include/llvm/ADT/DenseMap.h - llvm - Git at Google

 //===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the DenseMap class.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_ADT_DENSEMAP_H
 #define LLVM_ADT_DENSEMAP_H

 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/MathExtras.h"
 #include <cassert>
 #include <utility>

 namespace llvm {

 template<typename T>
 struct DenseMapInfo {
   //static inline T getEmptyKey();
   //static inline T getTombstoneKey();
   //static unsigned getHashValue(const T &Val);
   //static bool isEqual(const T &LHS, const T &RHS);
   //static bool isPod()
 };

 // Provide DenseMapInfo for all pointers.
 template<typename T>
 struct DenseMapInfo<T*> {
   static inline T* getEmptyKey() { return reinterpret_cast<T*>(-1); }
   static inline T* getTombstoneKey() { return reinterpret_cast<T*>(-2); }
   static unsigned getHashValue(const T *PtrVal) {
     return (unsigned((uintptr_t)PtrVal) >> 4) ^
            (unsigned((uintptr_t)PtrVal) >> 9);
   }
   static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
   static bool isPod() { return true; }
 };

 // Provide DenseMapInfo for unsigned ints.
 template<> struct DenseMapInfo<unsigned> {
   static inline unsigned getEmptyKey() { return ~0; }
   static inline unsigned getTombstoneKey() { return ~0 - 1; }
   static unsigned getHashValue(const unsigned& Val) { return Val * 37; }
   static bool isPod() { return true; }
   static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
   return LHS == RHS;
   }
 };

 // Provide DenseMapInfo for unsigned longs.
 template<> struct DenseMapInfo<unsigned long> {
   static inline unsigned long getEmptyKey() { return ~0L; }
   static inline unsigned long getTombstoneKey() { return ~0L - 1L; }
   static unsigned getHashValue(const unsigned long& Val) {
     return (unsigned)(Val * 37L);
   }
   static bool isPod() { return true; }
   static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
   return LHS == RHS;
   }
 };

 // Provide DenseMapInfo for all pairs whose members have info.
 template<typename T, typename U>
 struct DenseMapInfo<std::pair<T, U> > {
   typedef std::pair<T, U> Pair;
   typedef DenseMapInfo<T> FirstInfo;
   typedef DenseMapInfo<U> SecondInfo;

   static inline Pair getEmptyKey() {
     return std::make_pair(FirstInfo::getEmptyKey(),
                           SecondInfo::getEmptyKey());
   }
   static inline Pair getTombstoneKey() {
     return std::make_pair(FirstInfo::getTombstoneKey(),
                             SecondInfo::getEmptyKey());
   }
   static unsigned getHashValue(const Pair& PairVal) {
     uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
           | (uint64_t)SecondInfo::getHashValue(PairVal.second);
     key += ~(key << 32);
     key ^= (key >> 22);
     key += ~(key << 13);
     key ^= (key >> 8);
     key += (key << 3);
     key ^= (key >> 15);
     key += ~(key << 27);
     key ^= (key >> 31);
     return (unsigned)key;
   }
   static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; }
   static bool isPod() { return FirstInfo::isPod() && SecondInfo::isPod(); }
 };

 template<typename KeyT, typename ValueT,
          typename KeyInfoT = DenseMapInfo<KeyT>,
          typename ValueInfoT = DenseMapInfo<ValueT> >
 class DenseMapIterator;
 template<typename KeyT, typename ValueT,
          typename KeyInfoT = DenseMapInfo<KeyT>,
          typename ValueInfoT = DenseMapInfo<ValueT> >
 class DenseMapConstIterator;

 template<typename KeyT, typename ValueT,
          typename KeyInfoT = DenseMapInfo<KeyT>,
          typename ValueInfoT = DenseMapInfo<ValueT> >
 class DenseMap {
   typedef std::pair<KeyT, ValueT> BucketT;
   unsigned NumBuckets;
   BucketT *Buckets;

   unsigned NumEntries;
   unsigned NumTombstones;
 public:
   typedef KeyT key_type;
   typedef ValueT mapped_type;
   typedef BucketT value_type;

   DenseMap(const DenseMap& other) {
     NumBuckets = 0;
     CopyFrom(other);
   }

   explicit DenseMap(unsigned NumInitBuckets = 64) {
     init(NumInitBuckets);
   }

   ~DenseMap() {
     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
     for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
       if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
           !KeyInfoT::isEqual(P->first, TombstoneKey))
         P->second.~ValueT();
       P->first.~KeyT();
     }
     operator delete(Buckets);
   }

   typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
   typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
   inline iterator begin() {
      return iterator(Buckets, Buckets+NumBuckets);
   }
   inline iterator end() {
     return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
   }
   inline const_iterator begin() const {
     return const_iterator(Buckets, Buckets+NumBuckets);
   }
   inline const_iterator end() const {
     return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
   }

   bool empty() const { return NumEntries == 0; }
   unsigned size() const { return NumEntries; }

   /// Grow the densemap so that it has at least Size buckets. Does not shrink
   void resize(size_t Size) { grow(Size); }

   void clear() {
     // If the capacity of the array is huge, and the # elements used is small,
     // shrink the array.
     if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
       shrink_and_clear();
       return;
     }

     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
     for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
       if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
         if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
           P->second.~ValueT();
           --NumEntries;
         }
         P->first = EmptyKey;
       }
     }
     assert(NumEntries == 0 && "Node count imbalance!");
     NumTombstones = 0;
   }

   /// count - Return true if the specified key is in the map.
   bool count(const KeyT &Val) const {
     BucketT *TheBucket;
     return LookupBucketFor(Val, TheBucket);
   }

   iterator find(const KeyT &Val) {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return iterator(TheBucket, Buckets+NumBuckets);
     return end();
   }
   const_iterator find(const KeyT &Val) const {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return const_iterator(TheBucket, Buckets+NumBuckets);
     return end();
   }

   /// lookup - Return the entry for the specified key, or a default
   /// constructed value if no such entry exists.
   ValueT lookup(const KeyT &Val) const {
     BucketT *TheBucket;
     if (LookupBucketFor(Val, TheBucket))
       return TheBucket->second;
     return ValueT();
   }

   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
     BucketT *TheBucket;
     if (LookupBucketFor(KV.first, TheBucket))
       return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
                             false); // Already in map.

     // Otherwise, insert the new element.
     TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
     return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
                           true);
   }

   /// insert - Range insertion of pairs.
   template<typename InputIt>
   void insert(InputIt I, InputIt E) {
     for (; I != E; ++I)
       insert(*I);
   }


   bool erase(const KeyT &Val) {
     BucketT *TheBucket;
     if (!LookupBucketFor(Val, TheBucket))
       return false; // not in map.

     TheBucket->second.~ValueT();
     TheBucket->first = getTombstoneKey();
     --NumEntries;
     ++NumTombstones;
     return true;
   }
   bool erase(iterator I) {
     BucketT *TheBucket = &*I;
     TheBucket->second.~ValueT();
     TheBucket->first = getTombstoneKey();
     --NumEntries;
     ++NumTombstones;
     return true;
   }

   value_type& FindAndConstruct(const KeyT &Key) {
     BucketT *TheBucket;
     if (LookupBucketFor(Key, TheBucket))
       return *TheBucket;

     return *InsertIntoBucket(Key, ValueT(), TheBucket);
   }

   ValueT &operator[](const KeyT &Key) {
     return FindAndConstruct(Key).second;
   }

   DenseMap& operator=(const DenseMap& other) {
     CopyFrom(other);
     return *this;
   }

 private:
   void CopyFrom(const DenseMap& other) {
     if (NumBuckets != 0 && (!KeyInfoT::isPod() || !ValueInfoT::isPod())) {
       const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
       for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
         if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
             !KeyInfoT::isEqual(P->first, TombstoneKey))
           P->second.~ValueT();
         P->first.~KeyT();
       }
     }

     NumEntries = other.NumEntries;
     NumTombstones = other.NumTombstones;

     if (NumBuckets)
       operator delete(Buckets);
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) *
                                                  other.NumBuckets));

     if (KeyInfoT::isPod() && ValueInfoT::isPod())
       memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
     else
       for (size_t i = 0; i < other.NumBuckets; ++i) {
         new (&Buckets[i].first) KeyT(other.Buckets[i].first);
         if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
             !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
           new (&Buckets[i].second) ValueT(other.Buckets[i].second);
       }
     NumBuckets = other.NumBuckets;
   }

   BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
                             BucketT *TheBucket) {
     // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
     // the buckets are empty (meaning that many are filled with tombstones),
     // grow the table.
     //
     // The later case is tricky.  For example, if we had one empty bucket with
     // tons of tombstones, failing lookups (e.g. for insertion) would have to
     // probe almost the entire table until it found the empty bucket.  If the
     // table completely filled with tombstones, no lookup would ever succeed,
     // causing infinite loops in lookup.
     if (NumEntries*4 >= NumBuckets*3 ||
         NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
       this->grow(NumBuckets * 2);
       LookupBucketFor(Key, TheBucket);
     }
     ++NumEntries;

     // If we are writing over a tombstone, remember this.
     if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
       --NumTombstones;

     TheBucket->first = Key;
     new (&TheBucket->second) ValueT(Value);
     return TheBucket;
   }

   static unsigned getHashValue(const KeyT &Val) {
     return KeyInfoT::getHashValue(Val);
   }
   static const KeyT getEmptyKey() {
     return KeyInfoT::getEmptyKey();
   }
   static const KeyT getTombstoneKey() {
     return KeyInfoT::getTombstoneKey();
   }

   /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
   /// FoundBucket.  If the bucket contains the key and a value, this returns
   /// true, otherwise it returns a bucket with an empty marker or tombstone and
   /// returns false.
   bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
     unsigned BucketNo = getHashValue(Val);
     unsigned ProbeAmt = 1;
     BucketT *BucketsPtr = Buckets;

     // FoundTombstone - Keep track of whether we find a tombstone while probing.
     BucketT *FoundTombstone = 0;
     const KeyT EmptyKey = getEmptyKey();
     const KeyT TombstoneKey = getTombstoneKey();
     assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
            !KeyInfoT::isEqual(Val, TombstoneKey) &&
            "Empty/Tombstone value shouldn't be inserted into map!");

     while (1) {
       BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
       // Found Val's bucket?  If so, return it.
       if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
         FoundBucket = ThisBucket;
         return true;
       }

       // If we found an empty bucket, the key doesn't exist in the set.
       // Insert it and return the default value.
       if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
         // If we've already seen a tombstone while probing, fill it in instead
         // of the empty bucket we eventually probed to.
         if (FoundTombstone) ThisBucket = FoundTombstone;
         FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
         return false;
       }

       // If this is a tombstone, remember it.  If Val ends up not in the map, we
       // prefer to return it than something that would require more probing.
       if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
         FoundTombstone = ThisBucket;  // Remember the first tombstone found.

       // Otherwise, it's a hash collision or a tombstone, continue quadratic
       // probing.
       BucketNo += ProbeAmt++;
     }
   }

   void init(unsigned InitBuckets) {
     NumEntries = 0;
     NumTombstones = 0;
     NumBuckets = InitBuckets;
     assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
            "# initial buckets must be a power of two!");
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0; i != InitBuckets; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);
   }

   void grow(unsigned AtLeast) {
     unsigned OldNumBuckets = NumBuckets;
     BucketT *OldBuckets = Buckets;

     // Double the number of buckets.
     while (NumBuckets <= AtLeast)
       NumBuckets <<= 1;
     NumTombstones = 0;
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));

     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0, e = NumBuckets; i != e; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);

     // Insert all the old elements.
     const KeyT TombstoneKey = getTombstoneKey();
     for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
       if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
           !KeyInfoT::isEqual(B->first, TombstoneKey)) {
         // Insert the key/value into the new table.
         BucketT *DestBucket;
         bool FoundVal = LookupBucketFor(B->first, DestBucket);
         FoundVal = FoundVal; // silence warning.
         assert(!FoundVal && "Key already in new map?");
         DestBucket->first = B->first;
         new (&DestBucket->second) ValueT(B->second);

         // Free the value.
         B->second.~ValueT();
       }
       B->first.~KeyT();
     }

     // Free the old table.
     operator delete(OldBuckets);
   }

   void shrink_and_clear() {
     unsigned OldNumBuckets = NumBuckets;
     BucketT *OldBuckets = Buckets;

     // Reduce the number of buckets.
     NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
                                  : 64;
     NumTombstones = 0;
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*NumBuckets));

     // Initialize all the keys to EmptyKey.
     const KeyT EmptyKey = getEmptyKey();
     for (unsigned i = 0, e = NumBuckets; i != e; ++i)
       new (&Buckets[i].first) KeyT(EmptyKey);

     // Free the old buckets.
     const KeyT TombstoneKey = getTombstoneKey();
     for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
       if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
           !KeyInfoT::isEqual(B->first, TombstoneKey)) {
         // Free the value.
         B->second.~ValueT();
       }
       B->first.~KeyT();
     }

     // Free the old table.
     operator delete(OldBuckets);

     NumEntries = 0;
   }
 };

 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
 class DenseMapIterator {
   typedef std::pair<KeyT, ValueT> BucketT;
 protected:
   const BucketT *Ptr, *End;
 public:
   DenseMapIterator(void) : Ptr(0), End(0) {}

   DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
     AdvancePastEmptyBuckets();
   }

   std::pair<KeyT, ValueT> &operator*() const {
     return *const_cast<BucketT*>(Ptr);
   }
   std::pair<KeyT, ValueT> *operator->() const {
     return const_cast<BucketT*>(Ptr);
   }

   bool operator==(const DenseMapIterator &RHS) const {
     return Ptr == RHS.Ptr;
   }
   bool operator!=(const DenseMapIterator &RHS) const {
     return Ptr != RHS.Ptr;
   }

   inline DenseMapIterator& operator++() {          // Preincrement
     ++Ptr;
     AdvancePastEmptyBuckets();
     return *this;
   }
   DenseMapIterator operator++(int) {        // Postincrement
     DenseMapIterator tmp = *this; ++*this; return tmp;
   }

 private:
   void AdvancePastEmptyBuckets() {
     const KeyT Empty = KeyInfoT::getEmptyKey();
     const KeyT Tombstone = KeyInfoT::getTombstoneKey();

     while (Ptr != End &&
            (KeyInfoT::isEqual(Ptr->first, Empty) ||
             KeyInfoT::isEqual(Ptr->first, Tombstone)))
       ++Ptr;
   }
 };

 template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
 class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
 public:
   DenseMapConstIterator(void) : DenseMapIterator<KeyT, ValueT, KeyInfoT>() {}
   DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
                         const std::pair<KeyT, ValueT> *E)
     : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
   }
   const std::pair<KeyT, ValueT> &operator*() const {
     return *this->Ptr;
   }
   const std::pair<KeyT, ValueT> *operator->() const {
     return this->Ptr;
   }
 };

 } // end namespace llvm

 #endif
	//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines the DenseMap class.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_ADT_DENSEMAP_H
	#define LLVM_ADT_DENSEMAP_H

	#include "llvm/Support/DataTypes.h"
	#include "llvm/Support/MathExtras.h"
	#include <cassert>
	#include <utility>

	namespace llvm {

	template<typename T>
	struct DenseMapInfo {
	//static inline T getEmptyKey();
	//static inline T getTombstoneKey();
	//static unsigned getHashValue(const T &Val);
	//static bool isEqual(const T &LHS, const T &RHS);
	//static bool isPod()
	};

	// Provide DenseMapInfo for all pointers.
	template<typename T>
	struct DenseMapInfo<T*> {
	static inline T* getEmptyKey() { return reinterpret_cast<T*>(-1); }
	static inline T* getTombstoneKey() { return reinterpret_cast<T*>(-2); }
	static unsigned getHashValue(const T *PtrVal) {
	return (unsigned((uintptr_t)PtrVal) >> 4) ^
	(unsigned((uintptr_t)PtrVal) >> 9);
	}
	static bool isEqual(const T LHS, const T RHS) { return LHS == RHS; }
	static bool isPod() { return true; }
	};

	// Provide DenseMapInfo for unsigned ints.
	template<> struct DenseMapInfo<unsigned> {
	static inline unsigned getEmptyKey() { return ~0; }
	static inline unsigned getTombstoneKey() { return ~0 - 1; }
	static unsigned getHashValue(const unsigned& Val) { return Val * 37; }
	static bool isPod() { return true; }
	static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
	return LHS == RHS;
	}
	};

	// Provide DenseMapInfo for unsigned longs.
	template<> struct DenseMapInfo<unsigned long> {
	static inline unsigned long getEmptyKey() { return ~0L; }
	static inline unsigned long getTombstoneKey() { return ~0L - 1L; }
	static unsigned getHashValue(const unsigned long& Val) {
	return (unsigned)(Val * 37L);
	}
	static bool isPod() { return true; }
	static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
	return LHS == RHS;
	}
	};

	// Provide DenseMapInfo for all pairs whose members have info.
	template<typename T, typename U>
	struct DenseMapInfo<std::pair<T, U> > {
	typedef std::pair<T, U> Pair;
	typedef DenseMapInfo<T> FirstInfo;
	typedef DenseMapInfo<U> SecondInfo;

	static inline Pair getEmptyKey() {
	return std::make_pair(FirstInfo::getEmptyKey(),
	SecondInfo::getEmptyKey());
	}
	static inline Pair getTombstoneKey() {
	return std::make_pair(FirstInfo::getTombstoneKey(),
	SecondInfo::getEmptyKey());
	}
	static unsigned getHashValue(const Pair& PairVal) {
	uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
	\| (uint64_t)SecondInfo::getHashValue(PairVal.second);
	key += ~(key << 32);
	key ^= (key >> 22);
	key += ~(key << 13);
	key ^= (key >> 8);
	key += (key << 3);
	key ^= (key >> 15);
	key += ~(key << 27);
	key ^= (key >> 31);
	return (unsigned)key;
	}
	static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; }
	static bool isPod() { return FirstInfo::isPod() && SecondInfo::isPod(); }
	};

	template<typename KeyT, typename ValueT,
	typename KeyInfoT = DenseMapInfo<KeyT>,
	typename ValueInfoT = DenseMapInfo<ValueT> >
	class DenseMapIterator;
	template<typename KeyT, typename ValueT,
	typename KeyInfoT = DenseMapInfo<KeyT>,
	typename ValueInfoT = DenseMapInfo<ValueT> >
	class DenseMapConstIterator;

	template<typename KeyT, typename ValueT,
	typename KeyInfoT = DenseMapInfo<KeyT>,
	typename ValueInfoT = DenseMapInfo<ValueT> >
	class DenseMap {
	typedef std::pair<KeyT, ValueT> BucketT;
	unsigned NumBuckets;
	BucketT *Buckets;

	unsigned NumEntries;
	unsigned NumTombstones;
	public:
	typedef KeyT key_type;
	typedef ValueT mapped_type;
	typedef BucketT value_type;

	DenseMap(const DenseMap& other) {
	NumBuckets = 0;
	CopyFrom(other);
	}

	explicit DenseMap(unsigned NumInitBuckets = 64) {
	init(NumInitBuckets);
	}

	~DenseMap() {
	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
	!KeyInfoT::isEqual(P->first, TombstoneKey))
	P->second.~ValueT();
	P->first.~KeyT();
	}
	operator delete(Buckets);
	}

	typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
	typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
	inline iterator begin() {
	return iterator(Buckets, Buckets+NumBuckets);
	}
	inline iterator end() {
	return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
	}
	inline const_iterator begin() const {
	return const_iterator(Buckets, Buckets+NumBuckets);
	}
	inline const_iterator end() const {
	return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
	}

	bool empty() const { return NumEntries == 0; }
	unsigned size() const { return NumEntries; }

	/// Grow the densemap so that it has at least Size buckets. Does not shrink
	void resize(size_t Size) { grow(Size); }

	void clear() {
	// If the capacity of the array is huge, and the # elements used is small,
	// shrink the array.
	if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
	shrink_and_clear();
	return;
	}

	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey)) {
	if (!KeyInfoT::isEqual(P->first, TombstoneKey)) {
	P->second.~ValueT();
	--NumEntries;
	}
	P->first = EmptyKey;
	}
	}
	assert(NumEntries == 0 && "Node count imbalance!");
	NumTombstones = 0;
	}

	/// count - Return true if the specified key is in the map.
	bool count(const KeyT &Val) const {
	BucketT *TheBucket;
	return LookupBucketFor(Val, TheBucket);
	}

	iterator find(const KeyT &Val) {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return iterator(TheBucket, Buckets+NumBuckets);
	return end();
	}
	const_iterator find(const KeyT &Val) const {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return const_iterator(TheBucket, Buckets+NumBuckets);
	return end();
	}

	/// lookup - Return the entry for the specified key, or a default
	/// constructed value if no such entry exists.
	ValueT lookup(const KeyT &Val) const {
	BucketT *TheBucket;
	if (LookupBucketFor(Val, TheBucket))
	return TheBucket->second;
	return ValueT();
	}

	std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
	BucketT *TheBucket;
	if (LookupBucketFor(KV.first, TheBucket))
	return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
	false); // Already in map.

	// Otherwise, insert the new element.
	TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
	return std::make_pair(iterator(TheBucket, Buckets+NumBuckets),
	true);
	}

	/// insert - Range insertion of pairs.
	template<typename InputIt>
	void insert(InputIt I, InputIt E) {
	for (; I != E; ++I)
	insert(*I);
	}


	bool erase(const KeyT &Val) {
	BucketT *TheBucket;
	if (!LookupBucketFor(Val, TheBucket))
	return false; // not in map.

	TheBucket->second.~ValueT();
	TheBucket->first = getTombstoneKey();
	--NumEntries;
	++NumTombstones;
	return true;
	}
	bool erase(iterator I) {
	BucketT TheBucket = &I;
	TheBucket->second.~ValueT();
	TheBucket->first = getTombstoneKey();
	--NumEntries;
	++NumTombstones;
	return true;
	}

	value_type& FindAndConstruct(const KeyT &Key) {
	BucketT *TheBucket;
	if (LookupBucketFor(Key, TheBucket))
	return *TheBucket;

	return *InsertIntoBucket(Key, ValueT(), TheBucket);
	}

	ValueT &operator[](const KeyT &Key) {
	return FindAndConstruct(Key).second;
	}

	DenseMap& operator=(const DenseMap& other) {
	CopyFrom(other);
	return *this;
	}

	private:
	void CopyFrom(const DenseMap& other) {
	if (NumBuckets != 0 && (!KeyInfoT::isPod() \|\| !ValueInfoT::isPod())) {
	const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
	for (BucketT P = Buckets, E = Buckets+NumBuckets; P != E; ++P) {
	if (!KeyInfoT::isEqual(P->first, EmptyKey) &&
	!KeyInfoT::isEqual(P->first, TombstoneKey))
	P->second.~ValueT();
	P->first.~KeyT();
	}
	}

	NumEntries = other.NumEntries;
	NumTombstones = other.NumTombstones;

	if (NumBuckets)
	operator delete(Buckets);
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)
	other.NumBuckets));

	if (KeyInfoT::isPod() && ValueInfoT::isPod())
	memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
	else
	for (size_t i = 0; i < other.NumBuckets; ++i) {
	new (&Buckets[i].first) KeyT(other.Buckets[i].first);
	if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
	!KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
	new (&Buckets[i].second) ValueT(other.Buckets[i].second);
	}
	NumBuckets = other.NumBuckets;
	}

	BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
	BucketT *TheBucket) {
	// If the load of the hash table is more than 3/4, or if fewer than 1/8 of
	// the buckets are empty (meaning that many are filled with tombstones),
	// grow the table.
	//
	// The later case is tricky. For example, if we had one empty bucket with
	// tons of tombstones, failing lookups (e.g. for insertion) would have to
	// probe almost the entire table until it found the empty bucket. If the
	// table completely filled with tombstones, no lookup would ever succeed,
	// causing infinite loops in lookup.
	if (NumEntries4 >= NumBuckets3 \|\|
	NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
	this->grow(NumBuckets * 2);
	LookupBucketFor(Key, TheBucket);
	}
	++NumEntries;

	// If we are writing over a tombstone, remember this.
	if (!KeyInfoT::isEqual(TheBucket->first, getEmptyKey()))
	--NumTombstones;

	TheBucket->first = Key;
	new (&TheBucket->second) ValueT(Value);
	return TheBucket;
	}

	static unsigned getHashValue(const KeyT &Val) {
	return KeyInfoT::getHashValue(Val);
	}
	static const KeyT getEmptyKey() {
	return KeyInfoT::getEmptyKey();
	}
	static const KeyT getTombstoneKey() {
	return KeyInfoT::getTombstoneKey();
	}

	/// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
	/// FoundBucket. If the bucket contains the key and a value, this returns
	/// true, otherwise it returns a bucket with an empty marker or tombstone and
	/// returns false.
	bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
	unsigned BucketNo = getHashValue(Val);
	unsigned ProbeAmt = 1;
	BucketT *BucketsPtr = Buckets;

	// FoundTombstone - Keep track of whether we find a tombstone while probing.
	BucketT *FoundTombstone = 0;
	const KeyT EmptyKey = getEmptyKey();
	const KeyT TombstoneKey = getTombstoneKey();
	assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
	!KeyInfoT::isEqual(Val, TombstoneKey) &&
	"Empty/Tombstone value shouldn't be inserted into map!");

	while (1) {
	BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
	// Found Val's bucket? If so, return it.
	if (KeyInfoT::isEqual(ThisBucket->first, Val)) {
	FoundBucket = ThisBucket;
	return true;
	}

	// If we found an empty bucket, the key doesn't exist in the set.
	// Insert it and return the default value.
	if (KeyInfoT::isEqual(ThisBucket->first, EmptyKey)) {
	// If we've already seen a tombstone while probing, fill it in instead
	// of the empty bucket we eventually probed to.
	if (FoundTombstone) ThisBucket = FoundTombstone;
	FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
	return false;
	}

	// If this is a tombstone, remember it. If Val ends up not in the map, we
	// prefer to return it than something that would require more probing.
	if (KeyInfoT::isEqual(ThisBucket->first, TombstoneKey) && !FoundTombstone)
	FoundTombstone = ThisBucket; // Remember the first tombstone found.

	// Otherwise, it's a hash collision or a tombstone, continue quadratic
	// probing.
	BucketNo += ProbeAmt++;
	}
	}

	void init(unsigned InitBuckets) {
	NumEntries = 0;
	NumTombstones = 0;
	NumBuckets = InitBuckets;
	assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
	"# initial buckets must be a power of two!");
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)InitBuckets));
	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0; i != InitBuckets; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);
	}

	void grow(unsigned AtLeast) {
	unsigned OldNumBuckets = NumBuckets;
	BucketT *OldBuckets = Buckets;

	// Double the number of buckets.
	while (NumBuckets <= AtLeast)
	NumBuckets <<= 1;
	NumTombstones = 0;
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)NumBuckets));

	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0, e = NumBuckets; i != e; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);

	// Insert all the old elements.
	const KeyT TombstoneKey = getTombstoneKey();
	for (BucketT B = OldBuckets, E = OldBuckets+OldNumBuckets; B != E; ++B) {
	if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
	!KeyInfoT::isEqual(B->first, TombstoneKey)) {
	// Insert the key/value into the new table.
	BucketT *DestBucket;
	bool FoundVal = LookupBucketFor(B->first, DestBucket);
	FoundVal = FoundVal; // silence warning.
	assert(!FoundVal && "Key already in new map?");
	DestBucket->first = B->first;
	new (&DestBucket->second) ValueT(B->second);

	// Free the value.
	B->second.~ValueT();
	}
	B->first.~KeyT();
	}

	// Free the old table.
	operator delete(OldBuckets);
	}

	void shrink_and_clear() {
	unsigned OldNumBuckets = NumBuckets;
	BucketT *OldBuckets = Buckets;

	// Reduce the number of buckets.
	NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
	: 64;
	NumTombstones = 0;
	Buckets = static_cast<BucketT>(operator new(sizeof(BucketT)NumBuckets));

	// Initialize all the keys to EmptyKey.
	const KeyT EmptyKey = getEmptyKey();
	for (unsigned i = 0, e = NumBuckets; i != e; ++i)
	new (&Buckets[i].first) KeyT(EmptyKey);

	// Free the old buckets.
	const KeyT TombstoneKey = getTombstoneKey();
	for (BucketT B = OldBuckets, E = OldBuckets+OldNumBuckets; B != E; ++B) {
	if (!KeyInfoT::isEqual(B->first, EmptyKey) &&
	!KeyInfoT::isEqual(B->first, TombstoneKey)) {
	// Free the value.
	B->second.~ValueT();
	}
	B->first.~KeyT();
	}

	// Free the old table.
	operator delete(OldBuckets);

	NumEntries = 0;
	}
	};

	template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
	class DenseMapIterator {
	typedef std::pair<KeyT, ValueT> BucketT;
	protected:
	const BucketT Ptr, End;
	public:
	DenseMapIterator(void) : Ptr(0), End(0) {}

	DenseMapIterator(const BucketT Pos, const BucketT E) : Ptr(Pos), End(E) {
	AdvancePastEmptyBuckets();
	}

	std::pair<KeyT, ValueT> &operator*() const {
	return const_cast<BucketT>(Ptr);
	}
	std::pair<KeyT, ValueT> *operator->() const {
	return const_cast<BucketT*>(Ptr);
	}

	bool operator==(const DenseMapIterator &RHS) const {
	return Ptr == RHS.Ptr;
	}
	bool operator!=(const DenseMapIterator &RHS) const {
	return Ptr != RHS.Ptr;
	}

	inline DenseMapIterator& operator++() { // Preincrement
	++Ptr;
	AdvancePastEmptyBuckets();
	return *this;
	}
	DenseMapIterator operator++(int) { // Postincrement
	DenseMapIterator tmp = this; ++this; return tmp;
	}

	private:
	void AdvancePastEmptyBuckets() {
	const KeyT Empty = KeyInfoT::getEmptyKey();
	const KeyT Tombstone = KeyInfoT::getTombstoneKey();

	while (Ptr != End &&
	(KeyInfoT::isEqual(Ptr->first, Empty) \|\|
	KeyInfoT::isEqual(Ptr->first, Tombstone)))
	++Ptr;
	}
	};

	template<typename KeyT, typename ValueT, typename KeyInfoT, typename ValueInfoT>
	class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
	public:
	DenseMapConstIterator(void) : DenseMapIterator<KeyT, ValueT, KeyInfoT>() {}
	DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
	const std::pair<KeyT, ValueT> *E)
	: DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
	}
	const std::pair<KeyT, ValueT> &operator*() const {
	return *this->Ptr;
	}
	const std::pair<KeyT, ValueT> *operator->() const {
	return this->Ptr;
	}
	};

	} // end namespace llvm

	#endif