AdventOfCode23/Day18/Parser.cs

using System.Drawing;
using System.Text.RegularExpressions;

namespace Day18;

public partial class Parser
{
    [GeneratedRegex(@"([UDLR])\s+(\d+)\s+\((.*)\)")]
    private partial Regex LineMatch();
    
    public IEnumerable<Instruction> Parse(string inputFile)
    {
        using var reader = File.OpenText(inputFile);
        var colorConverter = new ColorConverter();
        
        while (!reader.EndOfStream)
        {
            var line = reader.ReadLine()!;
            var match = LineMatch().Match(line);
            if (!match.Success)
            {
                throw new Exception($"Invalid instruction: {line}");
            }

            yield return new Instruction(
                match.Groups[1].Value[0],
                int.Parse(match.Groups[2].Value),
                (Color)colorConverter.ConvertFromString(match.Groups[3].Value)!);
        }
    }
}