1//===- llvm/ADT/ilist_node_options.h - ilist_node Options -------*- 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#ifndef LLVM_ADT_ILIST_NODE_OPTIONS_H
10#define LLVM_ADT_ILIST_NODE_OPTIONS_H
11
12#include "llvm/Config/abi-breaking.h"
13
14#include <type_traits>
15
16namespace llvm {
17
18template <bool EnableSentinelTracking> class ilist_node_base;
19template <bool EnableSentinelTracking> class ilist_base;
20
21/// Option to choose whether to track sentinels.
22///
23/// This option affects the ABI for the nodes. When not specified explicitly,
24/// the ABI depends on LLVM_ENABLE_ABI_BREAKING_CHECKS. Specify explicitly to
25/// enable \a ilist_node::isSentinel().
26template <bool EnableSentinelTracking> struct ilist_sentinel_tracking {};
27
28/// Option to specify a tag for the node type.
29///
30/// This option allows a single value type to be inserted in multiple lists
31/// simultaneously. See \a ilist_node for usage examples.
32template <class Tag> struct ilist_tag {};
33
34namespace ilist_detail {
35
36/// Helper trait for recording whether an option is specified explicitly.
37template <bool IsExplicit> struct explicitness {
38 static const bool is_explicit = IsExplicit;
39};
40typedef explicitness<true> is_explicit;
41typedef explicitness<false> is_implicit;
42
43/// Check whether an option is valid.
44///
45/// The steps for adding and enabling a new ilist option include:
46/// \li define the option, ilist_foo<Bar>, above;
47/// \li add new parameters for Bar to \a ilist_detail::node_options;
48/// \li add an extraction meta-function, ilist_detail::extract_foo;
49/// \li call extract_foo from \a ilist_detail::compute_node_options and pass it
50/// into \a ilist_detail::node_options; and
51/// \li specialize \c is_valid_option<ilist_foo<Bar>> to inherit from \c
52/// std::true_type to get static assertions passing in \a simple_ilist and \a
53/// ilist_node.
54template <class Option> struct is_valid_option : std::false_type {};
55
56/// Extract sentinel tracking option.
57///
58/// Look through \p Options for the \a ilist_sentinel_tracking option, with the
59/// default depending on LLVM_ENABLE_ABI_BREAKING_CHECKS.
60template <class... Options> struct extract_sentinel_tracking;
61template <bool EnableSentinelTracking, class... Options>
62struct extract_sentinel_tracking<
63 ilist_sentinel_tracking<EnableSentinelTracking>, Options...>
64 : std::integral_constant<bool, EnableSentinelTracking>, is_explicit {};
65template <class Option1, class... Options>
66struct extract_sentinel_tracking<Option1, Options...>
67 : extract_sentinel_tracking<Options...> {};
68#if LLVM_ENABLE_ABI_BREAKING_CHECKS
69template <> struct extract_sentinel_tracking<> : std::true_type, is_implicit {};
70#else
71template <>
72struct extract_sentinel_tracking<> : std::false_type, is_implicit {};
73#endif
74template <bool EnableSentinelTracking>
75struct is_valid_option<ilist_sentinel_tracking<EnableSentinelTracking>>
76 : std::true_type {};
77
78/// Extract custom tag option.
79///
80/// Look through \p Options for the \a ilist_tag option, pulling out the
81/// custom tag type, using void as a default.
82template <class... Options> struct extract_tag;
83template <class Tag, class... Options>
84struct extract_tag<ilist_tag<Tag>, Options...> {
85 typedef Tag type;
86};
87template <class Option1, class... Options>
88struct extract_tag<Option1, Options...> : extract_tag<Options...> {};
89template <> struct extract_tag<> { typedef void type; };
90template <class Tag> struct is_valid_option<ilist_tag<Tag>> : std::true_type {};
91
92/// Check whether options are valid.
93///
94/// The conjunction of \a is_valid_option on each individual option.
95template <class... Options> struct check_options;
96template <> struct check_options<> : std::true_type {};
97template <class Option1, class... Options>
98struct check_options<Option1, Options...>
99 : std::integral_constant<bool, is_valid_option<Option1>::value &&
100 check_options<Options...>::value> {};
101
102/// Traits for options for \a ilist_node.
103///
104/// This is usually computed via \a compute_node_options.
105template <class T, bool EnableSentinelTracking, bool IsSentinelTrackingExplicit,
106 class TagT>
107struct node_options {
108 typedef T value_type;
109 typedef T *pointer;
110 typedef T &reference;
111 typedef const T *const_pointer;
112 typedef const T &const_reference;
113
114 static const bool enable_sentinel_tracking = EnableSentinelTracking;
115 static const bool is_sentinel_tracking_explicit = IsSentinelTrackingExplicit;
116 typedef TagT tag;
117 typedef ilist_node_base<enable_sentinel_tracking> node_base_type;
118 typedef ilist_base<enable_sentinel_tracking> list_base_type;
119};
120
121template <class T, class... Options> struct compute_node_options {
122 typedef node_options<T, extract_sentinel_tracking<Options...>::value,
123 extract_sentinel_tracking<Options...>::is_explicit,
124 typename extract_tag<Options...>::type>
125 type;
126};
127
128} // end namespace ilist_detail
129} // end namespace llvm
130
131#endif // LLVM_ADT_ILIST_NODE_OPTIONS_H
132