TDD hashtable

hashtable.rb

require 'rspec'
#http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx


class String

  def hashKey
    rot_hash
  end

  #add hash
  def add_key
    key  = 0
    size.times do |i|
      key ^= self[i].ord
    end
    key
  end


  def xor_hash
    key  = 0
    size.times do |i|
      key ^= self[i].ord
    end
    key
  end

  def xor_hash
    key  = 0
    size.times do |i|
      key ^= self[i].ord
    end
    key
  end

  def rot_hash
    key  = 0
    size.times do |i|
     key = ( key << 4 ) ^ ( key >> 28) ^ self[i].ord
    end
    key
  end

end


class HashTable
  def initialize(store_size=100)
    @store_size = store_size
    @store = Array.new(store_size)
  end

  def put(key,value)
    @store[key_in_range(key)] = value
  end

  def get(key)
    @store[key_in_range(key)]
  end

  def key_in_range(key)
    key.hashKey % @store_size
  end
end

describe 'Hashing' do

 it "string key maps to a int" do
   "hello".hashKey.class.should eql Fixnum
 end

 it 'is different for each sting you give it' do
  'hello'.hashKey.should_not == 'hellx'.hashKey
 end

 it 'should be the same for every key you give it' do
   'hello'.hashKey.should == 'hello'.hashKey
 end

 #it 'will have collisions with since the aloritm sucks' do
   #'abs'.hashKey.should eql 'asb'.hashKey
 #end

end

describe HashTable do
  let(:table) { HashTable.new }

  it ' allows you to put an object in the table with a sting key' do
    table.put('key','object')
  end

  it 'allows you to get a value out of the table with a given key' do
    table.put('key','object')
    table.get('key').should eql('object')
  end

  it 'should return nil if key is not filled' do
    table.get('nothere').should eql nil
  end

end