479 lines
15 KiB
C++
479 lines
15 KiB
C++
//===--- StringMap.h - String Hash table map interface ----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the StringMap class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_STRINGMAP_H
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#define LLVM_ADT_STRINGMAP_H
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Allocator.h"
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#include <cstring>
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#include <string>
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namespace llvm {
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template<typename ValueT>
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class StringMapConstIterator;
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template<typename ValueT>
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class StringMapIterator;
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template<typename ValueTy>
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class StringMapEntry;
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/// StringMapEntryInitializer - This datatype can be partially specialized for
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/// various datatypes in a stringmap to allow them to be initialized when an
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/// entry is default constructed for the map.
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template<typename ValueTy>
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class StringMapEntryInitializer {
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public:
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template <typename InitTy>
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static void Initialize(StringMapEntry<ValueTy> &T, InitTy InitVal) {
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T.second = InitVal;
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}
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};
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/// StringMapEntryBase - Shared base class of StringMapEntry instances.
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class StringMapEntryBase {
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unsigned StrLen;
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public:
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explicit StringMapEntryBase(unsigned Len) : StrLen(Len) {}
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unsigned getKeyLength() const { return StrLen; }
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};
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/// StringMapImpl - This is the base class of StringMap that is shared among
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/// all of its instantiations.
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class StringMapImpl {
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public:
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/// ItemBucket - The hash table consists of an array of these. If Item is
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/// non-null, this is an extant entry, otherwise, it is a hole.
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struct ItemBucket {
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/// FullHashValue - This remembers the full hash value of the key for
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/// easy scanning.
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unsigned FullHashValue;
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/// Item - This is a pointer to the actual item object.
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StringMapEntryBase *Item;
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};
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protected:
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ItemBucket *TheTable;
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unsigned NumBuckets;
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unsigned NumItems;
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unsigned NumTombstones;
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unsigned ItemSize;
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protected:
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explicit StringMapImpl(unsigned itemSize) : ItemSize(itemSize) {
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// Initialize the map with zero buckets to allocation.
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TheTable = 0;
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NumBuckets = 0;
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NumItems = 0;
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NumTombstones = 0;
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}
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StringMapImpl(unsigned InitSize, unsigned ItemSize);
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void RehashTable();
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/// ShouldRehash - Return true if the table should be rehashed after a new
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/// element was recently inserted.
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bool ShouldRehash() const {
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// If the hash table is now more than 3/4 full, or if fewer than 1/8 of
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// the buckets are empty (meaning that many are filled with tombstones),
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// grow the table.
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return NumItems*4 > NumBuckets*3 ||
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NumBuckets-(NumItems+NumTombstones) < NumBuckets/8;
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}
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/// LookupBucketFor - Look up the bucket that the specified string should end
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/// up in. If it already exists as a key in the map, the Item pointer for the
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/// specified bucket will be non-null. Otherwise, it will be null. In either
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/// case, the FullHashValue field of the bucket will be set to the hash value
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/// of the string.
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unsigned LookupBucketFor(const StringRef &Key);
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/// FindKey - Look up the bucket that contains the specified key. If it exists
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/// in the map, return the bucket number of the key. Otherwise return -1.
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/// This does not modify the map.
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int FindKey(const StringRef &Key) const;
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/// RemoveKey - Remove the specified StringMapEntry from the table, but do not
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/// delete it. This aborts if the value isn't in the table.
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void RemoveKey(StringMapEntryBase *V);
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/// RemoveKey - Remove the StringMapEntry for the specified key from the
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/// table, returning it. If the key is not in the table, this returns null.
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StringMapEntryBase *RemoveKey(const StringRef &Key);
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private:
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void init(unsigned Size);
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public:
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static StringMapEntryBase *getTombstoneVal() {
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return (StringMapEntryBase*)-1;
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}
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unsigned getNumBuckets() const { return NumBuckets; }
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unsigned getNumItems() const { return NumItems; }
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bool empty() const { return NumItems == 0; }
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unsigned size() const { return NumItems; }
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};
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/// StringMapEntry - This is used to represent one value that is inserted into
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/// a StringMap. It contains the Value itself and the key: the string length
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/// and data.
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template<typename ValueTy>
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class StringMapEntry : public StringMapEntryBase {
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public:
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ValueTy second;
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explicit StringMapEntry(unsigned strLen)
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: StringMapEntryBase(strLen), second() {}
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StringMapEntry(unsigned strLen, const ValueTy &V)
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: StringMapEntryBase(strLen), second(V) {}
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StringRef getKey() const {
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return StringRef(getKeyData(), getKeyLength());
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}
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const ValueTy &getValue() const { return second; }
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ValueTy &getValue() { return second; }
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void setValue(const ValueTy &V) { second = V; }
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/// getKeyData - Return the start of the string data that is the key for this
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/// value. The string data is always stored immediately after the
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/// StringMapEntry object.
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const char *getKeyData() const {return reinterpret_cast<const char*>(this+1);}
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const char *first() const { return getKeyData(); }
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/// Create - Create a StringMapEntry for the specified key and default
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/// construct the value.
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template<typename AllocatorTy, typename InitType>
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static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
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AllocatorTy &Allocator,
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InitType InitVal) {
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unsigned KeyLength = static_cast<unsigned>(KeyEnd-KeyStart);
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// Okay, the item doesn't already exist, and 'Bucket' is the bucket to fill
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// in. Allocate a new item with space for the string at the end and a null
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// terminator.
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unsigned AllocSize = static_cast<unsigned>(sizeof(StringMapEntry))+
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KeyLength+1;
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unsigned Alignment = alignof<StringMapEntry>();
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StringMapEntry *NewItem =
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static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize,Alignment));
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// Default construct the value.
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new (NewItem) StringMapEntry(KeyLength);
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// Copy the string information.
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char *StrBuffer = const_cast<char*>(NewItem->getKeyData());
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memcpy(StrBuffer, KeyStart, KeyLength);
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StrBuffer[KeyLength] = 0; // Null terminate for convenience of clients.
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// Initialize the value if the client wants to.
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StringMapEntryInitializer<ValueTy>::Initialize(*NewItem, InitVal);
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return NewItem;
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}
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template<typename AllocatorTy>
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static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
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AllocatorTy &Allocator) {
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return Create(KeyStart, KeyEnd, Allocator, 0);
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}
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/// Create - Create a StringMapEntry with normal malloc/free.
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template<typename InitType>
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static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
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InitType InitVal) {
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MallocAllocator A;
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return Create(KeyStart, KeyEnd, A, InitVal);
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}
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static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd) {
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return Create(KeyStart, KeyEnd, ValueTy());
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}
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/// GetStringMapEntryFromValue - Given a value that is known to be embedded
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/// into a StringMapEntry, return the StringMapEntry itself.
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static StringMapEntry &GetStringMapEntryFromValue(ValueTy &V) {
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StringMapEntry *EPtr = 0;
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char *Ptr = reinterpret_cast<char*>(&V) -
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(reinterpret_cast<char*>(&EPtr->second) -
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reinterpret_cast<char*>(EPtr));
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return *reinterpret_cast<StringMapEntry*>(Ptr);
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}
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static const StringMapEntry &GetStringMapEntryFromValue(const ValueTy &V) {
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return GetStringMapEntryFromValue(const_cast<ValueTy&>(V));
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}
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/// Destroy - Destroy this StringMapEntry, releasing memory back to the
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/// specified allocator.
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template<typename AllocatorTy>
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void Destroy(AllocatorTy &Allocator) {
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// Free memory referenced by the item.
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this->~StringMapEntry();
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Allocator.Deallocate(this);
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}
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/// Destroy this object, releasing memory back to the malloc allocator.
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void Destroy() {
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MallocAllocator A;
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Destroy(A);
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}
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};
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/// StringMap - This is an unconventional map that is specialized for handling
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/// keys that are "strings", which are basically ranges of bytes. This does some
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/// funky memory allocation and hashing things to make it extremely efficient,
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/// storing the string data *after* the value in the map.
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template<typename ValueTy, typename AllocatorTy = MallocAllocator>
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class StringMap : public StringMapImpl {
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AllocatorTy Allocator;
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typedef StringMapEntry<ValueTy> MapEntryTy;
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public:
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StringMap() : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {}
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explicit StringMap(unsigned InitialSize)
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: StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
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explicit StringMap(const StringMap &RHS)
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: StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {
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assert(RHS.empty() &&
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"Copy ctor from non-empty stringmap not implemented yet!");
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}
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void operator=(const StringMap &RHS) {
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assert(RHS.empty() &&
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"assignment from non-empty stringmap not implemented yet!");
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clear();
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}
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AllocatorTy &getAllocator() { return Allocator; }
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const AllocatorTy &getAllocator() const { return Allocator; }
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typedef const char* key_type;
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typedef ValueTy mapped_type;
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typedef StringMapEntry<ValueTy> value_type;
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typedef size_t size_type;
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typedef StringMapConstIterator<ValueTy> const_iterator;
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typedef StringMapIterator<ValueTy> iterator;
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iterator begin() {
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return iterator(TheTable, NumBuckets == 0);
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}
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iterator end() {
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return iterator(TheTable+NumBuckets, true);
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}
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const_iterator begin() const {
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return const_iterator(TheTable, NumBuckets == 0);
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}
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const_iterator end() const {
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return const_iterator(TheTable+NumBuckets, true);
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}
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iterator find(const StringRef &Key) {
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int Bucket = FindKey(Key);
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if (Bucket == -1) return end();
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return iterator(TheTable+Bucket);
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}
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const_iterator find(const StringRef &Key) const {
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int Bucket = FindKey(Key);
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if (Bucket == -1) return end();
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return const_iterator(TheTable+Bucket);
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}
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/// lookup - Return the entry for the specified key, or a default
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/// constructed value if no such entry exists.
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ValueTy lookup(const StringRef &Key) const {
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const_iterator it = find(Key);
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if (it != end())
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return it->second;
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return ValueTy();
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}
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ValueTy& operator[](const StringRef &Key) {
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return GetOrCreateValue(Key).getValue();
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}
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size_type count(const StringRef &Key) const {
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return find(Key) == end() ? 0 : 1;
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}
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/// insert - Insert the specified key/value pair into the map. If the key
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/// already exists in the map, return false and ignore the request, otherwise
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/// insert it and return true.
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bool insert(MapEntryTy *KeyValue) {
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unsigned BucketNo = LookupBucketFor(KeyValue->getKey());
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ItemBucket &Bucket = TheTable[BucketNo];
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if (Bucket.Item && Bucket.Item != getTombstoneVal())
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return false; // Already exists in map.
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if (Bucket.Item == getTombstoneVal())
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--NumTombstones;
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Bucket.Item = KeyValue;
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++NumItems;
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if (ShouldRehash())
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RehashTable();
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return true;
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}
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// clear - Empties out the StringMap
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void clear() {
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if (empty()) return;
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// Zap all values, resetting the keys back to non-present (not tombstone),
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// which is safe because we're removing all elements.
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for (ItemBucket *I = TheTable, *E = TheTable+NumBuckets; I != E; ++I) {
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if (I->Item && I->Item != getTombstoneVal()) {
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static_cast<MapEntryTy*>(I->Item)->Destroy(Allocator);
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I->Item = 0;
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}
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}
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NumItems = 0;
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}
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/// GetOrCreateValue - Look up the specified key in the table. If a value
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/// exists, return it. Otherwise, default construct a value, insert it, and
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/// return.
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template <typename InitTy>
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StringMapEntry<ValueTy> &GetOrCreateValue(const StringRef &Key,
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InitTy Val) {
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unsigned BucketNo = LookupBucketFor(Key);
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ItemBucket &Bucket = TheTable[BucketNo];
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if (Bucket.Item && Bucket.Item != getTombstoneVal())
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return *static_cast<MapEntryTy*>(Bucket.Item);
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MapEntryTy *NewItem =
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MapEntryTy::Create(Key.begin(), Key.end(), Allocator, Val);
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if (Bucket.Item == getTombstoneVal())
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--NumTombstones;
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++NumItems;
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// Fill in the bucket for the hash table. The FullHashValue was already
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// filled in by LookupBucketFor.
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Bucket.Item = NewItem;
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if (ShouldRehash())
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RehashTable();
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return *NewItem;
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}
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StringMapEntry<ValueTy> &GetOrCreateValue(const StringRef &Key) {
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return GetOrCreateValue(Key, ValueTy());
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}
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template <typename InitTy>
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StringMapEntry<ValueTy> &GetOrCreateValue(const char *KeyStart,
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const char *KeyEnd,
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InitTy Val) {
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return GetOrCreateValue(StringRef(KeyStart, KeyEnd - KeyStart), Val);
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}
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StringMapEntry<ValueTy> &GetOrCreateValue(const char *KeyStart,
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const char *KeyEnd) {
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return GetOrCreateValue(StringRef(KeyStart, KeyEnd - KeyStart));
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}
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/// remove - Remove the specified key/value pair from the map, but do not
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/// erase it. This aborts if the key is not in the map.
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void remove(MapEntryTy *KeyValue) {
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RemoveKey(KeyValue);
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}
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void erase(iterator I) {
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MapEntryTy &V = *I;
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remove(&V);
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V.Destroy(Allocator);
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}
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bool erase(const StringRef &Key) {
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iterator I = find(Key);
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if (I == end()) return false;
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erase(I);
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return true;
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}
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~StringMap() {
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clear();
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free(TheTable);
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}
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};
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template<typename ValueTy>
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class StringMapConstIterator {
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protected:
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StringMapImpl::ItemBucket *Ptr;
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public:
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typedef StringMapEntry<ValueTy> value_type;
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explicit StringMapConstIterator(StringMapImpl::ItemBucket *Bucket,
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bool NoAdvance = false)
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: Ptr(Bucket) {
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if (!NoAdvance) AdvancePastEmptyBuckets();
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}
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const value_type &operator*() const {
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return *static_cast<StringMapEntry<ValueTy>*>(Ptr->Item);
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}
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const value_type *operator->() const {
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return static_cast<StringMapEntry<ValueTy>*>(Ptr->Item);
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}
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bool operator==(const StringMapConstIterator &RHS) const {
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return Ptr == RHS.Ptr;
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}
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bool operator!=(const StringMapConstIterator &RHS) const {
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return Ptr != RHS.Ptr;
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}
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inline StringMapConstIterator& operator++() { // Preincrement
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++Ptr;
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AdvancePastEmptyBuckets();
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return *this;
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}
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StringMapConstIterator operator++(int) { // Postincrement
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StringMapConstIterator tmp = *this; ++*this; return tmp;
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}
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private:
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void AdvancePastEmptyBuckets() {
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while (Ptr->Item == 0 || Ptr->Item == StringMapImpl::getTombstoneVal())
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++Ptr;
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}
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};
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template<typename ValueTy>
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class StringMapIterator : public StringMapConstIterator<ValueTy> {
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public:
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explicit StringMapIterator(StringMapImpl::ItemBucket *Bucket,
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bool NoAdvance = false)
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: StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
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}
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StringMapEntry<ValueTy> &operator*() const {
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return *static_cast<StringMapEntry<ValueTy>*>(this->Ptr->Item);
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}
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StringMapEntry<ValueTy> *operator->() const {
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return static_cast<StringMapEntry<ValueTy>*>(this->Ptr->Item);
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}
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};
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}
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#endif
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