001/*
002 * Copyright (C) 2009-2011 Mathias Doenitz
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.parboiled.trees;
018
019import org.parboiled.common.ImmutableLinkedList;
020import org.parboiled.common.ImmutableList;
021
022import java.util.List;
023
024/**
025 * A simple, immutable {@link GraphNode} implementation.
026 *
027 * @param <T> the actual implementation type of this ImmutableGraphNode
028 */
029public class ImmutableGraphNode<T extends GraphNode<T>> implements GraphNode<T> {
030
031    private final List<T> children;
032
033    public ImmutableGraphNode() {
034        this(null);
035    }
036
037    public ImmutableGraphNode(List<T> children) {
038        this.children = children ==
039                null ? ImmutableList.<T>of() :
040                children instanceof ImmutableList ? children :
041                children instanceof ImmutableLinkedList ? children :
042                ImmutableList.copyOf(children);
043    }
044
045    public List<T> getChildren() {
046        return children;
047    }
048}