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hashmap.cc

#ifndef LCDF_HASHMAP_CC
#define LCDF_HASHMAP_CC

/*
 * hashmap.{cc,hh} -- simple open-coded hash table class
 * Eddie Kohler
 *
 * Copyright (c) 1999-2000 Massachusetts Institute of Technology
 * Copyright (c) 2001-2003 International Computer Science Institute
 *
 * 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, subject to the conditions
 * listed in the Click LICENSE file. These conditions include: you must
 * preserve this copyright notice, and you cannot mention the copyright
 * holders in advertising related to the Software without their permission.
 * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
 * notice is a summary of the Click LICENSE file; the license in that file is
 * legally binding.
 */

/* #include <lcdf/hashmap.hh> */

template <class K, class V>
HashMap<K, V>::HashMap()
    : _capacity(0), _grow_limit(0), _n(0), _e(0), _default_value()
{
    increase(-1);
}

template <class K, class V>
HashMap<K, V>::HashMap(const V &def)
    : _capacity(0), _grow_limit(0), _n(0), _e(0), _default_value(def)
{
    increase(-1);
}


template <class K, class V>
HashMap<K, V>::HashMap(const HashMap<K, V> &m)
    : _capacity(m._capacity), _grow_limit(m._grow_limit), _n(m._n),
      _e(new Pair[m._capacity]), _default_value(m._default_value)
{
    for (int i = 0; i < _capacity; i++)
      _e[i] = m._e[i];
}


template <class K, class V>
HashMap<K, V> &
HashMap<K, V>::operator=(const HashMap<K, V> &o)
{
    // This works with self-assignment.

    _capacity = o._capacity;
    _grow_limit = o._grow_limit;
    _n = o._n;
    _default_value = o._default_value;
  
    Pair *new_e = new Pair[_capacity];
    for (int i = 0; i < _capacity; i++)
      new_e[i] = o._e[i];

    delete[] _e;
    _e = new_e;

    return *this;
}


template <class K, class V>
void
HashMap<K, V>::increase(int min_size)
{
    int ncap = (_capacity < 8 ? 8 : _capacity * 2);
    while (ncap < min_size && ncap > 0)
      ncap *= 2;
    if (ncap <= 0)            // want too many elements
      return;

    Pair *ne = new Pair[ncap];
    if (!ne)                  // out of memory
      return;

    Pair *oe = _e;
    int ocap = _capacity;
    _e = ne;
    _capacity = ncap;
    _grow_limit = ((3 * _capacity) >> 2) - 1;
    
    Pair *otrav = oe;
    for (int i = 0; i < ocap; i++, otrav++)
      if (otrav->key) {
          int j = bucket(otrav->key);
          _e[j] = *otrav;
      }

    delete[] oe;
}

template <class K, class V>
inline void
HashMap<K, V>::check_capacity()
{
    if (_n >= _grow_limit)
      increase(-1);
}

template <class K, class V>
bool
HashMap<K, V>::insert(const K &key, const V &val)
{
    check_capacity();
    int i = bucket(key);
    bool is_new = !(bool)_e[i].key;
    _e[i].key = key;
    _e[i].value = val;
    _n += is_new;
    return is_new;
}

template <class K, class V>
V &
HashMap<K, V>::find_force(const K &key)
{
    check_capacity();
    int i = bucket(key);
    if (!(bool)_e[i].key) {
      _e[i].key = key;
      _e[i].value = _default_value;
      _n++;
    }
    return _e[i].value;
}

template <class K, class V>
void
HashMap<K, V>::clear()
{
    delete[] _e;
    _e = 0;
    _capacity = _grow_limit = _n = 0;
    increase(-1);
}

template <class K, class V>
void
HashMap<K, V>::swap(HashMap<K, V> &o)
{
    int capacity = _capacity;
    int grow_limit = _grow_limit;
    int n = _n;
    Pair *e = _e;
    V default_value = _default_value;
    _capacity = o._capacity;
    _grow_limit = o._grow_limit;
    _n = o._n;
    _e = o._e;
    _default_value = o._default_value;
    o._capacity = capacity;
    o._grow_limit = grow_limit;
    o._n = n;
    o._e = e;
    o._default_value = default_value;
}

template <class K, class V>
_HashMap_const_iterator<K, V>::_HashMap_const_iterator(const HashMap<K, V> *hm, int pos)
    : _hm(hm), _pos(pos)
{
    typename HashMap<K, V>::Pair *e = _hm->_e;
    int capacity = _hm->_capacity;
    while (_pos < capacity && !(bool)e[_pos].key)
      _pos++;
}

template <class K, class V>
void
_HashMap_const_iterator<K, V>::operator++(int)
{
    typename HashMap<K, V>::Pair *e = _hm->_e;
    int capacity = _hm->_capacity;
    for (_pos++; _pos < capacity && !(bool)e[_pos].key; _pos++)
      ;
}

#endif

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