refhashtableof.c

开源xml解析库,非常有名

// whatever key2 has originally will be purged (if adopted)
template <class TVal> void RefHashTableOf<TVal>::transferElement(const void* const key1, void* key2)
{
    put(key2, orphanKey(key1));
}


// ---------------------------------------------------------------------------
//  RefHashTableOf: Getters
// ---------------------------------------------------------------------------
template <class TVal> TVal* RefHashTableOf<TVal>::get(const void* const key)
{
    unsigned int hashVal;
    RefHashTableBucketElem<TVal>* findIt = findBucketElem(key, hashVal);
    if (!findIt)
        return 0;
    return findIt->fData;
}

template <class TVal> const TVal* RefHashTableOf<TVal>::
get(const void* const key) const
{
    unsigned int hashVal;
    const RefHashTableBucketElem<TVal>* findIt = findBucketElem(key, hashVal);
    if (!findIt)
        return 0;
    return findIt->fData;
}

template <class TVal>
MemoryManager* RefHashTableOf<TVal>::getMemoryManager() const
{
    return fMemoryManager;
}

template <class TVal>
unsigned int RefHashTableOf<TVal>::getHashModulus() const
{
    return fHashModulus;
}

template <class TVal>
unsigned int RefHashTableOf<TVal>::getCount() const
{
    return fCount;
}

// ---------------------------------------------------------------------------
//  RefHashTableOf: Getters
// ---------------------------------------------------------------------------
template <class TVal>
void RefHashTableOf<TVal>::setAdoptElements(const bool aValue)
{
    fAdoptedElems = aValue;
}

// ---------------------------------------------------------------------------
//  RefHashTableOf: Putters
// ---------------------------------------------------------------------------
template <class TVal> void RefHashTableOf<TVal>::put(void* key, TVal* const valueToAdopt)
{
    // Apply 0.75 load factor to find threshold.
    unsigned int threshold = fHashModulus * 3 / 4;
    
    // If we've grown too big, expand the table and rehash.
    if (fCount >= threshold)
        rehash();

    // First see if the key exists already
    unsigned int hashVal;
    RefHashTableBucketElem<TVal>* newBucket = findBucketElem(key, hashVal);

    //
    //  If so,then update its value. If not, then we need to add it to
    //  the right bucket
    //
    if (newBucket)
    {
        if (fAdoptedElems)
            delete newBucket->fData;
        newBucket->fData = valueToAdopt;
		newBucket->fKey = key;
    }
    else
    {
        //newBucket = new (fMemoryManager) RefHashTableBucketElem<TVal>(key, valueToAdopt, fBucketList[hashVal]);
		newBucket =
             new (fMemoryManager->allocate(sizeof(RefHashTableBucketElem<TVal>)))
             RefHashTableBucketElem<TVal>(key, valueToAdopt, fBucketList[hashVal]);        
        fBucketList[hashVal] = newBucket;
        fCount++;
    }
}



// ---------------------------------------------------------------------------
//  RefHashTableOf: Private methods
// ---------------------------------------------------------------------------
template <class TVal> void RefHashTableOf<TVal>::rehash()
{
    const unsigned int newMod = fHashModulus * 2;

    RefHashTableBucketElem<TVal>** newBucketList =
        (RefHashTableBucketElem<TVal>**) fMemoryManager->allocate
    (
        newMod * sizeof(RefHashTableBucketElem<TVal>*)
    );//new RefHashTableBucketElem<TVal>*[newMod];

    // Make sure the new bucket list is destroyed if an
    // exception is thrown.
    ArrayJanitor<RefHashTableBucketElem<TVal>*>  guard(newBucketList, fMemoryManager);

    memset(newBucketList, 0, newMod * sizeof(newBucketList[0]));
    
    
    // Rehash all existing entries.
    for (unsigned int index = 0; index < fHashModulus; index++)
    {
        // Get the bucket list head for this entry
        RefHashTableBucketElem<TVal>* curElem = fBucketList[index];

        while (curElem)
        {
            // Save the next element before we detach this one
            RefHashTableBucketElem<TVal>* const nextElem = curElem->fNext;

            const unsigned int hashVal = fHash->getHashVal(curElem->fKey, newMod, fMemoryManager);
            assert(hashVal < newMod);

            RefHashTableBucketElem<TVal>* const newHeadElem = newBucketList[hashVal];

            // Insert at the start of this bucket's list.
            curElem->fNext = newHeadElem;
            newBucketList[hashVal] = curElem;

            curElem = nextElem;
        }
    }

    RefHashTableBucketElem<TVal>** const oldBucketList = fBucketList;

    // Everything is OK at this point, so update the
    // member variables.
    fBucketList = guard.release();
    fHashModulus = newMod;

    // Delete the old bucket list.
    fMemoryManager->deallocate(oldBucketList);//delete[] oldBucketList;
    
}

template <class TVal> RefHashTableBucketElem<TVal>* RefHashTableOf<TVal>::
findBucketElem(const void* const key, unsigned int& hashVal)
{
    // Hash the key
    hashVal = fHash->getHashVal(key, fHashModulus, fMemoryManager);
    assert(hashVal < fHashModulus);

    // Search that bucket for the key
    RefHashTableBucketElem<TVal>* curElem = fBucketList[hashVal];
    while (curElem)
    {
		if (fHash->equals(key, curElem->fKey))
            return curElem;

        curElem = curElem->fNext;
    }
    return 0;
}

template <class TVal> const RefHashTableBucketElem<TVal>* RefHashTableOf<TVal>::
findBucketElem(const void* const key, unsigned int& hashVal) const
{
    // Hash the key
    hashVal = fHash->getHashVal(key, fHashModulus, fMemoryManager);
    assert(hashVal < fHashModulus);

    // Search that bucket for the key
    const RefHashTableBucketElem<TVal>* curElem = fBucketList[hashVal];
    while (curElem)
    {
        if (fHash->equals(key, curElem->fKey))
            return curElem;

        curElem = curElem->fNext;
    }
    return 0;
}


// ---------------------------------------------------------------------------
//  RefHashTableOfEnumerator: Constructors and Destructor
// ---------------------------------------------------------------------------
template <class TVal> RefHashTableOfEnumerator<TVal>::
RefHashTableOfEnumerator(RefHashTableOf<TVal>* const toEnum
                         , const bool adopt
                         , MemoryManager* const manager)
	: fAdopted(adopt), fCurElem(0), fCurHash((unsigned int)-1), fToEnum(toEnum)
    , fMemoryManager(manager)
{
    if (!toEnum)
        ThrowXMLwithMemMgr(NullPointerException, XMLExcepts::CPtr_PointerIsZero, fMemoryManager);

    //
    //  Find the next available bucket element in the hash table. If it
    //  comes back zero, that just means the table is empty.
    //
    //  Note that the -1 in the current hash tells it to start from the
    //  beginning.
    //
    findNext();
}

template <class TVal> RefHashTableOfEnumerator<TVal>::~RefHashTableOfEnumerator()
{
    if (fAdopted)
        delete fToEnum;
}


template <class TVal> RefHashTableOfEnumerator<TVal>::
RefHashTableOfEnumerator(const RefHashTableOfEnumerator<TVal>& toCopy) :
    XMLEnumerator<TVal>(toCopy)
    , XMemory(toCopy)
    , fAdopted(toCopy.fAdopted)
    , fCurElem(toCopy.fCurElem)
    , fCurHash(toCopy.fCurHash)
    , fToEnum(toCopy.fToEnum)
    , fMemoryManager(toCopy.fMemoryManager)
{
}
// ---------------------------------------------------------------------------
//  RefHashTableOfEnumerator: Enum interface
// ---------------------------------------------------------------------------
template <class TVal> bool RefHashTableOfEnumerator<TVal>::hasMoreElements() const
{
    //
    //  If our current has is at the max and there are no more elements
    //  in the current bucket, then no more elements.
    //
    if (!fCurElem && (fCurHash == fToEnum->fHashModulus))
        return false;
    return true;
}

template <class TVal> TVal& RefHashTableOfEnumerator<TVal>::nextElement()
{
    // Make sure we have an element to return
    if (!hasMoreElements())
        ThrowXMLwithMemMgr(NoSuchElementException, XMLExcepts::Enum_NoMoreElements, fMemoryManager);

    //
    //  Save the current element, then move up to the next one for the
    //  next time around.
    //
    RefHashTableBucketElem<TVal>* saveElem = fCurElem;
    findNext();

    return *saveElem->fData;
}

template <class TVal> void* RefHashTableOfEnumerator<TVal>::nextElementKey()
{
    // Make sure we have an element to return
    if (!hasMoreElements())
        ThrowXMLwithMemMgr(NoSuchElementException, XMLExcepts::Enum_NoMoreElements, fMemoryManager);

    //
    //  Save the current element, then move up to the next one for the
    //  next time around.
    //
    RefHashTableBucketElem<TVal>* saveElem = fCurElem;
    findNext();

    return saveElem->fKey;
}

template <class TVal> void RefHashTableOfEnumerator<TVal>::Reset()
{
    fCurHash = (unsigned int)-1;
    fCurElem = 0;
    findNext();
}



// ---------------------------------------------------------------------------
//  RefHashTableOfEnumerator: Private helper methods
// ---------------------------------------------------------------------------
template <class TVal> void RefHashTableOfEnumerator<TVal>::findNext()
{
    //
    //  If there is a current element, move to its next element. If this
    //  hits the end of the bucket, the next block will handle the rest.
    //
    if (fCurElem)
        fCurElem = fCurElem->fNext;

    //
    //  If the current element is null, then we have to move up to the
    //  next hash value. If that is the hash modulus, then we cannot
    //  go further.
    //
    if (!fCurElem)
    {
        fCurHash++;
        if (fCurHash == fToEnum->fHashModulus)
            return;

        // Else find the next non-empty bucket
        while (fToEnum->fBucketList[fCurHash]==0)
        {
            // Bump to the next hash value. If we max out return
            fCurHash++;
            if (fCurHash == fToEnum->fHashModulus)
                return;
        }
        fCurElem = fToEnum->fBucketList[fCurHash];
    }
}

XERCES_CPP_NAMESPACE_END