ics.cs is a C# repl

ics.cs

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.CSharp;
using System.CodeDom.Compiler;
using System.Reflection;
using System.IO;

namespace ics
{
    class Program
    {
        const string classname = "ClassNameWhichMustNotBeNamed";
        const string methodname = "MethodNameWhichMustNotBeNamed";

        static string template =
            String.Format(
                "using {{0}};public static class {0}{{{{ public static object {1}(List<string> useList, Dictionary<string, object> dict, object _) {{{{object ret=\n{{1}}; return ret; }}}} }}}}",
                classname, methodname);

        static void Main(string[] args)
        {
            CSharpCodeProvider p = new CSharpCodeProvider();
            CompilerParameters param = new CompilerParameters();
            param.GenerateInMemory = true;

            List<string> useList = new List<string>();
            Dictionary<string, object> dict = new Dictionary<string, object>();
            object last = null;

            useList.Add("System");
            useList.Add("System.Collections.Generic");

            for (; ; )
            {
                Console.Write("> ");

                string line = Console.ReadLine();

                if (line == null) break;
                else if (line == "") continue;

                if (line == "help")
                {
                    Console.WriteLine("手抜き C# インタプリタ");
                    Console.WriteLine("エラー表示の左の数字は入力の桁数です");
                    Console.WriteLine("定義済みの変数:\n  _: 前回の返り値か例外\n  useList: using節で使う名前空間のリスト\n  dict: ご自由にお使いください");
                    Console.WriteLine("tips:\n  ・末尾のセミコロンは省略可\n  ・void型の文はこうすると動く");
                    Console.WriteLine("      > null; Console.WriteLine(\"fuga\")");
                    continue;
                }

                string code = String.Format(template, String.Join(";using ", useList.ToArray()), line);

                CompilerResults r = p.CompileAssemblyFromSource(param, code);


                //System.Reflection.Assembly.LoadFile("maze.exe");
                if (r.NativeCompilerReturnValue != 0)
                {
                    foreach (CompilerError err in r.Errors)
                    {
                        Console.WriteLine("{0}: {1}", err.Column, err.ErrorText);
                    }
                }
                else
                {
                    MethodInfo m = r.CompiledAssembly.GetType(classname).GetMethod(methodname);
                    try
                    {
                        object result = m.Invoke(null, new object[] { useList, dict, last });

                        if (result != null)
                        {
                            Console.WriteLine(result);
                            last = result;
                        }
                    }
                    catch (TargetInvocationException e)
                    {
                        Console.WriteLine("例外が飛びました (変数 _ に入っています)");
                        last = e.InnerException;
                    }
                }
            }
        }
    }
}