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