no.ssb.vtl.script.operations.join.JoinKeyExtractor.java Source code

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Here is the source code for no.ssb.vtl.script.operations.join.JoinKeyExtractor.java

Source

package no.ssb.vtl.script.operations.join;

/*-
 * ========================LICENSE_START=================================
 * Java VTL
 * %%
 * Copyright (C) 2016 - 2018 Hadrien Kohl
 * %%
 * Licensed 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.
 * =========================LICENSE_END==================================
 */

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.primitives.Ints;
import no.ssb.vtl.model.Component;
import no.ssb.vtl.model.DataPoint;
import no.ssb.vtl.model.DataStructure;
import no.ssb.vtl.model.Order;

import java.util.ArrayList;
import java.util.Map;
import java.util.function.Function;
import java.util.function.UnaryOperator;

/**
 * A key extractor used in join operations.
 */
public class JoinKeyExtractor implements UnaryOperator<DataPoint> {

    private final DataPoint buffer;
    private final int[] indices;

    /**
     * Create a new JoinKeyExtractor.
     *
     * @param childStructure original structure.
     * @param order          the order representing the component to extract.
     * @param mapping        the mapping used to translate order component to child components.
     */
    public JoinKeyExtractor(DataStructure childStructure, Order order, Map<Component, Component> mapping) {
        this(childStructure, order, mapping::get);
    }

    public JoinKeyExtractor(DataStructure childStructure, Order order, Function<Component, Component> mapper) {

        ImmutableList<Component> fromList = ImmutableList.copyOf(childStructure.values());
        ImmutableList<Component> toList = ImmutableList.copyOf(order.keySet());

        ArrayList<Integer> indices = Lists.newArrayList();

        // For each component in order, find the child index.
        for (Component orderComponent : order.keySet()) {
            indices.add(toList.indexOf(orderComponent), fromList.indexOf(mapper.apply(orderComponent)));
        }

        this.indices = Ints.toArray(indices);
        this.buffer = DataPoint.create(order.size());
    }

    @Override
    public DataPoint apply(DataPoint dataPoint) {
        for (int i = 0; i < indices.length; i++) {
            buffer.set(i, dataPoint.get(indices[i]));
        }
        return (DataPoint) buffer.clone();
    }
}