org.eclipse.aether.util.graph.traverser.AndDependencyTraverser Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2014 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.traverser;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;
import org.eclipse.aether.collection.DependencyCollectionContext;
import org.eclipse.aether.collection.DependencyTraverser;
import org.eclipse.aether.graph.Dependency;
/**
* A dependency traverser that combines zero or more other traversers using a logical {@code AND}. The resulting
* traverser enables processing of child dependencies if and only if all constituent traversers request traversal.
*/
public final class AndDependencyTraverser
implements DependencyTraverser
{
private final Set traversers;
private int hashCode;
/**
* Creates a new traverser from the specified traversers. Prefer
* {@link #newInstance(DependencyTraverser, DependencyTraverser)} if any of the input traversers might be
* {@code null}.
*
* @param traversers The traversers to combine, may be {@code null} but must not contain {@code null} elements.
*/
public AndDependencyTraverser( DependencyTraverser... traversers )
{
if ( traversers != null && traversers.length > 0 )
{
this.traversers = new LinkedHashSet( Arrays.asList( traversers ) );
}
else
{
this.traversers = Collections.emptySet();
}
}
/**
* Creates a new traverser from the specified traversers.
*
* @param traversers The traversers to combine, may be {@code null} but must not contain {@code null} elements.
*/
public AndDependencyTraverser( Collection traversers )
{
if ( traversers != null && !traversers.isEmpty() )
{
this.traversers = new LinkedHashSet( traversers );
}
else
{
this.traversers = Collections.emptySet();
}
}
private AndDependencyTraverser( Set traversers )
{
if ( traversers != null && !traversers.isEmpty() )
{
this.traversers = traversers;
}
else
{
this.traversers = Collections.emptySet();
}
}
/**
* Creates a new traverser from the specified traversers.
*
* @param traverser1 The first traverser to combine, may be {@code null}.
* @param traverser2 The second traverser to combine, may be {@code null}.
* @return The combined traverser or {@code null} if both traversers were {@code null}.
*/
public static DependencyTraverser newInstance( DependencyTraverser traverser1, DependencyTraverser traverser2 )
{
if ( traverser1 == null )
{
return traverser2;
}
else if ( traverser2 == null || traverser2.equals( traverser1 ) )
{
return traverser1;
}
return new AndDependencyTraverser( traverser1, traverser2 );
}
public boolean traverseDependency( Dependency dependency )
{
for ( DependencyTraverser traverser : traversers )
{
if ( !traverser.traverseDependency( dependency ) )
{
return false;
}
}
return true;
}
public DependencyTraverser deriveChildTraverser( DependencyCollectionContext context )
{
int seen = 0;
Set childTraversers = null;
for ( DependencyTraverser traverser : traversers )
{
DependencyTraverser childTraverser = traverser.deriveChildTraverser( context );
if ( childTraversers != null )
{
if ( childTraverser != null )
{
childTraversers.add( childTraverser );
}
}
else if ( traverser != childTraverser )
{
childTraversers = new LinkedHashSet();
if ( seen > 0 )
{
for ( DependencyTraverser s : traversers )
{
if ( childTraversers.size() >= seen )
{
break;
}
childTraversers.add( s );
}
}
if ( childTraverser != null )
{
childTraversers.add( childTraverser );
}
}
else
{
seen++;
}
}
if ( childTraversers == null )
{
return this;
}
if ( childTraversers.size() <= 1 )
{
if ( childTraversers.isEmpty() )
{
return null;
}
return childTraversers.iterator().next();
}
return new AndDependencyTraverser( childTraversers );
}
@Override
public boolean equals( Object obj )
{
if ( this == obj )
{
return true;
}
else if ( null == obj || !getClass().equals( obj.getClass() ) )
{
return false;
}
AndDependencyTraverser that = (AndDependencyTraverser) obj;
return traversers.equals( that.traversers );
}
@Override
public int hashCode()
{
if ( hashCode == 0 )
{
int hash = 17;
hash = hash * 31 + traversers.hashCode();
hashCode = hash;
}
return hashCode;
}
}