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Hash.h
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Hash.h
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//
// Thread-safe hash template class
//
// Copyright (c) 2004, Algin Technology LLC
// Written by Alan Klietz
// Distributed under GNU General Public License version 2.
//
// $Id: Hash.h,v 1.4 2008/08/28 22:44:31 cvsalan Exp $
//
//
// WARNING: HACKED TO COMPILE WITH VS6 TEMPLATE BRAIN-DAMAGE AND WITH
// VS2005/VS2008. NOT GURANTEED TO COMPILE WITH LITERAL FUTURE IMPLEMENTATIONS
// OF THE ANSI C++ STANDARD.
//
////////////////////////////////////////////////////////////////////////
//
// Example:
//
// CHash<CHData<int>, CHData<CString> > MyHash;
//
// MyHash.SetAt(3, _T("test"));
//
// int iKey; CString strVal;
// if (MyHash.Lookup(iKey, strVal)) { found(iKey, strVal); }
//
// MyHash.RemoveKey(3);
// i = MyHash.GetCount();
// if (MyHash.IsEmpty()) { .. }
//
// Unsorted enumeration:
//
// {
// CGrabLock w(Hash.m_WriteLock);
// POSITION pos = Hash.GetStartPosition();
// while (pos != NULL) {
// Hash.GetNextAssoc(pos, key, val);
// use(key, val);
// }
// }
//
////////////////////////////////////////////////////////////////////////
#pragma warning(disable: 4710) // ignore failure to inline under /EHa
// CHData<T>
template<class T>
class CHData {
public:
typedef T DATATYPE;
// Must never hash to 0 or -1
static LONG HashVal(const T& d);
static BOOL Equal(const T& d1, const T& d2);
#ifdef _DEBUG
static void Trace(const T& d);
#endif
};
//
// CHData<int> explicit user specialization
//
template<> inline LONG CHData<int>::HashVal(const int& d)
{ return (d == 0 || d == -1) ? -2L : d; }
template<> inline BOOL CHData<int>::Equal(const int& d1, const int& d2)
{ return d1 == d2; }
#ifdef _DEBUG
template<> inline void CHData<int>::Trace(const int& d)
{ TRACE1(_T("%d"), d); }
#endif
//
// CHData<DWORD> explicit user specialization
//
template<> inline LONG CHData<DWORD>::HashVal(const DWORD& d)
{ return (d == 0 || (long)d == -1L) ? (DWORD)-2L : d; }
template<> inline BOOL CHData<DWORD>::Equal(const DWORD& d1, const DWORD& d2)
{ return d1 == d2; }
#ifdef _DEBUG
template<> inline void CHData<DWORD>::Trace(const DWORD& d)
{ TRACE1(_T("%lu"), d); }
#endif
//
// CHData<UINT> explicit user specialization
//
template<> inline LONG CHData<UINT>::HashVal(const UINT& d)
{ return (d == 0 || (long)d == -1) ? (UINT)-2L : d; }
template<> inline BOOL CHData<UINT>::Equal(const UINT& d1, const UINT& d2)
{ return d1 == d2; }
#ifdef _DEBUG
template<> inline void CHData<UINT>::Trace(const UINT& d)
{ TRACE1(_T("%u"), d); }
#endif
//
// CHData<PVOID> explicit user specialization
//
template<> inline LONG CHData<PVOID>::HashVal(const PVOID& d)
{ return (!d || ((LONG)d) == -1) ? -2L : (LONG)d; }
template<> inline BOOL CHData<PVOID>::Equal(const PVOID& d1, const PVOID& d2)
{ return d1 == d2; }
#ifdef _DEBUG
template<> inline void CHData<PVOID>::Trace(const PVOID& d)
{ TRACE1(_T("%#x"), d); }
#endif
//
// CHData<CString> explicit user specialization
//
template<> inline LONG CHData<CString>::HashVal(const CString& d)
{
// The hash algorithm requires unsigned char.
int iLen = d.GetLength();
#ifndef _UNICODE
# define _STYPE const unsigned char*
#else
# define _STYPE LPCWSTR // const unsigned short*
iLen <<= 1;
#endif
register _STYPE p = (_STYPE)(LPCTSTR)d;
#undef _STYPE
register LONG x;
x = *p << 7;
for (register int i=iLen; --i >= 0;) {
x = (1000003*x) ^ *p++;
}
x ^= iLen;
if (x == 0 || x == -1)
x = -2;
return x;
}
template<> inline BOOL CHData<CString>::Equal(const CString& d1, const CString& d2)
{ return d1 == d2; }
#ifdef _DEBUG
template<> inline void CHData<CString>::Trace(const CString& d)
{ TRACE1(_T("%s"), (LPCTSTR)d); }
#endif
////////////////////////////////////////////////////////////////////////
// CHashEntry< CHData<KeyType>, CHData<ValueType> >
////////////////////////////////////////////////////////////////////////
template<class HDATAKEY, class HDATAVALUE>
class CHashEntry {
public:
//
// Microsoft Visual C++ compiler BUG:
//
// The compiler generates free(p-1) if the class has non-empty
// destructors. Otherwise it generates free(p).
// The address at (p-1) holds the count of the number of elements
// in the array.
//
// BUG: The compiler wrongly generates free(p-1) instead of free(p)
// for CHashEntry<CHData<int>, CHData<int> >.
// Therefore we use this dummy destructor to force p=malloc(len+1)+1
// instead of p=malloc(len), so that free(p-1) does not GPF.
//
~CHashEntry() { m_lHashVal = 0; };
public:
LONG m_lHashVal; // 0 means empty, -1 means deleted
typedef typename HDATAKEY::DATATYPE KEYTYPE;
typedef typename HDATAVALUE::DATATYPE DATATYPE;
KEYTYPE m_Key;
DATATYPE m_Value;
};
////////////////////////////////////////////////////////////////////////////
EXPORT ULONG CalcHashIncr(LONG lHashVal, int cSize);
EXPORT LONG NewPrimeSize(int cSize);
////////////////////////////////////////////////////////////////////////
// CHash< CHData<KeyType>, CHData<ValueType> >
////////////////////////////////////////////////////////////////////////
template<class HDATAKEY, class HDATAVALUE>
class CHash
#ifdef __AFX_H__
: public CObject
#endif
{
#ifdef __AFX_H__
#define CHASH CHash<HDATAKEY, HDATAVALUE>
DECLARE_SERIALx(CHASH)
#undef CHASH
#endif __AFX_H__
public:
typedef typename HDATAKEY::DATATYPE KEYTYPE;
typedef typename HDATAVALUE::DATATYPE DATATYPE;
CHash(int cSize=6) {
m_cSize = NewPrimeSize(cSize);
//TRACE(_T("Creating hash table, size %d.\n"), m_cSize);
m_pTable = new CHashEntry<HDATAKEY, HDATAVALUE>[m_cSize];
for (register int i=0; i < m_cSize; ++i) {
m_pTable[i].m_lHashVal = 0;
}
m_cFill = 0;
m_cUsed = 0;
};
~CHash() {
delete [] m_pTable;
m_pTable = NULL;
};
int GetCount() const { return m_cUsed; };
BOOL IsEmpty() const { return m_cUsed == 0; };
UINT GetHashTableSize() const { return m_cSize; };
BOOL Lookup(const KEYTYPE& rKey, DATATYPE& rValue) {
CHashEntry<HDATAKEY, HDATAVALUE>* pHashEntry;
#ifdef LOCKING
CGrabLock w(m_WriteLock);
#endif
pHashEntry = LookMapping(rKey, HDATAKEY::HashVal(rKey));
if (pHashEntry->m_lHashVal != 0 && pHashEntry->m_lHashVal != -1) {
rValue = pHashEntry->m_Value;
return TRUE;
} else {
return FALSE;
}
};
//
// Dangerous because the lock is lost prematurely: Hash["key"]=val.
//
DATATYPE& operator[](const KEYTYPE& rKey) {
#ifdef LOCKING
CGrabLock w(m_WriteLock);
#endif
//
// A readlock is useless because the assignment happens
// after the fact.
//
LONG lHashVal = HDATAKEY::HashVal(rKey);
CHashEntry<HDATAKEY, HDATAVALUE>* pHashEntry;
pHashEntry = LookMapping(rKey, lHashVal);
if (pHashEntry->m_lHashVal != 0 && pHashEntry->m_lHashVal != -1) {
// found
return pHashEntry->m_Value;
}
if (((m_cFill<<1)+m_cFill) >= (m_cSize<<1)) { // m_cFill*3 >= m_cSize*2
MappingResize();
pHashEntry = LookMapping(rKey, lHashVal);
ASSERT(pHashEntry->m_lHashVal == 0);
}
if (pHashEntry->m_lHashVal == 0) {
m_cFill++;
}
pHashEntry->m_lHashVal = lHashVal;
pHashEntry->m_Key = rKey;
m_cUsed++;
return pHashEntry->m_Value;
};
void SetAt(const KEYTYPE& rKey, const DATATYPE& rValue) {
#ifdef LOCKING
CGrabLock w(m_WriteLock);
CGrabLock r(m_ReadLock);
#endif
if (((m_cFill<<1)+m_cFill) >= (m_cSize<<1)) { // m_cFill*3 >= m_cSize*2
MappingResize();
}
InsertMapping(rKey, HDATAKEY::HashVal(rKey), rValue);
};
BOOL RemoveKey(const KEYTYPE& rKey) {
CHashEntry<HDATAKEY, HDATAVALUE>* pHashEntry;
#ifdef LOCKING
CGrabLock w(m_WriteLock);
CGrabLock r(m_ReadLock);
#endif
pHashEntry = LookMapping(rKey, HDATAKEY::HashVal(rKey));
if (pHashEntry->m_lHashVal == 0 || pHashEntry->m_lHashVal == -1) {
return FALSE;
}
pHashEntry->m_lHashVal = -1; // mark deleted
m_cUsed--;
return TRUE;
};
void RemoveAll() {
#ifdef LOCKING
CGrabLock w(m_WriteLock);
CGrabLock r(m_ReadLock);
#endif
delete [] m_pTable;
m_cFill = 0;
m_cUsed = 0;
m_cSize = NewPrimeSize(6);
m_pTable = new CHashEntry<HDATAKEY, HDATAVALUE>[m_cSize];
for (register int i=0; i < m_cSize; ++i) {
m_pTable[i].m_lHashVal = 0;
}
return;
};
POSITION GetStartPosition() const {
return (m_cUsed == 0 ? NULL : BEFORE_START_POSITION);
};
void GetNextAssoc(POSITION& rNextPosition,
KEYTYPE& rKey, DATATYPE& rValue) const {
register int i = 0;
if (rNextPosition == BEFORE_START_POSITION) {
i = 0;
} else if (rNextPosition == NULL ) {
#ifdef UNDEFINED
ThrowTSException(AEMSG, AE_FATAL_ERROR, AE_CATEGORY_FATAL,
_T("Tried to go beyond the end of the hash table."));
#else
more_fputs("Tried to go beyond the end of the hash table.\n", stdmore_err);
exit(1);
#endif
} else {
i = (int)rNextPosition;
}
ASSERT(i >= 0);
while (i < m_cSize && (m_pTable[i].m_lHashVal == 0 || m_pTable[i].m_lHashVal == -1)) {
++i;
}
ASSERT(i < m_cSize);
rKey = m_pTable[i].m_Key;
rValue = m_pTable[i].m_Value;
++i;
while (i < m_cSize && (m_pTable[i].m_lHashVal == 0 || m_pTable[i].m_lHashVal == -1)) {
++i;
}
if (i >= m_cSize) {
rNextPosition = NULL;
} else {
rNextPosition = (POSITION)i;
}
return;
};
#ifdef __AFX_H__
void Serialize(CArchive& ar) {
DWORD dwCount;
KEYTYPE key;
DATATYPE val;
CObject::Serialize(ar);
if (ar.IsStoring()) {
#ifdef LOCKING
CGrabLock w(m_WriteLock);
#endif
ar.WriteCount((DWORD)m_cUsed);
#ifdef _DEBUG
dwCount = 0;
#endif
POSITION pos = GetStartPosition();
while (pos != NULL) {
GetNextAssoc(pos, key, val);
ar << key;
ar << val;
#ifdef _DEBUG
++dwCount;
#endif
}
ASSERT(dwCount == (DWORD)m_cUsed);
} else {
#ifdef LOCKING
CGrabLock w(m_WriteLock);
CGrabLock r(m_ReadLock);
#endif
dwCount = ar.ReadCount();
while (dwCount--) {
#pragma warning(push)
#pragma warning(disable: 4701) // ignore warning about use before set
ar >> key;
ar >> val;
#pragma warning(pop)
if (((m_cFill<<1)+m_cFill) >= (m_cSize<<1)) { // m_cFill*3 >= m_cSize*2
MappingResize();
}
InsertMapping(key, HDATAKEY::HashVal(key), val);
}
}
}
#endif __AFX_H__
#if defined(__AFX_H__) && defined(_DEBUG)
//
// To display, call Hash.Dump(afxDump) from the debugger.
//
void Dump(CDumpContext& dc) {
CObject::Dump(dc);
dc << "with " << m_cUsed << " elements";
// if (dc.GetDepth() > 0) // dc.SetDepth(1);
{
KEYTYPE key;
DATATYPE val;
POSITION pos = GetStartPosition();
while (pos != NULL) {
GetNextAssoc(pos, key, val);
dc << "\n map[";
//
// We cannot send hash elements to the dc because
// hash elements cannot be not CObjects.
// Hash elements cannot be CObjects because CObjects
// cannot be copied nor assigned to.
//
HDATAKEY::Trace(key);
dc << "] = ";
HDATAVALUE::Trace(val);
}
}
dc << "\n";
};
#endif
//
// Public to allow explicit locking for GetNextAssoc() loops.
//
#ifdef LOCKING
CLock m_ReadLock;
CLock m_WriteLock;
#endif
private:
int m_cFill; // number of non-empty keys
int m_cUsed; // number of non-empty, non-deleted keys
int m_cSize;
CHashEntry<HDATAKEY, HDATAVALUE>* m_pTable;
CHashEntry<HDATAKEY, HDATAVALUE>* LookMapping(const KEYTYPE& rKey, long lHashVal) {
//
// Returns a pointer to a free slot if no match
//
register ULONG uPos, uIncr;
register CHashEntry<HDATAKEY, HDATAVALUE> *pHashEntry, *pFreeSlot=NULL;
uPos = (ULONG)lHashVal % (ULONG)m_cSize;
uIncr = CalcHashIncr(lHashVal, m_cSize);
for (;;) {
ASSERT(((int)uPos) >= 0 && ((int)uPos) < m_cSize);
pHashEntry = &m_pTable[uPos];
if (pHashEntry->m_lHashVal == 0) { // if end of chain
return pFreeSlot ? pFreeSlot : pHashEntry;
}
if (pHashEntry->m_lHashVal == -1) { // if deleted
if (pFreeSlot == NULL) {
pFreeSlot = pHashEntry;
}
} else if (pHashEntry->m_lHashVal == lHashVal &&
HDATAKEY::Equal(pHashEntry->m_Key, rKey)) {
return pHashEntry;
}
uPos = (uPos + uIncr) % (ULONG)m_cSize;
}
};
void InsertMapping(const KEYTYPE& rKey, long lHashVal,
const DATATYPE& rValue) {
CHashEntry<HDATAKEY, HDATAVALUE>* pHashEntry;
pHashEntry = LookMapping(rKey, lHashVal);
if (pHashEntry->m_lHashVal != 0 && pHashEntry->m_lHashVal != -1) {
// found
pHashEntry->m_Value = rValue;
} else {
if (pHashEntry->m_lHashVal == 0) {
m_cFill++;
}
pHashEntry->m_lHashVal = lHashVal;
pHashEntry->m_Key = rKey;
pHashEntry->m_Value = rValue;
m_cUsed++;
}
};
void MappingResize() {
register int cOldSize = m_cSize;
register int cNewSize = NewPrimeSize(m_cSize<<1); // cSize*2
register CHashEntry<HDATAKEY, HDATAVALUE> *pOldTable, *pNewTable;
register int i;
TRACE(_T("Growing hash table to %d entries.\n"), cNewSize);
pOldTable = m_pTable;
pNewTable = new CHashEntry<HDATAKEY, HDATAVALUE>[cNewSize];
m_pTable = pNewTable;
m_cSize = cNewSize;
m_cFill = 0;
m_cUsed = 0;
for (i=0; i < m_cSize; ++i) {
m_pTable[i].m_lHashVal = 0;
}
CHashEntry<HDATAKEY, HDATAVALUE>* pHashEntry = &pOldTable[0];
for (i=0; i < cOldSize; ++i, ++pHashEntry) {
if (pHashEntry->m_lHashVal != 0 && pHashEntry->m_lHashVal != -1) {
InsertMapping(pHashEntry->m_Key, pHashEntry->m_lHashVal,
pHashEntry->m_Value);
}
}
delete [] pOldTable;
};
};
////////////////////////////////////////////////////////////////////////////
/*
vim:tabstop=4:shiftwidth=4:noexpandtab
*/