HashTable.h

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/*
 * Copyright (C) 2015 Niek Linnenbank
 *
 * 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/>.
 */
 
#ifndef __LIB_LIBSTD_HASHTABLE_H
#define __LIB_LIBSTD_HASHTABLE_H
 
#include "Types.h"
#include "Macros.h"
#include "Vector.h"
#include "List.h"
#include "ListIterator.h"
#include "HashFunction.h"
#include "Associative.h"
#include "Assert.h"
 
#define HASHTABLE_DEFAULT_SIZE    64
 
template <class K, class V> class HashTable : public Associative<K,V>
{
  public:
 
    class Bucket
    {
      public:
 
        Bucket()
        {
        }
 
        Bucket(K k, V v)
            : key(k), value(v)
        {
        }
 
        Bucket(const Bucket & b)
            : key(b.key), value(b.value)
        {
        }
 
        bool operator == (const Bucket & b) const
        {
            return key == b.key && value == b.value;
        }
 
        bool operator != (const Bucket & b) const
        {
            return !(key == b.key && value == b.value);
        }
 
        K key;
 
        V value;
    };
 
    HashTable(Size size = HASHTABLE_DEFAULT_SIZE)
        : m_table(size)
    {
        assert(size > 0);
 
        m_count = ZERO;
 
        // Fill the Vector with empty Bucket Lists.
        for (Size i = 0; i < m_table.size(); i++)
            m_table.insert(List<Bucket>());
    }
 
    virtual bool insert(const K & key, const V & value)
    {
 
        Size idx = hash(key, m_table.size());
 
        // See if the given key exists. Overwrite if so.
        for (ListIterator<Bucket> i(m_table[idx]); i.hasCurrent(); i++)
        {
            if (i.current().key == key)
            {
                i.current().value = value;
                return true;
            }
        }
 
        // Key does not exist. Append it.
        m_table[idx].append(Bucket(key, value));
        m_count++;
        return true;
    }
 
    virtual bool append(const K & key, const V & value)
    {
 
        // Always append
        m_table[hash(key, m_table.size())].append(Bucket(key, value));
        m_count++;
        return true;
    }
 
    virtual int remove(const K & key)
    {
        int removed = 0;
 
        for (ListIterator<Bucket> i(m_table[hash(key, m_table.size())]); i.hasCurrent(); )
        {
            if (i.current().key == key)
            {
                i.remove();
                m_count--;
                removed++;
            }
            else
                i++;
        }
        return removed;
    }
 
    virtual Size size() const
    {
        return m_table.size();
    }
 
    virtual Size count() const
    {
        return m_count;
    }
 
    virtual List<K> keys() const
    {
        List<K> lst;
 
        for (Size i = 0; i < m_table.count(); i++)
            for (ListIterator<Bucket> j(m_table[i]); j.hasCurrent(); j++)
                if (!lst.contains(j.current().key))
                    lst << j.current().key;
 
        return lst;
    }
 
    virtual List<K> keys(const V & value) const
    {
        List<K> lst;
 
        for (Size i = 0; i < m_table.count(); i++)
            for (ListIterator<Bucket> j(m_table[i]); j.hasCurrent(); j++)
                if (j.current().value == value && !lst.contains(j.current().key))
                    lst << j.current().key;
 
        return lst;
    }
 
    virtual List<V> values() const
    {
        List<V> lst;
 
        for (Size i = 0; i < m_table.count(); i++)
            for (ListIterator<Bucket> j(m_table[i]); j.hasCurrent(); j++)
                lst << j.current().value;
 
        return lst;
    }
 
    virtual List<V> values(const K & key) const
    {
        List<V> lst;
 
        for (ListIterator<Bucket> i(m_table[hash(key, m_table.size())]); i.hasCurrent(); i++)
            if (i.current().key == key)
                lst << i.current().value;
 
        return lst;
    }
 
    virtual const V * get(const K & key) const
    {
        const List<Bucket> & lst = m_table[hash(key, m_table.size())];
 
        for (ListIterator<Bucket> i(lst); i.hasCurrent(); i++)
            if (i.current().key == key)
                return &i.current().value;
 
        return ZERO;
    }
 
    virtual const V & at(const K & key) const
    {
        const List<Bucket> & lst = m_table[hash(key, m_table.size())];
 
        for (ListIterator<Bucket> i(lst); i.hasCurrent(); i++)
            if (i.current().key == key)
                return i.current().value;
 
        return m_table[0].head()->data.value;
    }
 
    virtual const V value(const K & key, const V defaultValue = V()) const
    {
        const List<Bucket> & lst = m_table[hash(key, m_table.size())];
 
        for (ListIterator<Bucket> i(lst); i.hasCurrent(); i++)
            if (i.current().key == key)
                return i.current().value;
 
        return defaultValue;
    }
 
    Vector<List<Bucket> > & table()
    {
        return m_table;
    }
 
    V & operator[](const K & key)
    {
        return (V &) at(key);
    }
 
    const V & operator[](const K & key) const
    {
        return (const V &) at(key);
    }
 
  private:
 
    Vector<List<Bucket> > m_table;
 
    Size m_count;
};
 
#endif /* __LIB_LIBSTD_HASHTABLE_H */