vhash_table.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */

#ifndef BAGEL_BOFLIB_VHASH_TABLE_H
#define BAGEL_BOFLIB_VHASH_TABLE_H

#include "bagel/boflib/list.h"

namespace Bagel {

template<class T, int S>
class CBofVHashTable {
public:
    CBofVHashTable(unsigned(*hashFun)(const T &));
    virtual ~CBofVHashTable();
    bool contains(const T &val);
    void insert(const T &val);

private:
    // Default constructor is not allowed.  A declaration is provided,
    // but an implementation is not.  A link error will result if an
    // attempt is made to use this constructor.  The location which
    // is attempting to reference the default constructor should be changed
    // so that it calls the class constructor which takes a pointer to a
    // function and a table size.
    CBofVHashTable();

    // Member which holds the hash table itself.
    CBofList<T *> _xHashTable[S];

    // Member which holds a pointer to the table's hashing
    // function.
    unsigned(*_pHashFunction)(const T &);

    // Member which holds the count of buckets in the hash table.
    int _nHashTableSize;

    // Boolean which affords a light-weight test of whether the hash
    // table is empty.
    //
    bool _bisEmpty;
};

// CBofVHashTable::CBofVHashTable - class constructor.
//
template<class T, int S>
CBofVHashTable<T, S>::CBofVHashTable(unsigned(*hashFun)(const T &)) : _nHashTableSize(S),
    _pHashFunction(hashFun), _bisEmpty(true) {
}

// CBofVHashTable::~CBofVHashTable - class destructor.
template<class T, int S>
CBofVHashTable<T, S>::~CBofVHashTable() {
    for (int x = 0; x < _nHashTableSize; x++) {
        CBofList<T *> *pHashBucket = &_xHashTable[x];
        int nListEntries = pHashBucket->getActualCount();

        for (int i = 0; i < nListEntries; i++) {
            T *pListItem = pHashBucket->getNodeItem(i);
            delete pListItem;
            pHashBucket->setNodeItem(i, (T *)nullptr);
        }
    }
}

// CBofVHashTable<T, S>::insert - add a value to the hash table.
template<class T, int S>
void CBofVHashTable<T, S>::insert(const T &val) {
    T *pNodeValue = new T(val);
    CBofListNode<T *> *pNode = new CBofListNode<T *>(pNodeValue);
    assert(pNode != nullptr);

    int nHashBucketIndex = ((*_pHashFunction)(val)) % _nHashTableSize;
    assert(nHashBucketIndex < _nHashTableSize);

    CBofList<T *> *pHashBucket = &_xHashTable[nHashBucketIndex];
    assert(pHashBucket != nullptr);
    pHashBucket->addToTail(pNode);
}

// CBofVHashTable<T, S>contains - predicate to test whether a value is stored in the hash table.
template<class T, int S>
bool CBofVHashTable<T, S>::contains(const T &val) {
    bool returnValue = false;
    int nHashBucketIndex = ((*_pHashFunction)(val)) % _nHashTableSize;
    assert(nHashBucketIndex < _nHashTableSize);

    CBofVHashTable<T, S> *const fakeThis = (CBofVHashTable<T, S> *const)this;
    CBofList<T *> *pHashBucket = &(fakeThis->_xHashTable[nHashBucketIndex]);
    assert(pHashBucket != nullptr);
    int nItemsInBucket = pHashBucket->getCount();
    for (int i = 0; i < nItemsInBucket; i++) {
        T *TableEntry = pHashBucket->getNodeItem(i);
        if (TableEntry->compareNoCase((const char *)val) == 0) {
            returnValue = true;
            break;
        }
    }
    return returnValue;
}

} // namespace Bagel

#endif