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
18namespace llvm {
19
20namespace ilist_detail {
21
22/// Find const-correct node types.
23template <class OptionsT, bool IsConst> struct IteratorTraits;
24template <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};
31template <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
39template <bool IsReverse> struct IteratorHelper;
40template <> 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};
46template <> 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.
56template <class OptionsT, bool IsReverse, bool IsConst>
57class 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
65public:
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
74private:
75  using node_pointer = typename Traits::node_pointer;
76  using node_reference = typename Traits::node_reference;
77
78  node_pointer NodePtr = nullptr;
79
80public:
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
178template <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.
184template <class OptionsT, bool IsConst>
185struct 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};
191template <class OptionsT, bool IsConst>
192struct 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