llvm-6502/include/llvm/ADT/StringMap.h
2007-04-04 00:44:31 +00:00

347 lines
11 KiB
C++

//===--- StringMap.h - String Hash table map interface ----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the StringMap class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STRINGMAP_H
#define LLVM_ADT_STRINGMAP_H
#include "llvm/Support/Allocator.h"
#include <cstring>
namespace llvm {
template<typename ValueT>
class StringMapConstIterator;
template<typename ValueT>
class StringMapIterator;
/// StringMapEntryBase - Shared base class of StringMapEntry instances.
class StringMapEntryBase {
unsigned StrLen;
public:
StringMapEntryBase(unsigned Len) : StrLen(Len) {}
unsigned getKeyLength() const { return StrLen; }
};
/// StringMapImpl - This is the base class of StringMap that is shared among
/// all of its instantiations.
class StringMapImpl {
public:
/// ItemBucket - The hash table consists of an array of these. If Item is
/// non-null, this is an extant entry, otherwise, it is a hole.
struct ItemBucket {
/// FullHashValue - This remembers the full hash value of the key for
/// easy scanning.
unsigned FullHashValue;
/// Item - This is a pointer to the actual item object.
StringMapEntryBase *Item;
};
protected:
ItemBucket *TheTable;
unsigned NumBuckets;
unsigned NumItems;
unsigned NumTombstones;
unsigned ItemSize;
protected:
StringMapImpl(unsigned itemSize) : ItemSize(itemSize) { init(16); }
StringMapImpl(unsigned InitSize, unsigned ItemSize);
void RehashTable();
/// ShouldRehash - Return true if the table should be rehashed after a new
/// element was recently inserted.
bool ShouldRehash() const {
// If the hash table is now more than 3/4 full, or if fewer than 1/8 of
// the buckets are empty (meaning that many are filled with tombstones),
// grow the table.
return NumItems*4 > NumBuckets*3 ||
NumBuckets-(NumItems+NumTombstones) < NumBuckets/8;
}
/// LookupBucketFor - Look up the bucket that the specified string should end
/// up in. If it already exists as a key in the map, the Item pointer for the
/// specified bucket will be non-null. Otherwise, it will be null. In either
/// case, the FullHashValue field of the bucket will be set to the hash value
/// of the string.
unsigned LookupBucketFor(const char *KeyStart, const char *KeyEnd);
/// FindKey - Look up the bucket that contains the specified key. If it exists
/// in the map, return the bucket number of the key. Otherwise return -1.
/// This does not modify the map.
int FindKey(const char *KeyStart, const char *KeyEnd) const;
/// RemoveKey - Remove the specified StringMapEntry from the table, but do not
/// delete it. This aborts if the value isn't in the table.
void RemoveKey(StringMapEntryBase *V);
/// RemoveKey - Remove the StringMapEntry for the specified key from the
/// table, returning it. If the key is not in the table, this returns null.
StringMapEntryBase *RemoveKey(const char *KeyStart, const char *KeyEnd);
private:
void init(unsigned Size);
public:
static StringMapEntryBase *getTombstoneVal() {
return (StringMapEntryBase*)-1;
}
unsigned getNumBuckets() const { return NumBuckets; }
unsigned getNumItems() const { return NumItems; }
bool empty() const { return NumItems == 0; }
unsigned size() const { return NumItems; }
};
/// StringMapEntry - This is used to represent one value that is inserted into
/// a StringMap. It contains the Value itself and the key: the string length
/// and data.
template<typename ValueTy>
class StringMapEntry : public StringMapEntryBase {
ValueTy Val;
public:
StringMapEntry(unsigned StrLen)
: StringMapEntryBase(StrLen), Val() {}
StringMapEntry(unsigned StrLen, const ValueTy &V)
: StringMapEntryBase(StrLen), Val(V) {}
const ValueTy &getValue() const { return Val; }
ValueTy &getValue() { return Val; }
void setValue(const ValueTy &V) { Val = V; }
/// getKeyData - Return the start of the string data that is the key for this
/// value. The string data is always stored immediately after the
/// StringMapEntry object.
const char *getKeyData() const {return reinterpret_cast<const char*>(this+1);}
/// Create - Create a StringMapEntry for the specified key and default
/// construct the value.
template<typename AllocatorTy>
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
AllocatorTy &Allocator) {
unsigned KeyLength = KeyEnd-KeyStart;
// Okay, the item doesn't already exist, and 'Bucket' is the bucket to fill
// in. Allocate a new item with space for the string at the end and a null
// terminator.
unsigned AllocSize = sizeof(StringMapEntry)+KeyLength+1;
#ifdef __GNUC__
unsigned Alignment = __alignof__(StringMapEntry);
#else
// FIXME: ugly.
unsigned Alignment = 8;
#endif
StringMapEntry *NewItem =
static_cast<StringMapEntry*>(Allocator.Allocate(AllocSize, Alignment));
// Default construct the value.
new (NewItem) StringMapEntry(KeyLength);
// Copy the string information.
char *StrBuffer = const_cast<char*>(NewItem->getKeyData());
memcpy(StrBuffer, KeyStart, KeyLength);
StrBuffer[KeyLength] = 0; // Null terminate for convenience of clients.
return NewItem;
}
/// Create - Create a StringMapEntry with normal malloc/free.
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd) {
MallocAllocator A;
return Create(KeyStart, KeyEnd, A);
}
/// Destroy - Destroy this StringMapEntry, releasing memory back to the
/// specified allocator.
template<typename AllocatorTy>
void Destroy(AllocatorTy &Allocator) {
// Free memory referenced by the item.
this->~StringMapEntry();
Allocator.Deallocate(this);
}
/// Destroy this object, releasing memory back to the malloc allocator.
void Destroy() {
MallocAllocator A;
Destroy(A);
}
};
/// StringMap - This is an unconventional map that is specialized for handling
/// keys that are "strings", which are basically ranges of bytes. This does some
/// funky memory allocation and hashing things to make it extremely efficient,
/// storing the string data *after* the value in the map.
template<typename ValueTy, typename AllocatorTy = MallocAllocator>
class StringMap : public StringMapImpl {
AllocatorTy Allocator;
typedef StringMapEntry<ValueTy> MapEntryTy;
public:
StringMap() : StringMapImpl(sizeof(MapEntryTy)) {}
StringMap(unsigned InitialSize)
: StringMapImpl(InitialSize, sizeof(MapEntryTy)) {}
AllocatorTy &getAllocator() { return Allocator; }
const AllocatorTy &getAllocator() const { return Allocator; }
typedef StringMapConstIterator<ValueTy> const_iterator;
typedef StringMapIterator<ValueTy> iterator;
iterator begin() {
return iterator(TheTable, NumBuckets == 0);
}
iterator end() {
return iterator(TheTable+NumBuckets, true);
}
const_iterator begin() const {
return const_iterator(TheTable, NumBuckets == 0);
}
const_iterator end() const {
return const_iterator(TheTable+NumBuckets, true);
}
iterator find(const char *KeyStart, const char *KeyEnd) {
int Bucket = FindKey(KeyStart, KeyEnd);
if (Bucket == -1) return end();
return iterator(TheTable+Bucket);
}
const_iterator find(const char *KeyStart, const char *KeyEnd) const {
int Bucket = FindKey(KeyStart, KeyEnd);
if (Bucket == -1) return end();
return const_iterator(TheTable+Bucket);
}
/// insert - Insert the specified key/value pair into the map. If the key
/// already exists in the map, return false and ignore the request, otherwise
/// insert it and return true.
bool insert(MapEntryTy *KeyValue) {
unsigned BucketNo =
LookupBucketFor(KeyValue->getKeyData(),
KeyValue->getKeyData()+KeyValue->getKeyLength());
ItemBucket &Bucket = TheTable[BucketNo];
if (Bucket.Item && Bucket.Item != getTombstoneVal())
return false; // Already exists in map.
if (Bucket.Item == getTombstoneVal())
--NumTombstones;
Bucket.Item = KeyValue;
++NumItems;
if (ShouldRehash())
RehashTable();
return true;
}
/// GetOrCreateValue - Look up the specified key in the table. If a value
/// exists, return it. Otherwise, default construct a value, insert it, and
/// return.
StringMapEntry<ValueTy> &GetOrCreateValue(const char *KeyStart,
const char *KeyEnd) {
unsigned BucketNo = LookupBucketFor(KeyStart, KeyEnd);
ItemBucket &Bucket = TheTable[BucketNo];
if (Bucket.Item && Bucket.Item != getTombstoneVal())
return *static_cast<MapEntryTy*>(Bucket.Item);
MapEntryTy *NewItem = MapEntryTy::Create(KeyStart, KeyEnd, Allocator);
if (Bucket.Item == getTombstoneVal())
--NumTombstones;
++NumItems;
// Fill in the bucket for the hash table. The FullHashValue was already
// filled in by LookupBucketFor.
Bucket.Item = NewItem;
if (ShouldRehash())
RehashTable();
return *NewItem;
}
/// remove - Remove the specified key/value pair from the map, but do not
/// erase it. This aborts if the key is not in the map.
void remove(MapEntryTy *KeyValue) {
RemoveKey(KeyValue);
}
~StringMap() {
for (ItemBucket *I = TheTable, *E = TheTable+NumBuckets; I != E; ++I) {
if (I->Item && I->Item != getTombstoneVal())
static_cast<MapEntryTy*>(I->Item)->Destroy(Allocator);
}
free(TheTable);
}
};
template<typename ValueTy>
class StringMapConstIterator {
protected:
StringMapImpl::ItemBucket *Ptr;
public:
StringMapConstIterator(StringMapImpl::ItemBucket *Bucket,
bool NoAdvance = false)
: Ptr(Bucket) {
if (!NoAdvance) AdvancePastEmptyBuckets();
}
const StringMapEntry<ValueTy> &operator*() const {
return *static_cast<StringMapEntry<ValueTy>*>(Ptr->Item);
}
const StringMapEntry<ValueTy> *operator->() const {
return static_cast<StringMapEntry<ValueTy>*>(Ptr->Item);
}
bool operator==(const StringMapConstIterator &RHS) const {
return Ptr == RHS.Ptr;
}
bool operator!=(const StringMapConstIterator &RHS) const {
return Ptr != RHS.Ptr;
}
inline StringMapConstIterator& operator++() { // Preincrement
++Ptr;
AdvancePastEmptyBuckets();
return *this;
}
StringMapConstIterator operator++(int) { // Postincrement
StringMapConstIterator tmp = *this; ++*this; return tmp;
}
private:
void AdvancePastEmptyBuckets() {
while (Ptr->Item == 0 || Ptr->Item == StringMapImpl::getTombstoneVal())
++Ptr;
}
};
template<typename ValueTy>
class StringMapIterator : public StringMapConstIterator<ValueTy> {
public:
StringMapIterator(StringMapImpl::ItemBucket *Bucket,
bool NoAdvance = false)
: StringMapConstIterator<ValueTy>(Bucket, NoAdvance) {
}
StringMapEntry<ValueTy> &operator*() const {
return *static_cast<StringMapEntry<ValueTy>*>(this->Ptr->Item);
}
StringMapEntry<ValueTy> *operator->() const {
return static_cast<StringMapEntry<ValueTy>*>(this->Ptr->Item);
}
};
}
#endif