Recognizer.java

/* 
** Author(s): Miguel Calejo
** Contact:   interprolog@declarativa.com, http://www.declarativa.com
** Copyright (C) Declarativa, Portugal, 2000-2002
** Use and distribution, without any warranties, under the terms of the 
** GNU Library General Public License, readable in http://www.fsf.org/copyleft/lgpl.html
*/
package com.declarativa.interprolog.util;
import com.declarativa.interprolog.util.*;
import java.util.*;

public class Recognizer implements OutputListener{
        Vector listeners;
        int nextInPattern; // next byte to recognize
        byte[] bytePattern;
        boolean collectRestOfBuffer;

        public Recognizer(){
                this(null);
        }
        public Recognizer(String pattern){
                this(pattern,false);
        }
        public Recognizer(String pattern,boolean collectRestOfBuffer){
                listeners = new Vector();
                if (pattern==null) bytePattern=new byte[0];
                else bytePattern = pattern.getBytes();
                nextInPattern=0;
                this.collectRestOfBuffer=collectRestOfBuffer;
        }
        
        public int numberListeners(){ return listeners.size(); }

        // OutputListener methods:
        public void analyseBytes(byte[] buffer,int nbytes){
                if (bytePattern.length==0) 
                        fireRecognized(new String(buffer,0,nbytes));
                else for(int b=0;b<nbytes;b++) {
                        if(buffer[b]==bytePattern[nextInPattern]){
                                nextInPattern++;
                                if (nextInPattern>=bytePattern.length) {
                                        nextInPattern = 0;
                                        if (collectRestOfBuffer && b+1<nbytes) {
                                                fireRecognized(new String(buffer,b+1,nbytes-(b+1)));
                                                break;
                                        }
                                        else fireRecognized("");
                                }
                        }
                        else nextInPattern = 0;
                }
        }
        public void streamEnded(){
                throw new IPException("Unexpected end of stream, Prolog may have died abruptly");
        }
        
        public synchronized void addRecognizerListener(RecognizerListener l){
                listeners.addElement(l);
        }
        public synchronized void removeRecognizerListener(RecognizerListener l){
                listeners.removeElement(l);
        }
        void fireRecognized(String extra){
                for (int l=0; l<listeners.size(); l++)
                        ((RecognizerListener)(listeners.elementAt(l))).recognized(this,extra);
        }
}

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