vxquery-core/src/main/java/org/apache/vxquery/runtime/functions/trace/FnTraceScalarEvaluatorFactory.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,
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* See the License for the specific language governing permissions and
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package org.apache.vxquery.runtime.functions.trace;

import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
import org.apache.hyracks.api.context.IHyracksTaskContext;
import org.apache.hyracks.data.std.api.IPointable;
import org.apache.vxquery.datamodel.accessors.TaggedValuePointable;
import org.apache.vxquery.datamodel.values.ValueTag;
import org.apache.vxquery.exceptions.ErrorCode;
import org.apache.vxquery.exceptions.SystemException;
import org.apache.vxquery.runtime.functions.base.AbstractTaggedValueArgumentScalarEvaluator;
import org.apache.vxquery.runtime.functions.base.AbstractTaggedValueArgumentScalarEvaluatorFactory;
import org.apache.vxquery.serializer.XMLSerializer;

public class FnTraceScalarEvaluatorFactory extends AbstractTaggedValueArgumentScalarEvaluatorFactory {

    private static final long serialVersionUID = 1L;

    public FnTraceScalarEvaluatorFactory(IScalarEvaluatorFactory[] args) {
        super(args);
    }

    @Override
    protected IScalarEvaluator createEvaluator(IHyracksTaskContext ctx, IScalarEvaluator[] args)
            throws AlgebricksException {
        return new AbstractTaggedValueArgumentScalarEvaluator(args) {

            @Override
            protected void evaluate(TaggedValuePointable[] args, IPointable result) throws SystemException {
                TaggedValuePointable tvpValue = args[0];
                TaggedValuePointable tvpLabel = args[1];
                if (tvpLabel.getTag() != ValueTag.XS_STRING_TAG) {
                    throw new SystemException(ErrorCode.FORG0006);
                }
                result.set(tvpValue);
                XMLSerializer printer = new XMLSerializer();
                printer.printTaggedValuePointable(System.err, tvpLabel);
                printer.printTaggedValuePointable(System.err, tvpValue);
            }
        };
    }

}