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Core sketch algorithms used alone and by other Java repositories in the DataSketches library.

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/*
 * 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.
 */

package org.apache.datasketches.tuple.arrayofdoubles;

import org.apache.datasketches.memory.Memory;

/**
 * Iterator over the off-heap, Direct tuple sketch of type ArrayOfDoubles (compact or hash table).
 * 

This implementation uses data in a given Memory that is owned and managed by the caller. * This Memory can be off-heap, which if managed properly will greatly reduce the need for * the JVM to perform garbage collection.

*/ final class DirectArrayOfDoublesSketchIterator implements ArrayOfDoublesSketchIterator { private Memory mem_; private int offset_; private int numEntries_; private int numValues_; private int i_; private static final int SIZE_OF_KEY_BYTES = 8; private static final int SIZE_OF_VALUE_BYTES = 8; DirectArrayOfDoublesSketchIterator(final Memory mem, final int offset, final int numEntries, final int numValues) { mem_ = mem; offset_ = offset; numEntries_ = numEntries; numValues_ = numValues; i_ = -1; } @Override public boolean next() { i_++; while (i_ < numEntries_) { if (mem_.getLong(offset_ + ((long) SIZE_OF_KEY_BYTES * i_)) != 0) { return true; } i_++; } return false; } @Override public long getKey() { return mem_.getLong(offset_ + ((long) SIZE_OF_KEY_BYTES * i_)); } @Override public double[] getValues() { if (numValues_ == 1) { return new double[] { mem_.getDouble(offset_ + ((long) SIZE_OF_KEY_BYTES * numEntries_) + ((long) SIZE_OF_VALUE_BYTES * i_)) }; } final double[] array = new double[numValues_]; mem_.getDoubleArray(offset_ + ((long) SIZE_OF_KEY_BYTES * numEntries_) + ((long) SIZE_OF_VALUE_BYTES * i_ * numValues_), array, 0, numValues_); return array; } }




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