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* }
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*
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* void move2(T * from, T * to) {
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* memcpy(to, from, sizeof(T));
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* }
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*
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* Most C++ types are relocatable; the ones that aren't would include
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* internal pointers or (very rarely) would need to update remote
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* pointers to pointers tracking them. All C++ primitive types and
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* type constructors are relocatable.
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*
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* This property can be used in a variety of optimizations. Currently
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* fbvector uses this property intensively.
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*
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* The default conservatively assumes the type is not
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* relocatable. Several specializations are defined for known
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* types. You may want to add your own specializations. Do so in
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* namespace folly and make sure you keep the specialization of
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* IsRelocatable<SomeStruct> in the same header as SomeStruct.
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*
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* You may also declare a type to be relocatable by including
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* `typedef std::true_type IsRelocatable;`
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* in the class header.
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*
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* It may be unset in a base class by overriding the typedef to false_type.
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*/
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/*
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* IsZeroInitializable describes the property that default construction is the
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* same as memset(dst, 0, sizeof(T)).
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*/
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namespace traits_detail {
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#define FOLLY_HAS_TRUE_XXX(name) \
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FOLLY_CREATE_HAS_MEMBER_TYPE_TRAITS(has_##name, name); \
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template <class T> \
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struct name##_is_true : std::is_same<typename T::name, std::true_type> {}; \
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template <class T> \
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struct has_true_##name : std::conditional< \
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has_##name<T>::value, \
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name##_is_true<T>, \
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std::false_type>::type {}
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FOLLY_HAS_TRUE_XXX(IsRelocatable);
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FOLLY_HAS_TRUE_XXX(IsZeroInitializable);
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#undef FOLLY_HAS_TRUE_XXX
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} // namespace traits_detail
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struct Ignore {
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Ignore() = default;
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template <class T>
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constexpr /* implicit */ Ignore(const T&) {}
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template <class T>
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const Ignore& operator=(T const&) const {
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return *this;
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}
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};
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template <class...>
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using Ignored = Ignore;
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namespace traits_detail_IsEqualityComparable {
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Ignore operator==(Ignore, Ignore);
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template <class T, class U = T>
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struct IsEqualityComparable
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: std::is_convertible<
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decltype(std::declval<T>() == std::declval<U>()),
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bool> {};
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} // namespace traits_detail_IsEqualityComparable
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/* using override */ using traits_detail_IsEqualityComparable::
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IsEqualityComparable;
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namespace traits_detail_IsLessThanComparable {
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Ignore operator<(Ignore, Ignore);
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template <class T, class U = T>
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struct IsLessThanComparable
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: std::is_convertible<
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decltype(std::declval<T>() < std::declval<U>()),
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bool> {};
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} // namespace traits_detail_IsLessThanComparable
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/* using override */ using traits_detail_IsLessThanComparable::
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IsLessThanComparable;
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namespace traits_detail_IsNothrowSwappable {
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#if defined(__cpp_lib_is_swappable) || (_CPPLIB_VER && _HAS_CXX17)
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// MSVC already implements the C++17 P0185R1 proposal which adds
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// std::is_nothrow_swappable, so use it instead if C++17 mode is
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// enabled.
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template <typename T>
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using IsNothrowSwappable = std::is_nothrow_swappable<T>;
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#elif _CPPLIB_VER
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// MSVC defines the base even if C++17 is disabled, and MSVC has
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// issues with our fallback implementation due to over-eager
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// evaluation of noexcept.
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template <typename T>
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using IsNothrowSwappable = std::_Is_nothrow_swappable<T>;
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#else
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/* using override */ using std::swap;
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template <class T>
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struct IsNothrowSwappable
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: bool_constant<std::is_nothrow_move_constructible<T>::value&& noexcept(
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swap(std::declval<T&>(), std::declval<T&>()))> {};
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#endif
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} // namespace traits_detail_IsNothrowSwappable
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/* using override */ using traits_detail_IsNothrowSwappable::IsNothrowSwappable;
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template <class T>
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struct IsRelocatable : std::conditional<
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traits_detail::has_IsRelocatable<T>::value,
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traits_detail::has_true_IsRelocatable<T>,
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|
// TODO add this line (and some tests for it) when we
|
|
// upgrade to gcc 4.7
|
|
// std::is_trivially_move_constructible<T>::value ||
|
|
is_trivially_copyable<T>>::type {};
|
|
|
|
template <class T>
|
|
struct IsZeroInitializable
|
|
: std::conditional<
|
|
traits_detail::has_IsZeroInitializable<T>::value,
|
|
traits_detail::has_true_IsZeroInitializable<T>,
|
|
bool_constant<!std::is_class<T>::value>>::type {};
|
|
|
|
namespace detail {
|
|
template <bool>
|
|
struct conditional_;
|
|
template <>
|
|
struct conditional_<false> {
|
|
template <typename, typename T>
|
|
using apply = T;
|
|
};
|
|
template <>
|
|
struct conditional_<true> {
|
|
template <typename T, typename>
|
|
using apply = T;
|
|
};
|
|
} // namespace detail
|
|
|
|
// conditional_t
|
|
//
|
|
// Like std::conditional_t but with only two total class template instances,
|
|
// rather than as many class template instances as there are uses.
|
|
//
|
|
// As one effect, the result can be used in deducible contexts, allowing
|
|
// deduction of conditional_t<V, T, F> to work when T or F is a template param.
|
|
template <bool V, typename T, typename F>
|
|
using conditional_t = typename detail::conditional_<V>::template apply<T, F>;
|
|
|
|
template <typename...>
|
|
struct Conjunction : std::true_type {};
|
|
template <typename T>
|
|
struct Conjunction<T> : T {};
|
|
template <typename T, typename... TList>
|
|
struct Conjunction<T, TList...>
|
|
: std::conditional<T::value, Conjunction<TList...>, T>::type {};
|
|
|
|
template <typename...>
|
|
struct Disjunction : std::false_type {};
|
|
template <typename T>
|
|
struct Disjunction<T> : T {};
|
|
template <typename T, typename... TList>
|
|
struct Disjunction<T, TList...>
|
|
: std::conditional<T::value, T, Disjunction<TList...>>::type {};
|
|
|
|
template <typename T>
|
|
struct Negation : bool_constant<!T::value> {};
|
|
|
|
template <bool... Bs>
|
|
struct Bools {
|
|
using valid_type = bool;
|
|
static constexpr std::size_t size() {
|
|
return sizeof...(Bs);
|
|
}
|
|
};
|
|
|
|
// Lighter-weight than Conjunction, but evaluates all sub-conditions eagerly.
|
|
template <class... Ts>
|
|
struct StrictConjunction
|
|
: std::is_same<Bools<Ts::value...>, Bools<(Ts::value || true)...>> {};
|
|
|
|
template <class... Ts>
|
|
struct StrictDisjunction
|
|
: Negation<
|
|
std::is_same<Bools<Ts::value...>, Bools<(Ts::value && false)...>>> {};
|
|
|
|
namespace detail {
|
|
template <typename, typename>
|
|
struct is_transparent_ : std::false_type {};
|
|
template <typename T>
|
|
struct is_transparent_<void_t<typename T::is_transparent>, T> : std::true_type {
|
|
};
|
|
} // namespace detail
|
|
|
|
// is_transparent
|
|
//
|
|
// To test whether a less, equal-to, or hash type follows the is-transparent
|
|
// protocol used by containers with optional heterogeneous access.
|
|
template <typename T>
|
|
struct is_transparent : detail::is_transparent_<void, T> {};
|
|
|
|
} // namespace folly
|
|
|
|
/**
|
|
* Use this macro ONLY inside namespace folly. When using it with a
|
|
* regular type, use it like this:
|
|
*
|
|
* // Make sure you're at namespace ::folly scope
|
|
* template <> FOLLY_ASSUME_RELOCATABLE(MyType)
|
|
*
|
|
* When using it with a template type, use it like this:
|
|
*
|
|
* // Make sure you're at namespace ::folly scope
|
|
* template <class T1, class T2>
|
|
* FOLLY_ASSUME_RELOCATABLE(MyType<T1, T2>)
|
|
*/
|
|
#define FOLLY_ASSUME_RELOCATABLE(...) \
|
|
struct IsRelocatable<__VA_ARGS__> : std::true_type {}
|
|
|
|
/**
|
|
* The FOLLY_ASSUME_FBVECTOR_COMPATIBLE* macros below encode the
|
|
* assumption that the type is relocatable per IsRelocatable
|
|
* above. Many types can be assumed to satisfy this condition, but
|
|
* it is the responsibility of the user to state that assumption.
|
|
* User-defined classes will not be optimized for use with
|
|
* fbvector (see FBVector.h) unless they state that assumption.
|
|
*
|
|
* Use FOLLY_ASSUME_FBVECTOR_COMPATIBLE with regular types like this:
|
|
*
|
|
* FOLLY_ASSUME_FBVECTOR_COMPATIBLE(MyType)
|
|
*
|
|
* The versions FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1, _2, _3, and _4
|
|
* allow using the macro for describing templatized classes with 1, 2,
|
|
* 3, and 4 template parameters respectively. For template classes
|
|
* just use the macro with the appropriate number and pass the name of
|
|
* the template to it. Example:
|
|
*
|
|
* template <class T1, class T2> class MyType { ... };
|
|
* ...
|
|
* // Make sure you're at global scope
|
|
* FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(MyType)
|
|
*/
|
|
|
|
// Use this macro ONLY at global level (no namespace)
|
|
#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE(...) \
|
|
namespace folly { \
|
|
template <> \
|
|
FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__); \
|
|
}
|
|
// Use this macro ONLY at global level (no namespace)
|
|
#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(...) \
|
|
namespace folly { \
|
|
template <class T1> \
|
|
FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1>); \
|
|
}
|
|
// Use this macro ONLY at global level (no namespace)
|
|
#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(...) \
|
|
namespace folly { \
|
|
template <class T1, class T2> \
|
|
FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2>); \
|
|
}
|
|
// Use this macro ONLY at global level (no namespace)
|
|
#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(...) \
|
|
namespace folly { \
|
|
template <class T1, class T2, class T3> \
|
|
FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3>); \
|
|
}
|
|
// Use this macro ONLY at global level (no namespace)
|
|
#define FOLLY_ASSUME_FBVECTOR_COMPATIBLE_4(...) \
|
|
namespace folly { \
|
|
template <class T1, class T2, class T3, class T4> \
|
|
FOLLY_ASSUME_RELOCATABLE(__VA_ARGS__<T1, T2, T3, T4>); \
|
|
}
|
|
|
|
namespace folly {
|
|
|
|
// STL commonly-used types
|
|
template <class T, class U>
|
|
struct IsRelocatable<std::pair<T, U>>
|
|
: bool_constant<IsRelocatable<T>::value && IsRelocatable<U>::value> {};
|
|
|
|
// Is T one of T1, T2, ..., Tn?
|
|
template <typename T, typename... Ts>
|
|
using IsOneOf = StrictDisjunction<std::is_same<T, Ts>...>;
|
|
|
|
/*
|
|
* Complementary type traits for integral comparisons.
|
|
*
|
|
* For instance, `if(x < 0)` yields an error in clang for unsigned types
|
|
* when -Werror is used due to -Wtautological-compare
|
|
*
|
|
*
|
|
* @author: Marcelo Juchem <marcelo@fb.com>
|
|
*/
|
|
|
|
namespace detail {
|
|
|
|
// folly::to integral specializations can end up generating code
|
|
// inside what are really static ifs (not executed because of the templated
|
|
// types) that violate -Wsign-compare and/or -Wbool-compare so suppress them
|
|
// in order to not prevent all calling code from using it.
|
|
FOLLY_PUSH_WARNING
|
|
FOLLY_GNU_DISABLE_WARNING("-Wsign-compare")
|
|
FOLLY_GCC_DISABLE_WARNING("-Wbool-compare")
|
|
FOLLY_MSVC_DISABLE_WARNING(4287) // unsigned/negative constant mismatch
|
|
FOLLY_MSVC_DISABLE_WARNING(4388) // sign-compare
|
|
FOLLY_MSVC_DISABLE_WARNING(4804) // bool-compare
|
|
|
|
template <typename RHS, RHS rhs, typename LHS>
|
|
bool less_than_impl(LHS const lhs) {
|
|
// clang-format off
|
|
return
|
|
rhs > std::numeric_limits<LHS>::max() ? true :
|
|
rhs <= std::numeric_limits<LHS>::min() ? false :
|
|
lhs < rhs;
|
|
// clang-format on
|
|
}
|
|
|
|
template <typename RHS, RHS rhs, typename LHS>
|
|
bool greater_than_impl(LHS const lhs) {
|
|
// clang-format off
|
|
return
|
|
rhs > std::numeric_limits<LHS>::max() ? false :
|
|
rhs < std::numeric_limits<LHS>::min() ? true :
|
|
lhs > rhs;
|
|
// clang-format on
|
|
}
|
|
|
|
FOLLY_POP_WARNING
|
|
|
|
} // namespace detail
|
|
|
|
// same as `x < 0`
|
|
template <typename T>
|
|
constexpr bool is_negative(T x) {
|
|
return std::is_signed<T>::value && x < T(0);
|
|
}
|
|
|
|
// same as `x <= 0`
|
|
template <typename T>
|
|
constexpr bool is_non_positive(T x) {
|
|
return !x || folly::is_negative(x);
|
|
}
|
|
|
|
// same as `x > 0`
|
|
template <typename T>
|
|
constexpr bool is_positive(T x) {
|
|
return !is_non_positive(x);
|
|
}
|
|
|
|
// same as `x >= 0`
|
|
template <typename T>
|
|
constexpr bool is_non_negative(T x) {
|
|
return !x || is_positive(x);
|
|
}
|
|
|
|
template <typename RHS, RHS rhs, typename LHS>
|
|
bool less_than(LHS const lhs) {
|
|
return detail::
|
|
less_than_impl<RHS, rhs, typename std::remove_reference<LHS>::type>(lhs);
|
|
}
|
|
|
|
template <typename RHS, RHS rhs, typename LHS>
|
|
bool greater_than(LHS const lhs) {
|
|
return detail::
|
|
greater_than_impl<RHS, rhs, typename std::remove_reference<LHS>::type>(
|
|
lhs);
|
|
}
|
|
} // namespace folly
|
|
|
|
// Assume nothing when compiling with MSVC.
|
|
#ifndef _MSC_VER
|
|
FOLLY_ASSUME_FBVECTOR_COMPATIBLE_2(std::unique_ptr)
|
|
FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(std::shared_ptr)
|
|
#endif
|
|
|
|
/* Some combinations of compilers and C++ libraries make __int128 and
|
|
* unsigned __int128 available but do not correctly define their standard type
|
|
* traits.
|
|
*
|
|
* If FOLLY_SUPPLY_MISSING_INT128_TRAITS is defined, we define these traits
|
|
* here.
|
|
*
|
|
* @author: Phil Willoughby <philwill@fb.com>
|
|
*/
|
|
#if FOLLY_SUPPLY_MISSING_INT128_TRAITS
|
|
FOLLY_NAMESPACE_STD_BEGIN
|
|
template <>
|
|
struct is_arithmetic<__int128> : ::std::true_type {};
|
|
template <>
|
|
struct is_arithmetic<unsigned __int128> : ::std::true_type {};
|
|
template <>
|
|
struct is_integral<__int128> : ::std::true_type {};
|
|
template <>
|
|
struct is_integral<unsigned __int128> : ::std::true_type {};
|
|
template <>
|
|
struct make_unsigned<__int128> {
|
|
typedef unsigned __int128 type;
|
|
};
|
|
template <>
|
|
struct make_signed<__int128> {
|
|
typedef __int128 type;
|
|
};
|
|
template <>
|
|
struct make_unsigned<unsigned __int128> {
|
|
typedef unsigned __int128 type;
|
|
};
|
|
template <>
|
|
struct make_signed<unsigned __int128> {
|
|
typedef __int128 type;
|
|
};
|
|
template <>
|
|
struct is_signed<__int128> : ::std::true_type {};
|
|
template <>
|
|
struct is_unsigned<unsigned __int128> : ::std::true_type {};
|
|
FOLLY_NAMESPACE_STD_END
|
|
#endif // FOLLY_SUPPLY_MISSING_INT128_TRAITS
|
|
|
|
namespace folly {
|
|
|
|
/**
|
|
* Extension point for containers to provide an order such that if entries are
|
|
* inserted into a new instance in that order, iteration order of the new
|
|
* instance matches the original's. This can be useful for containers that have
|
|
* defined but non-FIFO iteration order, such as F14Vector*.
|
|
*
|
|
* Should return an iterable view (a type that provides begin() and end()).
|
|
*
|
|
* Containers should provide overloads in their own namespace; resolution is
|
|
* expected to be done via ADL.
|
|
*/
|
|
template <typename Container>
|
|
const Container& order_preserving_reinsertion_view(const Container& container) {
|
|
return container;
|
|
}
|
|
|
|
} // namespace folly
|