sdrangel/qrtplib/rtphashtable.h

/*

 This file is a part of JRTPLIB
 Copyright (c) 1999-2017 Jori Liesenborgs

 Contact: jori.liesenborgs@gmail.com

 This library was developed at the Expertise Centre for Digital Media
 (http://www.edm.uhasselt.be), a research center of the Hasselt University
 (http://www.uhasselt.be). The library is based upon work done for
 my thesis at the School for Knowledge Technology (Belgium/The Netherlands).

 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),
 to deal in the Software without restriction, including without limitation
 the rights to use, copy, modify, merge, publish, distribute, sublicense,
 and/or sell copies of the Software, and to permit persons to whom the
 Software is furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included
 in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 IN THE SOFTWARE.

 */

#ifndef RTPHASHTABLE_H

#define RTPHASHTABLE_H

/**
 * \file rtphashtable.h
 */

#include "rtperrors.h"

namespace qrtplib
{

//template<class Element,int GetIndex(const Element &k),int hashsize>
template<class Element, class GetIndex, int hashsize>
class RTPHashTable
{
public:
    RTPHashTable();
    ~RTPHashTable()
    {
        Clear();
    }

    void GotoFirstElement()
    {
        curhashelem = firsthashelem;
    }
    void GotoLastElement()
    {
        curhashelem = lasthashelem;
    }
    bool HasCurrentElement()
    {
        return (curhashelem == 0) ? false : true;
    }
    int DeleteCurrentElement();
    Element &GetCurrentElement()
    {
        return curhashelem->GetElement();
    }
    int GotoElement(const Element &e);
    bool HasElement(const Element &e);
    void GotoNextElement();
    void GotoPreviousElement();
    void Clear();

    int AddElement(const Element &elem);
    int DeleteElement(const Element &elem);

private:
    class HashElement
    {
    public:
        HashElement(const Element &e, int index) :
                element(e)
        {
            hashprev = 0;
            hashnext = 0;
            listnext = 0;
            listprev = 0;
            hashindex = index;
        }
        int GetHashIndex()
        {
            return hashindex;
        }
        Element &GetElement()
        {
            return element;
        }

    private:
        int hashindex;
        Element element;
    public:
        HashElement *hashprev, *hashnext;
        HashElement *listprev, *listnext;
    };

    HashElement *table[hashsize];
    HashElement *firsthashelem, *lasthashelem;
    HashElement *curhashelem;
#ifdef RTP_SUPPORT_MEMORYMANAGEMENT
    int memorytype;
#endif // RTP_SUPPORT_MEMORYMANAGEMENT
};

template<class Element, class GetIndex, int hashsize>
inline RTPHashTable<Element, GetIndex, hashsize>::RTPHashTable()
{
    for (int i = 0; i < hashsize; i++)
        table[i] = 0;
    firsthashelem = 0;
    lasthashelem = 0;
}

template<class Element, class GetIndex, int hashsize>
inline int RTPHashTable<Element, GetIndex, hashsize>::DeleteCurrentElement()
{
    if (curhashelem)
    {
        HashElement *tmp1, *tmp2;
        int index;

        // First, relink elements in current hash bucket

        index = curhashelem->GetHashIndex();
        tmp1 = curhashelem->hashprev;
        tmp2 = curhashelem->hashnext;
        if (tmp1 == 0) // no previous element in hash bucket
        {
            table[index] = tmp2;
            if (tmp2 != 0)
                tmp2->hashprev = 0;
        }
        else // there is a previous element in the hash bucket
        {
            tmp1->hashnext = tmp2;
            if (tmp2 != 0)
                tmp2->hashprev = tmp1;
        }

        // Relink elements in list

        tmp1 = curhashelem->listprev;
        tmp2 = curhashelem->listnext;
        if (tmp1 == 0) // curhashelem is first in list
        {
            firsthashelem = tmp2;
            if (tmp2 != 0)
                tmp2->listprev = 0;
            else
                // curhashelem is also last in list
                lasthashelem = 0;
        }
        else
        {
            tmp1->listnext = tmp2;
            if (tmp2 != 0)
                tmp2->listprev = tmp1;
            else
                // curhashelem is last in list
                lasthashelem = tmp1;
        }

        // finally, with everything being relinked, we can delete curhashelem
        delete curhashelem;
        curhashelem = tmp2; // Set to next element in the list
    }
    else
        return ERR_RTP_HASHTABLE_NOCURRENTELEMENT;
    return 0;
}

template<class Element, class GetIndex, int hashsize>
inline int RTPHashTable<Element, GetIndex, hashsize>::GotoElement(const Element &e)
{
    int index;
    bool found;

    index = GetIndex::GetIndex(e);
    if (index >= hashsize)
        return ERR_RTP_HASHTABLE_FUNCTIONRETURNEDINVALIDHASHINDEX;

    curhashelem = table[index];
    found = false;
    while (!found && curhashelem != 0)
    {
        if (curhashelem->GetElement() == e)
            found = true;
        else
            curhashelem = curhashelem->hashnext;
    }
    if (!found)
        return ERR_RTP_HASHTABLE_ELEMENTNOTFOUND;
    return 0;
}

template<class Element, class GetIndex, int hashsize>
inline bool RTPHashTable<Element, GetIndex, hashsize>::HasElement(const Element &e)
{
    int index;
    bool found;
    HashElement *tmp;

    index = GetIndex::GetIndex(e);
    if (index >= hashsize)
        return false;

    tmp = table[index];
    found = false;
    while (!found && tmp != 0)
    {
        if (tmp->GetElement() == e)
            found = true;
        else
            tmp = tmp->hashnext;
    }
    return found;
}

template<class Element, class GetIndex, int hashsize>
inline void RTPHashTable<Element, GetIndex, hashsize>::GotoNextElement()
{
    if (curhashelem)
        curhashelem = curhashelem->listnext;
}

template<class Element, class GetIndex, int hashsize>
inline void RTPHashTable<Element, GetIndex, hashsize>::GotoPreviousElement()
{
    if (curhashelem)
        curhashelem = curhashelem->listprev;
}

template<class Element, class GetIndex, int hashsize>
inline void RTPHashTable<Element, GetIndex, hashsize>::Clear()
{
    HashElement *tmp1, *tmp2;

    for (int i = 0; i < hashsize; i++)
        table[i] = 0;

    tmp1 = firsthashelem;
    while (tmp1 != 0)
    {
        tmp2 = tmp1->listnext;
        delete tmp1;
        tmp1 = tmp2;
    }
    firsthashelem = 0;
    lasthashelem = 0;
}

template<class Element, class GetIndex, int hashsize>
inline int RTPHashTable<Element, GetIndex, hashsize>::AddElement(const Element &elem)
{
    int index;
    bool found;
    HashElement *e, *newelem;

    index = GetIndex::GetIndex(elem);
    if (index >= hashsize)
        return ERR_RTP_HASHTABLE_FUNCTIONRETURNEDINVALIDHASHINDEX;

    e = table[index];
    found = false;
    while (!found && e != 0)
    {
        if (e->GetElement() == elem)
            found = true;
        else
            e = e->hashnext;
    }
    if (found)
        return ERR_RTP_HASHTABLE_ELEMENTALREADYEXISTS;

    // Okay, the key doesn't exist, so we can add the new element in the hash table

    newelem = new HashElement(elem, index);
    if (newelem == 0)
        return ERR_RTP_OUTOFMEM;

    e = table[index];
    table[index] = newelem;
    newelem->hashnext = e;
    if (e != 0)
        e->hashprev = newelem;

    // Now, we still got to add it to the linked list

    if (firsthashelem == 0)
    {
        firsthashelem = newelem;
        lasthashelem = newelem;
    }
    else // there already are some elements in the list
    {
        lasthashelem->listnext = newelem;
        newelem->listprev = lasthashelem;
        lasthashelem = newelem;
    }
    return 0;
}

template<class Element, class GetIndex, int hashsize>
inline int RTPHashTable<Element, GetIndex, hashsize>::DeleteElement(const Element &elem)
{
    int status;

    status = GotoElement(elem);
    if (status < 0)
        return status;
    return DeleteCurrentElement();
}

} // end namespace

#endif // RTPHASHTABLE_H