externalmessageio.java

ALGAE是一个快速创建算法演示的框架。目前支持的算法实现语言包括java和c

/**
 * ExternalMessageIO.java
 *
 *
 * Created: Fri Apr 17 22:14:01 1998
 *
 * @author Steven Zeil
 * @version
 */

package edu.odu.cs.zeil.AlgAE;

import edu.odu.cs.zeil.AlgAE.Application;
import edu.odu.cs.zeil.AlgAE.Debug;

import edu.odu.cs.zeil.AlgAE.Message;
import edu.odu.cs.zeil.AlgAE.MessageIO;
import edu.odu.cs.zeil.AlgAE.ParameterizedMessage;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.Reader;

import java.util.Hashtable;
import java.util.Vector;

public class ExternalMessageIO
  implements MessageIO
{
  private java.io.Reader inStream;
  private PrintWriter outStream;
  private Application application;
  
  public ExternalMessageIO(java.io.Reader istream,
			   PrintWriter ostream,
			   Application appl)
  {
    inStream = istream;
    outStream = ostream;
    application = appl;
  }


  /**
   *   Send a message
   */
  public void send (ParameterizedMessage pmsg)
  {
    if (outStream != null)
      {
	outStream.print (pmsg);
	outStream.print ("\n");
	if (pmsg.getMessage().isForcing())
	  outStream.flush();
      }
  }
  
	      
  /**
   *  Read a message
   **/
  public ParameterizedMessage read()
  {
    String line;
    ParameterizedMessage pmsg = null;
    boolean keepTrying = true;
    while (keepTrying) {
      keepTrying = false;
	
      try {
	  line = getLine();
	  Debug.show (Debug.tokenizer, "ExtMsgIO.read.line: /" + line + "/");
	  String kind;
	  Vector params = new Vector();
	  if (line != null)
	      {
		line.trim();
		int lineSize = line.length();
		    
		if (lineSize > 0)
		  {
		    // Extract the message kind
		    int blankPos = line.indexOf(' ');
		    if (blankPos >= 0)
			kind = line.substring(0, blankPos);
		    else
			kind = line;
			    
		    if (!kind.equals("//"))
		      {
			if (blankPos < 0)
			    blankPos = lineSize;
				    
			// Extract the message parameters
			while (blankPos < lineSize) {
			    int lexemeStart = blankPos;
					
			    // Skip over any blanks
			    while ((lexemeStart < lineSize) &&
				   (line.charAt(lexemeStart) == ' '))
				++lexemeStart;
			    if (lexemeStart < lineSize)
			      {
				if (line.charAt(lexemeStart) == '"')
				  {
				    // Parameter is a string.
				    int lexemeEnd = lexemeStart + 1;
				    while ((lexemeEnd < lineSize) &&
					   (line.charAt(lexemeEnd) != '"'))
					++lexemeEnd;
				    params.addElement
					(ParameterizedMessage.decode
					 (line.substring(lexemeStart+1,
							 lexemeEnd)));
				    blankPos = lexemeEnd + 1;
				  }
				else
				  {
				    // Parameter should be an integer
				    blankPos = line.indexOf(' ',
							    lexemeStart+1);
				    if (blankPos < 0)
					blankPos = lineSize;
				    String lexeme =
					line.substring(lexemeStart, blankPos);
				    try {
				      params.addElement (new Integer(lexeme));
				    }
				    catch (NumberFormatException e) 
				      {
					Debug.error
					    ("Communications error\n" +
					     "Bad message parameter: " +
					     lexeme +
					     " in\n" + line);
				      }
				  }
			      }
			    else
				blankPos = lexemeStart;
			}

			// Build and queue up the message.
			Message msg = application.msgs.get (kind);
			if (msg == null)
			    Debug.error
				("Communications error\n" +
				 "Unregistered message: " + kind);
			else {
			    pmsg = new ParameterizedMessage(msg,params);
			    Debug.show (Debug.tokenizer, "read " + pmsg);
			}
		      }
		  }
		else
		    keepTrying = true;
	      }
      }
      catch (java.io.IOException e)
	  {
	      Debug.error ("Communications error\nIOException raised");
	      pmsg = null;
	  }
    }
    return pmsg;
  }


  public void close()
  {
    try {
      inStream.close();
    }
    catch (Throwable e) { }
    try {
      if (outStream != null)
	outStream.close();
    }
    catch (Throwable e) { }
  }
  
  
  private String getLine() throws java.io.IOException
  {
    StringBuffer s = new StringBuffer ();
    while (true)
      {
	int ch = inStream.read();
	//Debug.show (Debug.tokenizer, "Read char " + (char)ch + " (" + ch + ")");
	if (ch  < ' ')
	  break;
	else
	  s.append ((char)ch);
      }
    return s.toString();
  }


  
 
 } // ExternalMessageIO