org.apache.asterix.om.base.ANull Maven / Gradle / Ivy

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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.asterix.om.base;

import org.json.JSONException;
import org.json.JSONObject;

import org.apache.asterix.common.exceptions.AsterixException;
import org.apache.asterix.om.types.BuiltinType;
import org.apache.asterix.om.types.IAType;
import org.apache.asterix.om.visitors.IOMVisitor;

// We should avoid representing nulls explicitly. This class is for cases when it is
// harder not to.
public class ANull implements IAObject {

    private ANull() {
    }

    public final static ANull NULL = new ANull();

    @Override
    public void accept(IOMVisitor visitor) throws AsterixException {
        visitor.visitANull(this);
    }

    @Override
    public IAType getType() {
        return BuiltinType.ANULL;
    }

    @Override
    public boolean deepEqual(IAObject obj) {
        return obj == this;
    }

    @Override
    public int hash() {
        return 0;
    }

    @Override
    public String toString() {
        return "null";
    }

    @Override
    public JSONObject toJSON() throws JSONException {
        JSONObject json = new JSONObject();

        json.put("ANull", "null");

        return json;
    }
}