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package com.sun.enterprise.deployment.annotation.introspection;

import java.util.HashSet;
import java.util.Set;

/**
 * Abstract superclass for instance-based annotation scanners.
 *
 * @author tjquinn
 */
public abstract class AbstractAnnotationScanner implements CustomAnnotationScanner {
    
    /** holds the annotations of interest to the specific type of scanner */
    protected Set<String> annotations=null;
    
    /** Creates a new instance of AbstractAnnotationScanner */
    public AbstractAnnotationScanner() {
    }
  
    /**
     * Invoked so the concrete subclass can populate the annotations set.
     * <p>
     * Concrete implementations of this method should add to the set one or more Strings 
     * corresponding to the annotations of interest.  
     *
     * @param annotationsSet the Set object to be populated
     */
    protected abstract void init(Set<String> annotationsSet);

    /**
     * Test if the passed constant pool string is a reference to 
     * a Type.TYPE annotation of a J2EE component
     *
     * @String the constant pool info string 
     * @return true if it is an annotation reference of interest to this scanner
     */
    public boolean isAnnotation(String value) {
        if (annotations==null) {
            synchronized(this) {
                if (annotations == null) {
                    annotations = new HashSet();
                    init(annotations);
                }
            }
        }
        return annotations.contains(value);
    }
}