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/**

 * @test

 * @summary unit test for Arrays.ParallelPrefix().

 * @author Tristan Yan

 * @run testng ParallelPrefix

 */

import java.util.Arrays;

import java.util.function.BinaryOperator;

import java.util.function.DoubleBinaryOperator;

import java.util.function.Function;

import java.util.function.IntBinaryOperator;

import java.util.function.LongBinaryOperator;

import java.util.stream.IntStream;

import java.util.stream.LongStream;

import static org.testng.Assert.*;

import org.testng.annotations.DataProvider;

import org.testng.annotations.Test;

public class ParallelPrefix {

    //Array size less than MIN_PARTITION

    private final static int SMALL_ARRAY_SIZE = 1 << 3;

    //Array size equals MIN_PARTITION

    private final static int THRESHOLD_ARRAY_SIZE = 1 << 4;

    //Array size greater than MIN_PARTITION

    private final static int MEDIUM_ARRAY_SIZE = 1 << 8;

    //Array size much greater than MIN_PARTITION

    private final static int LARGE_ARRAY_SIZE = 1 << 12;

    private final static int[] ARRAY_SIZE_COLLECTION  = new int[]{

        SMALL_ARRAY_SIZE, THRESHOLD_ARRAY_SIZE,MEDIUM_ARRAY_SIZE, LARGE_ARRAY_SIZE};

    @DataProvider

    public static Object[][] intSet(){

        return genericData(size -> IntStream.range(0, size).toArray(), new IntBinaryOperator[]{Integer::sum, Integer::min});

    }

    @DataProvider

    public static Object[][] longSet(){

        return genericData(size -> LongStream.range(0, size).toArray(), new LongBinaryOperator[]{Long::sum, Long::min});

    }

    @DataProvider

    public static Object[][] doubleSet(){

        return genericData(size -> IntStream.range(0, size).mapToDouble(i -> (double)i).toArray(),

                new DoubleBinaryOperator[]{Double::sum, Double::min});

    }

    @DataProvider

    public static Object[][] stringSet(){

        Function<Integer, String[]> stringsFunc = size ->

                IntStream.range(0, size).mapToObj(Integer::toString).toArray(String[]::new);

        BinaryOperator<String> cancatBop = String::concat;

        return genericData(stringsFunc,  new BinaryOperator[]{cancatBop});

    }

    private static <T, OPS> Object[][] genericData(Function<Integer, T> generateFunc, OPS[] ops) {

        //test arrays which size is equals n-1, n, n+1, test random data

        Object[][] data = new Object[ARRAY_SIZE_COLLECTION.length * 3 * ops.length][4];

        for(int n = 0; n < ARRAY_SIZE_COLLECTION.length; n++ ) {

            for(int testValue = -1 ; testValue <= 1; testValue++) {

                int array_size = ARRAY_SIZE_COLLECTION[n] + testValue;

                for(int opsN = 0; opsN < ops.length; opsN++) {

                    int index = n * 3 * ops.length + (testValue + 1) * ops.length + opsN;

                    data[index][0] = generateFunc.apply(array_size);

                    data[index][1] = array_size / 3;

                    data[index][2] = 2 * array_size / 3;

                    data[index][3] = ops[opsN];

                }

            }

        }

        return data;

    }

    @Test(dataProvider="intSet")

    public void testParallelPrefixForInt(int[] data, int fromIndex, int toIndex, IntBinaryOperator op) {

        int[] sequentialResult = data.clone();

        for (int index = fromIndex + 1; index < toIndex; index++) {

            sequentialResult[index ] = op.applyAsInt(sequentialResult[index  - 1], sequentialResult[index]);

        }

        int[] parallelResult = data.clone();

        Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);

        assertEquals(parallelResult, sequentialResult);

        int[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);

        Arrays.parallelPrefix(parallelRangeResult, op);

        assertEquals(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));

    }

    @Test(dataProvider="longSet")

    public void testParallelPrefixForLong(long[] data, int fromIndex, int toIndex, LongBinaryOperator op) {

        long[] sequentialResult = data.clone();

        for (int index = fromIndex + 1; index < toIndex; index++) {

            sequentialResult[index ] = op.applyAsLong(sequentialResult[index  - 1], sequentialResult[index]);

        }

        long[] parallelResult = data.clone();

        Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);

        assertEquals(parallelResult, sequentialResult);

        long[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);

        Arrays.parallelPrefix(parallelRangeResult, op);

        assertEquals(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));

    }

    @Test(dataProvider="doubleSet")

    public void testParallelPrefixForDouble(double[] data, int fromIndex, int toIndex, DoubleBinaryOperator op) {

        double[] sequentialResult = data.clone();

        for (int index = fromIndex + 1; index < toIndex; index++) {

            sequentialResult[index ] = op.applyAsDouble(sequentialResult[index  - 1], sequentialResult[index]);

        }

        double[] parallelResult = data.clone();

        Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);

        assertEquals(parallelResult, sequentialResult);

        double[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);

        Arrays.parallelPrefix(parallelRangeResult, op);

        assertEquals(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));

    }

    @Test(dataProvider="stringSet")

    public void testParallelPrefixForStringr(String[] data , int fromIndex, int toIndex, BinaryOperator<String> op) {

        String[] sequentialResult = data.clone();

        for (int index = fromIndex + 1; index < toIndex; index++) {

            sequentialResult[index ] = op.apply(sequentialResult[index  - 1], sequentialResult[index]);

        }

        String[] parallelResult = data.clone();

        Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);

        assertEquals(parallelResult, sequentialResult);

        String[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);

        Arrays.parallelPrefix(parallelRangeResult, op);

        assertEquals(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));

    }

}