// Пацеев Андрей. Лабараторная №1. Задания №1 - №5

​

public class LexerException : System.Exception

{

    public LexerException(string msg)

        : base(msg)

    {

    }

​

}

​

public class Lexer

{

​

    protected int position;

    protected char currentCh;      

    protected int currentCharValue; 

    protected System.IO.StringReader inputReader;

    protected string inputString;

​

    public Lexer(string input)

    {

        inputReader = new System.IO.StringReader(input);

        inputString = input;

    }

​

    public void Error()

    {

        System.Text.StringBuilder o = new System.Text.StringBuilder();

        o.Append(inputString + '\n');

        o.Append(new System.String(' ', position - 1) + "^\n");

        o.AppendFormat("Error in symbol {0}", currentCh);

        throw new LexerException(o.ToString());

    }

​

    protected void NextCh()

    {

        this.currentCharValue = this.inputReader.Read();

        this.currentCh = (char)currentCharValue;

        this.position += 1;

    }

​

    public virtual void Parse()

    {

​

    }

}

​

public class IntLexer : Lexer

{

​

    protected System.Text.StringBuilder intString;

    protected string tester;

​

    public IntLexer(string input)

        : base(input)

    {

        intString = new System.Text.StringBuilder();

    }

​

    public override void Parse()

    {

        NextCh();

        if (currentCh == '+' || currentCh == '-')

        {

            tester += currentCh;

            NextCh();

        }

​

        if (char.IsDigit(currentCh))

        {

            tester += currentCh;

            NextCh();

        }

        else

        {

            Error();

        }

​

        while (char.IsDigit(currentCh))

        {

            tester += currentCh;

            NextCh();

        }

​

​

        if (currentCharValue != -1)

        {

            Error();

        }

​

        System.Console.WriteLine("Integer is recognized");

        System.Console.WriteLine("Recognized int: " + int.Parse(this.tester));

​

    }

}

​

// б(б|ц)*

public class IdLexer : Lexer

{

​

    protected System.Text.StringBuilder intString;

​

    public IdLexer(string input)

        : base(input)

    {

        intString = new System.Text.StringBuilder();

    }

​

    public override void Parse()

    {

        NextCh();

        if (char.IsLetter(currentCh))

        {

            NextCh();

        } 

        else 

        {

            Error();

        }

​

        while (char.IsDigit(currentCh) || char.IsLetter(currentCh))

        {

            NextCh();

        }

​

​

        if (currentCharValue != -1)

        {

            Error();

        }

​

        System.Console.WriteLine("Id is recognized");

​

    }

}

​

// (+ | -)(1..9)(0..9)*

public class CorrectIntLexer : Lexer

{

​

    protected System.Text.StringBuilder intString;

​

    public CorrectIntLexer(string input)

        : base(input)

    {

        intString = new System.Text.StringBuilder();

    }

​

    public override void Parse()

    {

        NextCh();

        if (currentCh == '+' || currentCh == '-')

        {

            NextCh();

        } 

        else 

        {

            Error();

        }

        if (currentCh == '0')

            Error();

​

        while (char.IsDigit(currentCh))

        {

            NextCh();

        }

​

​

        if (currentCharValue != -1)

        {

            Error();

        }

​

        System.Console.WriteLine("Correct int is recognized");

​

    }

}

​

// 

public class AlternateLetterDigitLexer : Lexer

{

​

    protected System.Text.StringBuilder intString;

​

    public AlternateLetterDigitLexer(string input)

        : base(input)

    {

        intString = new System.Text.StringBuilder();

    }

​

    public override void Parse()

    {

        bool valid = true;

        NextCh();

        while (valid && currentCharValue != -1) {

            if (char.IsLetter(currentCh)) {

                NextCh();

                if (currentCharValue == -1)

                    break;

                else if (char.IsDigit(currentCh))

                    NextCh();

                else

                    valid = false;

            } else

                valid = false;

        }

        if (!valid)

        {

            Error();

        } 

​

        System.Console.WriteLine("Correct alternate is recognized");

​

    }

}

​

// (a..z)(, | ;)...

public class SeparatedLetters : Lexer

{

​

    protected System.Text.StringBuilder intString;

    protected string tester;

​

    public SeparatedLetters(string input)

        : base(input)

    {

        intString = new System.Text.StringBuilder();

    }

​

    public override void Parse()

    {

        bool valid = true;

        bool letterNext = true;

        NextCh();

        while (letterNext && valid && currentCharValue != -1) {

            if (char.IsLetter(currentCh)) {

                tester += currentCh;

                letterNext = false;

                NextCh();

                if (currentCharValue == -1)

                    break;

                else if (currentCh == ';' || currentCh == ',') {

                    NextCh();

                    letterNext = true;

                } else

                    valid = false;

            } else

             valid = false;

        }

        if (!valid || letterNext)

        {

            Error();

        } 

​

        System.Console.WriteLine("Separated letters is recognized");

        System.Console.WriteLine("Separated string is: " + tester);

​

    }

}

​

​

​

public class Program

{

    public static void Main()

    {

        string input = "154216";

        string id = "a423423a";

        string idIncorrect = "432b";

        string correctInt1 = "+423432a";

        string correctInt2 = "-33213";

        string incorrectInt3 = "-3";

        string alternate = "a2b3c";

        string alternateIncorrect = "a22b";

        string separated = ";";

        string separatedIncorrect = "a";

        Lexer intLex = new IntLexer(input);

        Lexer idLex = new IdLexer(id);

        Lexer idLex2 = new IdLexer(idIncorrect);

        Lexer correctIntLex1 = new CorrectIntLexer(correctInt1);

        Lexer correctIntLex2 = new CorrectIntLexer(correctInt2);

        Lexer incorrectIntLex3 = new CorrectIntLexer(incorrectInt3);

        Lexer altLex = new AlternateLetterDigitLexer(alternate);

        Lexer altLex2 = new AlternateLetterDigitLexer(alternateIncorrect);

        Lexer sepLex = new SeparatedLetters(separated);

        Lexer sepLex2 = new SeparatedLetters(separatedIncorrect);

        try

        {

            //intLex.Parse();

            //idLex.Parse();

            //idLex2.Parse();

            //correctIntLex1.Parse();

            //correctIntLex2.Parse();

            //incorrectIntLex3.Parse();

            //altLex.Parse();

            //altLex2.Parse();

            //sepLex.Parse();

            //sepLex2.Parse();

        }

        catch (LexerException e)

        {

            System.Console.WriteLine(e.Message);

        }

​

    }

}