1 //===- llvm/ADT/ilist_node_options.h - ilist_node Options -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_ADT_ILIST_NODE_OPTIONS_H
11 #define LLVM_ADT_ILIST_NODE_OPTIONS_H
13 #include "llvm/Config/abi-breaking.h"
15 #include <type_traits>
19 template <bool EnableSentinelTracking> class ilist_node_base;
20 template <bool EnableSentinelTracking> class ilist_base;
22 /// Option to choose whether to track sentinels.
24 /// This option affects the ABI for the nodes. When not specified explicitly,
25 /// the ABI depends on LLVM_ENABLE_ABI_BREAKING_CHECKS. Specify explicitly to
26 /// enable \a ilist_node::isSentinel().
27 template <bool EnableSentinelTracking> struct ilist_sentinel_tracking {};
29 /// Option to specify a tag for the node type.
31 /// This option allows a single value type to be inserted in multiple lists
32 /// simultaneously. See \a ilist_node for usage examples.
33 template <class Tag> struct ilist_tag {};
35 namespace ilist_detail {
37 /// Helper trait for recording whether an option is specified explicitly.
38 template <bool IsExplicit> struct explicitness {
39 static const bool is_explicit = IsExplicit;
41 typedef explicitness<true> is_explicit;
42 typedef explicitness<false> is_implicit;
44 /// Check whether an option is valid.
46 /// The steps for adding and enabling a new ilist option include:
47 /// \li define the option, ilist_foo<Bar>, above;
48 /// \li add new parameters for Bar to \a ilist_detail::node_options;
49 /// \li add an extraction meta-function, ilist_detail::extract_foo;
50 /// \li call extract_foo from \a ilist_detail::compute_node_options and pass it
51 /// into \a ilist_detail::node_options; and
52 /// \li specialize \c is_valid_option<ilist_foo<Bar>> to inherit from \c
53 /// std::true_type to get static assertions passing in \a simple_ilist and \a
55 template <class Option> struct is_valid_option : std::false_type {};
57 /// Extract sentinel tracking option.
59 /// Look through \p Options for the \a ilist_sentinel_tracking option, with the
60 /// default depending on LLVM_ENABLE_ABI_BREAKING_CHECKS.
61 template <class... Options> struct extract_sentinel_tracking;
62 template <bool EnableSentinelTracking, class... Options>
63 struct extract_sentinel_tracking<
64 ilist_sentinel_tracking<EnableSentinelTracking>, Options...>
65 : std::integral_constant<bool, EnableSentinelTracking>, is_explicit {};
66 template <class Option1, class... Options>
67 struct extract_sentinel_tracking<Option1, Options...>
68 : extract_sentinel_tracking<Options...> {};
69 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
70 template <> struct extract_sentinel_tracking<> : std::true_type, is_implicit {};
73 struct extract_sentinel_tracking<> : std::false_type, is_implicit {};
75 template <bool EnableSentinelTracking>
76 struct is_valid_option<ilist_sentinel_tracking<EnableSentinelTracking>>
79 /// Extract custom tag option.
81 /// Look through \p Options for the \a ilist_tag option, pulling out the
82 /// custom tag type, using void as a default.
83 template <class... Options> struct extract_tag;
84 template <class Tag, class... Options>
85 struct extract_tag<ilist_tag<Tag>, Options...> {
88 template <class Option1, class... Options>
89 struct extract_tag<Option1, Options...> : extract_tag<Options...> {};
90 template <> struct extract_tag<> { typedef void type; };
91 template <class Tag> struct is_valid_option<ilist_tag<Tag>> : std::true_type {};
93 /// Check whether options are valid.
95 /// The conjunction of \a is_valid_option on each individual option.
96 template <class... Options> struct check_options;
97 template <> struct check_options<> : std::true_type {};
98 template <class Option1, class... Options>
99 struct check_options<Option1, Options...>
100 : std::integral_constant<bool, is_valid_option<Option1>::value &&
101 check_options<Options...>::value> {};
103 /// Traits for options for \a ilist_node.
105 /// This is usually computed via \a compute_node_options.
106 template <class T, bool EnableSentinelTracking, bool IsSentinelTrackingExplicit,
108 struct node_options {
109 typedef T value_type;
111 typedef T &reference;
112 typedef const T *const_pointer;
113 typedef const T &const_reference;
115 static const bool enable_sentinel_tracking = EnableSentinelTracking;
116 static const bool is_sentinel_tracking_explicit = IsSentinelTrackingExplicit;
118 typedef ilist_node_base<enable_sentinel_tracking> node_base_type;
119 typedef ilist_base<enable_sentinel_tracking> list_base_type;
122 template <class T, class... Options> struct compute_node_options {
123 typedef node_options<T, extract_sentinel_tracking<Options...>::value,
124 extract_sentinel_tracking<Options...>::is_explicit,
125 typename extract_tag<Options...>::type>
129 } // end namespace ilist_detail
130 } // end namespace llvm
132 #endif // LLVM_ADT_ILIST_NODE_OPTIONS_H