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 /// \file 10 /// This file defines the DenseSet and SmallDenseSet classes. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ADT_DENSESET_H 15 #define LLVM_ADT_DENSESET_H 16 17 #include "llvm/ADT/DenseMap.h" 18 #include "llvm/ADT/DenseMapInfo.h" 19 #include "llvm/Support/MathExtras.h" 20 #include "llvm/Support/type_traits.h" 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() { TheMap.clear(); } 93 94 /// Return 1 if the specified key is in the set, 0 otherwise. 95 size_type count(const_arg_type_t<ValueT> V) const { return TheMap.count(V); } 96 97 bool erase(const ValueT &V) { return TheMap.erase(V); } 98 99 void swap(DenseSetImpl &RHS) { TheMap.swap(RHS.TheMap); } 100 101 // Iterators. 102 103 class ConstIterator; 104 105 class Iterator { 106 typename MapTy::iterator I; 107 friend class DenseSetImpl; 108 friend class ConstIterator; 109 110 public: 111 using difference_type = typename MapTy::iterator::difference_type; 112 using value_type = ValueT; 113 using pointer = value_type *; 114 using reference = value_type &; 115 using iterator_category = std::forward_iterator_tag; 116 117 Iterator() = default; 118 Iterator(const typename MapTy::iterator &i) : I(i) {} 119 120 ValueT &operator*() { return I->getFirst(); } 121 const ValueT &operator*() const { return I->getFirst(); } 122 ValueT *operator->() { return &I->getFirst(); } 123 const ValueT *operator->() const { return &I->getFirst(); } 124 125 Iterator &operator++() { 126 ++I; 127 return *this; 128 } 129 Iterator operator++(int) { 130 auto T = *this; 131 ++I; 132 return T; 133 } 134 friend bool operator==(const Iterator &X, const Iterator &Y) { 135 return X.I == Y.I; 136 } 137 friend bool operator!=(const Iterator &X, const Iterator &Y) { 138 return X.I != Y.I; 139 } 140 }; 141 142 class ConstIterator { 143 typename MapTy::const_iterator I; 144 friend class DenseSetImpl; 145 friend class Iterator; 146 147 public: 148 using difference_type = typename MapTy::const_iterator::difference_type; 149 using value_type = ValueT; 150 using pointer = const value_type *; 151 using reference = const value_type &; 152 using iterator_category = std::forward_iterator_tag; 153 154 ConstIterator() = default; 155 ConstIterator(const Iterator &B) : I(B.I) {} 156 ConstIterator(const typename MapTy::const_iterator &i) : I(i) {} 157 158 const ValueT &operator*() const { return I->getFirst(); } 159 const ValueT *operator->() const { return &I->getFirst(); } 160 161 ConstIterator &operator++() { 162 ++I; 163 return *this; 164 } 165 ConstIterator operator++(int) { 166 auto T = *this; 167 ++I; 168 return T; 169 } 170 friend bool operator==(const ConstIterator &X, const ConstIterator &Y) { 171 return X.I == Y.I; 172 } 173 friend bool operator!=(const ConstIterator &X, const ConstIterator &Y) { 174 return X.I != Y.I; 175 } 176 }; 177 178 using iterator = Iterator; 179 using const_iterator = ConstIterator; 180 181 iterator begin() { return Iterator(TheMap.begin()); } 182 iterator end() { return Iterator(TheMap.end()); } 183 184 const_iterator begin() const { return ConstIterator(TheMap.begin()); } 185 const_iterator end() const { return ConstIterator(TheMap.end()); } 186 187 iterator find(const_arg_type_t<ValueT> V) { return Iterator(TheMap.find(V)); } 188 const_iterator find(const_arg_type_t<ValueT> V) const { 189 return ConstIterator(TheMap.find(V)); 190 } 191 192 /// Check if the set contains the given element. 193 bool contains(const_arg_type_t<ValueT> V) const { 194 return TheMap.find(V) != TheMap.end(); 195 } 196 197 /// Alternative version of find() which allows a different, and possibly less 198 /// expensive, key type. 199 /// The DenseMapInfo is responsible for supplying methods 200 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key type 201 /// used. 202 template <class LookupKeyT> iterator find_as(const LookupKeyT &Val) { 203 return Iterator(TheMap.find_as(Val)); 204 } 205 template <class LookupKeyT> 206 const_iterator find_as(const LookupKeyT &Val) const { 207 return ConstIterator(TheMap.find_as(Val)); 208 } 209 210 void erase(Iterator I) { return TheMap.erase(I.I); } 211 void erase(ConstIterator CI) { return TheMap.erase(CI.I); } 212 213 std::pair<iterator, bool> insert(const ValueT &V) { 214 detail::DenseSetEmpty Empty; 215 return TheMap.try_emplace(V, Empty); 216 } 217 218 std::pair<iterator, bool> insert(ValueT &&V) { 219 detail::DenseSetEmpty Empty; 220 return TheMap.try_emplace(std::move(V), Empty); 221 } 222 223 /// Alternative version of insert that uses a different (and possibly less 224 /// expensive) key type. 225 template <typename LookupKeyT> 226 std::pair<iterator, bool> insert_as(const ValueT &V, 227 const LookupKeyT &LookupKey) { 228 return TheMap.insert_as({V, detail::DenseSetEmpty()}, LookupKey); 229 } 230 template <typename LookupKeyT> 231 std::pair<iterator, bool> insert_as(ValueT &&V, const LookupKeyT &LookupKey) { 232 return TheMap.insert_as({std::move(V), detail::DenseSetEmpty()}, LookupKey); 233 } 234 235 // Range insertion of values. 236 template <typename InputIt> void insert(InputIt I, InputIt E) { 237 for (; I != E; ++I) 238 insert(*I); 239 } 240 }; 241 242 /// Equality comparison for DenseSet. 243 /// 244 /// Iterates over elements of LHS confirming that each element is also a member 245 /// of RHS, and that RHS contains no additional values. 246 /// Equivalent to N calls to RHS.count. Amortized complexity is linear, worst 247 /// case is O(N^2) (if every hash collides). 248 template <typename ValueT, typename MapTy, typename ValueInfoT> 249 bool operator==(const DenseSetImpl<ValueT, MapTy, ValueInfoT> &LHS, 250 const DenseSetImpl<ValueT, MapTy, ValueInfoT> &RHS) { 251 if (LHS.size() != RHS.size()) 252 return false; 253 254 for (auto &E : LHS) 255 if (!RHS.count(E)) 256 return false; 257 258 return true; 259 } 260 261 /// Inequality comparison for DenseSet. 262 /// 263 /// Equivalent to !(LHS == RHS). See operator== for performance notes. 264 template <typename ValueT, typename MapTy, typename ValueInfoT> 265 bool operator!=(const DenseSetImpl<ValueT, MapTy, ValueInfoT> &LHS, 266 const DenseSetImpl<ValueT, MapTy, ValueInfoT> &RHS) { 267 return !(LHS == RHS); 268 } 269 270 } // end namespace detail 271 272 /// Implements a dense probed hash-table based set. 273 template <typename ValueT, typename ValueInfoT = DenseMapInfo<ValueT>> 274 class DenseSet : public detail::DenseSetImpl< 275 ValueT, 276 DenseMap<ValueT, detail::DenseSetEmpty, ValueInfoT, 277 detail::DenseSetPair<ValueT>>, 278 ValueInfoT> { 279 using BaseT = 280 detail::DenseSetImpl<ValueT, 281 DenseMap<ValueT, detail::DenseSetEmpty, ValueInfoT, 282 detail::DenseSetPair<ValueT>>, 283 ValueInfoT>; 284 285 public: 286 using BaseT::BaseT; 287 }; 288 289 /// Implements a dense probed hash-table based set with some number of buckets 290 /// stored inline. 291 template <typename ValueT, unsigned InlineBuckets = 4, 292 typename ValueInfoT = DenseMapInfo<ValueT>> 293 class SmallDenseSet 294 : public detail::DenseSetImpl< 295 ValueT, 296 SmallDenseMap<ValueT, detail::DenseSetEmpty, InlineBuckets, 297 ValueInfoT, detail::DenseSetPair<ValueT>>, 298 ValueInfoT> { 299 using BaseT = detail::DenseSetImpl< 300 ValueT, 301 SmallDenseMap<ValueT, detail::DenseSetEmpty, InlineBuckets, ValueInfoT, 302 detail::DenseSetPair<ValueT>>, 303 ValueInfoT>; 304 305 public: 306 using BaseT::BaseT; 307 }; 308 309 } // end namespace llvm 310 311 #endif // LLVM_ADT_DENSESET_H 312