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 {
34 explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
36 unsigned getKeyLength() const { return StrLen; }
39 /// StringMapImpl - This is the base class of StringMap that is shared among
40 /// all of its instantiations.
43 // Array of NumBuckets pointers to entries, null pointers are holes.
44 // TheTable[NumBuckets] contains a sentinel value for easy iteration. Followed
45 // by an array of the actual hash values as unsigned integers.
46 StringMapEntryBase **TheTable;
49 unsigned NumTombstones;
52 explicit StringMapImpl(unsigned itemSize)
54 // Initialize the map with zero buckets to allocation.
55 NumBuckets(0), NumItems(0), NumTombstones(0), ItemSize(itemSize) {}
56 StringMapImpl(StringMapImpl &&RHS)
57 : TheTable(RHS.TheTable), NumBuckets(RHS.NumBuckets),
58 NumItems(RHS.NumItems), NumTombstones(RHS.NumTombstones),
59 ItemSize(RHS.ItemSize) {
60 RHS.TheTable = nullptr;
63 RHS.NumTombstones = 0;
66 StringMapImpl(unsigned InitSize, unsigned ItemSize);
67 unsigned RehashTable(unsigned BucketNo = 0);
69 /// LookupBucketFor - Look up the bucket that the specified string should end
70 /// up in. If it already exists as a key in the map, the Item pointer for the
71 /// specified bucket will be non-null. Otherwise, it will be null. In either
72 /// case, the FullHashValue field of the bucket will be set to the hash value
74 unsigned LookupBucketFor(StringRef Key);
76 /// FindKey - Look up the bucket that contains the specified key. If it exists
77 /// in the map, return the bucket number of the key. Otherwise return -1.
78 /// This does not modify the map.
79 int FindKey(StringRef Key) const;
81 /// RemoveKey - Remove the specified StringMapEntry from the table, but do not
82 /// delete it. This aborts if the value isn't in the table.
83 void RemoveKey(StringMapEntryBase *V);
85 /// RemoveKey - Remove the StringMapEntry for the specified key from the
86 /// table, returning it. If the key is not in the table, this returns null.
87 StringMapEntryBase *RemoveKey(StringRef Key);
89 void init(unsigned Size);
91 static StringMapEntryBase *getTombstoneVal() {
92 return (StringMapEntryBase*)-1;
95 unsigned getNumBuckets() const { return NumBuckets; }
96 unsigned getNumItems() const { return NumItems; }
98 bool empty() const { return NumItems == 0; }
99 unsigned size() const { return NumItems; }
101 void swap(StringMapImpl &Other) {
102 std::swap(TheTable, Other.TheTable);
103 std::swap(NumBuckets, Other.NumBuckets);
104 std::swap(NumItems, Other.NumItems);
105 std::swap(NumTombstones, Other.NumTombstones);
109 /// StringMapEntry - This is used to represent one value that is inserted into
110 /// a StringMap. It contains the Value itself and the key: the string length
112 template<typename ValueTy>
113 class StringMapEntry : public StringMapEntryBase {
114 StringMapEntry(StringMapEntry &E) = delete;
118 explicit StringMapEntry(unsigned strLen)
119 : StringMapEntryBase(strLen), second() {}
120 template <class InitTy>
121 StringMapEntry(unsigned strLen, InitTy &&V)
122 : StringMapEntryBase(strLen), second(std::forward<InitTy>(V)) {}
124 StringRef getKey() const {
125 return StringRef(getKeyData(), getKeyLength());
128 const ValueTy &getValue() const { return second; }
129 ValueTy &getValue() { return second; }
131 void setValue(const ValueTy &V) { second = V; }
133 /// getKeyData - Return the start of the string data that is the key for this
134 /// value. The string data is always stored immediately after the
135 /// StringMapEntry object.
136 const char *getKeyData() const {return reinterpret_cast<const char*>(this+1);}
138 StringRef first() const { return StringRef(getKeyData(), getKeyLength()); }
140 /// Create - Create a StringMapEntry for the specified key and default
141 /// construct the value.
142 template <typename AllocatorTy, typename InitType>
143 static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator,
144 InitType &&InitVal) {
145 unsigned KeyLength = Key.size();
147 // Allocate a new item with space for the string at the end and a null
149 unsigned AllocSize = static_cast<unsigned>(sizeof(StringMapEntry))+
151 unsigned Alignment = alignOf<StringMapEntry>();
153 StringMapEntry *NewItem =
154 static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize,Alignment));
156 // Default construct the value.
157 new (NewItem) StringMapEntry(KeyLength, std::forward<InitType>(InitVal));
159 // Copy the string information.
160 char *StrBuffer = const_cast<char*>(NewItem->getKeyData());
161 memcpy(StrBuffer, Key.data(), KeyLength);
162 StrBuffer[KeyLength] = 0; // Null terminate for convenience of clients.
166 template<typename AllocatorTy>
167 static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator) {
168 return Create(Key, Allocator, ValueTy());
171 /// Create - Create a StringMapEntry with normal malloc/free.
172 template<typename InitType>
173 static StringMapEntry *Create(StringRef Key, InitType &&InitVal) {
175 return Create(Key, A, std::forward<InitType>(InitVal));
178 static StringMapEntry *Create(StringRef Key) {
179 return Create(Key, ValueTy());
182 /// GetStringMapEntryFromKeyData - Given key data that is known to be embedded
183 /// into a StringMapEntry, return the StringMapEntry itself.
184 static StringMapEntry &GetStringMapEntryFromKeyData(const char *KeyData) {
185 char *Ptr = const_cast<char*>(KeyData) - sizeof(StringMapEntry<ValueTy>);
186 return *reinterpret_cast<StringMapEntry*>(Ptr);
189 /// Destroy - Destroy this StringMapEntry, releasing memory back to the
190 /// specified allocator.
191 template<typename AllocatorTy>
192 void Destroy(AllocatorTy &Allocator) {
193 // Free memory referenced by the item.
195 static_cast<unsigned>(sizeof(StringMapEntry)) + getKeyLength() + 1;
196 this->~StringMapEntry();
197 Allocator.Deallocate(static_cast<void *>(this), AllocSize);
200 /// Destroy this object, releasing memory back to the malloc allocator.
208 /// StringMap - This is an unconventional map that is specialized for handling
209 /// keys that are "strings", which are basically ranges of bytes. This does some
210 /// funky memory allocation and hashing things to make it extremely efficient,
211 /// storing the string data *after* the value in the map.
212 template<typename ValueTy, typename AllocatorTy = MallocAllocator>
213 class StringMap : public StringMapImpl {
214 AllocatorTy Allocator;
216 typedef StringMapEntry<ValueTy> MapEntryTy;
218 StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
219 explicit StringMap(unsigned InitialSize)
220 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
222 explicit StringMap(AllocatorTy A)
223 : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
225 StringMap(unsigned InitialSize, AllocatorTy A)
226 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
229 StringMap(StringMap &&RHS)
230 : StringMapImpl(std::move(RHS)), Allocator(std::move(RHS.Allocator)) {}
232 StringMap &operator=(StringMap RHS) {
233 StringMapImpl::swap(RHS);
234 std::swap(Allocator, RHS.Allocator);
238 // FIXME: Implement copy operations if/when they're needed.
240 AllocatorTy &getAllocator() { return Allocator; }
241 const AllocatorTy &getAllocator() const { return Allocator; }
243 typedef const char* key_type;
244 typedef ValueTy mapped_type;
245 typedef StringMapEntry<ValueTy> value_type;
246 typedef size_t size_type;
248 typedef StringMapConstIterator<ValueTy> const_iterator;
249 typedef StringMapIterator<ValueTy> iterator;
252 return iterator(TheTable, NumBuckets == 0);
255 return iterator(TheTable+NumBuckets, true);
257 const_iterator begin() const {
258 return const_iterator(TheTable, NumBuckets == 0);
260 const_iterator end() const {
261 return const_iterator(TheTable+NumBuckets, true);
264 iterator find(StringRef Key) {
265 int Bucket = FindKey(Key);
266 if (Bucket == -1) return end();
267 return iterator(TheTable+Bucket, true);
270 const_iterator find(StringRef Key) const {
271 int Bucket = FindKey(Key);
272 if (Bucket == -1) return end();
273 return const_iterator(TheTable+Bucket, true);
276 /// lookup - Return the entry for the specified key, or a default
277 /// constructed value if no such entry exists.
278 ValueTy lookup(StringRef Key) const {
279 const_iterator it = find(Key);
285 ValueTy &operator[](StringRef Key) {
286 return insert(std::make_pair(Key, ValueTy())).first->second;
289 /// count - Return 1 if the element is in the map, 0 otherwise.
290 size_type count(StringRef Key) const {
291 return find(Key) == end() ? 0 : 1;
294 /// insert - Insert the specified key/value pair into the map. If the key
295 /// already exists in the map, return false and ignore the request, otherwise
296 /// insert it and return true.
297 bool insert(MapEntryTy *KeyValue) {
298 unsigned BucketNo = LookupBucketFor(KeyValue->getKey());
299 StringMapEntryBase *&Bucket = TheTable[BucketNo];
300 if (Bucket && Bucket != getTombstoneVal())
301 return false; // Already exists in map.
303 if (Bucket == getTombstoneVal())
307 assert(NumItems + NumTombstones <= NumBuckets);
313 /// insert - Inserts the specified key/value pair into the map if the key
314 /// isn't already in the map. The bool component of the returned pair is true
315 /// if and only if the insertion takes place, and the iterator component of
316 /// the pair points to the element with key equivalent to the key of the pair.
317 std::pair<iterator, bool> insert(std::pair<StringRef, ValueTy> KV) {
318 unsigned BucketNo = LookupBucketFor(KV.first);
319 StringMapEntryBase *&Bucket = TheTable[BucketNo];
320 if (Bucket && Bucket != getTombstoneVal())
321 return std::make_pair(iterator(TheTable + BucketNo, false),
322 false); // Already exists in map.
324 if (Bucket == getTombstoneVal())
327 MapEntryTy::Create(KV.first, Allocator, std::move(KV.second));
329 assert(NumItems + NumTombstones <= NumBuckets);
331 BucketNo = RehashTable(BucketNo);
332 return std::make_pair(iterator(TheTable + BucketNo, false), true);
335 // clear - Empties out the StringMap
339 // Zap all values, resetting the keys back to non-present (not tombstone),
340 // which is safe because we're removing all elements.
341 for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
342 StringMapEntryBase *&Bucket = TheTable[I];
343 if (Bucket && Bucket != getTombstoneVal()) {
344 static_cast<MapEntryTy*>(Bucket)->Destroy(Allocator);
353 /// remove - Remove the specified key/value pair from the map, but do not
354 /// erase it. This aborts if the key is not in the map.
355 void remove(MapEntryTy *KeyValue) {
359 void erase(iterator I) {
362 V.Destroy(Allocator);
365 bool erase(StringRef Key) {
366 iterator I = find(Key);
367 if (I == end()) return false;
373 // Delete all the elements in the map, but don't reset the elements
374 // to default values. This is a copy of clear(), but avoids unnecessary
375 // work not required in the destructor.
377 for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
378 StringMapEntryBase *Bucket = TheTable[I];
379 if (Bucket && Bucket != getTombstoneVal()) {
380 static_cast<MapEntryTy*>(Bucket)->Destroy(Allocator);
389 template<typename ValueTy>
390 class StringMapConstIterator {
392 StringMapEntryBase **Ptr;
394 typedef StringMapEntry<ValueTy> value_type;
396 StringMapConstIterator() : Ptr(nullptr) { }
398 explicit StringMapConstIterator(StringMapEntryBase **Bucket,
399 bool NoAdvance = false)
401 if (!NoAdvance) AdvancePastEmptyBuckets();
404 const value_type &operator*() const {
405 return *static_cast<StringMapEntry<ValueTy>*>(*Ptr);
407 const value_type *operator->() const {
408 return static_cast<StringMapEntry<ValueTy>*>(*Ptr);
411 bool operator==(const StringMapConstIterator &RHS) const {
412 return Ptr == RHS.Ptr;
414 bool operator!=(const StringMapConstIterator &RHS) const {
415 return Ptr != RHS.Ptr;
418 inline StringMapConstIterator& operator++() { // Preincrement
420 AdvancePastEmptyBuckets();
423 StringMapConstIterator operator++(int) { // Postincrement
424 StringMapConstIterator tmp = *this; ++*this; return tmp;
428 void AdvancePastEmptyBuckets() {
429 while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
434 template<typename ValueTy>
435 class StringMapIterator : public StringMapConstIterator<ValueTy> {
437 StringMapIterator() {}
438 explicit StringMapIterator(StringMapEntryBase **Bucket,
439 bool NoAdvance = false)
440 : StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
442 StringMapEntry<ValueTy> &operator*() const {
443 return *static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
445 StringMapEntry<ValueTy> *operator->() const {
446 return static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);