1 //===--- StringMap.h - String Hash table map interface ----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the StringMap class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_STRINGMAP_H
15 #define LLVM_ADT_STRINGMAP_H
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Support/Allocator.h"
23 template<typename ValueT>
24 class StringMapConstIterator;
25 template<typename ValueT>
26 class StringMapIterator;
27 template<typename ValueTy>
30 /// StringMapEntryBase - Shared base class of StringMapEntry instances.
31 class StringMapEntryBase {
35 explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
37 unsigned getKeyLength() const { return StrLen; }
40 /// StringMapImpl - This is the base class of StringMap that is shared among
41 /// all of its instantiations.
44 // Array of NumBuckets pointers to entries, null pointers are holes.
45 // TheTable[NumBuckets] contains a sentinel value for easy iteration. Followed
46 // by an array of the actual hash values as unsigned integers.
47 StringMapEntryBase **TheTable;
50 unsigned NumTombstones;
54 explicit StringMapImpl(unsigned itemSize)
56 // Initialize the map with zero buckets to allocation.
57 NumBuckets(0), NumItems(0), NumTombstones(0), ItemSize(itemSize) {}
58 StringMapImpl(StringMapImpl &&RHS)
59 : TheTable(RHS.TheTable), NumBuckets(RHS.NumBuckets),
60 NumItems(RHS.NumItems), NumTombstones(RHS.NumTombstones),
61 ItemSize(RHS.ItemSize) {
62 RHS.TheTable = nullptr;
65 RHS.NumTombstones = 0;
68 StringMapImpl(unsigned InitSize, unsigned ItemSize);
69 unsigned RehashTable(unsigned BucketNo = 0);
71 /// LookupBucketFor - Look up the bucket that the specified string should end
72 /// up in. If it already exists as a key in the map, the Item pointer for the
73 /// specified bucket will be non-null. Otherwise, it will be null. In either
74 /// case, the FullHashValue field of the bucket will be set to the hash value
76 unsigned LookupBucketFor(StringRef Key);
78 /// FindKey - Look up the bucket that contains the specified key. If it exists
79 /// in the map, return the bucket number of the key. Otherwise return -1.
80 /// This does not modify the map.
81 int FindKey(StringRef Key) const;
83 /// RemoveKey - Remove the specified StringMapEntry from the table, but do not
84 /// delete it. This aborts if the value isn't in the table.
85 void RemoveKey(StringMapEntryBase *V);
87 /// RemoveKey - Remove the StringMapEntry for the specified key from the
88 /// table, returning it. If the key is not in the table, this returns null.
89 StringMapEntryBase *RemoveKey(StringRef Key);
92 void init(unsigned Size);
95 static StringMapEntryBase *getTombstoneVal() {
96 return (StringMapEntryBase*)-1;
99 unsigned getNumBuckets() const { return NumBuckets; }
100 unsigned getNumItems() const { return NumItems; }
102 bool empty() const { return NumItems == 0; }
103 unsigned size() const { return NumItems; }
105 void swap(StringMapImpl &Other) {
106 std::swap(TheTable, Other.TheTable);
107 std::swap(NumBuckets, Other.NumBuckets);
108 std::swap(NumItems, Other.NumItems);
109 std::swap(NumTombstones, Other.NumTombstones);
113 /// StringMapEntry - This is used to represent one value that is inserted into
114 /// a StringMap. It contains the Value itself and the key: the string length
116 template<typename ValueTy>
117 class StringMapEntry : public StringMapEntryBase {
118 StringMapEntry(StringMapEntry &E) = delete;
123 explicit StringMapEntry(unsigned strLen)
124 : StringMapEntryBase(strLen), second() {}
125 template <class InitTy>
126 StringMapEntry(unsigned strLen, InitTy &&V)
127 : StringMapEntryBase(strLen), second(std::forward<InitTy>(V)) {}
129 StringRef getKey() const {
130 return StringRef(getKeyData(), getKeyLength());
133 const ValueTy &getValue() const { return second; }
134 ValueTy &getValue() { return second; }
136 void setValue(const ValueTy &V) { second = V; }
138 /// getKeyData - Return the start of the string data that is the key for this
139 /// value. The string data is always stored immediately after the
140 /// StringMapEntry object.
141 const char *getKeyData() const {return reinterpret_cast<const char*>(this+1);}
143 StringRef first() const { return StringRef(getKeyData(), getKeyLength()); }
145 /// Create - Create a StringMapEntry for the specified key and default
146 /// construct the value.
147 template <typename AllocatorTy, typename InitType>
148 static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator,
149 InitType &&InitVal) {
150 unsigned KeyLength = Key.size();
152 // Allocate a new item with space for the string at the end and a null
154 unsigned AllocSize = static_cast<unsigned>(sizeof(StringMapEntry))+
156 unsigned Alignment = alignOf<StringMapEntry>();
158 StringMapEntry *NewItem =
159 static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize,Alignment));
161 // Default construct the value.
162 new (NewItem) StringMapEntry(KeyLength, std::forward<InitType>(InitVal));
164 // Copy the string information.
165 char *StrBuffer = const_cast<char*>(NewItem->getKeyData());
167 memcpy(StrBuffer, Key.data(), KeyLength);
168 StrBuffer[KeyLength] = 0; // Null terminate for convenience of clients.
172 template<typename AllocatorTy>
173 static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator) {
174 return Create(Key, Allocator, ValueTy());
177 /// Create - Create a StringMapEntry with normal malloc/free.
178 template<typename InitType>
179 static StringMapEntry *Create(StringRef Key, InitType &&InitVal) {
181 return Create(Key, A, std::forward<InitType>(InitVal));
184 static StringMapEntry *Create(StringRef Key) {
185 return Create(Key, ValueTy());
188 /// GetStringMapEntryFromKeyData - Given key data that is known to be embedded
189 /// into a StringMapEntry, return the StringMapEntry itself.
190 static StringMapEntry &GetStringMapEntryFromKeyData(const char *KeyData) {
191 char *Ptr = const_cast<char*>(KeyData) - sizeof(StringMapEntry<ValueTy>);
192 return *reinterpret_cast<StringMapEntry*>(Ptr);
195 /// Destroy - Destroy this StringMapEntry, releasing memory back to the
196 /// specified allocator.
197 template<typename AllocatorTy>
198 void Destroy(AllocatorTy &Allocator) {
199 // Free memory referenced by the item.
201 static_cast<unsigned>(sizeof(StringMapEntry)) + getKeyLength() + 1;
202 this->~StringMapEntry();
203 Allocator.Deallocate(static_cast<void *>(this), AllocSize);
206 /// Destroy this object, releasing memory back to the malloc allocator.
213 /// StringMap - This is an unconventional map that is specialized for handling
214 /// keys that are "strings", which are basically ranges of bytes. This does some
215 /// funky memory allocation and hashing things to make it extremely efficient,
216 /// storing the string data *after* the value in the map.
217 template<typename ValueTy, typename AllocatorTy = MallocAllocator>
218 class StringMap : public StringMapImpl {
219 AllocatorTy Allocator;
222 typedef StringMapEntry<ValueTy> MapEntryTy;
224 StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
225 explicit StringMap(unsigned InitialSize)
226 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
228 explicit StringMap(AllocatorTy A)
229 : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
231 StringMap(unsigned InitialSize, AllocatorTy A)
232 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
235 StringMap(std::initializer_list<std::pair<StringRef, ValueTy>> List)
236 : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {
237 for (const auto &P : List) {
242 StringMap(StringMap &&RHS)
243 : StringMapImpl(std::move(RHS)), Allocator(std::move(RHS.Allocator)) {}
245 StringMap &operator=(StringMap RHS) {
246 StringMapImpl::swap(RHS);
247 std::swap(Allocator, RHS.Allocator);
251 // FIXME: Implement copy operations if/when they're needed.
253 AllocatorTy &getAllocator() { return Allocator; }
254 const AllocatorTy &getAllocator() const { return Allocator; }
256 typedef const char* key_type;
257 typedef ValueTy mapped_type;
258 typedef StringMapEntry<ValueTy> value_type;
259 typedef size_t size_type;
261 typedef StringMapConstIterator<ValueTy> const_iterator;
262 typedef StringMapIterator<ValueTy> iterator;
265 return iterator(TheTable, NumBuckets == 0);
268 return iterator(TheTable+NumBuckets, true);
270 const_iterator begin() const {
271 return const_iterator(TheTable, NumBuckets == 0);
273 const_iterator end() const {
274 return const_iterator(TheTable+NumBuckets, true);
277 iterator find(StringRef Key) {
278 int Bucket = FindKey(Key);
279 if (Bucket == -1) return end();
280 return iterator(TheTable+Bucket, true);
283 const_iterator find(StringRef Key) const {
284 int Bucket = FindKey(Key);
285 if (Bucket == -1) return end();
286 return const_iterator(TheTable+Bucket, true);
289 /// lookup - Return the entry for the specified key, or a default
290 /// constructed value if no such entry exists.
291 ValueTy lookup(StringRef Key) const {
292 const_iterator it = find(Key);
298 ValueTy &operator[](StringRef Key) {
299 return insert(std::make_pair(Key, ValueTy())).first->second;
302 /// count - Return 1 if the element is in the map, 0 otherwise.
303 size_type count(StringRef Key) const {
304 return find(Key) == end() ? 0 : 1;
307 /// insert - Insert the specified key/value pair into the map. If the key
308 /// already exists in the map, return false and ignore the request, otherwise
309 /// insert it and return true.
310 bool insert(MapEntryTy *KeyValue) {
311 unsigned BucketNo = LookupBucketFor(KeyValue->getKey());
312 StringMapEntryBase *&Bucket = TheTable[BucketNo];
313 if (Bucket && Bucket != getTombstoneVal())
314 return false; // Already exists in map.
316 if (Bucket == getTombstoneVal())
320 assert(NumItems + NumTombstones <= NumBuckets);
326 /// insert - Inserts the specified key/value pair into the map if the key
327 /// isn't already in the map. The bool component of the returned pair is true
328 /// if and only if the insertion takes place, and the iterator component of
329 /// the pair points to the element with key equivalent to the key of the pair.
330 std::pair<iterator, bool> insert(std::pair<StringRef, ValueTy> KV) {
331 unsigned BucketNo = LookupBucketFor(KV.first);
332 StringMapEntryBase *&Bucket = TheTable[BucketNo];
333 if (Bucket && Bucket != getTombstoneVal())
334 return std::make_pair(iterator(TheTable + BucketNo, false),
335 false); // Already exists in map.
337 if (Bucket == getTombstoneVal())
340 MapEntryTy::Create(KV.first, Allocator, std::move(KV.second));
342 assert(NumItems + NumTombstones <= NumBuckets);
344 BucketNo = RehashTable(BucketNo);
345 return std::make_pair(iterator(TheTable + BucketNo, false), true);
348 // clear - Empties out the StringMap
352 // Zap all values, resetting the keys back to non-present (not tombstone),
353 // which is safe because we're removing all elements.
354 for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
355 StringMapEntryBase *&Bucket = TheTable[I];
356 if (Bucket && Bucket != getTombstoneVal()) {
357 static_cast<MapEntryTy*>(Bucket)->Destroy(Allocator);
366 /// remove - Remove the specified key/value pair from the map, but do not
367 /// erase it. This aborts if the key is not in the map.
368 void remove(MapEntryTy *KeyValue) {
372 void erase(iterator I) {
375 V.Destroy(Allocator);
378 bool erase(StringRef Key) {
379 iterator I = find(Key);
380 if (I == end()) return false;
386 // Delete all the elements in the map, but don't reset the elements
387 // to default values. This is a copy of clear(), but avoids unnecessary
388 // work not required in the destructor.
390 for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
391 StringMapEntryBase *Bucket = TheTable[I];
392 if (Bucket && Bucket != getTombstoneVal()) {
393 static_cast<MapEntryTy*>(Bucket)->Destroy(Allocator);
401 template <typename ValueTy> class StringMapConstIterator {
403 StringMapEntryBase **Ptr;
406 typedef StringMapEntry<ValueTy> value_type;
408 StringMapConstIterator() : Ptr(nullptr) { }
410 explicit StringMapConstIterator(StringMapEntryBase **Bucket,
411 bool NoAdvance = false)
413 if (!NoAdvance) AdvancePastEmptyBuckets();
416 const value_type &operator*() const {
417 return *static_cast<StringMapEntry<ValueTy>*>(*Ptr);
419 const value_type *operator->() const {
420 return static_cast<StringMapEntry<ValueTy>*>(*Ptr);
423 bool operator==(const StringMapConstIterator &RHS) const {
424 return Ptr == RHS.Ptr;
426 bool operator!=(const StringMapConstIterator &RHS) const {
427 return Ptr != RHS.Ptr;
430 inline StringMapConstIterator& operator++() { // Preincrement
432 AdvancePastEmptyBuckets();
435 StringMapConstIterator operator++(int) { // Postincrement
436 StringMapConstIterator tmp = *this; ++*this; return tmp;
440 void AdvancePastEmptyBuckets() {
441 while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
446 template<typename ValueTy>
447 class StringMapIterator : public StringMapConstIterator<ValueTy> {
449 StringMapIterator() {}
450 explicit StringMapIterator(StringMapEntryBase **Bucket,
451 bool NoAdvance = false)
452 : StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
454 StringMapEntry<ValueTy> &operator*() const {
455 return *static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
457 StringMapEntry<ValueTy> *operator->() const {
458 return static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);