1 //===- llvm/ADT/DenseSet.h - Dense probed hash table ------------*- 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 defines the DenseSet and SmallDenseSet classes. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_ADT_DENSESET_H 14 #define LLVM_ADT_DENSESET_H 15 16 #include "llvm/ADT/DenseMap.h" 17 #include "llvm/ADT/DenseMapInfo.h" 18 #include "llvm/Support/MathExtras.h" 19 #include "llvm/Support/type_traits.h" 20 #include <algorithm> 21 #include <cstddef> 22 #include <initializer_list> 23 #include <iterator> 24 #include <utility> 25 26 namespace llvm { 27 28 namespace detail { 29 30 struct DenseSetEmpty {}; 31 32 // Use the empty base class trick so we can create a DenseMap where the buckets 33 // contain only a single item. 34 template <typename KeyT> class DenseSetPair : public DenseSetEmpty { 35 KeyT key; 36 37 public: 38 KeyT &getFirst() { return key; } 39 const KeyT &getFirst() const { return key; } 40 DenseSetEmpty &getSecond() { return *this; } 41 const DenseSetEmpty &getSecond() const { return *this; } 42 }; 43 44 /// Base class for DenseSet and DenseSmallSet. 45 /// 46 /// MapTy should be either 47 /// 48 /// DenseMap<ValueT, detail::DenseSetEmpty, ValueInfoT, 49 /// detail::DenseSetPair<ValueT>> 50 /// 51 /// or the equivalent SmallDenseMap type. ValueInfoT must implement the 52 /// DenseMapInfo "concept". 53 template <typename ValueT, typename MapTy, typename ValueInfoT> 54 class DenseSetImpl { 55 static_assert(sizeof(typename MapTy::value_type) == sizeof(ValueT), 56 "DenseMap buckets unexpectedly large!"); 57 MapTy TheMap; 58 59 template <typename T> 60 using const_arg_type_t = typename const_pointer_or_const_ref<T>::type; 61 62 public: 63 using key_type = ValueT; 64 using value_type = ValueT; 65 using size_type = unsigned; 66 67 explicit DenseSetImpl(unsigned InitialReserve = 0) : TheMap(InitialReserve) {} 68 69 template <typename InputIt> 70 DenseSetImpl(const InputIt &I, const InputIt &E) 71 : DenseSetImpl(PowerOf2Ceil(std::distance(I, E))) { 72 insert(I, E); 73 } 74 75 DenseSetImpl(std::initializer_list<ValueT> Elems) 76 : DenseSetImpl(PowerOf2Ceil(Elems.size())) { 77 insert(Elems.begin(), Elems.end()); 78 } 79 80 bool empty() const { return TheMap.empty(); } 81 size_type size() const { return TheMap.size(); } 82 size_t getMemorySize() const { return TheMap.getMemorySize(); } 83 84 /// Grow the DenseSet so that it has at least Size buckets. Will not shrink 85 /// the Size of the set. 86 void resize(size_t Size) { TheMap.resize(Size); } 87 88 /// Grow the DenseSet so that it can contain at least \p NumEntries items 89 /// before resizing again. 90 void reserve(size_t Size) { TheMap.reserve(Size); } 91 92 void clear() { 93 TheMap.clear(); 94 } 95 96 /// Return 1 if the specified key is in the set, 0 otherwise. 97 size_type count(const_arg_type_t<ValueT> V) const { 98 return TheMap.count(V); 99 } 100 101 bool erase(const ValueT &V) { 102 return TheMap.erase(V); 103 } 104 105 void swap(DenseSetImpl &RHS) { TheMap.swap(RHS.TheMap); } 106 107 // Iterators. 108 109 class ConstIterator; 110 111 class Iterator { 112 typename MapTy::iterator I; 113 friend class DenseSetImpl; 114 friend class ConstIterator; 115 116 public: 117 using difference_type = typename MapTy::iterator::difference_type; 118 using value_type = ValueT; 119 using pointer = value_type *; 120 using reference = value_type &; 121 using iterator_category = std::forward_iterator_tag; 122 123 Iterator() = default; 124 Iterator(const typename MapTy::iterator &i) : I(i) {} 125 126 ValueT &operator*() { return I->getFirst(); } 127 const ValueT &operator*() const { return I->getFirst(); } 128 ValueT *operator->() { return &I->getFirst(); } 129 const ValueT *operator->() const { return &I->getFirst(); } 130 131 Iterator& operator++() { ++I; return *this; } 132 Iterator operator++(int) { auto T = *this; ++I; return T; } 133 bool operator==(const ConstIterator& X) const { return I == X.I; } 134 bool operator!=(const ConstIterator& X) const { return I != X.I; } 135 }; 136 137 class ConstIterator { 138 typename MapTy::const_iterator I; 139 friend class DenseSetImpl; 140 friend class Iterator; 141 142 public: 143 using difference_type = typename MapTy::const_iterator::difference_type; 144 using value_type = ValueT; 145 using pointer = const value_type *; 146 using reference = const value_type &; 147 using iterator_category = std::forward_iterator_tag; 148 149 ConstIterator() = default; 150 ConstIterator(const Iterator &B) : I(B.I) {} 151 ConstIterator(const typename MapTy::const_iterator &i) : I(i) {} 152 153 const ValueT &operator*() const { return I->getFirst(); } 154 const ValueT *operator->() const { return &I->getFirst(); } 155 156 ConstIterator& operator++() { ++I; return *this; } 157 ConstIterator operator++(int) { auto T = *this; ++I; return T; } 158 bool operator==(const ConstIterator& X) const { return I == X.I; } 159 bool operator!=(const ConstIterator& X) const { return I != X.I; } 160 }; 161 162 using iterator = Iterator; 163 using const_iterator = ConstIterator; 164 165 iterator begin() { return Iterator(TheMap.begin()); } 166 iterator end() { return Iterator(TheMap.end()); } 167 168 const_iterator begin() const { return ConstIterator(TheMap.begin()); } 169 const_iterator end() const { return ConstIterator(TheMap.end()); } 170 171 iterator find(const_arg_type_t<ValueT> V) { return Iterator(TheMap.find(V)); } 172 const_iterator find(const_arg_type_t<ValueT> V) const { 173 return ConstIterator(TheMap.find(V)); 174 } 175 176 /// Alternative version of find() which allows a different, and possibly less 177 /// expensive, key type. 178 /// The DenseMapInfo is responsible for supplying methods 179 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key type 180 /// used. 181 template <class LookupKeyT> 182 iterator find_as(const LookupKeyT &Val) { 183 return Iterator(TheMap.find_as(Val)); 184 } 185 template <class LookupKeyT> 186 const_iterator find_as(const LookupKeyT &Val) const { 187 return ConstIterator(TheMap.find_as(Val)); 188 } 189 190 void erase(Iterator I) { return TheMap.erase(I.I); } 191 void erase(ConstIterator CI) { return TheMap.erase(CI.I); } 192 193 std::pair<iterator, bool> insert(const ValueT &V) { 194 detail::DenseSetEmpty Empty; 195 return TheMap.try_emplace(V, Empty); 196 } 197 198 std::pair<iterator, bool> insert(ValueT &&V) { 199 detail::DenseSetEmpty Empty; 200 return TheMap.try_emplace(std::move(V), Empty); 201 } 202 203 /// Alternative version of insert that uses a different (and possibly less 204 /// expensive) key type. 205 template <typename LookupKeyT> 206 std::pair<iterator, bool> insert_as(const ValueT &V, 207 const LookupKeyT &LookupKey) { 208 return TheMap.insert_as({V, detail::DenseSetEmpty()}, LookupKey); 209 } 210 template <typename LookupKeyT> 211 std::pair<iterator, bool> insert_as(ValueT &&V, const LookupKeyT &LookupKey) { 212 return TheMap.insert_as({std::move(V), detail::DenseSetEmpty()}, LookupKey); 213 } 214 215 // Range insertion of values. 216 template<typename InputIt> 217 void insert(InputIt I, InputIt E) { 218 for (; I != E; ++I) 219 insert(*I); 220 } 221 }; 222 223 /// Equality comparison for DenseSet. 224 /// 225 /// Iterates over elements of LHS confirming that each element is also a member 226 /// of RHS, and that RHS contains no additional values. 227 /// Equivalent to N calls to RHS.count. Amortized complexity is linear, worst 228 /// case is O(N^2) (if every hash collides). 229 template <typename ValueT, typename MapTy, typename ValueInfoT> 230 bool operator==(const DenseSetImpl<ValueT, MapTy, ValueInfoT> &LHS, 231 const DenseSetImpl<ValueT, MapTy, ValueInfoT> &RHS) { 232 if (LHS.size() != RHS.size()) 233 return false; 234 235 for (auto &E : LHS) 236 if (!RHS.count(E)) 237 return false; 238 239 return true; 240 } 241 242 /// Inequality comparison for DenseSet. 243 /// 244 /// Equivalent to !(LHS == RHS). See operator== for performance notes. 245 template <typename ValueT, typename MapTy, typename ValueInfoT> 246 bool operator!=(const DenseSetImpl<ValueT, MapTy, ValueInfoT> &LHS, 247 const DenseSetImpl<ValueT, MapTy, ValueInfoT> &RHS) { 248 return !(LHS == RHS); 249 } 250 251 } // end namespace detail 252 253 /// Implements a dense probed hash-table based set. 254 template <typename ValueT, typename ValueInfoT = DenseMapInfo<ValueT>> 255 class DenseSet : public detail::DenseSetImpl< 256 ValueT, DenseMap<ValueT, detail::DenseSetEmpty, ValueInfoT, 257 detail::DenseSetPair<ValueT>>, 258 ValueInfoT> { 259 using BaseT = 260 detail::DenseSetImpl<ValueT, 261 DenseMap<ValueT, detail::DenseSetEmpty, ValueInfoT, 262 detail::DenseSetPair<ValueT>>, 263 ValueInfoT>; 264 265 public: 266 using BaseT::BaseT; 267 }; 268 269 /// Implements a dense probed hash-table based set with some number of buckets 270 /// stored inline. 271 template <typename ValueT, unsigned InlineBuckets = 4, 272 typename ValueInfoT = DenseMapInfo<ValueT>> 273 class SmallDenseSet 274 : public detail::DenseSetImpl< 275 ValueT, SmallDenseMap<ValueT, detail::DenseSetEmpty, InlineBuckets, 276 ValueInfoT, detail::DenseSetPair<ValueT>>, 277 ValueInfoT> { 278 using BaseT = detail::DenseSetImpl< 279 ValueT, SmallDenseMap<ValueT, detail::DenseSetEmpty, InlineBuckets, 280 ValueInfoT, detail::DenseSetPair<ValueT>>, 281 ValueInfoT>; 282 283 public: 284 using BaseT::BaseT; 285 }; 286 287 } // end namespace llvm 288 289 #endif // LLVM_ADT_DENSESET_H 290