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//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_STRINGMAP_H
15#define LLVM_ADT_STRINGMAP_H
16
17#include "llvm/ADT/StringRef.h"
18#include "llvm/Support/Allocator.h"
19#include <cstring>
20#include <utility>
21
22namespace llvm {
23  template<typename ValueT>
24  class StringMapConstIterator;
25  template<typename ValueT>
26  class StringMapIterator;
27  template<typename ValueTy>
28  class StringMapEntry;
29
30/// StringMapEntryBase - Shared base class of StringMapEntry instances.
31class StringMapEntryBase {
32  unsigned StrLen;
33
34public:
35  explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
36
37  unsigned getKeyLength() const { return StrLen; }
38};
39
40/// StringMapImpl - This is the base class of StringMap that is shared among
41/// all of its instantiations.
42class StringMapImpl {
43protected:
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;
48  unsigned NumBuckets;
49  unsigned NumItems;
50  unsigned NumTombstones;
51  unsigned ItemSize;
52
53protected:
54  explicit StringMapImpl(unsigned itemSize)
55      : TheTable(nullptr),
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;
63    RHS.NumBuckets = 0;
64    RHS.NumItems = 0;
65    RHS.NumTombstones = 0;
66  }
67
68  StringMapImpl(unsigned InitSize, unsigned ItemSize);
69  unsigned RehashTable(unsigned BucketNo = 0);
70
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
75  /// of the string.
76  unsigned LookupBucketFor(StringRef Key);
77
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;
82
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);
86
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);
90
91private:
92  void init(unsigned Size);
93
94public:
95  static StringMapEntryBase *getTombstoneVal() {
96    return (StringMapEntryBase*)-1;
97  }
98
99  unsigned getNumBuckets() const { return NumBuckets; }
100  unsigned getNumItems() const { return NumItems; }
101
102  bool empty() const { return NumItems == 0; }
103  unsigned size() const { return NumItems; }
104
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);
110  }
111};
112
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
115/// and data.
116template<typename ValueTy>
117class StringMapEntry : public StringMapEntryBase {
118  StringMapEntry(StringMapEntry &E) = delete;
119
120public:
121  ValueTy second;
122
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)) {}
128
129  StringRef getKey() const {
130    return StringRef(getKeyData(), getKeyLength());
131  }
132
133  const ValueTy &getValue() const { return second; }
134  ValueTy &getValue() { return second; }
135
136  void setValue(const ValueTy &V) { second = V; }
137
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);}
142
143  StringRef first() const { return StringRef(getKeyData(), getKeyLength()); }
144
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();
151
152    // Allocate a new item with space for the string at the end and a null
153    // terminator.
154    unsigned AllocSize = static_cast<unsigned>(sizeof(StringMapEntry))+
155      KeyLength+1;
156    unsigned Alignment = alignOf<StringMapEntry>();
157
158    StringMapEntry *NewItem =
159      static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize,Alignment));
160
161    // Default construct the value.
162    new (NewItem) StringMapEntry(KeyLength, std::forward<InitType>(InitVal));
163
164    // Copy the string information.
165    char *StrBuffer = const_cast<char*>(NewItem->getKeyData());
166    if (KeyLength > 0)
167      memcpy(StrBuffer, Key.data(), KeyLength);
168    StrBuffer[KeyLength] = 0;  // Null terminate for convenience of clients.
169    return NewItem;
170  }
171
172  template<typename AllocatorTy>
173  static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator) {
174    return Create(Key, Allocator, ValueTy());
175  }
176
177  /// Create - Create a StringMapEntry with normal malloc/free.
178  template<typename InitType>
179  static StringMapEntry *Create(StringRef Key, InitType &&InitVal) {
180    MallocAllocator A;
181    return Create(Key, A, std::forward<InitType>(InitVal));
182  }
183
184  static StringMapEntry *Create(StringRef Key) {
185    return Create(Key, ValueTy());
186  }
187
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);
193  }
194
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.
200    unsigned AllocSize =
201        static_cast<unsigned>(sizeof(StringMapEntry)) + getKeyLength() + 1;
202    this->~StringMapEntry();
203    Allocator.Deallocate(static_cast<void *>(this), AllocSize);
204  }
205
206  /// Destroy this object, releasing memory back to the malloc allocator.
207  void Destroy() {
208    MallocAllocator A;
209    Destroy(A);
210  }
211};
212
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.
217template<typename ValueTy, typename AllocatorTy = MallocAllocator>
218class StringMap : public StringMapImpl {
219  AllocatorTy Allocator;
220
221public:
222  typedef StringMapEntry<ValueTy> MapEntryTy;
223
224  StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
225  explicit StringMap(unsigned InitialSize)
226    : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
227
228  explicit StringMap(AllocatorTy A)
229    : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
230
231  StringMap(unsigned InitialSize, AllocatorTy A)
232    : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
233      Allocator(A) {}
234
235  StringMap(std::initializer_list<std::pair<StringRef, ValueTy>> List)
236      : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {
237    for (const auto &P : List) {
238      insert(P);
239    }
240  }
241
242  StringMap(StringMap &&RHS)
243      : StringMapImpl(std::move(RHS)), Allocator(std::move(RHS.Allocator)) {}
244
245  StringMap &operator=(StringMap RHS) {
246    StringMapImpl::swap(RHS);
247    std::swap(Allocator, RHS.Allocator);
248    return *this;
249  }
250
251  // FIXME: Implement copy operations if/when they're needed.
252
253  AllocatorTy &getAllocator() { return Allocator; }
254  const AllocatorTy &getAllocator() const { return Allocator; }
255
256  typedef const char* key_type;
257  typedef ValueTy mapped_type;
258  typedef StringMapEntry<ValueTy> value_type;
259  typedef size_t size_type;
260
261  typedef StringMapConstIterator<ValueTy> const_iterator;
262  typedef StringMapIterator<ValueTy> iterator;
263
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  }
276
277  iterator find(StringRef Key) {
278    int Bucket = FindKey(Key);
279    if (Bucket == -1) return end();
280    return iterator(TheTable+Bucket, true);
281  }
282
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  }
288
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  }
297
298  ValueTy &operator[](StringRef Key) {
299    return insert(std::make_pair(Key, ValueTy())).first->second;
300  }
301
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  }
306
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.
315
316    if (Bucket == getTombstoneVal())
317      --NumTombstones;
318    Bucket = KeyValue;
319    ++NumItems;
320    assert(NumItems + NumTombstones <= NumBuckets);
321
322    RehashTable();
323    return true;
324  }
325
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.
336
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);
343
344    BucketNo = RehashTable(BucketNo);
345    return std::make_pair(iterator(TheTable + BucketNo, false), true);
346  }
347
348  // clear - Empties out the StringMap
349  void clear() {
350    if (empty()) return;
351
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    }
361
362    NumItems = 0;
363    NumTombstones = 0;
364  }
365
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) {
369    RemoveKey(KeyValue);
370  }
371
372  void erase(iterator I) {
373    MapEntryTy &V = *I;
374    remove(&V);
375    V.Destroy(Allocator);
376  }
377
378  bool erase(StringRef Key) {
379    iterator I = find(Key);
380    if (I == end()) return false;
381    erase(I);
382    return true;
383  }
384
385  ~StringMap() {
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.
389    if (!empty()) {
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);
394        }
395      }
396    }
397    free(TheTable);
398  }
399};
400
401template <typename ValueTy> class StringMapConstIterator {
402protected:
403  StringMapEntryBase **Ptr;
404
405public:
406  typedef StringMapEntry<ValueTy> value_type;
407
408  StringMapConstIterator() : Ptr(nullptr) { }
409
410  explicit StringMapConstIterator(StringMapEntryBase **Bucket,
411                                  bool NoAdvance = false)
412  : Ptr(Bucket) {
413    if (!NoAdvance) AdvancePastEmptyBuckets();
414  }
415
416  const value_type &operator*() const {
417    return *static_cast<StringMapEntry<ValueTy>*>(*Ptr);
418  }
419  const value_type *operator->() const {
420    return static_cast<StringMapEntry<ValueTy>*>(*Ptr);
421  }
422
423  bool operator==(const StringMapConstIterator &RHS) const {
424    return Ptr == RHS.Ptr;
425  }
426  bool operator!=(const StringMapConstIterator &RHS) const {
427    return Ptr != RHS.Ptr;
428  }
429
430  inline StringMapConstIterator& operator++() {   // Preincrement
431    ++Ptr;
432    AdvancePastEmptyBuckets();
433    return *this;
434  }
435  StringMapConstIterator operator++(int) {        // Postincrement
436    StringMapConstIterator tmp = *this; ++*this; return tmp;
437  }
438
439private:
440  void AdvancePastEmptyBuckets() {
441    while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
442      ++Ptr;
443  }
444};
445
446template<typename ValueTy>
447class StringMapIterator : public StringMapConstIterator<ValueTy> {
448public:
449  StringMapIterator() {}
450  explicit StringMapIterator(StringMapEntryBase **Bucket,
451                             bool NoAdvance = false)
452    : StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
453  }
454  StringMapEntry<ValueTy> &operator*() const {
455    return *static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
456  }
457  StringMapEntry<ValueTy> *operator->() const {
458    return static_cast<StringMapEntry<ValueTy>*>(*this->Ptr);
459  }
460};
461}
462
463#endif
464