/*******************************************************************************
* Copyright (c) 2010, 2012 Sonatype, Inc.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Sonatype, Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.aether.util.graph.visitor;
import org.eclipse.aether.graph.DependencyFilter;
import org.eclipse.aether.graph.DependencyNode;
import org.eclipse.aether.graph.DependencyVisitor;
/**
* A dependency visitor that delegates to another visitor if nodes match a filter. Note that in case of a mismatching
* node, the children of that node are still visisted and presented to the filter.
*/
public final class FilteringDependencyVisitor
implements DependencyVisitor
{
private final DependencyFilter filter;
private final DependencyVisitor visitor;
private final Stack<Boolean> accepts;
private final Stack<DependencyNode> parents;
/**
* Creates a new visitor that delegates traversal of nodes matching the given filter to the specified visitor.
*
* @param visitor The visitor to delegate to, must not be {@code null}.
* @param filter The filter to apply, may be {@code null} to not filter.
*/
public FilteringDependencyVisitor( DependencyVisitor visitor, DependencyFilter filter )
{
if ( visitor == null )
{
throw new IllegalArgumentException( "dependency visitor not specified" );
}
this.visitor = visitor;
this.filter = filter;
this.accepts = new Stack<Boolean>();
this.parents = new Stack<DependencyNode>();
}
/**
* Gets the visitor to which this visitor delegates to.
*
* @return The visitor being delegated to, never {@code null}.
*/
public DependencyVisitor getVisitor()
{
return visitor;
}
/**
* Gets the filter being applied before delegation.
*
* @return The filter being applied or {@code null} if none.
*/
public DependencyFilter getFilter()
{
return filter;
}
public boolean visitEnter( DependencyNode node )
{
boolean accept = filter == null || filter.accept( node, parents );
accepts.push( accept );
parents.push( node );
if ( accept )
{
return visitor.visitEnter( node );
}
else
{
return true;
}
}
public boolean visitLeave( DependencyNode node )
{
parents.pop();
Boolean accept = accepts.pop();
if ( accept )
{
return visitor.visitLeave( node );
}
else
{
return true;
}
}
}