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;
33public:
34  explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
35
36  unsigned getKeyLength() const { return StrLen; }
37};
38
39/// StringMapImpl - This is the base class of StringMap that is shared among
40/// all of its instantiations.
41class StringMapImpl {
42protected:
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;
51protected:
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  }
65
66  StringMapImpl(unsigned InitSize, unsigned ItemSize);
67  unsigned RehashTable(unsigned BucketNo = 0);
68
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);
75
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;
80
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);
84
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);
88private:
89  void init(unsigned Size);
90public:
91  static StringMapEntryBase *getTombstoneVal() {
92    return (StringMapEntryBase*)-1;
93  }
94
95  unsigned getNumBuckets() const { return NumBuckets; }
96  unsigned getNumItems() const { return NumItems; }
97
98  bool empty() const { return NumItems == 0; }
99  unsigned size() const { return NumItems; }
100
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};
108
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.
112template<typename ValueTy>
113class StringMapEntry : public StringMapEntryBase {
114  StringMapEntry(StringMapEntry &E) LLVM_DELETED_FUNCTION;
115public:
116  ValueTy second;
117
118  explicit StringMapEntry(unsigned strLen)
119    : StringMapEntryBase(strLen), second() {}
120  StringMapEntry(unsigned strLen, ValueTy V)
121      : StringMapEntryBase(strLen), second(std::move(V)) {}
122
123  StringRef getKey() const {
124    return StringRef(getKeyData(), getKeyLength());
125  }
126
127  const ValueTy &getValue() const { return second; }
128  ValueTy &getValue() { return second; }
129
130  void setValue(const ValueTy &V) { second = V; }
131
132  /// getKeyData - Return the start of the string data that is the key for this
133  /// value.  The string data is always stored immediately after the
134  /// StringMapEntry object.
135  const char *getKeyData() const {return reinterpret_cast<const char*>(this+1);}
136
137  StringRef first() const { return StringRef(getKeyData(), getKeyLength()); }
138
139  /// Create - Create a StringMapEntry for the specified key and default
140  /// construct the value.
141  template<typename AllocatorTy, typename InitType>
142  static StringMapEntry *Create(StringRef Key,
143                                AllocatorTy &Allocator,
144                                InitType InitVal) {
145    unsigned KeyLength = Key.size();
146
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>();
152
153    StringMapEntry *NewItem =
154      static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize,Alignment));
155
156    // Default construct the value.
157    new (NewItem) StringMapEntry(KeyLength, std::move(InitVal));
158
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  }
165
166  template<typename AllocatorTy>
167  static StringMapEntry *Create(StringRef Key, AllocatorTy &Allocator) {
168    return Create(Key, Allocator, ValueTy());
169  }
170
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  }
177
178  static StringMapEntry *Create(StringRef Key) {
179    return Create(Key, ValueTy());
180  }
181
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  }
194
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  }
201
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  }
212
213  /// Destroy this object, releasing memory back to the malloc allocator.
214  void Destroy() {
215    MallocAllocator A;
216    Destroy(A);
217  }
218};
219
220
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.
225template<typename ValueTy, typename AllocatorTy = MallocAllocator>
226class StringMap : public StringMapImpl {
227  AllocatorTy Allocator;
228public:
229  typedef StringMapEntry<ValueTy> MapEntryTy;
230
231  StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
232  explicit StringMap(unsigned InitialSize)
233    : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
234
235  explicit StringMap(AllocatorTy A)
236    : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
237
238  StringMap(unsigned InitialSize, AllocatorTy A)
239    : StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))),
240      Allocator(A) {}
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 GetOrCreateValue(Key).getValue();
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  /// 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  }
373
374  MapEntryTy &GetOrCreateValue(StringRef Key) {
375    return GetOrCreateValue(Key, ValueTy());
376  }
377
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  }
383
384  void erase(iterator I) {
385    MapEntryTy &V = *I;
386    remove(&V);
387    V.Destroy(Allocator);
388  }
389
390  bool erase(StringRef Key) {
391    iterator I = find(Key);
392    if (I == end()) return false;
393    erase(I);
394    return true;
395  }
396
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};
412
413
414template<typename ValueTy>
415class StringMapConstIterator {
416protected:
417  StringMapEntryBase **Ptr;
418public:
419  typedef StringMapEntry<ValueTy> value_type;
420
421  StringMapConstIterator() : Ptr(nullptr) { }
422
423  explicit StringMapConstIterator(StringMapEntryBase **Bucket,
424                                  bool NoAdvance = false)
425  : Ptr(Bucket) {
426    if (!NoAdvance) AdvancePastEmptyBuckets();
427  }
428
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  }
435
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  }
442
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  }
451
452private:
453  void AdvancePastEmptyBuckets() {
454    while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
455      ++Ptr;
456  }
457};
458
459template<typename ValueTy>
460class StringMapIterator : public StringMapConstIterator<ValueTy> {
461public:
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};
474
475}
476
477#endif
478