Hash.cpp

#include "Hash.h"
#include <iostream>

using std::string;
using std::list;

template <typename V>
Hash<V>::Hash(int size) {
 height = size;
 table = new list< Entry<V> >[size];
}

template <typename V>
Hash<V>::~Hash() {
 delete[] table;
}

template <typename V>
void Hash<V>::insert(string key, V v) {
 if(table[hash(key)].empty()) //empty spot
  table[hash(key)].push_back(Entry<V>(key,v));
 else{ //non-empty spot
  typename list< Entry<V> >::iterator it;
  bool inserted = false;
  for(it = table[hash(key)].begin(); it != table[hash(key)].end() && inserted == false; it++) {
    if(it->getKey() == key) {
    it->setValue(v);
    inserted = true;
   }
  }
  if(inserted == false) { //non-empty and non-duplicate.
   table[hash(key)].push_back(Entry<V>(key,v));
  }
 }
}

template <typename V>
void Hash<V>::remove(string key) {
 if(!table[hash(key)].empty()){ // Non empty spot, no need to remove if empty
  bool erased = false;
  typename list< Entry<V> >::iterator it;
  for(it = table[hash(key)].begin(); it != table[hash(key)].end() && erased == false; it++) {
    if(it->getKey() == key) {
     it = table[hash(key)].erase(it); // Erase it!
     erased == true;
   }
  }
 }
}

template <typename V>
V Hash<V>::get(string key) {
 int hashed = hash(key);
 if(!table[hashed].empty()) {                                       // If the spot in the table is not empty...
  typename list< Entry<V> >::iterator it;                             //
  for(it = table[hashed].begin(); it != table[hashed].end(); it++) {  // it = Entry obj in list
   std::cout << hashed << std::endl;
   if(it->getKey() == key)                                          // And the key is the same...
    return it->getValue();                                          // return the value.
  }
 }                                                                  //else the key was not present in the table
 return (V)0;
}

template <typename V>
int Hash<V>::hash(string key) {
 int value = 0;
 for(int i = 0; i < (int)key.length(); i++) {
  value += key[i];
 }
 value = value%height;
 return value;
}

template <typename V>
void Hash<V>::print() {
 std::cout << "[ " ;
 for(int i = 0; i < height; i++) {
  std::cout << "{ " ; 
   if(!table[i].empty()){
   typename list< Entry<V> >::iterator it;
   for(it = table[i].begin(); it != table[i].end(); it++) {
    std::cout << "(" << it->getKey() << ", " << it->getValue() << ") " ;
   }
  }
 std::cout << " }";
 if(i+1 != height)
  std::cout << std::endl;
 }
 std::cout << " ]" << std::endl;
}

template class Hash<int>;
template class Hash<string>;
template class Hash<double>;