1//===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides useful additions to the standard type_traits library.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_TYPE_TRAITS_H
14#define LLVM_SUPPORT_TYPE_TRAITS_H
15
16#include "llvm/Support/Compiler.h"
17#include <type_traits>
18#include <utility>
19
20namespace llvm {
21
22
23/// Metafunction that determines whether the given type is either an
24/// integral type or an enumeration type, including enum classes.
25///
26/// Note that this accepts potentially more integral types than is_integral
27/// because it is based on being implicitly convertible to an integral type.
28/// Also note that enum classes aren't implicitly convertible to integral types,
29/// the value may therefore need to be explicitly converted before being used.
30template <typename T> class is_integral_or_enum {
31 using UnderlyingT = std::remove_reference_t<T>;
32
33public:
34 static const bool value =
35 !std::is_class_v<UnderlyingT> && // Filter conversion operators.
36 !std::is_pointer_v<UnderlyingT> &&
37 !std::is_floating_point_v<UnderlyingT> &&
38 (std::is_enum_v<UnderlyingT> ||
39 std::is_convertible_v<UnderlyingT, unsigned long long>);
40};
41
42/// If T is a pointer, just return it. If it is not, return T&.
43template<typename T, typename Enable = void>
44struct add_lvalue_reference_if_not_pointer { using type = T &; };
45
46template <typename T>
47struct add_lvalue_reference_if_not_pointer<
48 T, std::enable_if_t<std::is_pointer_v<T>>> {
49 using type = T;
50};
51
52/// If T is a pointer to X, return a pointer to const X. If it is not,
53/// return const T.
54template<typename T, typename Enable = void>
55struct add_const_past_pointer { using type = const T; };
56
57template <typename T>
58struct add_const_past_pointer<T, std::enable_if_t<std::is_pointer_v<T>>> {
59 using type = const std::remove_pointer_t<T> *;
60};
61
62template <typename T, typename Enable = void>
63struct const_pointer_or_const_ref {
64 using type = const T &;
65};
66template <typename T>
67struct const_pointer_or_const_ref<T, std::enable_if_t<std::is_pointer_v<T>>> {
68 using type = typename add_const_past_pointer<T>::type;
69};
70
71namespace detail {
72template<class T>
73union trivial_helper {
74 T t;
75};
76
77} // end namespace detail
78
79template <typename T>
80struct is_copy_assignable {
81 template<class F>
82 static auto get(F*) -> decltype(std::declval<F &>() = std::declval<const F &>(), std::true_type{});
83 static std::false_type get(...);
84 static constexpr bool value = decltype(get((T*)nullptr))::value;
85};
86
87template <typename T>
88struct is_move_assignable {
89 template<class F>
90 static auto get(F*) -> decltype(std::declval<F &>() = std::declval<F &&>(), std::true_type{});
91 static std::false_type get(...);
92 static constexpr bool value = decltype(get((T*)nullptr))::value;
93};
94
95} // end namespace llvm
96
97#endif // LLVM_SUPPORT_TYPE_TRAITS_H
98

source code of include/llvm-17/llvm/Support/type_traits.h