| /* |
| * 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.quantiles; |
| |
| /** |
| * Iterator over ItemsSketch. The order is not defined. |
| * @param <T> type of item |
| */ |
| public class ItemsSketchIterator<T> { |
| |
| private final ItemsSketch<T> sketch_; |
| private Object[] combinedBuffer_; |
| private long bits_; |
| private int level_; |
| private long weight_; |
| private int i_; |
| private int offset_; |
| private int num_; |
| |
| ItemsSketchIterator(final ItemsSketch<T> sketch, final long bitPattern) { |
| sketch_ = sketch; |
| bits_ = bitPattern; |
| level_ = -1; |
| weight_ = 1; |
| i_ = 0; |
| offset_ = 0; |
| } |
| |
| /** |
| * Advancing the iterator and checking existence of the next entry |
| * is combined here for efficiency. This results in an undefined |
| * state of the iterator before the first call of this method. |
| * @return true if the next element exists |
| */ |
| public boolean next() { |
| if (combinedBuffer_ == null) { // initial setup |
| combinedBuffer_ = sketch_.combinedBuffer_; |
| num_ = sketch_.getBaseBufferCount(); |
| } else { // advance index within the current level |
| i_++; |
| } |
| if (i_ < num_) { |
| return true; |
| } |
| // go to the next non-empty level |
| do { |
| level_++; |
| if (level_ > 0) { |
| bits_ >>>= 1; |
| } |
| if (bits_ == 0L) { |
| return false; // run out of levels |
| } |
| weight_ *= 2; |
| } while ((bits_ & 1L) == 0L); |
| i_ = 0; |
| offset_ = (2 + level_) * sketch_.getK(); |
| num_ = sketch_.getK(); |
| return true; |
| } |
| |
| /** |
| * Gets a value from the current entry in the sketch. |
| * Don't call this before calling next() for the first time |
| * or after getting false from next(). |
| * @return value from the current entry |
| */ |
| @SuppressWarnings("unchecked") |
| public T getValue() { |
| return (T) combinedBuffer_[offset_ + i_]; |
| } |
| |
| /** |
| * Gets a weight for the value from the current entry in the sketch. |
| * Don't call this before calling next() for the first time |
| * or after getting false from next(). |
| * @return weight for the value from the current entry |
| */ |
| public long getWeight() { |
| return weight_; |
| } |
| |
| } |