vxquery-core/src/main/java/org/apache/vxquery/runtime/functions/json/KeysOrMembersScalarEvaluator.java

/*
* 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.
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package org.apache.vxquery.runtime.functions.json;

import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
import org.apache.hyracks.api.context.IHyracksTaskContext;
import org.apache.hyracks.data.std.api.IPointable;
import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
import org.apache.vxquery.datamodel.accessors.TaggedValuePointable;
import org.apache.vxquery.datamodel.builders.sequence.SequenceBuilder;
import org.apache.vxquery.exceptions.ErrorCode;
import org.apache.vxquery.exceptions.SystemException;
import org.apache.vxquery.runtime.functions.base.AbstractTaggedValueArgumentScalarEvaluator;

import java.io.IOException;

public class KeysOrMembersScalarEvaluator extends AbstractTaggedValueArgumentScalarEvaluator {
    protected final IHyracksTaskContext ctx;
    private ArrayBackedValueStorage abvs;
    private final SequenceBuilder sb;
    private final TaggedValuePointable tempTvp;
    private final KeysOrMembersUnnesting keysOrMembers;

    public KeysOrMembersScalarEvaluator(IHyracksTaskContext ctx, IScalarEvaluator[] args) {
        super(args);
        this.ctx = ctx;
        abvs = new ArrayBackedValueStorage();
        sb = new SequenceBuilder();
        tempTvp = (TaggedValuePointable) TaggedValuePointable.FACTORY.createPointable();
        keysOrMembers = new KeysOrMembersUnnesting(ctx, ppool);
    }

    @Override
    protected void evaluate(TaggedValuePointable[] args, IPointable result) throws SystemException {
        abvs = abvsPool.takeOne();
        keysOrMembers.init(args);
        try {
            abvs.reset();
            sb.reset(abvs);
            while (keysOrMembers.step(tempTvp)) {
                sb.addItem(tempTvp);
            }
            sb.finish();
            result.set(abvs);
        } catch (IOException e) {
            throw new SystemException(ErrorCode.SYSE0001, e);
        } finally {
            abvsPool.giveBack(abvs);
        }
    }
}