dweiss commented on a change in pull request #163: URL: https://github.com/apache/lucene/pull/163#discussion_r650372453
########## File path: lucene/core/src/java/org/apache/lucene/util/automaton/StateSet.java ########## @@ -0,0 +1,106 @@ +/* + * 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.lucene.util.automaton; + +import java.util.Arrays; +import org.apache.lucene.util.BitMixer; +import org.apache.lucene.util.IntIntHashMap; + +/** A thin wrapper of {@link IntIntHashMap} */ +final class StateSet extends IntSet { + + private final IntIntHashMap inner; + private long hashCode; + private boolean hashUpdated = true; + private boolean arrayUpdated = true; + private int[] arrayCache = new int[0]; + + StateSet(int capacity) { + inner = new IntIntHashMap(capacity); + } + + // Adds this state to the set + void incr(int num) { + if (inner.addTo(num, 1) == 1) { + keyChanged(); + } + } + + // Removes this state from the set, if count decrs to 0 + void decr(int num) { + assert inner.containsKey(num); + int keyIndex = inner.indexOf(num); + int count = inner.indexGet(keyIndex) - 1; + if (count == 0) { + inner.remove(num); + keyChanged(); + } else { + inner.indexReplace(keyIndex, count); + } + } + + /** + * Create a snapshot of this int set associated with a given state. The snapshot will not retain + * any frequency information about the elements of this set, only existence. + * + * @param state the state to associate with the frozen set. + * @return A new FrozenIntSet with the same values as this set. + */ + FrozenIntSet freeze(int state) { + return new FrozenIntSet(getArray(), longHashCode(), state); + } + + private void keyChanged() { + hashUpdated = false; + arrayUpdated = false; + } + + @Override + int[] getArray() { + if (arrayUpdated) { + return arrayCache; + } + arrayCache = new int[inner.size()]; + int i = 0; + for (IntIntHashMap.IntCursor cursor : inner.keys()) { + arrayCache[i++] = cursor.value; + } + // we need to sort this array since "equals" method depend on this + Arrays.sort(arrayCache); + arrayUpdated = true; + return arrayCache; + } + + @Override + int size() { + return inner.size(); + } + + @Override + long longHashCode() { + if (hashUpdated) { + return hashCode; + } + hashCode = inner.size(); + for (IntIntHashMap.IntCursor cursor : inner.keys()) { + hashCode += BitMixer.mix(cursor.value); Review comment: I'd still think the simple aggregation 37 * hashCode + cursor.value with a final mix step would be a good enough (or maybe even better) choice here. ########## File path: lucene/core/src/java/org/apache/lucene/util/BitMixer.java ########## @@ -0,0 +1,130 @@ +/* + * 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.lucene.util; + +/** + * Bit mixing utilities. The purpose of these methods is to evenly distribute key space over int32 + * range. + * + * <p>Forked from com.carrotsearch.hppc.BitMixer Review comment: I'd make it a link back to the original project and include a comment which hash ref of the repository this was copied from, for reference and in case somebody wishes to sync/update in the future. ########## File path: lucene/core/src/java/org/apache/lucene/util/automaton/StateSet.java ########## @@ -0,0 +1,106 @@ +/* + * 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.lucene.util.automaton; + +import java.util.Arrays; +import org.apache.lucene.util.BitMixer; +import org.apache.lucene.util.IntIntHashMap; + +/** A thin wrapper of {@link IntIntHashMap} */ +final class StateSet extends IntSet { + + private final IntIntHashMap inner; + private long hashCode; + private boolean hashUpdated = true; + private boolean arrayUpdated = true; + private int[] arrayCache = new int[0]; + + StateSet(int capacity) { + inner = new IntIntHashMap(capacity); + } + + // Adds this state to the set + void incr(int num) { + if (inner.addTo(num, 1) == 1) { + keyChanged(); + } + } + + // Removes this state from the set, if count decrs to 0 + void decr(int num) { + assert inner.containsKey(num); + int keyIndex = inner.indexOf(num); + int count = inner.indexGet(keyIndex) - 1; + if (count == 0) { + inner.remove(num); + keyChanged(); + } else { + inner.indexReplace(keyIndex, count); + } + } + + /** + * Create a snapshot of this int set associated with a given state. The snapshot will not retain + * any frequency information about the elements of this set, only existence. + * + * @param state the state to associate with the frozen set. + * @return A new FrozenIntSet with the same values as this set. + */ + FrozenIntSet freeze(int state) { + return new FrozenIntSet(getArray(), longHashCode(), state); + } + + private void keyChanged() { + hashUpdated = false; + arrayUpdated = false; + } + + @Override + int[] getArray() { + if (arrayUpdated) { + return arrayCache; + } + arrayCache = new int[inner.size()]; + int i = 0; + for (IntIntHashMap.IntCursor cursor : inner.keys()) { + arrayCache[i++] = cursor.value; + } + // we need to sort this array since "equals" method depend on this + Arrays.sort(arrayCache); + arrayUpdated = true; + return arrayCache; + } + + @Override + int size() { + return inner.size(); + } + + @Override + long longHashCode() { + if (hashUpdated) { + return hashCode; + } + hashCode = inner.size(); + for (IntIntHashMap.IntCursor cursor : inner.keys()) { + hashCode += BitMixer.mix(cursor.value); Review comment: Duh. 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