EvtStringHash.hh

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* Copyright 1998-2020 CERN for the benefit of the EvtGen authors       *
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* This file is part of EvtGen.                                         *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
* GNU General Public License for more details.                         *
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***********************************************************************/

#ifndef EVTSTRINGHASH_HH
#define EVTSTRINGHASH_HH

#include <string>

template <class T>
class EvtStringHash {
  public:
    inline EvtStringHash( int size );
    inline void add( const std::string& str, T* data );
    inline T* get( const std::string& str );
    inline ~EvtStringHash();

  private:
    EvtStringHash();
    int _size;
    inline int hash( const std::string& str );
    std::string*** _strings;
    T*** _data;
    int* _entries;
};

template <class T>
EvtStringHash<T>::EvtStringHash( int size )
{
    _size = size;

    typedef std::string** EvtStringPtrPtr;
    typedef T** TPtrPtr;

    _strings = new EvtStringPtrPtr[_size];
    _data = new TPtrPtr[_size];
    _entries = new int[_size];

    int i;

    for ( i = 0; i < _size; i++ ) {
        _entries[i] = 0;
    }
}

template <class T>
EvtStringHash<T>::~EvtStringHash()
{
    int i;
    for ( i = 0; i < _size; i++ ) {
        int j;
        for ( j = 0; j < _entries[i]; j++ ) {
            delete _strings[i][j];
        }
        if ( _entries[i] > 0 ) {
            delete[] _strings[i];
            delete[] _data[i];
        }
    }

    delete[] _strings;
    delete[] _data;
    delete[] _entries;
}

template <class T>
void EvtStringHash<T>::add( const std::string& str, T* data )
{
    int ihash = hash( str );

    typedef std::string* EvtStringPtr;
    typedef T* TPtr;

    std::string** newstrings = new EvtStringPtr[_entries[ihash] + 1];
    T** newdata = new TPtr[_entries[ihash] + 1];

    int i;

    for ( i = 0; i < _entries[ihash]; i++ ) {
        newstrings[i] = _strings[ihash][i];
        newdata[i] = _data[ihash][i];
    }

    newstrings[_entries[ihash]] = new std::string;
    *( newstrings[_entries[ihash]] ) = str;
    newdata[_entries[ihash]] = data;

    if ( _entries[ihash] != 0 ) {
        delete[] _strings[ihash];
        delete[] _data[ihash];
    }

    _entries[ihash]++;

    _strings[ihash] = newstrings;
    _data[ihash] = newdata;
}

template <class T>
T* EvtStringHash<T>::get( const std::string& str )
{
    int ihash = hash( str );

    int i;

    for ( i = 0; i < _entries[ihash]; i++ ) {
        if ( *( _strings[ihash][i] ) == str )
            return _data[ihash][i];
    }

    return 0;
}

template <class T>
int EvtStringHash<T>::hash( const std::string& str )
{
    const char* cstr = str.c_str();

    int i = 0;

    int value = 0;

    while ( cstr[i] != 0 ) {
        value += (int)cstr[i];
        i++;
    }

    return value % _size;
}

#endif