day2parser.ex

defmodule Day02.Parser do
  import NimbleParsec

  # Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue

  game_id = ignore(string("Game ")) |> integer(min: 1, max: 4) |> unwrap_and_tag(:game_id)

  red = replace(string("red"), :red)
  green = replace(string("green"), :green)
  blue = replace(string("blue"), :blue)

  color = choice([red, green, blue])

  cube_separator = optional(string(", "))

  cube = integer(min: 1, max: 4) |> ignore(string(" ")) |> concat(color) |> ignore(optional(cube_separator)) 

  round_separator = optional(string("; "))

  round = times(cube, min: 1) |> ignore(round_separator) |> tag(:round)

  rounds = times(round, min: 1) |> tag(:rounds)

  defparsec :game, game_id |> ignore(string(": ")) |> concat(rounds) |> eos(), debug: true

end

output.txt

iex(1)> line = "Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue"
iex(2)> Day02.Parser.game(line)
{:ok,
 [
   game_id: 2,
   rounds: [
     round: [1, :blue, 2, :green],
     round: [3, :green, 4, :blue, 1, :red],
     round: [1, :green, 1, :blue]
   ]
 ], "", %{}, {1, 0}, 64}
iex(3)>