---

Lexer.java

package gov.nasa.arc.ase.util;

public class Lexer {
  public static final char STRING = 'S';
  public static final char INTEGER = 'I';
  public static final char END = 'E';
  public static final char ID = 'i';
  public static final char LOGICAND = 'a';
  public static final char LOGICOR = 'o';
  public static final char EQUAL = 'e';
  public static final char LESSEQUAL = 'l';
  public static final char GREATEREQUAL = 'g';

  private char[] data;
  private int length;
  private int offset;
  private StringBuffer string;

  public Lexer(String s) {
    length = s.length();
    data = new char[length];
    for(int i = 0; i < length; i++)
      data[i] = s.charAt(i);
    offset = 0;
  }  
  public int getIntValue() {
    return Integer.parseInt(string.toString());
  }  
  public String getStringValue() {
    return string.toString();
  }  
  public char lex() throws LexerException {
    try {
      while(true) {
    switch(data[offset]) {
      case '\'': offset++; return parseQuoted('\'');
      case '"':  offset++; return parseQuoted('"');
      case ',':  offset++; return ',';
      case ';':  offset++; return ';';
      case ':':  offset++; return ':';
      case '.':  offset++; return '.';
      case '(':  offset++; return '(';
      case ')':  offset++; return ')';
      case ' ':  offset++; break;
      case '\t': offset++; break;

      case '=':
             offset++;
             if(data[offset] == '=') {
               offset++;
               return Lexer.EQUAL;
             }
             throw new LexerException("Unexpected character '" + data[offset] + "'");

      case '<':
             offset++;
             if(data[offset] == '=') {
               offset++;
               return Lexer.LESSEQUAL;
             }
             return '<';

      case '>':
             offset++;
             if(data[offset] == '=') {
               offset++;
               return Lexer.GREATEREQUAL;
             }
             return '>';

      case '&':
             offset++;
             if(data[offset] == '&') {
               offset++;
               return Lexer.LOGICAND;
             }
             return '&';

      case '|':
             offset++;
             if(data[offset] == '|') {
               offset++;
               return Lexer.LOGICOR;
             }
             return '|';

      default:
             if(Character.isDigit(data[offset])) return parseInt();
             if(Character.isJavaIdentifierStart(data[offset])) return parseId();
             throw new LexerException("invalid character '" + data[offset] + "'");
    }
      }
    } catch(ArrayIndexOutOfBoundsException e) {
      return END; 
    }
  }  
  private char parseId() {
    string = new StringBuffer();

    try {
      while(Character.isJavaIdentifierPart(data[offset]))
    string.append(data[offset++]);
    } catch(IndexOutOfBoundsException e) {
    }

    return ID;
  }  
  private char parseInt() {
    string = new StringBuffer();

    try {
      while(Character.isDigit(data[offset]))
    string.append(data[offset++]);
    } catch(IndexOutOfBoundsException e) {
    }

    return INTEGER;
  }  
  private char parseQuoted(char quote) {
    string = new StringBuffer();

    try {
      while(data[offset] != quote)
    string.append(data[offset++]);
      offset++;
    } catch(IndexOutOfBoundsException e) {
    }

    return STRING;
  }  
}

---