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    • org.glassfish.pfl.dynamic.codegen.impl.Attribute Maven / Gradle / Ivy

    /*
 * Copyright (c) 1997, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.pfl.dynamic.codegen.impl;

import java.util.Set ;
import java.util.HashSet ;
import java.util.List ;
import java.util.ArrayList ;
import org.glassfish.pfl.basic.func.NullaryFunction;

/** Class used to define dynamic attributes on AttributedObject instances.
 * Note that T cannot be a generic type, due to problems with
 * {@code Class} when T is a generic.  To work around this problem,
 * simply create an interface that extends the generic type
 * (you are programming to interfaces, right?).
 */
public class Attribute {
    private static List> attributes =
	new ArrayList>() ;

    private static synchronized int next( Attribute attr ) {
	for (int ctr=0; ctr get( int index ) {
	if ((index >= 0) && (index < attributes.size()))
	    return attributes.get( index ) ;
	else
	    throw new IllegalArgumentException() ;
    }

    public static Set> getAttributes( AttributedObject node ) {
	List attrs = node.attributes() ;
	Set> result = new HashSet>() ;

	if (attrs == null)
	    return result ;

	for (int ctr=0; ctr initializer ;
    private T defaultValue ;
    private Class cls ;
    private int attributeIndex ;

    public String toString() {
	return "Attribute[" + name + ":" + cls.getName() + ":" + 
	    attributeIndex + "]" ;
    }

    public Attribute( Class cls, String name, T defaultValue ) {
	this.cls = cls ;
	this.name = name ;
	this.initializer = null ;
	this.defaultValue = defaultValue ;

	attributeIndex = next( this ) ;
    }

    public Attribute( Class cls, String name, 
	NullaryFunction initializer ) {
	this.cls = cls ;
	this.name = name ;
	this.initializer = initializer ;
	this.defaultValue = null ;

	attributeIndex = next( this ) ;
    }

    public T get( AttributedObject node ) {
	T result = cls.cast( node.get( attributeIndex ) ) ;
	if (result == null) {
	    if (initializer != null)
		result = initializer.evaluate() ;
	    else
		result = defaultValue ;

	    node.set( attributeIndex, result ) ;
	}
	return result ;
    }

    public void set( AttributedObject node, T arg ) {
	node.set( attributeIndex, arg ) ;
    }

    public boolean isSet( AttributedObject node ) {
	return node.get( attributeIndex ) != null ;
    }

    public String name() {
	return name ;
    }

    public int index() {
	return attributeIndex ;
    }

    public Class type() {
	return cls ;
    }
}
    
    
    
    

    




    
    
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