LINQPadless helper for LINQPad's Util 📄 http://share.linqpad.net/age6lg.linq

Util.linq

<Query Kind="Program">
  <Namespace>System.Globalization</Namespace>
  <RemoveNamespace>System.Collections</RemoveNamespace>
  <RemoveNamespace>System.Data</RemoveNamespace>
  <RemoveNamespace>System.Diagnostics</RemoveNamespace>
  <RemoveNamespace>System.Linq.Expressions</RemoveNamespace>
  <RemoveNamespace>System.Reflection</RemoveNamespace>
  <RemoveNamespace>System.Text</RemoveNamespace>
  <RemoveNamespace>System.Text.RegularExpressions</RemoveNamespace>
  <RemoveNamespace>System.Threading</RemoveNamespace>
  <RemoveNamespace>System.Transactions</RemoveNamespace>
  <RemoveNamespace>System.Xml</RemoveNamespace>
  <RemoveNamespace>System.Xml.Linq</RemoveNamespace>
  <RemoveNamespace>System.Xml.XPath</RemoveNamespace>
</Query>

static class Util
{
#if LINQPAD

    public static string CurrentQueryName => LINQPad.Util.CurrentQuery.Name;
    public static string CurrentQueryPath => LINQPad.Util.CurrentQueryPath;

    public static string ReadLine() =>
        ReadLine(null);
    public static string ReadLine(string prompt) =>
        LINQPad.Util.ReadLine(prompt);

    public static string ReadLine(string prompt, string defaultValue) =>
        LINQPad.Util.ReadLine(prompt, defaultValue);

    public static string ReadLine(string prompt, string defaultValue, IEnumerable<string> suggestions) =>
        LINQPad.Util.ReadLine(prompt, defaultValue, suggestions);

#else

    static LINQPad.Query _currentQuery;

    public static string CurrentQueryPath => Environment.GetEnvironmentVariable("LPLESS_LINQ_FILE_PATH") ?? UserQuery.PATH;
    public static LINQPad.Query CurrentQuery => _currentQuery ??= new LINQPad.Query(CurrentQueryPath);
    public static string CurrentQueryName => CurrentQuery.Name;

    public static string ReadLine() =>
        ReadLine(null);

    public static string ReadLine(string prompt) =>
        ReadLine(prompt, null);

    public static string ReadLine(string prompt, string defaultValue) =>
        ReadLine(prompt, defaultValue, null);

    public static string ReadLine(string prompt, string defaultValue, IEnumerable<string> suggestions)
    {
        var suggestionList =
            (suggestions ?? Enumerable.Empty<string>())
                .Select((s, i) => new KeyValuePair<int, string>(i + 1, s))
                .ToList();

        if (defaultValue != null)
            suggestionList.Insert(0, new KeyValuePair<int, string>(0, defaultValue));

        foreach (var (n, s) in suggestionList)
            Console.Error.WriteLine($"{n}. {s}");

        var raw = suggestionList.Count == 0;
        if (!raw)
            Console.Error.WriteLine("(start with $ for custom line where \"$example\" becomes \"example\")");

        while (true)
        {
            Console.Error.Write(prompt + " ");
            Console.Error.Flush();
            var line = Console.ReadLine();

            Console.Error.WriteLine(line);

            if (line is null)
                return null;

            if (raw)
                return line;

            if (line.Length > 0 && line[0] == '$')
                return line.Substring(1);

            if (defaultValue != null && line.Length == 0)
                return defaultValue;

            if (int.TryParse(line, NumberStyles.None, CultureInfo.InvariantCulture, out var selection)
                && suggestionList.FindIndex(s => s.Key == selection) is {} i && i >= 0)
            {
                return suggestionList[i].Value;
            }

            Console.Error.WriteLine("Invalid entry!");
        }
    }

#endif
}

namespace LINQPad
{
#if !LINQPAD

    public sealed class Query
    {
        public Query(string path) =>
            FilePath = path ?? throw new ArgumentNullException(nameof(path));

        public string Name => Path.GetFileNameWithoutExtension(FilePath);
        public string FilePath { get; }
        public string Location => Path.GetDirectoryName(FilePath);
    }

#endif
}

void Main() {}