io.deephaven.engine.table.impl.join.stamp.ShortReverseStampKernel Maven / Gradle / Ivy

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/**
 * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
 */
/*
 * ---------------------------------------------------------------------------------------------------------------------
 * AUTO-GENERATED CLASS - DO NOT EDIT MANUALLY - for any changes edit CharStampKernel and regenerate
 * ---------------------------------------------------------------------------------------------------------------------
 */
package io.deephaven.engine.table.impl.join.stamp;

import io.deephaven.chunk.*;
import io.deephaven.engine.rowset.chunkattributes.RowKeys;
import io.deephaven.chunk.attributes.Values;
import io.deephaven.engine.rowset.RowSequence;


public class ShortReverseStampKernel implements StampKernel {
    static final ShortReverseStampKernel INSTANCE = new ShortReverseStampKernel();
    private ShortReverseStampKernel() {} // static use only

    @Override
    public void computeRedirections(Chunk leftStamps, Chunk rightStamps, LongChunk rightKeyIndices, WritableLongChunk leftRedirections) {
        computeRedirections(leftStamps.asShortChunk(), rightStamps.asShortChunk(), rightKeyIndices, leftRedirections);
    }

    static private void computeRedirections(ShortChunk leftStamps, ShortChunk rightStamps, LongChunk rightKeyIndices, WritableLongChunk leftRedirections) {
        final int leftSize = leftStamps.size();
        final int rightSize = rightStamps.size();
        if (rightSize == 0) {
            leftRedirections.fillWithValue(0, leftSize, RowSequence.NULL_ROW_KEY);
            leftRedirections.setSize(leftSize);
            return;
        }

        int rightLowIdx = 0;
        short rightLowValue = rightStamps.get(0);

        final int maxRightIdx = rightSize - 1;

        for (int li = 0; li < leftSize; ) {
            final short leftValue = leftStamps.get(li);
            if (lt(leftValue, rightLowValue)) {
                leftRedirections.set(li++, RowSequence.NULL_ROW_KEY);
                continue;
            }
            else if (eq(leftValue, rightLowValue)) {
                leftRedirections.set(li++, rightKeyIndices.get(rightLowIdx));
                continue;
            }

            int rightHighIdx = rightSize;

            while (rightLowIdx < rightHighIdx) {
                final int rightMidIdx = ((rightHighIdx - rightLowIdx) / 2) + rightLowIdx;
                final short rightMidValue = rightStamps.get(rightMidIdx);
                if (leq(rightMidValue, leftValue)) {
                    rightLowIdx = rightMidIdx;
                    rightLowValue = rightMidValue;
                    if (rightLowIdx == rightHighIdx - 1 || eq(rightLowValue, leftValue)) {
                        break;
                    }
                } else {
                    rightHighIdx = rightMidIdx;
                }
            }

            final long redirectionKey = rightKeyIndices.get(rightLowIdx);
            if (rightLowIdx == maxRightIdx) {
                leftRedirections.fillWithValue(li, leftSize - li, redirectionKey);
                return;
            } else {
                leftRedirections.set(li++, redirectionKey);
                final short nextRightValue = rightStamps.get(rightLowIdx + 1);
                while (li < leftSize && lt(leftStamps.get(li), nextRightValue)) {
                    leftRedirections.set(li++, redirectionKey);
                }
            }
        }
    }
    // region comparison functions
    // note that this is a descending kernel, thus the comparisons here are backwards (e.g., the lt function is in terms of the sort direction, so is implemented by gt)
    private static int doComparison(short lhs, short rhs) {
        return -1 * Short.compare(lhs, rhs);
    }
    // endregion comparison functions

    private static boolean lt(short lhs, short rhs) {
        return doComparison(lhs, rhs) < 0;
    }

    private static boolean leq(short lhs, short rhs) {
        return doComparison(lhs, rhs) <= 0;
    }

    private static boolean eq(short lhs, short rhs) {
        // region equality function
        return lhs == rhs;
        // endregion equality function
    }
}