scanword.java

java 作图的程序

package graph;

import java.awt.*;
import java.applet.*;
import java.util.*;
import java.lang.*;
import java.io.StreamTokenizer;
import java.io.InputStream;
import java.io.IOException;
import java.net.URL;

/*
************************************************************************
**
**    Class  ScanWord
**
**************************************************************************
**    Copyright (C) 1996 Leigh Brookshaw
**
**    This program is free software; you can redistribute it and/or modify
**    it under the terms of the GNU General Public License as published by
**    the Free Software Foundation; either version 2 of the License, or
**    (at your option) any later version.
**
**    This program is distributed in the hope that it will be useful,
**    but WITHOUT ANY WARRANTY; without even the implied warranty of
**    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**    GNU General Public License for more details.
**
**    You should have received a copy of the GNU General Public License
**    along with this program; if not, write to the Free Software
*    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**************************************************************************/


/**
 * This class extends the StreamTokenizer class. It allows words
 * to be defined and recognised and returned as a token. The TT_NUMBER
 * token of the StreamTokenizer is also modified so that scientific notation
 * is recognised.
 *
 * @version $Revision: 1.5 $, $Date: 1996/07/24 00:19:41 $
 * @author Leigh Brookshaw
 */

public class ScanWord extends StreamTokenizer {

/*
*********************
** Public Constants
********************/

/**
 * Token returned when an unknown characters match nothing
 */
     public final static int UNKNOWN = -256;

/**
 * Token returned when an error is encountered
 */
     public final static int ERROR   = -257;
/**
 * Token returned when a string has been found. A string is defined to be
 * text between matching quotes " ".
 */
     public final static int STRING  = -258;


/********************
** Private Variables
********************/

     private InputStream is = null;
/*
**   The hash table containing the keyword/value pairs.
*/     
     private Hashtable kwords = new Hashtable();
/*
**   The character that delimeters a string
*/
     private char StringChar  = '"';

/*
******************
**
** Constructors
**
*****************/

/**
 * Instantiate the class with the parsed input stream.
 * @param in Input stream to read from
 */
     public ScanWord( InputStream in ) {
           super(in);
           this.is = in;
           resetWordSyntax();
     }
     
/*
*******************
**
**  Public Methods
**
*******************/

/**
 * Add a keyword/token pair.
 * @param s String contining the keyword
 * @param i Token to return when the keyword is encountered.
 */
     public void addKeyWord ( String s, int i) {

          if(s == null) return;

          kwords.put(s.toLowerCase(), new Integer(i));

	}
/**
 *   return the matching token given the keyword
 * @param s Keyword.
 */
     public int getKeyValue (String s) {

          if(s == null) return UNKNOWN;

          Integer i = (Integer)kwords.get(s.toLowerCase());

          if(i == null) return UNKNOWN;
          else          return i.intValue();
	}
/**
 *   Clear the internal table containing the keyword/token pairs
 */
     public void resetKeyWords () {
          kwords.clear();
	}
/**
 *  Read the input stream and return the next token found.
 */
     public int nextWord() {
        int word;       
   
        try {
              ttype = nextToken();
	    }
        catch (Exception e) {
              return ERROR;
	    }

        if(ttype == StringChar ) {
              return STRING;
        } else
        if(ttype == TT_WORD) {
               word = getKeyValue(super.sval);
               if( word == UNKNOWN ) word = getNumber(super.sval);
               if( word == UNKNOWN ) return ttype;
               ttype = word;
               return word;
	     } else {
	             return ttype;
	     }
     }
     
/**
 * Set the character that delimeters a string.
 * @param c character to delimeter strings. Default is ".
 */
     public void setStringChar(char c)  {
     	StringChar = c;
     	quoteChar(StringChar);
     }
     
     
     
/*
*********************
**
** Protected Methods
**
********************/

/**
 *   Check to see if the returned word is a number
 *   The native StreamTokenizer number method does not work for
 *   scientific notation so we us the Double class doubleValue() method
 * @param s String to find number.
 *
 */
      protected int getNumber(String s) {

         try {
               super.nval = Double.valueOf(s).doubleValue();
               return TT_NUMBER;
	     }
         catch (Exception e) {
               return UNKNOWN;
	     }

       }

/**
 *   Reset the syntax of the parent class
 */
     protected void resetWordSyntax() {
           resetSyntax();
           wordChars('a','z');
           wordChars('A','Z');
           wordChars('0','9');
           wordChars('.','.');
           wordChars('_','_');
           wordChars('{','}');
           wordChars('+','+');
           wordChars('-','-');
           wordChars(128+32, 255);
           
           quoteChar(StringChar);

           whitespaceChars(0,' ');
        
           commentChar('#');

           lowerCaseMode(false);

           eolIsSignificant(true);
	 }
/**
 *  Close the input stream
 */
     protected void closeStream() {
         try {
              is.close();
	    }
         catch (Exception e) {}

         is = null;
       }

   }