hash part 2

Author: nagano564

hash_part_2/node.rb

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+class Node
+  attr_accessor :next
+  attr_accessor :key
+  attr_accessor :value
+
+  def initialize(key, value)
+  end
+end

hash_part_2/open_addressing.rb

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+require_relative 'node'
+
+class OpenAddressing
+  def initialize(size)
+  end
+
+  def []=(key, value)
+  end
+
+  def [](key)
+  end
+
+  # Returns a unique, deterministically reproducible index into an array
+  # We are hashing based on strings, let's use the ascii value of each string as
+  # a starting point.
+  def index(key, size)
+  end
+
+  # Given an index, find the next open index in @items
+  def next_open_index(index)
+  end
+
+  # Simple method to return the number of items in the hash
+  def size
+  end
+
+  # Resize the hash
+  def resize
+  end
+end

hash_part_2/open_addressing_spec.rb

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+include RSpec
+
+require_relative 'node'
+require_relative 'open_addressing'
+
+RSpec.describe OpenAddressing, type: Class do
+  let(:star_wars_movies) { OpenAddressing.new(6) }
+
+  before do
+    star_wars_movies["Star Wars: The Phantom Menace"] = "Number One"
+    star_wars_movies["Star Wars: Attack of the Clones"] = "Number Two"
+    star_wars_movies["Star Wars: Revenge of the Sith"] = "Number Three"
+    star_wars_movies["Star Wars: A New Hope"] = "Number Four"
+    star_wars_movies["Star Wars: The Empire Strikes Back"] = "Number Five"
+    star_wars_movies["Star Wars: Return of the Jedi"] = "Number Six"
+  end
+
+  describe "#index" do
+    it "creates a hash key based on the string value passed in" do
+      i = star_wars_movies.index("Star Wars: A New Hope", 6)
+      expect(i).to eq 4
+    end
+  end
+
+  describe "#key" do
+    it "returns the sum of the ascii values of the string value" do
+      key = "test"
+      expect(star_wars_movies.index(key, 6)).to eq 4
+    end
+  end
+
+  describe "#hash[key] = value" do
+    it "does not resizes the array when a collision occurs and hash is not full" do
+      hash = OpenAddressing.new(4)
+      hash["key"] = "value"
+      expect(hash.size).to eq 4
+      hash["key"] = "second value"
+      expect(hash.size).to eq 4
+    end
+
+    it "resizes the array when a collision occurs and hash is full" do
+      hash = OpenAddressing.new(1)
+      hash["key"] = "value"
+      expect(hash.size).to eq 1
+      hash["key"] = "second value"
+      expect(hash.size).to eq 2
+    end
+
+    it "sets the value of key to value" do
+      expect(star_wars_movies["Star Wars: The Phantom Menace"]).to eq "Number One"
+      expect(star_wars_movies["Star Wars: Attack of the Clones"]).to eq "Number Two"
+      expect(star_wars_movies["Star Wars: Revenge of the Sith"]).to eq "Number Three"
+      expect(star_wars_movies["Star Wars: A New Hope"]).to eq "Number Four"
+      expect(star_wars_movies["Star Wars: The Empire Strikes Back"]).to eq "Number Five"
+      expect(star_wars_movies["Star Wars: Return of the Jedi"]).to eq "Number Six"
+    end
+  end
+
+  describe "#next_open_index" do
+    it "returns -1 if there are no open indices" do
+      inception = OpenAddressing.new(1)
+      inception["The Original"] = "The Best Movie Ever"
+      expect(inception.next_open_index(0)).to eq -1
+    end
+
+  end
+
+  describe "#resize" do
+    it "doubles the size of the array when invoked" do
+      movies = OpenAddressing.new(6)
+      expect(movies.size).to eq 6
+      movies.resize
+      expect(movies.size).to eq 12
+    end
+
+    it "copies existing values properly when the array is resized" do
+      movies = OpenAddressing.new(6)
+      movies["A New Hope"] = "Average"
+      movies["Empire Strikes Back"] = "Excellent"
+      movies["Return of the Jedi"] = "The Best"
+      movies.resize
+      expect(movies.size).to eq 12
+      expect(movies["A New Hope"]).to eq "Average"
+      expect(movies["Empire Strikes Back"]).to eq "Excellent"
+      expect(movies["Return of the Jedi"]).to eq "The Best"
+    end
+  end
+end