HashMap

#ifndef HASHMAP_H
#define HASHMAP_H

#include "stdlib.h"

template class HashMap;

/*
===============================================================================================

 HashNode

===============================================================================================
*/

template
class HashNode
{
friend class HashMap;
public:

    K&              Key() { return key; }
    V&              Value() { return value; }
    
private:
    HashNode*  next;
    K               key;
    V               value;
};

/*
===============================================================================================

 HashMap
 
===============================================================================================
*/

template
class HashMap
{
public:
    typedef HashNode  Node;

    HashMap(int bucketSize = 16);
    ~HashMap();
    
    void                    Clear();
    
    V*                      GetPtr(K& key);
    bool                    Get(K& key, V& value);
    void                    Set(K& key, V& value);

    bool                    HasKey(K& key);
    void                    Remove(K& key);

    Node*                   First();
    Node*                   Next(Node* it);

private:
    Node**                  buckets;
    size_t                  bucketSize;
    size_t                  num;
    
    size_t                  GetHash(K& key);
};

/*
===============================================================================================
*/

template
HashMap::HashMap(int bucketSize_)
{
    num = 0;
    bucketSize = bucketSize_;
    buckets = new Node*[bucketSize];
    memset(buckets, 0, bucketSize * sizeof(Node*));
}

template
HashMap::~HashMap()
{
    Clear();
    delete[] buckets;
}

template
void HashMap::Clear()
{
    size_t	i;
    Node*   node;
    Node*   next;
    
    for (i = 0; i < bucketSize; i++)
    {
        for (node = buckets[i]; node; node = next)
        {
            next = node->next;
            delete node;
        }
        buckets[i] = NULL;
    }
    num = 0;
}

template
V* HashMap::GetPtr(K& key)
{
    size_t  hash;
    Node*   node;
    
    hash = GetHash(key);
    for (node = buckets[hash]; node; node = node->next)
    {
        if (node->key == key)
            return &node->value;
    }
    
    return NULL;
}

template
bool HashMap::Get(K& key, V& value)
{
    size_t  hash;
    Node*   node;
    
    hash = GetHash(key);
    for (node = buckets[hash]; node; node = node->next)
    {
        if (node->key == key)
        {
            value = node->value;
            return true;
        }
    }
    
    return false;
}

template
void HashMap::Set(K& key, V& value)
{
    size_t  hash;
    Node*   node;
    
    hash = GetHash(key);
    for (node = buckets[hash]; node; node = node->next)
    {
        if (node->key == key)
        {
            node->value = value;
            return;
        }
    }
    
    node = new Node;
    node->key = key;
    node->value = value;
    
    node->next = buckets[hash];
    buckets[hash] = node;
    num++;
    
    // TODO resize if too small
    return;
}

template
bool HashMap::HasKey(K& key)
{
    if (GetPtr(key))
        return true;
        
    return false;
}

template
void HashMap::Remove(K& key)
{
    size_t  hash;
    Node*   node;
    Node*   next;
    Node**  prev;
    
    hash = GetHash(key);
    prev = &buckets[hash];
    for (node = buckets[hash]; node; node = next)
    {
        next = node->next;
        if (node->key == key)
        {
            *prev = next;
            delete node;
            num--;
            break;
        }
        prev = &node->next;
    }
    
    // TODO resize if too big
}

template
HashNode* HashMap::First()
{
    size_t  i;
    
    for (i = 0; i < bucketSize; i++)
    {
        if (buckets[i])
            return buckets[i];
    }
    
    return NULL;
}

template
HashNode* HashMap::Next(Node* it)
{
    size_t  i;
    size_t  hash;
    
    if (it->next)
        return it->next;

    hash = GetHash(it->key);
    for (i = hash + 1; i < bucketSize; i++)
    {
        if (buckets[i])
            return buckets[i];
    }
    
    return NULL;
}

template
size_t HashMap::GetHash(K& key)
{
    return Hash(key) % bucketSize;
}

#endif