lambder

/*
=====================================================================
   @license MIT
   @author Daniel Kwiecinski <daniel.kwiecinski@lambder.com>
   @copyright 2009 Daniel Kwiecinski.
   @end
=====================================================================
*/
var HashMap = function() {
  this.initialize();
}
 
HashMap.prototype = {
  hashkey_prefix: "<#HashMapHashkeyPerfix>",
  hashcode_field: "<#HashMapHashcodeField>",
  hashmap_instance_id: 0,
 
  initialize: function() {
    this.backing_hash = {};
    this.code = 0;
    this.hashmap_instance_id += 1;
    this.instance_id = this.hashmap_instance_id;
  },
 
  hashcodeField: function() {
    return this.hashcode_field + this.instance_id;
  },
  /*
   maps value to key returning previous assocciation
   */
  put: function(key, value) {
    var prev;
 
    if (key && value) {
      var hashCode;
      if (typeof(key) === "number" || typeof(key) === "string") {
        hashCode = key;
      } else {
        hashCode = key[this.hashcodeField()];
      }
      if (hashCode) {
        prev = this.backing_hash[hashCode];
      } else {
        this.code += 1;
        hashCode = this.hashkey_prefix + this.code;
        key[this.hashcodeField()] = hashCode;
      }
      this.backing_hash[hashCode] = value;
    }
    return prev;
  },
  /*
   returns value associated with given key
   */
  get: function(key) {
    var value;
    if (key) {
      var hashCode;
      if (typeof(key) === "number" || typeof(key) === "string") {
        hashCode = key;
      } else {
        hashCode = key[this.hashcodeField()];
      }
      if (hashCode) {
        value = this.backing_hash[hashCode];
      }
    }
    return value;
  },
  /*
   deletes association by given key.
   Returns true if the assocciation existed, false otherwise
   */
  del: function(key) {
    var success = false;
    if (key) {
      var hashCode;
      if (typeof(key) === "number" || typeof(key) === "string") {
        hashCode = key;
      } else {
        hashCode = key[this.hashcodeField()];
      }
      if (hashCode) {
        var prev = this.backing_hash[hashCode];
        this.backing_hash[hashCode] = undefined;
        if (prev !== undefined)
          success = true;
      }
    }
    return success;
  }
}
 
/*
 =====================================================================
       usage
 =====================================================================
*/
 
 
// creation
 
var my_map = new HashMap();
 
// insertion
 
var a_key = {};
var a_value = {struct: "structA"};
var b_key = {};
var b_value = {struct: "structB"};
var c_key = {};
var c_value = {struct: "structC"};
 
my_map.put(a_key, a_value);
my_map.put(b_key, b_value);
var prev_b = my_map.put(b_key, c_value);
 
// retrieval
 
if(my_map.get(a_key) !== a_value){
  throw("fail1")
}
if(my_map.get(b_key) !== c_value){
  throw("fail2")
}
if(prev_b !== b_value){
  throw("fail3")
}
 
// deletion
 
var a_existed = my_map.del(a_key);
var c_existed = my_map.del(c_key);
var a2_existed = my_map.del(a_key);
 
if(a_existed !== true){
  throw("fail4")
}
if(c_existed !== false){
  throw("fail5")
}
if(a2_existed !== false){
  throw("fail6")
}
 
 
// primitive types keys 
var d_value = {struct: "structD"};
my_map.put(1, d_value);
 
if (my_map.get(1) !== d_value) {
  throw("fail7")
}