AdventOfCode23/Day3/SchematicParser.cs

using System.Text.RegularExpressions;

namespace Day3;

public partial class SchematicParser
{
    [GeneratedRegex(@"\d+|[^\d.]+")]
    private partial Regex TokenExtractor();
    
    public int Width { get; private set; }
    public int Height { get; private set; }
    
    public IEnumerable<Token> Parse(string inputFile)
    {
        using var reader = File.OpenText(inputFile);
        var row = 0;
        while (!reader.EndOfStream)
        {
            var line = reader.ReadLine()!;
            if (Width == 0)
            {
                Width = line.Length;
            }
            foreach (Match match in TokenExtractor().Matches(line))
            {
                if (match.Value[0] >= '0' && match.Value[0] <= '9')
                {
                    yield return new NumberToken(match.Index, row, match.Value);
                }
                else
                {
                    if (match.Length > 1)
                    {
                        throw new Exception($"Unexpected symbol token: {match.Value}");
                    }

                    yield return new SymbolToken(match.Index, row, match.Value);
                }
            }

            row++;
        }

        Height = row;
    }
}