C# port of java's StreamTokenizer class. Everything kept same except some renaming for following C# naming convention. And it also implements IEnumerable for foreach support

StreamTokenizer.cs

/**
   * The <code>StreamTokenizer</code> class takes an input stream and
   * parses it into "tokens", allowing the tokens to be
   * Read one at a time. The parsing process is controlled by a table
   * and a number of flags that can be set to various states. The
   * stream tokenizer can recognize identifiers, numbers, quoted
   * strings, and various comment styles.
   * <p>
   * Each byte Read from the input stream is regarded as a character
   * in the range <code>'&#92;u0000'</code> through <code>'&#92;u00FF'</code>.
   * The character value is used to look up five possible attributes of
   * the character: <i>white space</i>, <i>alphabetic</i>,
   * <i>numeric</i>, <i>string quote</i>, and <i>comment character</i>.
   * Each character can have zero or more of these attributes.
   * <p>
   * In addition, an instance has four flags. These flags indicate:
   * <ul>
   * <li>Whether line terminators are to be returned as tokens or treated
   *     as white space that merely separates tokens.
   * <li>Whether C-style comments are to be recognized and skipped.
   * <li>Whether C++-style comments are to be recognized and skipped.
   * <li>Whether the characters of identifiers are converted to lowercase.
   * </ul>
   * <p>
   * A typical application first constructs an instance of this class,
   * sets up the syntax tables, and then repeatedly loops calling the
   * <code>nextToken</code> method in each iteration of the loop until
   * it returns the value <code>TT_EOF</code>.
   *
   */

  public class StreamTokenizer : IEnumerable<int>
  {

      /* Only one of these will be non-null */
      private StreamReader reader = null;

      private List<char> buf = new List<char>();

      /**
       * The next character to be considered by the nextToken method.  May also
       * be NEED_CHAR to indicate that a new character should be Read, or SKIP_LF
       * to indicate that a new character should be Read and, if it is a '\n'
       * character, it should be discarded and a second new character should be
       * Read.
       */
      private int peekc = NEED_CHAR;

      private const int NEED_CHAR = Int32.MaxValue;
      private const int SKIP_LF = Int32.MaxValue - 1;

      private bool pushedBack;
      private bool forceLower;
      /** The line number of the last token Read */

      private bool eolIsSignificantP = false;
      private bool slashSlashCommentsP = false;
      private bool slashStarCommentsP = false;

      private byte[] characterType = new byte[256];
      private const byte CT_WHITESPACE = 1;
      private const byte CT_DIGIT = 2;
      private const byte CT_ALPHA = 4;
      private const byte CT_QUOTE = 8;
      private const byte CT_COMMENT = 16;

      public int LineNumber { get; private set; }

      /**
       * After a call to the <code>nextToken</code> method, this field
       * contains the type of the token just Read. For a single character
       * token, its value is the single character, converted to an integer.
       * For a quoted string token, its value is the quote character.
       * Otherwise, its value is one of the following:
       * <ul>
       * <li><code>TT_WORD</code> indicates that the token is a word.
       * <li><code>TT_NUMBER</code> indicates that the token is a number.
       * <li><code>TT_EOL</code> indicates that the end of line has been Read.
       *     The field can only have this value if the
       *     <code>eolIsSignificant</code> method has been called with the
       *     argument <code>true</code>.
       * <li><code>TT_EOF</code> indicates that the end of the input stream
       *     has been reached.
       * </ul>
       * <p>
       * The initial value of this field is -4.
       *
       */
      public int ttype = TT_NOTHING;

      /**
       * A constant indicating that the end of the stream has been Read.
       */
      public const int TT_EOF = -1;

      /**
       * A constant indicating that the end of the line has been Read.
       */
      public const int TT_EOL = '\n';

      /**
       * A constant indicating that a number token has been Read.
       */
      public const int TT_NUMBER = -2;

      /**
       * A constant indicating that a word token has been Read.
       */
      public const int TT_WORD = -3;

      /* A constant indicating that no token has been Read, used for
       * initializing ttype.  FIXME This could be made public and
       * made available as the part of the API in a future release.
       */
      private const int TT_NOTHING = -4;

      /**
       * If the current token is a word token, this field contains a
       * string giving the characters of the word token. When the current
       * token is a quoted string token, this field contains the body of
       * the string.
       * <p>
       * The current token is a word when the value of the
       * <code>ttype</code> field is <code>TT_WORD</code>. The current token is
       * a quoted string token when the value of the <code>ttype</code> field is
       * a quote character.
       * <p>
       * The initial value of this field is null.
       *
       * @see     java.io.StreamTokenizer#quoteChar(int)
       * @see     java.io.StreamTokenizer#TT_WORD
       * @see     java.io.StreamTokenizer#ttype
       */
      public string StringValue { get; private set; }

      /**
       * If the current token is a number, this field contains the value
       * of that number. The current token is a number when the value of
       * the <code>ttype</code> field is <code>TT_NUMBER</code>.
       * <p>
       * The initial value of this field is 0.0.
       */
      public double NumberValue { get; private set; }

      /** Private constructor that initializes everything except the streams. */
      private StreamTokenizer() 
      {
          WordChars('a', 'z');
          WordChars('A', 'Z');
          WordChars(128 + 32, 255);
          WhitespaceChars(0, ' ');
          CommentChar('/');
          QuoteChar('"');
          QuoteChar('\'');
          ParseNumbers();
          LineNumber = 1;
      }

      /**
       * Create a tokenizer that parses the given character stream.
       *
       * @param r  a Reader object providing the input stream.
       */
      public StreamTokenizer(StreamReader r) : this()
      {
          if (r == null) 
          {
              throw new ArgumentNullException();
          }
          reader = r;
      }

      /**
       * Resets this tokenizer's syntax table so that all characters are
       * "ordinary." See the <code>ordinaryChar</code> method
       * for more information on a character being ordinary.
       */
      public void ResetSyntax() 
      {
          Array.Clear(characterType, 0, characterType.Length);
      }

      /**
       * Specifies that all characters <i>c</i> in the range
       * <code>low&nbsp;&lt;=&nbsp;<i>c</i>&nbsp;&lt;=&nbsp;high</code>
       * are word constituents. A word token consists of a word constituent
       * followed by zero or more word constituents or number constituents.
       *
       * @param   low   the low end of the range.
       * @param   hi    the high end of the range.
       */
      public void WordChars(int low, int hi) 
      {
          if (low < 0)
          {
              low = 0;
          }
          if (hi >= characterType.Length)
          {
              hi = characterType.Length - 1;
          }
          while (low <= hi)
          {
              characterType[low++] |= CT_ALPHA;
          }
      }

      /**
       * Specifies that all characters <i>c</i> in the range
       * <code>low&nbsp;&lt;=&nbsp;<i>c</i>&nbsp;&lt;=&nbsp;high</code>
       * are white space characters. White space characters serve only to
       * separate tokens in the input stream.
       *
       * <p>Any other attribute settings for the characters in the specified
       * range are cleared.
       *
       * @param   low   the low end of the range.
       * @param   hi    the high end of the range.
       */
      public void WhitespaceChars(int low, int hi) 
      {
          if (low < 0)
          {
              low = 0;
          }
          if (hi >= characterType.Length)
          {
              hi = characterType.Length - 1;
          }
          while (low <= hi)
          {
              characterType[low++] = CT_WHITESPACE;
          }
      }

      /**
       * Specifies that all characters <i>c</i> in the range
       * <code>low&nbsp;&lt;=&nbsp;<i>c</i>&nbsp;&lt;=&nbsp;high</code>
       * are "ordinary" in this tokenizer. See the
       * <code>ordinaryChar</code> method for more information on a
       * character being ordinary.
       *
       * @param   low   the low end of the range.
       * @param   hi    the high end of the range.
       * @see     java.io.StreamTokenizer#ordinaryChar(int)
       */
      public void OrdinaryChars(int low, int hi) 
      {
          if (low < 0)
          {
              low = 0;
          }
          if (hi >= characterType.Length)
          {
              hi = characterType.Length - 1;
          }
          while (low <= hi)
          {
              characterType[low++] = 0;
          }
      }
      /**
       * Specifies that the character argument is "ordinary"
       * in this tokenizer. It removes any special significance the
       * character has as a comment character, word component, string
       * delimiter, white space, or number character. When such a character
       * is encountered by the parser, the parser treats it as a
       * single-character token and sets <code>ttype</code> field to the
       * character value.
       *
       * <p>Making a line terminator character "ordinary" may interfere
       * with the ability of a <code>StreamTokenizer</code> to count
       * lines. The <code>lineno</code> method may no longer reflect
       * the presence of such terminator characters in its line count.
       *
       * @param   ch   the character.
       */
      public void OrdinaryChar(int ch) 
      {
          if (ch >= 0 && ch < characterType.Length)
              characterType[ch] = 0;
      }

      /**
       * Specified that the character argument starts a single-line
       * comment. All characters from the comment character to the end of
       * the line are ignored by this stream tokenizer.
       *
       * <p>Any other attribute settings for the specified character are cleared.
       *
       * @param   ch   the character.
       */
      public void CommentChar(int ch) 
      {
          if (ch >= 0 && ch < characterType.Length)
          {
              characterType[ch] = CT_COMMENT;
          }
      }
      
      /**
       * Specifies that matching pairs of this character delimit string
       * constants in this tokenizer.
       * <p>
       * When the <code>nextToken</code> method encounters a string
       * constant, the <code>ttype</code> field is set to the string
       * delimiter and the <code>sval</code> field is set to the body of
       * the string.
       * <p>
       * If a string quote character is encountered, then a string is
       * recognized, consisting of all characters after (but not including)
       * the string quote character, up to (but not including) the next
       * occurrence of that same string quote character, or a line
       * terminator, or end of file. The usual escape sequences such as
       * <code>"&#92;n"</code> and <code>"&#92;t"</code> are recognized and
       * converted to single characters as the string is parsed.
       *
       * <p>Any other attribute settings for the specified character are cleared.
       *
       * @param   ch   the character.
       */
      public void QuoteChar(int ch) {
          if (ch >= 0 && ch < characterType.Length)
          characterType[ch] = CT_QUOTE;
      }

      /**
       * Specifies that numbers should be parsed by this tokenizer. The
       * syntax table of this tokenizer is modified so that each of the twelve
       * characters:
       * <blockquote><pre>
       *      0 1 2 3 4 5 6 7 8 9 . -
       * </pre></blockquote>
       * <p>
       * has the "numeric" attribute.
       * <p>
       * When the parser encounters a word token that has the format of a
       * double precision floating-point number, it treats the token as a
       * number rather than a word, by setting the <code>ttype</code>
       * field to the value <code>TT_NUMBER</code> and putting the numeric
       * value of the token into the <code>nval</code> field.
       */
      public void ParseNumbers() 
      {
          for (int i = '0'; i <= '9'; i++)
          {
              characterType[i] |= CT_DIGIT;
          }
          characterType['.'] |= CT_DIGIT;
          characterType['-'] |= CT_DIGIT;
      }

      /**
       * Determines whether or not ends of line are treated as tokens.
       * If the flag argument is true, this tokenizer treats end of lines
       * as tokens; the <code>nextToken</code> method returns
       * <code>TT_EOL</code> and also sets the <code>ttype</code> field to
       * this value when an end of line is Read.
       * <p>
       * A line is a sequence of characters ending with either a
       * carriage-return character (<code>'&#92;r'</code>) or a newline
       * character (<code>'&#92;n'</code>). In addition, a carriage-return
       * character followed immediately by a newline character is treated
       * as a single end-of-line token.
       * <p>
       * If the <code>flag</code> is false, end-of-line characters are
       * treated as white space and serve only to separate tokens.
       *
       * @param   flag   <code>true</code> indicates that end-of-line characters
       *                 are separate tokens; <code>false</code> indicates that
       *                 end-of-line characters are white space.
       */
      public void EolIsSignificant(bool flag) 
      {
          eolIsSignificantP = flag;
      }

      /**
       * Determines whether or not the tokenizer recognizes C-style comments.
       * If the flag argument is <code>true</code>, this stream tokenizer
       * recognizes C-style comments. All text between successive
       * occurrences of <code>/*</code> and <code>*&#47;</code> are discarded.
       * <p>
       * If the flag argument is <code>false</code>, then C-style comments
       * are not treated specially.
       *
       * @param   flag   <code>true</code> indicates to recognize and ignore
       *                 C-style comments.
       */
      public bool SlashStarComments 
      {
          get { return slashStarCommentsP; }
          set { slashStarCommentsP=value; }
      }

      /**
       * Determines whether or not the tokenizer recognizes C++-style comments.
       * If the flag argument is <code>true</code>, this stream tokenizer
       * recognizes C++-style comments. Any occurrence of two consecutive
       * slash characters (<code>'/'</code>) is treated as the beginning of
       * a comment that extends to the end of the line.
       * <p>
       * If the flag argument is <code>false</code>, then C++-style
       * comments are not treated specially.
       *
       * @param   flag   <code>true</code> indicates to recognize and ignore
       *                 C++-style comments.
       */
      public bool SlashSlashComments 
      {
          get { return slashSlashCommentsP; }
          set { slashSlashCommentsP = value; }
      }

      /**
       * Determines whether or not word token are automatically lowercased.
       * If the flag argument is <code>true</code>, then the value in the
       * <code>sval</code> field is lowercased whenever a word token is
       * returned (the <code>ttype</code> field has the
       * value <code>TT_WORD</code> by the <code>nextToken</code> method
       * of this tokenizer.
       * <p>
       * If the flag argument is <code>false</code>, then the
       * <code>sval</code> field is not modified.
       *
       * @param   fl   <code>true</code> indicates that all word tokens should
       *               be lowercased.
       */
      public bool LowerCaseMode 
      {
          set{ forceLower = value; }
      }

      /** Read the next character */
      private int Read()
      {
          if (reader != null)
          {
              return reader.Read();
          }
          else
          {
              throw new InvalidOperationException();
          }
      }

      /**
       * Parses the next token from the input stream of this tokenizer.
       * The type of the next token is returned in the <code>ttype</code>
       * field. Additional information about the token may be in the
       * <code>nval</code> field or the <code>sval</code> field of this
       * tokenizer.
       * <p>
       * Typical clients of this
       * class first set up the syntax tables and then sit in a loop
       * calling nextToken to parse successive tokens until TT_EOF
       * is returned.
       *
       * @return     the value of the <code>ttype</code> field.
       */
      public int NextToken()
      {
          if (pushedBack) 
          {
              pushedBack = false;
              return ttype;
          }
          byte[] ct = characterType;
          StringValue = null;

          int c = peekc;
          if (c < 0)
              c = NEED_CHAR;
          if (c == SKIP_LF) {
              c = Read();
              if (c < 0)
              return ttype = TT_EOF;
              if (c == '\n')
              c = NEED_CHAR;
          }
          if (c == NEED_CHAR) {
              c = Read();
              if (c < 0)
              return ttype = TT_EOF;
          }
          ttype = c;      /* Just to be safe */

          /* Set peekc so that the next invocation of nextToken will Read
           * another character unless peekc is reset in this invocation
           */
          peekc = NEED_CHAR;

          int ctype = c < 256 ? ct[c] : CT_ALPHA;
          while ((ctype & CT_WHITESPACE) != 0) {
              if (c == '\r') {
              LineNumber++;
              if (eolIsSignificantP) {
                  peekc = SKIP_LF;
                  return ttype = TT_EOL;
              }
              c = Read();
              if (c == '\n')
                  c = Read();
              } else {
              if (c == '\n') {
                  LineNumber++;
                  if (eolIsSignificantP) {
                  return ttype = TT_EOL;
                  }
              }
              c = Read();
              }
              if (c < 0)
              return ttype = TT_EOF;
              ctype = c < 256 ? ct[c] : CT_ALPHA;
          }

          if ((ctype & CT_DIGIT) != 0) {
              bool neg = false;
              if (c == '-') {
              c = Read();
              if (c != '.' && (c < '0' || c > '9')) {
                  peekc = c;
                  return ttype = '-';
              }
              neg = true;
              }
              double v = 0;
              int decexp = 0;
              int seendot = 0;
              while (true) {
              if (c == '.' && seendot == 0)
                  seendot = 1;
              else if ('0' <= c && c <= '9') {
                  v = v * 10 + (c - '0');
                  decexp += seendot;
              } else
                  break;
              c = Read();
              }
              peekc = c;
              if (decexp != 0) {
              double denom = 10;
              decexp--;
              while (decexp > 0) {
                  denom *= 10;
                  decexp--;
              }
              /* Do one division of a likely-to-be-more-accurate number */
              v = v / denom;
              }
              NumberValue = neg ? -v : v;
              return ttype = TT_NUMBER;
          }

          if ((ctype & CT_ALPHA) != 0) {
              int i = 0;
              do {
              buf[i++] = (char) c;
              c = Read();
              ctype = c < 0 ? CT_WHITESPACE : c < 256 ? ct[c] : CT_ALPHA;
              } while ((ctype & (CT_ALPHA | CT_DIGIT)) != 0);
              peekc = c;
              StringValue = new string(buf.ToArray(), 0, i);
              if (forceLower)
              StringValue = StringValue.ToLower();
              return ttype = TT_WORD;
          }

          if ((ctype & CT_QUOTE) != 0) {
              ttype = c;
              int i = 0;
              /* Invariants (because \Octal needs a lookahead):
               *   (i)  c contains char value
               *   (ii) d contains the lookahead
               */
              int d = Read();
              while (d >= 0 && d != ttype && d != '\n' && d != '\r') {
                  if (d == '\\') {
                  c = Read();
                  int first = c;   /* To allow \377, but not \477 */
                  if (c >= '0' && c <= '7') {
                  c = c - '0';
                  int c2 = Read();
                  if ('0' <= c2 && c2 <= '7') {
                      c = (c << 3) + (c2 - '0');
                      c2 = Read();
                      if ('0' <= c2 && c2 <= '7' && first <= '3') {
                      c = (c << 3) + (c2 - '0');
                      d = Read();
                      } else
                      d = c2;
                  } else
                    d = c2;
                  } else {
                      switch (c) {
                  case 'a':
                      c = 0x7;
                      break;
                  case 'b':
                      c = '\b';
                      break;
                  case 'f':
                      c = 0xC;
                      break;
                  case 'n':
                      c = '\n';
                      break;
                      case 'r':
                      c = '\r';
                      break;
                  case 't':
                      c = '\t';
                      break;
                  case 'v':
                      c = 0xB;
                      break;
                  }
                  d = Read();
                  }
              } else {
                  c = d;
                  d = Read();
              }
              buf[i++] = (char)c;
              }

              /* If we broke out of the loop because we found a matching quote
               * character then arrange to Read a new character next time
               * around; otherwise, save the character.
               */
              peekc = (d == ttype) ? NEED_CHAR : d;

              StringValue = new string(buf.ToArray(), 0, i);
              return ttype;
          }

          if (c == '/' && (slashSlashCommentsP || slashStarCommentsP)) {
              c = Read();
              if (c == '*' && slashStarCommentsP) {
              int prevc = 0;
              while ((c = Read()) != '/' || prevc != '*') {
                  if (c == '\r') {
                  LineNumber++;
                  c = Read();
                  if (c == '\n') {
                      c = Read();
                  }
                  } else {
                      if (c == '\n') {
                      LineNumber++;
                      c = Read();
                  }
                  }
                  if (c < 0)
                      return ttype = TT_EOF;
                  prevc = c;
              }
              return NextToken();
              } else if (c == '/' && slashSlashCommentsP) {
                  while ((c = Read()) != '\n' && c != '\r' && c >= 0);
                  peekc = c;
              return NextToken();
              } else {
                      /* Now see if it is still a single line comment */
                      if ((ct['/'] & CT_COMMENT) != 0) {
                          while ((c = Read()) != '\n' && c != '\r' && c >= 0);
                          peekc = c;
                          return NextToken();
                      } else {
                          peekc = c;
                          return ttype = '/';
                      }
              }
              }

              if ((ctype & CT_COMMENT) != 0) {
                  while ((c = Read()) != '\n' && c != '\r' && c >= 0);
                  peekc = c;
                  return NextToken();
              }

          return ttype = c;
      }

      /**
       * Causes the next call to the <code>nextToken</code> method of this
       * tokenizer to return the current value in the <code>ttype</code>
       * field, and not to modify the value in the <code>nval</code> or
       * <code>sval</code> field.
       */
      public void PushBack()
      {
          if (ttype != TT_NOTHING)   /* No-op if nextToken() not called */
          {
              pushedBack = true;
          }
      }

      /**
       * Returns the string representation of the current stream token and
       * the line number it occurs on.
       *
       * <p>The precise string returned is unspecified, although the following
       * example can be considered typical:
       *
       * <blockquote><pre>Token['a'], line 10</pre></blockquote>
       *
       * @return  a string representation of the token
       */
      public override string ToString() 
      {
          string ret;
          switch (ttype) {
            case TT_EOF:
              ret = "EOF";
              break;
            case TT_EOL:
              ret = "EOL";
              break;
            case TT_WORD:
              ret = StringValue;
              break;
            case TT_NUMBER:
              ret = "n=" + NumberValue;
              break;
            case TT_NOTHING:
              ret = "NOTHING";
              break;
            default: {
              /* 
               * ttype is the first character of either a quoted string or
               * is an ordinary character. ttype can definitely not be less
               * than 0, since those are reserved values used in the previous
               * case statements
               */
              if (ttype < 256 && 
                  ((characterType[ttype] & CT_QUOTE) != 0)) {
                  ret = StringValue;
                  break;
              }

              char[] s = new char[3];
              s[0] = s[2] = '\'';
              s[1] = (char) ttype;
              ret = new string(s);
              break;
              }
          }
          return "Token[" + ret + "], line " + LineNumber;
      }


      public IEnumerator<int> GetEnumerator()
      {
          ResetSyntax();
          while(true)
          {
              int token = NextToken();
              if(token == TT_EOF)
              {
                  yield break;
              }
              yield return token;
          }
      }

      System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
      {
          return GetEnumerator();
      }
  }

thank you

still seeing use