hash.js

function Hash() {
  this.length = 0;
  this.items = new Array();
  for (var i = 0; i < arguments.length; i += 2) {
    if (typeof(arguments[i + 1]) != 'undefined') {
      this.items[arguments[i]] = arguments[i + 1];
      this.length++;
    }
  }
   
  this.removeItem = function(in_key) {
    var tmp_value;
    if (typeof(this.items[in_key]) != 'undefined') {
      this.length--;
      var tmp_value = this.items[in_key];
      delete this.items[in_key];
    }
     
    return tmp_value;
  }

  this.getItem = function(in_key) {
    return this.items[in_key];
  }

  this.setItem = function(in_key, in_value) {
    if (typeof(in_value) != 'undefined') {
      if (typeof(this.items[in_key]) == 'undefined') {
        this.length++;
      }

      this.items[in_key] = in_value;
    }
     
    return in_value;
  }

  this.addItem = function(in_key) {
    if (this.hasItem(in_key)) {
      this.setItem(in_key,this.getItem(in_key) + 1);
    } else {
      this.setItem(in_key,1);
    }
  }

  this.subtractItem = function(in_key) {
    if (!this.hasItem(in_key)) {
      throw("Cannot subtract non-existent item! " + in_key);
    } else if (this.getItem(in_key) < 1) {
      throw("Cannot subtract 1! " + in_key + " " + this.getItem(in_key));
    } else if (this.getItem(in_key) == 1) {
      this.removeItem(in_key);
    } else {
      this.setItem(in_key, this.getItem(in_key) - 1);
    }
  }

  this.subtractOneOfEachItem = function() {
    for (var i in this.items) {
      this.subtractItem(i);
    }
  }

  this.hasItem = function(in_key) {
    return typeof(this.items[in_key]) != 'undefined';
  }
}