/IronBrainFuck/Parser/BrainParser.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace ZackFlame.IronBrainFuck.Parser

{

    /// <summary>

    /// Предоставляет методы для парсинга BrainFuck программы.

    /// </summary>

    public static class BrainParser

    {

        const string AllowedChars = "+-><[].,#@";



        internal static readonly BrainOperation[] SingleOperations =

            new BrainOperation[]

            {

                BrainOperation.CycleOpen,

                BrainOperation.CycleClose,

                BrainOperation.Write,

                BrainOperation.Read,

                BrainOperation.SpecialWrite,

                BrainOperation.SpecialRead,

            };



        /// <summary>

        /// Преобразует BrainFuck программу в массив экземпляров BrainAction.

        /// </summary>

        /// <param name="brainFuckProgram">BrainFuck программа.</param>

        /// <returns>Разобранная BrainFuck программа.</returns>

        public static BrainAction[] Parse(string brainFuckProgram)

        {

            // Удаляем лишние символы

            StringBuilder programBuilder = new StringBuilder();

            for (int i = 0; i < brainFuckProgram.Length; i++)

            {

                if (AllowedChars.IndexOf(brainFuckProgram[i]) != -1)

                    programBuilder.Append(brainFuckProgram[i]);

            }

            string program = programBuilder.ToString();



            // Парсим

            List<BrainAction> actions = new List<BrainAction>();

            BrainOperation previous = BrainOperation.None;

            BrainOperation operation = BrainOperation.None;

            uint count = 0;



            for (int i = 0; i < program.Length; i++)

            {

                previous = operation;



                switch (program[i])

                {

                    case '+':

                        operation = BrainOperation.Add;

                        break;

                    case '-':

                        operation = BrainOperation.Sub;

                        break;

                    case '>':

                        operation = BrainOperation.Right;

                        break;

                    case '<':

                        operation = BrainOperation.Left;

                        break;

                    case '[':

                        if (i < program.Length - 2 && program[i + 2] == ']' &&

                            (program[i + 1] == '-' || program[i] == '+'))

                        {

                            operation = BrainOperation.Zero;

                            i += 2;

                        }

                        else

                        {

                            operation = BrainOperation.CycleOpen;

                        }

                        break;

                    case ']':

                        operation = BrainOperation.CycleClose;

                        break;

                    case '.':

                        operation = BrainOperation.Write;

                        break;

                    case ',':

                        operation = BrainOperation.Read;

                        break;

                    case '#':

                        operation = BrainOperation.SpecialWrite;

                        break;

                    case '@':

                        operation = BrainOperation.SpecialRead;

                        break;

                    default:

                        operation = BrainOperation.None;

                        break;

                }



                if (operation != previous)

                {

                    actions.Add(new BrainAction(previous, count));

                    count = 1;

                }

                else

                {

                    if (SingleOperations.Contains(previous))

                        actions.Add(new BrainAction(previous, 1));

                    else

                        count++;

                }

            }



            if (operation != BrainOperation.None)

                actions.Add(new BrainAction(operation, count));



            return actions.ToArray();

        }

    }

}