llvm-6502/include/llvm/ADT/StringMap.h
Jakob Stoklund Olesen 03ef449917 Reset StringMap's NumTombstones on clears and rehashes.
StringMap was not properly updating NumTombstones after a clear or rehash.

This was not fatal until now because the table was growing faster than
NumTombstones could, but with the previous change of preventing infinite
growth of the table the invariant (NumItems + NumTombstones <= NumBuckets)
stopped being observed, causing infinite loops in certain situations.

Patch by José Fonseca!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128567 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-30 18:32:51 +00:00

485 lines
15 KiB
C++

//===--- StringMap.h - String Hash table map interface ----------*- 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 StringMap class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STRINGMAP_H
#define LLVM_ADT_STRINGMAP_H
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Allocator.h"
#include <cstring>
#include <string>
namespace llvm {
template<typename ValueT>
class StringMapConstIterator;
template<typename ValueT>
class StringMapIterator;
template<typename ValueTy>
class StringMapEntry;
/// StringMapEntryInitializer - This datatype can be partially specialized for
/// various datatypes in a stringmap to allow them to be initialized when an
/// entry is default constructed for the map.
template<typename ValueTy>
class StringMapEntryInitializer {
public:
template <typename InitTy>
static void Initialize(StringMapEntry<ValueTy> &T, InitTy InitVal) {
T.second = InitVal;
}
};
/// StringMapEntryBase - Shared base class of StringMapEntry instances.
class StringMapEntryBase {
unsigned StrLen;
public:
explicit 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:
explicit StringMapImpl(unsigned itemSize) : ItemSize(itemSize) {
// Initialize the map with zero buckets to allocation.
TheTable = 0;
NumBuckets = 0;
NumItems = 0;
NumTombstones = 0;
}
StringMapImpl(unsigned InitSize, unsigned ItemSize);
void RehashTable();
/// 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(StringRef Key);
/// 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(StringRef Key) 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(StringRef Key);
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 {
public:
ValueTy second;
explicit StringMapEntry(unsigned strLen)
: StringMapEntryBase(strLen), second() {}
StringMapEntry(unsigned strLen, const ValueTy &V)
: StringMapEntryBase(strLen), second(V) {}
StringRef getKey() const {
return StringRef(getKeyData(), getKeyLength());
}
const ValueTy &getValue() const { return second; }
ValueTy &getValue() { return second; }
void setValue(const ValueTy &V) { second = 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);}
const char *first() const { return getKeyData(); }
/// Create - Create a StringMapEntry for the specified key and default
/// construct the value.
template<typename AllocatorTy, typename InitType>
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
AllocatorTy &Allocator,
InitType InitVal) {
unsigned KeyLength = static_cast<unsigned>(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 = static_cast<unsigned>(sizeof(StringMapEntry))+
KeyLength+1;
unsigned Alignment = alignOf<StringMapEntry>();
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.
// Initialize the value if the client wants to.
StringMapEntryInitializer<ValueTy>::Initialize(*NewItem, InitVal);
return NewItem;
}
template<typename AllocatorTy>
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
AllocatorTy &Allocator) {
return Create(KeyStart, KeyEnd, Allocator, 0);
}
/// Create - Create a StringMapEntry with normal malloc/free.
template<typename InitType>
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd,
InitType InitVal) {
MallocAllocator A;
return Create(KeyStart, KeyEnd, A, InitVal);
}
static StringMapEntry *Create(const char *KeyStart, const char *KeyEnd) {
return Create(KeyStart, KeyEnd, ValueTy());
}
/// GetStringMapEntryFromValue - Given a value that is known to be embedded
/// into a StringMapEntry, return the StringMapEntry itself.
static StringMapEntry &GetStringMapEntryFromValue(ValueTy &V) {
StringMapEntry *EPtr = 0;
char *Ptr = reinterpret_cast<char*>(&V) -
(reinterpret_cast<char*>(&EPtr->second) -
reinterpret_cast<char*>(EPtr));
return *reinterpret_cast<StringMapEntry*>(Ptr);
}
static const StringMapEntry &GetStringMapEntryFromValue(const ValueTy &V) {
return GetStringMapEntryFromValue(const_cast<ValueTy&>(V));
}
/// GetStringMapEntryFromKeyData - Given key data that is known to be embedded
/// into a StringMapEntry, return the StringMapEntry itself.
static StringMapEntry &GetStringMapEntryFromKeyData(const char *KeyData) {
char *Ptr = const_cast<char*>(KeyData) - sizeof(StringMapEntry<ValueTy>);
return *reinterpret_cast<StringMapEntry*>(Ptr);
}
/// 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(static_cast<unsigned>(sizeof(MapEntryTy))) {}
explicit StringMap(unsigned InitialSize)
: StringMapImpl(InitialSize, static_cast<unsigned>(sizeof(MapEntryTy))) {}
explicit StringMap(AllocatorTy A)
: StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
explicit StringMap(const StringMap &RHS)
: StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {
assert(RHS.empty() &&
"Copy ctor from non-empty stringmap not implemented yet!");
(void)RHS;
}
void operator=(const StringMap &RHS) {
assert(RHS.empty() &&
"assignment from non-empty stringmap not implemented yet!");
(void)RHS;
clear();
}
typedef typename ReferenceAdder<AllocatorTy>::result AllocatorRefTy;
typedef typename ReferenceAdder<const AllocatorTy>::result AllocatorCRefTy;
AllocatorRefTy getAllocator() { return Allocator; }
AllocatorCRefTy getAllocator() const { return Allocator; }
typedef const char* key_type;
typedef ValueTy mapped_type;
typedef StringMapEntry<ValueTy> value_type;
typedef size_t size_type;
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(StringRef Key) {
int Bucket = FindKey(Key);
if (Bucket == -1) return end();
return iterator(TheTable+Bucket);
}
const_iterator find(StringRef Key) const {
int Bucket = FindKey(Key);
if (Bucket == -1) return end();
return const_iterator(TheTable+Bucket);
}
/// lookup - Return the entry for the specified key, or a default
/// constructed value if no such entry exists.
ValueTy lookup(StringRef Key) const {
const_iterator it = find(Key);
if (it != end())
return it->second;
return ValueTy();
}
ValueTy& operator[](StringRef Key) {
return GetOrCreateValue(Key).getValue();
}
size_type count(StringRef Key) const {
return find(Key) == end() ? 0 : 1;
}
/// 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->getKey());
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;
assert(NumItems + NumTombstones <= NumBuckets);
RehashTable();
return true;
}
// clear - Empties out the StringMap
void clear() {
if (empty()) return;
// Zap all values, resetting the keys back to non-present (not tombstone),
// which is safe because we're removing all elements.
for (ItemBucket *I = TheTable, *E = TheTable+NumBuckets; I != E; ++I) {
if (I->Item && I->Item != getTombstoneVal()) {
static_cast<MapEntryTy*>(I->Item)->Destroy(Allocator);
I->Item = 0;
}
}
NumItems = 0;
NumTombstones = 0;
}
/// GetOrCreateValue - Look up the specified key in the table. If a value
/// exists, return it. Otherwise, default construct a value, insert it, and
/// return.
template <typename InitTy>
StringMapEntry<ValueTy> &GetOrCreateValue(StringRef Key,
InitTy Val) {
unsigned BucketNo = LookupBucketFor(Key);
ItemBucket &Bucket = TheTable[BucketNo];
if (Bucket.Item && Bucket.Item != getTombstoneVal())
return *static_cast<MapEntryTy*>(Bucket.Item);
MapEntryTy *NewItem =
MapEntryTy::Create(Key.begin(), Key.end(), Allocator, Val);
if (Bucket.Item == getTombstoneVal())
--NumTombstones;
++NumItems;
assert(NumItems + NumTombstones <= NumBuckets);
// Fill in the bucket for the hash table. The FullHashValue was already
// filled in by LookupBucketFor.
Bucket.Item = NewItem;
RehashTable();
return *NewItem;
}
StringMapEntry<ValueTy> &GetOrCreateValue(StringRef Key) {
return GetOrCreateValue(Key, ValueTy());
}
template <typename InitTy>
StringMapEntry<ValueTy> &GetOrCreateValue(const char *KeyStart,
const char *KeyEnd,
InitTy Val) {
return GetOrCreateValue(StringRef(KeyStart, KeyEnd - KeyStart), Val);
}
StringMapEntry<ValueTy> &GetOrCreateValue(const char *KeyStart,
const char *KeyEnd) {
return GetOrCreateValue(StringRef(KeyStart, KeyEnd - KeyStart));
}
/// 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);
}
void erase(iterator I) {
MapEntryTy &V = *I;
remove(&V);
V.Destroy(Allocator);
}
bool erase(StringRef Key) {
iterator I = find(Key);
if (I == end()) return false;
erase(I);
return true;
}
~StringMap() {
clear();
free(TheTable);
}
};
template<typename ValueTy>
class StringMapConstIterator {
protected:
StringMapImpl::ItemBucket *Ptr;
public:
typedef StringMapEntry<ValueTy> value_type;
explicit StringMapConstIterator(StringMapImpl::ItemBucket *Bucket,
bool NoAdvance = false)
: Ptr(Bucket) {
if (!NoAdvance) AdvancePastEmptyBuckets();
}
const value_type &operator*() const {
return *static_cast<StringMapEntry<ValueTy>*>(Ptr->Item);
}
const value_type *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:
explicit 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