My implementation in Ruby of the KataBowling challenge, based on a game of standard 10-pin American bowling. It successfully scores a game of bowling if a valid turn sequence is passed in.
- 10 turns allowed per game.
- 2 rolls allowed per turn.
- If bowler fails to knock both down, score for that turn is sum of its rolls rolls.
- Spare: bowler knocks down 10 on roll #2. Score is 10 + next roll score.
- Strike: bowler knocks down 10 on roll #1. Score is 10 + next 2 throw scores.
- Spare or strike on last turn (turn 10), gets 1 or 2 bonus rolls respectively. These bonus rolls count toward the 10th turn.
I chose to structure the turns as an array of arrays. Since the kata doesn't require checking for invalid roll sequences, I simply check for a bonus based on the array count. If a bonus exists, it gets defined as bonus, removed from the turns, and added on to the final turn score.
To deal with consecutive strike scoring, I have a strike_scorer method that looks ahead at the following two turns, and checks to see if they are also strikes. My main scorer method is where the magic happens - a while loop iterates through each turn in the array except the 10th turn, then the 10th turn is dealt with based on whether a bonus exists or not.