001package org.eclipse.aether.util.artifact;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import org.eclipse.aether.artifact.ArtifactType;
023import org.eclipse.aether.artifact.ArtifactTypeRegistry;
024
025/**
026 * An artifact type registry which first consults its own mappings and in case of an unknown type falls back to another
027 * type registry.
028 */
029public final class OverlayArtifactTypeRegistry
030    extends SimpleArtifactTypeRegistry
031{
032
033    private final ArtifactTypeRegistry delegate;
034
035    /**
036     * Creates a new artifact type registry with initially no registered artifact types and the specified fallback
037     * registry. Use {@link #add(ArtifactType)} to populate the registry.
038     * 
039     * @param delegate The artifact type registry to fall back to, may be {@code null}.
040     */
041    public OverlayArtifactTypeRegistry( ArtifactTypeRegistry delegate )
042    {
043        this.delegate = delegate;
044    }
045
046    /**
047     * Adds the specified artifact type to the registry.
048     * 
049     * @param type The artifact type to add, must not be {@code null}.
050     * @return This registry for chaining, never {@code null}.
051     */
052    public OverlayArtifactTypeRegistry add( ArtifactType type )
053    {
054        super.add( type );
055        return this;
056    }
057
058    public ArtifactType get( String typeId )
059    {
060        ArtifactType type = super.get( typeId );
061
062        if ( type == null && delegate != null )
063        {
064            type = delegate.get( typeId );
065        }
066
067        return type;
068    }
069
070}