Error.cs

/*
 * Class: Error
 */
using System;

public class Error
{
    /*
     * Function: impos
     */
    public static void impos(String message)
    {
        Console.WriteLine("Lex Error: " + message);
    }

    /*
     * Constants
     * Description: Error codes for parse_error().
     */
    public const int E_BADEXPR = 0;
    public const int E_PAREN = 1;
    public const int E_LENGTH = 2;
    public const int E_BRACKET = 3;
    public const int E_BOL = 4;
    public const int E_CLOSE = 5;
    public const int E_NEWLINE = 6;
    public const int E_BADMAC = 7;
    public const int E_NOMAC = 8;
    public const int E_MACDEPTH = 9;
    public const int E_INIT = 10;
    public const int E_EOF = 11;
    public const int E_DIRECT = 12;
    public const int E_INTERNAL = 13;
    public const int E_STATE = 14;
    public const int E_MACDEF = 15;
    public const int E_SYNTAX = 16;
    public const int E_BRACE = 17;
    public const int E_DASH = 18;
    public const int E_ZERO = 19;

    /********************************************************
      Constants
      Description: String messages for parse_error();
      *******************************************************/
    public static String errmsg(int i)
    {
        switch (i)
        {
            case 0: return "Malformed regular expression.";
            case 1: return "Missing close parenthesis.";
            case 2: return "Too many regular expressions or expression too long.";
            case 3: return "Missing [ in character class.";
            case 4: return "^ must be at start of expression or after [.";
            case 5: return "+ ? or * must follow an expression or subexpression.";
            case 6: return "Newline in quoted string.";
            case 7: return "Missing } in macro expansion.";
            case 8: return "Macro does not exist.";
            case 9: return "Macro expansions nested too deeply.";
            case 10: return "Lex has not been successfully initialized.";
            case 11: return "Unexpected end-of-file found.";
            case 12: return "Undefined or badly-formed Lex directive.";
            case 13: return "Internal Lex error.";
            case 14: return "Unitialized state name.";
            case 15: return "Badly formed macro definition.";
            case 16: return "Syntax error.";
            case 17: return "Missing brace at start of lexical action.";
            case 18: return "Special character dash - in character class [...] must\n"
                  + "\tbe preceded by start-of-range character.";
            case 19: return "Zero-length regular expression.";
        };
        return null;
    }
    /*
     * Function: parse_error
     */
    public static void parse_error(int error_code, int line_number)
    {
        Console.WriteLine("Error: Parse error at line "
                  + line_number + ".");
        Console.WriteLine("Description: " + errmsg(error_code));
        //  throw new ApplicationException("Parse error.");
        System.Environment.Exit(1);
    }
}