/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.sparql.util;

import java.util.HashMap;
import java.util.Map;

import org.apache.jena.graph.Node;

/** Map nodes to nodes. */
public class NodeIsomorphismMap
{
    private Map<Node, Node> map = new HashMap<>();

    public NodeIsomorphismMap() {}

    private Node get(Node key)                { return map.get(key); }
    private void put(Node key, Node value)    { map.put(key, value); }

    public boolean makeIsomorphic(Node n1, Node n2) {
        if ( n1.isBlank() && n2.isBlank() ) {
            Node other = get(n1);
            if ( other == null ) {
                put(n1, n2);
                return true;
            }
            return other.equals(n2);
        }
        return n1.equals(n2);
    }

    @Override
    public String toString() {
        return "Iso["+map.toString()+"]";
    }
}
