1 //===- llvm/ADT/ilist_iterator.h - Intrusive List Iterator ------*- 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_ITERATOR_H 10 #define LLVM_ADT_ILIST_ITERATOR_H 11 12 #include "llvm/ADT/ilist_node.h" 13 #include <cassert> 14 #include <cstddef> 15 #include <iterator> 16 #include <type_traits> 17 18 namespace llvm { 19 20 namespace ilist_detail { 21 22 /// Find const-correct node types. 23 template <class OptionsT, bool IsConst> struct IteratorTraits; 24 template <class OptionsT> struct IteratorTraits<OptionsT, false> { 25 using value_type = typename OptionsT::value_type; 26 using pointer = typename OptionsT::pointer; 27 using reference = typename OptionsT::reference; 28 using node_pointer = ilist_node_impl<OptionsT> *; 29 using node_reference = ilist_node_impl<OptionsT> &; 30 }; 31 template <class OptionsT> struct IteratorTraits<OptionsT, true> { 32 using value_type = const typename OptionsT::value_type; 33 using pointer = typename OptionsT::const_pointer; 34 using reference = typename OptionsT::const_reference; 35 using node_pointer = const ilist_node_impl<OptionsT> *; 36 using node_reference = const ilist_node_impl<OptionsT> &; 37 }; 38 39 template <bool IsReverse> struct IteratorHelper; 40 template <> struct IteratorHelper<false> : ilist_detail::NodeAccess { 41 using Access = ilist_detail::NodeAccess; 42 43 template <class T> static void increment(T *&I) { I = Access::getNext(*I); } 44 template <class T> static void decrement(T *&I) { I = Access::getPrev(*I); } 45 }; 46 template <> struct IteratorHelper<true> : ilist_detail::NodeAccess { 47 using Access = ilist_detail::NodeAccess; 48 49 template <class T> static void increment(T *&I) { I = Access::getPrev(*I); } 50 template <class T> static void decrement(T *&I) { I = Access::getNext(*I); } 51 }; 52 53 } // end namespace ilist_detail 54 55 /// Iterator for intrusive lists based on ilist_node. 56 template <class OptionsT, bool IsReverse, bool IsConst> 57 class ilist_iterator : ilist_detail::SpecificNodeAccess<OptionsT> { 58 friend ilist_iterator<OptionsT, IsReverse, !IsConst>; 59 friend ilist_iterator<OptionsT, !IsReverse, IsConst>; 60 friend ilist_iterator<OptionsT, !IsReverse, !IsConst>; 61 62 using Traits = ilist_detail::IteratorTraits<OptionsT, IsConst>; 63 using Access = ilist_detail::SpecificNodeAccess<OptionsT>; 64 65 public: 66 using value_type = typename Traits::value_type; 67 using pointer = typename Traits::pointer; 68 using reference = typename Traits::reference; 69 using difference_type = ptrdiff_t; 70 using iterator_category = std::bidirectional_iterator_tag; 71 using const_pointer = typename OptionsT::const_pointer; 72 using const_reference = typename OptionsT::const_reference; 73 74 private: 75 using node_pointer = typename Traits::node_pointer; 76 using node_reference = typename Traits::node_reference; 77 78 node_pointer NodePtr = nullptr; 79 80 public: 81 /// Create from an ilist_node. 82 explicit ilist_iterator(node_reference N) : NodePtr(&N) {} 83 84 explicit ilist_iterator(pointer NP) : NodePtr(Access::getNodePtr(NP)) {} 85 explicit ilist_iterator(reference NR) : NodePtr(Access::getNodePtr(&NR)) {} 86 ilist_iterator() = default; 87 88 // This is templated so that we can allow constructing a const iterator from 89 // a nonconst iterator... 90 template <bool RHSIsConst> 91 ilist_iterator(const ilist_iterator<OptionsT, IsReverse, RHSIsConst> &RHS, 92 std::enable_if_t<IsConst || !RHSIsConst, void *> = nullptr) 93 : NodePtr(RHS.NodePtr) {} 94 95 // This is templated so that we can allow assigning to a const iterator from 96 // a nonconst iterator... 97 template <bool RHSIsConst> 98 std::enable_if_t<IsConst || !RHSIsConst, ilist_iterator &> 99 operator=(const ilist_iterator<OptionsT, IsReverse, RHSIsConst> &RHS) { 100 NodePtr = RHS.NodePtr; 101 return *this; 102 } 103 104 /// Explicit conversion between forward/reverse iterators. 105 /// 106 /// Translate between forward and reverse iterators without changing range 107 /// boundaries. The resulting iterator will dereference (and have a handle) 108 /// to the previous node, which is somewhat unexpected; but converting the 109 /// two endpoints in a range will give the same range in reverse. 110 /// 111 /// This matches std::reverse_iterator conversions. 112 explicit ilist_iterator( 113 const ilist_iterator<OptionsT, !IsReverse, IsConst> &RHS) 114 : ilist_iterator(++RHS.getReverse()) {} 115 116 /// Get a reverse iterator to the same node. 117 /// 118 /// Gives a reverse iterator that will dereference (and have a handle) to the 119 /// same node. Converting the endpoint iterators in a range will give a 120 /// different range; for range operations, use the explicit conversions. 121 ilist_iterator<OptionsT, !IsReverse, IsConst> getReverse() const { 122 if (NodePtr) 123 return ilist_iterator<OptionsT, !IsReverse, IsConst>(*NodePtr); 124 return ilist_iterator<OptionsT, !IsReverse, IsConst>(); 125 } 126 127 /// Const-cast. 128 ilist_iterator<OptionsT, IsReverse, false> getNonConst() const { 129 if (NodePtr) 130 return ilist_iterator<OptionsT, IsReverse, false>( 131 const_cast<typename ilist_iterator<OptionsT, IsReverse, 132 false>::node_reference>(*NodePtr)); 133 return ilist_iterator<OptionsT, IsReverse, false>(); 134 } 135 136 // Accessors... 137 reference operator*() const { 138 assert(!NodePtr->isKnownSentinel()); 139 return *Access::getValuePtr(NodePtr); 140 } 141 pointer operator->() const { return &operator*(); } 142 143 // Comparison operators 144 friend bool operator==(const ilist_iterator &LHS, const ilist_iterator &RHS) { 145 return LHS.NodePtr == RHS.NodePtr; 146 } 147 friend bool operator!=(const ilist_iterator &LHS, const ilist_iterator &RHS) { 148 return LHS.NodePtr != RHS.NodePtr; 149 } 150 151 // Increment and decrement operators... 152 ilist_iterator &operator--() { 153 NodePtr = IsReverse ? NodePtr->getNext() : NodePtr->getPrev(); 154 return *this; 155 } 156 ilist_iterator &operator++() { 157 NodePtr = IsReverse ? NodePtr->getPrev() : NodePtr->getNext(); 158 return *this; 159 } 160 ilist_iterator operator--(int) { 161 ilist_iterator tmp = *this; 162 --*this; 163 return tmp; 164 } 165 ilist_iterator operator++(int) { 166 ilist_iterator tmp = *this; 167 ++*this; 168 return tmp; 169 } 170 171 /// Get the underlying ilist_node. 172 node_pointer getNodePtr() const { return static_cast<node_pointer>(NodePtr); } 173 174 /// Check for end. Only valid if ilist_sentinel_tracking<true>. 175 bool isEnd() const { return NodePtr ? NodePtr->isSentinel() : false; } 176 }; 177 178 template <typename From> struct simplify_type; 179 180 /// Allow ilist_iterators to convert into pointers to a node automatically when 181 /// used by the dyn_cast, cast, isa mechanisms... 182 /// 183 /// FIXME: remove this, since there is no implicit conversion to NodeTy. 184 template <class OptionsT, bool IsConst> 185 struct simplify_type<ilist_iterator<OptionsT, false, IsConst>> { 186 using iterator = ilist_iterator<OptionsT, false, IsConst>; 187 using SimpleType = typename iterator::pointer; 188 189 static SimpleType getSimplifiedValue(const iterator &Node) { return &*Node; } 190 }; 191 template <class OptionsT, bool IsConst> 192 struct simplify_type<const ilist_iterator<OptionsT, false, IsConst>> 193 : simplify_type<ilist_iterator<OptionsT, false, IsConst>> {}; 194 195 } // end namespace llvm 196 197 #endif // LLVM_ADT_ILIST_ITERATOR_H 198