org.apache.somewhere.general.BlankNodeImpl.java Source code

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Here is the source code for org.apache.somewhere.general.BlankNodeImpl.java

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/**
 * 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
 *
 *     http://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.
 */

package org.apache.somewhere.general;

import java.nio.charset.StandardCharsets;
import java.util.UUID;

import org.apache.commons.rdf.api.BlankNode;

public class BlankNodeImpl implements BlankNode {
    private static final UUID SALT = UUID.randomUUID();
    final UUID uuid;

    /*package*/ BlankNodeImpl() {
        // Type 4 UUID. Can't clash with type 3.
        uuid = UUID.randomUUID();
    }

    /*package*/ BlankNodeImpl(String identifier) {
        // Mange the identifier with an internal startng point to produce a type 3 UUID. 
        uuid = UUID.nameUUIDFromBytes((SALT.toString() + ":" + identifier).getBytes(StandardCharsets.US_ASCII));
    }

    @Override
    public String ntriplesString() {
        // Because "-" is allowed in bNode labels. 
        return "_:" + uuid.toString();
    }

    @Override
    public String uniqueReference() {
        return uuid.toString();
    }

    @Override
    public String toString() {
        return ntriplesString();
    }

    @Override
    public int hashCode() {
        return uniqueReference().hashCode();
    }

    @Override
    public boolean equals(Object other) {
        if (other == this)
            return true;
        if (other == null)
            return false;
        if (!(other instanceof BlankNode))
            return false;
        BlankNode bNode = (BlankNode) other;
        return uniqueReference().equals(bNode.uniqueReference());
    }
}