/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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.
**********************************************************************************************************************/
/**
* This file is based on source code from the Hadoop Project (http://hadoop.apache.org/), licensed by the Apache
* Software Foundation (ASF) under the Apache License, Version 2.0. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package eu.stratosphere.pact.runtime.sort;
public final class HeapSort implements IndexedSorter {
public HeapSort() {
}
private static void downHeap(final IndexedSortable s, final int b, int i, final int N) {
for (int idx = i << 1; idx < N; idx = i << 1) {
if (idx + 1 < N && s.compare(b + idx, b + idx + 1) < 0) {
if (s.compare(b + i, b + idx + 1) < 0) {
s.swap(b + i, b + idx + 1);
} else {
return;
}
i = idx + 1;
} else if (s.compare(b + i, b + idx) < 0) {
s.swap(b + i, b + idx);
i = idx;
} else {
return;
}
}
}
public void sort(final IndexedSortable s, final int p, final int r) {
final int N = r - p;
// build heap w/ reverse comparator, then write in-place from end
final int t = Integer.highestOneBit(N);
for (int i = t; i > 1; i >>>= 1) {
for (int j = i >>> 1; j < i; ++j) {
downHeap(s, p - 1, j, N + 1);
}
}
for (int i = r - 1; i > p; --i) {
s.swap(p, i);
downHeap(s, p - 1, 1, i - p + 1);
}
}
@Override
public void sort(IndexedSortable s) {
sort(s, 0, s.size());
}
}