Queues - Cara Comfort - stacks-queues

lib/Queue.rb

@@ -1,22 +1,29 @@
 class Queue
   def initialize
+    @store = Array.new
   end
 
   def enqueue(element)
+    @store << element
   end
 
   def dequeue
+    @store.shift
   end
 
   def front
+    @store.first
   end
 
   def size
+    @store.length
   end
 
   def empty?
+    @store.empty?
   end
 
   def to_s
+    return @store.to_s
   end
 end

lib/Stack.rb

@@ -1,21 +1,29 @@
 class Stack
   def initialize
-    @store = Array.new
+    @store = Array.new # use an array to store the data
   end
 
   def push(element)
+    @store << element
   end
 
   def pop
+    raise ArgumentError.new("Cannot pop an empty stack") if @store.empty? #OR self.empty? 
+    @store.pop
   end
 
   def top
+    raise ArgumentError.new("There's no top in an empty stack") if self.size == 0
+    @store.last
   end
 
   def size
+    @store.length
   end
 
   def empty?
+    #@store.size == 0
+    @store.empty?
   end
 
   def to_s

lib/job-simulation.rb

@@ -5,12 +5,52 @@ class JobSimulation
   attr_reader :workers, :waiting, :roll
 
   def initialize (jobs_available, job_seekers)
+    # assume jobs_available and job_seekers are ints
+    # assume always more job_seekers than jobs_available
+    raise ArgumentError.new("The economy is bad. There will always be more job seekers than jobs.") if jobs_available > job_seekers
 
+    @workers = Stack.new
+    (1..jobs_available).each do |worker|
+      @workers.push("Worker ##{worker}")
+    end
+
+    @waiting = Queue.new
+    # seekers_left = job_seekers - jobs_available
+    ((jobs_available + 1)..job_seekers).each do |worker|
+      @waiting.enqueue("Worker ##{worker}")
+    end
+
+    @roll
   end
 
   def cycle
+    roll
+    puts "Managers roll a #{@roll}"
+
+    # fire workers specified by the roll, removing them from the hired list
+    # and adding them to the waiting list
+    (1..@roll).each do
+      fired_worker = @workers.pop
+      puts "Fire: #{fired_worker}"
+      @waiting.enqueue(fired_worker)
+    end
+
+    # hire workers specified by the roll, removing them from the waiting list
+    # and adding them to the hired list
+    (1..@roll).each do
+      hired_worker = @waiting.dequeue
+      puts "Hire: #{hired_worker}"
+      @workers.push(hired_worker)
+    end
 
   end
+
+  private
+
+  def roll
+    # Assume managers rolling a 6 sided die
+    @roll = rand(1..6)
+  end
 end
 
 ## Allows us to run our code and see what's happening:
@@ -29,3 +69,5 @@ def cycle
   puts "Employed: #{sim.workers}"
   puts "Waitlist: #{sim.waiting}"
 end
+
+# Code would probably be better organized by making hired and fired private methods

specs/test-queue-implementation.rb

@@ -10,14 +10,12 @@
   end
 
   it "adds something to an empty Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.to_s.must_equal "[10]"
   end
 
   it "adds multiple somethings to a Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
@@ -26,14 +24,12 @@
   end
 
   it "starts the size of a Queue at 0" do
-    skip
     q = Queue.new
     q.size.must_equal 0
     q.empty?.must_equal true
   end
 
   it "removes something from the Queue" do
-    skip
     q = Queue.new
     q.enqueue(5)
     removed = q.dequeue
@@ -43,7 +39,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
@@ -55,7 +50,6 @@
   end
 
   it "properly adjusts the size with enqueueing and dequeueing" do
-    skip
     q = Queue.new
     q.empty?.must_equal true
     q.enqueue(-1)
@@ -70,7 +64,6 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)

specs/test-stack-implementation.rb

@@ -10,14 +10,12 @@
   end
 
   it "pushes something onto a empty Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.to_s.must_equal "[10]"
   end
 
   it "pushes multiple somethings onto a Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.push(20)
@@ -26,14 +24,12 @@
   end
 
   it "starts the size of a Stack at 0" do
-    skip
     s = Stack.new
     s.size.must_equal 0
     s.empty?.must_equal true
   end
 
   it "removes something from the stack" do
-    skip
     s = Stack.new
     s.push(5)
     removed = s.pop
@@ -43,7 +39,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     s = Stack.new
     s.push(5)
     s.push(3)
@@ -55,7 +50,6 @@
   end
 
   it "properly adjusts the size with pushing and poping" do
-    skip
     s = Stack.new
     s.empty?.must_equal true
     s.push(-1)
@@ -70,13 +64,39 @@
   end
 
   it "returns the top element on the stack" do
-    skip
     s = Stack.new
     s.push(40)
     s.push(22)
     s.top.must_equal 22
   end
 
+  it "doesn't alter the size when you call top" do
+    s = Stack.new
+    s.push(8)
+    s.top
+    s.size.must_equal 1
+  end
+
+  it "raises an error if you try to pop from an empty stack" do
+    s = Stack.new
+    s.empty?.must_equal true
+
+    proc {
+      s.pop
+    }.must_raise ArgumentError
+
+  end
+
+  it "raises an error if you try to call top on an empty stack" do
+    s = Stack.new
+    s.empty?.must_equal true
+
+    proc {
+      s.top
+    }.must_raise ArgumentError
+  end
+
+
   # Challege Tests you could write yourself:
   # it "doesn't alter the size when you call top" do
   # it "raises an error if you try to pop from an empty stack" do