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/*****************************************************************************
* Copyright (C) PicoContainer Organization. All rights reserved. *
* ------------------------------------------------------------------------- *
* The software in this package is published under the terms of the BSD *
* style license a copy of which has been included with this distribution in *
* the LICENSE.txt file. *
*****************************************************************************/
package org.picocontainer;
/**
* Interface realizing a visitor pattern for {@link PicoContainer} as described in the GoF.
* The visitor should visit the container, its children, all registered {@link ComponentAdapter}
* instances and all instantiated components.
*
* @author Aslak Hellesøy
* @author Jörg Schaible
*/
public interface PicoVisitor {
/**
* Constant that indicates that the traversal should continue after the
* visit*() method has been called.
*/
boolean CONTINUE_TRAVERSAL = true;
/**
* Constant that indicates that the traversal should abort after the
* visit*() method has been called.
*/
boolean ABORT_TRAVERSAL = false;
/**
* Entry point for the PicoVisitor traversal. The given node is the first object, that is
* asked for acceptance. Only objects of type {@link PicoContainer}, {@link ComponentAdapter},
* or {@link Parameter} are valid.
*
* @param node the start node of the traversal.
* @return a visitor-specific value.
* @throws IllegalArgumentException in case of an argument of invalid type.
*/
Object traverse(Object node);
/**
* Visit a {@link PicoContainer} that has to accept the visitor.
*
* @param pico the visited container.
* @return CONTINUE_TRAVERSAL if the traversal should continue.
* Any visitor callback that returns ABORT_TRAVERSAL indicates
* the desire to abort any further traversal.
*/
boolean visitContainer(PicoContainer pico);
/**
* Visit a {@link ComponentAdapter} that has to accept the visitor.
*
* @param componentAdapter the visited ComponentAdapter.
*/
void visitComponentAdapter(ComponentAdapter componentAdapter);
/**
* Visit a {@link ComponentAdapter} that has to accept the visitor.
*
* @param componentAdapter the visited ComponentAdapter.
*/
void visitComponentFactory(ComponentFactory componentFactory);
/**
* Visit a {@link Parameter} that has to accept the visitor.
*
* @param parameter the visited Parameter.
*/
void visitParameter(Parameter parameter);
}