1 //===--- StringMap.h - String Hash table map interface ----------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the StringMap class.
11 //
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"
19 #include <cstring>
20 #include <utility>
22 namespace llvm {
23 template<typename ValueT>
24 class StringMapConstIterator;
25 template<typename ValueT>
26 class StringMapIterator;
27 template<typename ValueTy>
28 class StringMapEntry;
30 /// StringMapEntryBase - Shared base class of StringMapEntry instances.
31 class StringMapEntryBase {
32 unsigned StrLen;
33 public:
34 explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
36 unsigned getKeyLength() const { return StrLen; }
37 };
39 /// StringMapImpl - This is the base class of StringMap that is shared among
40 /// all of its instantiations.
41 class StringMapImpl {
42 protected:
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;
47 unsigned NumBuckets;
48 unsigned NumItems;
49 unsigned NumTombstones;
50 unsigned ItemSize;
51 protected:
52 explicit StringMapImpl(unsigned itemSize)
53 : TheTable(nullptr),
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;
61 RHS.NumBuckets = 0;
62 RHS.NumItems = 0;
63 RHS.NumTombstones = 0;
64 }
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
73 /// of the string.
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);
88 private:
89 void init(unsigned Size);
90 public:
91 static StringMapEntryBase *getTombstoneVal() {
92 return (StringMapEntryBase*)-1;
93 }
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);
106 }
107 };
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
111 /// and data.
112 template<typename ValueTy>
113 class StringMapEntry : public StringMapEntryBase {
114 StringMapEntry(StringMapEntry &E) LLVM_DELETED_FUNCTION;
115 public:
116 ValueTy second;
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());
126 }
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
148 // terminator.
149 unsigned AllocSize = static_cast<unsigned>(sizeof(StringMapEntry))+
150 KeyLength+1;
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.
163 return NewItem;
164 }
166 template<typename AllocatorTy>
167 static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator) {
168 return Create(Key, Allocator, ValueTy());
169 }
171 /// Create - Create a StringMapEntry with normal malloc/free.
172 template<typename InitType>
173 static StringMapEntry *Create(StringRef Key, InitType InitVal) {
174 MallocAllocator A;
175 return Create(Key, A, std::move(InitVal));
176 }
178 static StringMapEntry *Create(StringRef Key) {
179 return Create(Key, ValueTy());
180 }
182 /// GetStringMapEntryFromValue - Given a value that is known to be embedded
183 /// into a StringMapEntry, return the StringMapEntry itself.
184 static StringMapEntry &GetStringMapEntryFromValue(ValueTy &V) {
185 StringMapEntry *EPtr = 0;
186 char *Ptr = reinterpret_cast<char*>(&V) -
187 (reinterpret_cast<char*>(&EPtr->second) -
188 reinterpret_cast<char*>(EPtr));
189 return *reinterpret_cast<StringMapEntry*>(Ptr);
190 }
191 static const StringMapEntry &GetStringMapEntryFromValue(const ValueTy &V) {
192 return GetStringMapEntryFromValue(const_cast<ValueTy&>(V));
193 }
195 /// GetStringMapEntryFromKeyData - Given key data that is known to be embedded
196 /// into a StringMapEntry, return the StringMapEntry itself.
197 static StringMapEntry &GetStringMapEntryFromKeyData(const char *KeyData) {
198 char *Ptr = const_cast<char*>(KeyData) - sizeof(StringMapEntry<ValueTy>);
199 return *reinterpret_cast<StringMapEntry*>(Ptr);
200 }
202 /// Destroy - Destroy this StringMapEntry, releasing memory back to the
203 /// specified allocator.
204 template<typename AllocatorTy>
205 void Destroy(AllocatorTy &Allocator) {
206 // Free memory referenced by the item.
207 unsigned AllocSize =
208 static_cast<unsigned>(sizeof(StringMapEntry)) + getKeyLength() + 1;
209 this->~StringMapEntry();
210 Allocator.Deallocate(static_cast<void *>(this), AllocSize);
211 }
213 /// Destroy this object, releasing memory back to the malloc allocator.
214 void Destroy() {
215 MallocAllocator A;
216 Destroy(A);
217 }
218 };
221 /// StringMap - This is an unconventional map that is specialized for handling
222 /// keys that are "strings", which are basically ranges of bytes. This does some
223 /// funky memory allocation and hashing things to make it extremely efficient,
224 /// storing the string data *after* the value in the map.
225 template<typename ValueTy, typename AllocatorTy = MallocAllocator>
226 class StringMap : public StringMapImpl {
227 AllocatorTy Allocator;
228 public:
229 typedef StringMapEntry<ValueTy> MapEntryTy;
231 StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
232 explicit StringMap(unsigned InitialSize)
233 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
235 explicit StringMap(AllocatorTy A)
236 : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
238 StringMap(unsigned InitialSize, AllocatorTy A)
239 : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
240 Allocator(A) {}
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);
248 return *this;
249 }
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;
264 iterator begin() {
265 return iterator(TheTable, NumBuckets == 0);
266 }
267 iterator end() {
268 return iterator(TheTable+NumBuckets, true);
269 }
270 const_iterator begin() const {
271 return const_iterator(TheTable, NumBuckets == 0);
272 }
273 const_iterator end() const {
274 return const_iterator(TheTable+NumBuckets, true);
275 }
277 iterator find(StringRef Key) {
278 int Bucket = FindKey(Key);
279 if (Bucket == -1) return end();
280 return iterator(TheTable+Bucket, true);
281 }
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);
287 }
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);
293 if (it != end())
294 return it->second;
295 return ValueTy();
296 }
298 ValueTy &operator[](StringRef Key) {
299 return GetOrCreateValue(Key).getValue();
300 }
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;
305 }
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())
317 --NumTombstones;
318 Bucket = KeyValue;
319 ++NumItems;
320 assert(NumItems + NumTombstones <= NumBuckets);
322 RehashTable();
323 return true;
324 }
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())
338 --NumTombstones;
339 Bucket =
340 MapEntryTy::Create(KV.first, Allocator, std::move(KV.second));
341 ++NumItems;
342 assert(NumItems + NumTombstones <= NumBuckets);
344 BucketNo = RehashTable(BucketNo);
345 return std::make_pair(iterator(TheTable + BucketNo, false), true);
346 }
348 // clear - Empties out the StringMap
349 void clear() {
350 if (empty()) return;
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);
358 }
359 Bucket = nullptr;
360 }
362 NumItems = 0;
363 NumTombstones = 0;
364 }
366 /// GetOrCreateValue - Look up the specified key in the table. If a value
367 /// exists, return it. Otherwise, default construct a value, insert it, and
368 /// return.
369 template <typename InitTy>
370 MapEntryTy &GetOrCreateValue(StringRef Key, InitTy Val) {
371 return *insert(std::make_pair(Key, std::move(Val))).first;
372 }
374 MapEntryTy &GetOrCreateValue(StringRef Key) {
375 return GetOrCreateValue(Key, ValueTy());
376 }
378 /// remove - Remove the specified key/value pair from the map, but do not
379 /// erase it. This aborts if the key is not in the map.
380 void remove(MapEntryTy *KeyValue) {
381 RemoveKey(KeyValue);
382 }
384 void erase(iterator I) {
385 MapEntryTy &V = *I;
386 remove(&V);
387 V.Destroy(Allocator);
388 }
390 bool erase(StringRef Key) {
391 iterator I = find(Key);
392 if (I == end()) return false;
393 erase(I);
394 return true;
395 }
397 ~StringMap() {
398 // Delete all the elements in the map, but don't reset the elements
399 // to default values. This is a copy of clear(), but avoids unnecessary
400 // work not required in the destructor.
401 if (!empty()) {
402 for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
403 StringMapEntryBase *Bucket = TheTable[I];
404 if (Bucket && Bucket != getTombstoneVal()) {
405 static_cast<MapEntryTy*>(Bucket)->Destroy(Allocator);
406 }
407 }
408 }
409 free(TheTable);
410 }
411 };
414 template<typename ValueTy>
415 class StringMapConstIterator {
416 protected:
417 StringMapEntryBase **Ptr;
418 public:
419 typedef StringMapEntry<ValueTy> value_type;
421 StringMapConstIterator() : Ptr(nullptr) { }
423 explicit StringMapConstIterator(StringMapEntryBase **Bucket,
424 bool NoAdvance = false)
425 : Ptr(Bucket) {
426 if (!NoAdvance) AdvancePastEmptyBuckets();
427 }
429 const value_type &operator*() const {
430 return *static_cast<StringMapEntry<ValueTy>*>(*Ptr);
431 }
432 const value_type *operator->() const {
433 return static_cast<StringMapEntry<ValueTy>*>(*Ptr);
434 }
436 bool operator==(const StringMapConstIterator &RHS) const {
437 return Ptr == RHS.Ptr;
438 }
439 bool operator!=(const StringMapConstIterator &RHS) const {
440 return Ptr != RHS.Ptr;
441 }
443 inline StringMapConstIterator& operator++() { // Preincrement
444 ++Ptr;
445 AdvancePastEmptyBuckets();
446 return *this;
447 }
448 StringMapConstIterator operator++(int) { // Postincrement
449 StringMapConstIterator tmp = *this; ++*this; return tmp;
450 }
452 private:
453 void AdvancePastEmptyBuckets() {
454 while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
455 ++Ptr;
456 }
457 };
459 template<typename ValueTy>
460 class StringMapIterator : public StringMapConstIterator<ValueTy> {
461 public:
462 StringMapIterator() {}
463 explicit StringMapIterator(StringMapEntryBase **Bucket,
464 bool NoAdvance = false)
465 : StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
466 }
467 StringMapEntry<ValueTy> &operator*() const {
468 return *static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
469 }
470 StringMapEntry<ValueTy> *operator->() const {
471 return static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
472 }
473 };
475 }
477 #endif