| /* |
| * Copyright 2009-2010 by The Regents of the University of California |
| * 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 from |
| * |
| * 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 edu.uci.ics.hyracks.dataflow.std.util; |
| |
| import java.util.BitSet; |
| |
| public class SelectionTree { |
| private int size; |
| |
| private Entry[] entries; |
| |
| private int[] losers; |
| |
| private BitSet available; |
| |
| public SelectionTree(Entry[] e) { |
| size = (e.length + 1) & 0xfffffffe; |
| available = new BitSet(size); |
| available.set(0, e.length, true); |
| losers = new int[size]; |
| entries = e; |
| for (int i = 0; i < size; ++i) { |
| losers[i] = -1; |
| } |
| for (int i = 0; i < size; ++i) { |
| int slot = (size + i) >> 1; |
| |
| if (i < entries.length) { |
| available.set(i, entries[i].advance()); |
| } |
| int currIdx = i; |
| while (slot > 0) { |
| int cmp = 0; |
| if (losers[slot] < 0 || currIdx < 0) { |
| cmp = losers[slot] < 0 ? -1 : 1; |
| } else if (!available.get(losers[slot])) { |
| cmp = 1; |
| } else if (available.get(currIdx)) { |
| if (currIdx <= i) { |
| cmp = entries[losers[slot]].compareTo(entries[currIdx]); |
| } else { |
| cmp = 1; |
| } |
| } |
| |
| if (cmp <= 0) { |
| int tmp = losers[slot]; |
| losers[slot] = currIdx; |
| currIdx = tmp; |
| } |
| slot >>= 1; |
| } |
| losers[0] = currIdx; |
| } |
| } |
| |
| public Entry peek() { |
| if (entries.length == 0) { |
| return null; |
| } |
| return entries[losers[0]]; |
| } |
| |
| public void pop() { |
| int winner = losers[0]; |
| int slot = (size + winner) >> 1; |
| |
| boolean avail = entries[winner].advance(); |
| if (!avail) { |
| entries[winner] = null; |
| } |
| available.set(winner, avail); |
| int currIdx = winner; |
| while (!available.isEmpty() && slot > 0) { |
| int cmp = 0; |
| if (!available.get(losers[slot])) { |
| cmp = 1; |
| } else if (available.get(currIdx)) { |
| cmp = entries[losers[slot]].compareTo(entries[currIdx]); |
| } |
| |
| if (cmp <= 0) { |
| int tmp = losers[slot]; |
| losers[slot] = currIdx; |
| currIdx = tmp; |
| } |
| slot >>= 1; |
| } |
| losers[0] = currIdx; |
| } |
| |
| public interface Entry extends Comparable<Entry> { |
| public abstract boolean advance(); |
| } |
| } |