In Part 1, we configured classes for our stack of meals, and queue of guests. Now let's setup our Party class, which accepts our arrays of meals & guests, and initializes instances of MealStack and GuestQueue.
class Party
attr_accessor :meals, :guests
def initialize(meals_array, guest_array)
self.meals = MealStack.new(meals_array)
self.guests = GuestQueue.new(guest_array)
end
end
It would be nice to view the meals and guests at any point during the party, so let's create a view_party method for that:
def view_party
puts "Party Status:\n Meals: #{meals.display_meals}\n Guests: #{guests.display_queue}\n\n"
end
For a guest to be properly served, the meal at the top of the stack has to match the meal preference of the first guest in the queue. So we create a method match? that checks for this:
def match?
meals.top_meal == guests.first_guest
end
Next we create a move_queue method that does three things:
- Shows us the party status
- Removes guests that have been served successfully
- Moves guests in front of the queue to the back when the top meal doesn't match their preference
We're also including some statements to clue us in to what is happening.
For a meal-guest match, the top meal is removed and the first guest leaves the queue. For a mismatch, the first guest moves to the back of the queue and the move_queue method is called again for the updated first guest:
def move_queue
view_party
if match?
meals.take_meal
served = guests.leave_queue
puts "Guest wanting a #{served} meal has been served\n\n"
else
guests.rejoin_queue
puts "No one was served the last round\n\n"
move_queue
end
end
Finally, we'll create a meal_service method that sets everything in motion. The meal service will run until either all meals are gone, or all guests have been served. A cute "party report" is generated after the meal service concludes:
def meal_service
until meals.stack_empty? || guests.queue_empty?
move_queue
end
puts "Meals Left: #{meals.display_meals}\nUnserved Guests: #{guests.display_queue}"
end
Awesome! Let's build a party with the following meals and guests:
my_party = Party.new(%w[vegetarian vegan normal paleo], %w[normal paleo vegan vegetarian])
my_party.meal_service
And here's the complete file:
class MealStack
attr_accessor :meals
def initialize(meals_array)
self.meals = meals_array
end
def top_meal
meals.last
end
def take_meal
meals.pop
end
def stack_empty?
meals.empty?
end
def display_meals
meals.reverse.inspect
end
def size
meals.length
end
end
class GuestQueue
attr_accessor :guests
def initialize(guest_array)
self.guests = guest_array
end
def first_guest
guests.first
end
def join_queue(guest)
guests.push(guest)
end
def leave_queue
guests.shift
end
def rejoin_queue
join_queue(leave_queue)
end
def queue_empty?
guests.empty?
end
def display_queue
guests.inspect
end
def size
guests.length
end
end
class Party
attr_accessor :meals, :guests
def initialize(meals_array, guest_array)
self.meals = MealStack.new(meals_array)
self.guests = GuestQueue.new(guest_array)
end
def view_party
puts "Party Status:\n Meals: #{meals.display_meals}\n Guests: #{guests.display_queue}\n\n"
end
def match?
meals.top_meal == guests.first_guest
end
def move_queue
view_party
if match?
meals.take_meal
served = guests.leave_queue
puts "Guest wanting a #{served} meal has been served\n\n"
else
guests.rejoin_queue
puts "No one was served the last round\n\n"
move_queue
end
end
def meal_service
until meals.stack_empty? || guests.queue_empty?
move_queue
end
puts "Meals Left: #{meals.display_meals}\nUnserved Guests: #{guests.display_queue}"
end
end
my_party = Party.new(%w[vegetarian vegan normal paleo], %w[normal paleo vegan vegetarian])
my_party.meal_service
Here is my output after running my program's file in Terminal:
Party Status:
Meals: ["paleo", "normal", "vegan", "vegetarian"]
Guests: ["normal", "paleo", "vegan", "vegetarian"]
No one was served the last round
Party Status:
Meals: ["paleo", "normal", "vegan", "vegetarian"]
Guests: ["paleo", "vegan", "vegetarian", "normal"]
Guest wanting a paleo meal has been served
Party Status:
Meals: ["normal", "vegan", "vegetarian"]
Guests: ["vegan", "vegetarian", "normal"]
No one was served the last round
Party Status:
Meals: ["normal", "vegan", "vegetarian"]
Guests: ["vegetarian", "normal", "vegan"]
No one was served the last round
Party Status:
Meals: ["normal", "vegan", "vegetarian"]
Guests: ["normal", "vegan", "vegetarian"]
Guest wanting a normal meal has been served
Party Status:
Meals: ["vegan", "vegetarian"]
Guests: ["vegan", "vegetarian"]
Guest wanting a vegan meal has been served
Party Status:
Meals: ["vegetarian"]
Guests: ["vegetarian"]
Guest wanting a vegetarian meal has been served
Meals Left: []
Unserved Guests: []
YAY! Everyone was served, and our shindig was a success! But let's think for a minute: even though some of our guests had to rejoin the queue due to meal mismatches, everyone eventually got served because there was 1 meal present for every guest.
What if there was a meal on our stack that nobody wanted? Well, due to how stacks work, we can't access any meals under the unwanted meal until we get rid of said meal. However, we don't want to trash any top meal until we know for sure that no guests want it. That's what we'll be looking at in Part 3...
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