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 m_size;
    inline int hash( const std::string& str );
    std::string*** m_strings;
    T*** m_data;
    int* m_entries;
};
 
template <class T>
EvtStringHash<T>::EvtStringHash( int size )
{
    m_size = size;
 
    typedef std::string** EvtStringPtrPtr;
    typedef T** TPtrPtr;
 
    m_strings = new EvtStringPtrPtr[m_size];
    m_data = new TPtrPtr[m_size];
    m_entries = new int[m_size];
 
    int i;
 
    for ( i = 0; i < m_size; i++ ) {
        m_entries[i] = 0;
    }
}
 
template <class T>
EvtStringHash<T>::~EvtStringHash()
{
    int i;
    for ( i = 0; i < m_size; i++ ) {
        int j;
        for ( j = 0; j < m_entries[i]; j++ ) {
            delete m_strings[i][j];
        }
        if ( m_entries[i] > 0 ) {
            delete[] m_strings[i];
            delete[] m_data[i];
        }
    }
 
    delete[] m_strings;
    delete[] m_data;
    delete[] m_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[m_entries[ihash] + 1];
    T** newdata = new TPtr[m_entries[ihash] + 1];
 
    int i;
 
    for ( i = 0; i < m_entries[ihash]; i++ ) {
        newstrings[i] = m_strings[ihash][i];
        newdata[i] = m_data[ihash][i];
    }
 
    newstrings[m_entries[ihash]] = new std::string;
    *( newstrings[m_entries[ihash]] ) = str;
    newdata[m_entries[ihash]] = data;
 
    if ( m_entries[ihash] != 0 ) {
        delete[] m_strings[ihash];
        delete[] m_data[ihash];
    }
 
    m_entries[ihash]++;
 
    m_strings[ihash] = newstrings;
    m_data[ihash] = newdata;
}
 
template <class T>
T* EvtStringHash<T>::get( const std::string& str )
{
    int ihash = hash( str );
 
    int i;
 
    for ( i = 0; i < m_entries[ihash]; i++ ) {
        if ( *( m_strings[ihash][i] ) == str )
            return m_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 % m_size;
}
 
#endif