org.eclipse.sisu.wire.MergedProperties Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2010-present 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:
* Stuart McCulloch (Sonatype, Inc.) - initial API and implementation
*******************************************************************************/
package org.eclipse.sisu.wire;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* Delegating {@link Map} that merges a series of {@link Map}s into one consistent view.
*/
final class MergedProperties
extends AbstractMap
{
// ----------------------------------------------------------------------
// Implementation fields
// ----------------------------------------------------------------------
private transient volatile Set> entrySet; // NOSONAR
final Map[] properties;
// ----------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------
MergedProperties( final List> properties )
{
this.properties = properties.toArray( new Map[properties.size()] );
}
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
@Override
public Object get( final Object key )
{
for ( final Map p : properties )
{
final Object value = p.get( key );
if ( null != value )
{
return value;
}
}
return null;
}
@Override
public boolean containsKey( final Object key )
{
for ( final Map p : properties )
{
if ( p.containsKey( key ) )
{
return true;
}
}
return false;
}
@Override
public Set> entrySet()
{
if ( null == entrySet )
{
entrySet = new MergedEntries();
}
return entrySet;
}
// ----------------------------------------------------------------------
// Implementation types
// ----------------------------------------------------------------------
final class MergedEntries
extends AbstractSet>
{
@Override
public Iterator> iterator()
{
return new Iterator>()
{
@SuppressWarnings( "rawtypes" )
private Iterator itr;
private int index;
public boolean hasNext()
{
while ( null == itr || !itr.hasNext() )
{
if ( index >= properties.length )
{
return false;
}
itr = properties[index++].entrySet().iterator();
}
return true;
}
@SuppressWarnings( "unchecked" )
public Entry next()
{
if ( hasNext() )
{
return itr.next();
}
throw new NoSuchElementException();
}
public void remove()
{
throw new UnsupportedOperationException();
}
};
}
@Override
public int size()
{
int size = 0;
for ( final Map p : properties )
{
size += p.size();
}
return size;
}
}
}