org.apache.lucene.search.join.BlockJoinSelector Maven / Gradle / Ivy
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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.lucene.search.join;
import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.NumericDocValues;
import org.apache.lucene.index.SortedDocValues;
import org.apache.lucene.index.SortedNumericDocValues;
import org.apache.lucene.index.SortedSetDocValues;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.SortedNumericSelector;
import org.apache.lucene.search.SortedSetSelector;
import org.apache.lucene.util.BitSet;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.BytesRef;
/** Select a value from a block of documents.
* @lucene.internal */
public class BlockJoinSelector {
private BlockJoinSelector() {}
/** Type of selection to perform. If none of the documents in the block have
* a value then no value will be selected. */
public enum Type {
/** Only consider the minimum value from the block when sorting. */
MIN,
/** Only consider the maximum value from the block when sorting. */
MAX;
}
/** Return a {@link Bits} instance that returns true if, and only if, any of
* the children of the given parent document has a value. */
public static Bits wrap(final Bits docsWithValue, BitSet parents, BitSet children) {
return new Bits() {
@Override
public boolean get(int docID) {
assert parents.get(docID) : "this selector may only be used on parent documents";
if (docID == 0) {
// no children
return false;
}
final int firstChild = parents.prevSetBit(docID - 1) + 1;
for (int child = children.nextSetBit(firstChild); child < docID; child = children.nextSetBit(child + 1)) {
if (docsWithValue.get(child)) {
return true;
}
}
return false;
}
@Override
public int length() {
return docsWithValue.length();
}
};
}
/** Wraps the provided {@link SortedSetDocValues} in order to only select
* one value per parent among its {@code children} using the configured
* {@code selection} type. */
public static SortedDocValues wrap(SortedSetDocValues sortedSet, Type selection, BitSet parents, BitSet children) {
SortedDocValues values;
switch (selection) {
case MIN:
values = SortedSetSelector.wrap(sortedSet, SortedSetSelector.Type.MIN);
break;
case MAX:
values = SortedSetSelector.wrap(sortedSet, SortedSetSelector.Type.MAX);
break;
default:
throw new AssertionError();
}
return wrap(values, selection, parents, children);
}
/** Wraps the provided {@link SortedDocValues} in order to only select
* one value per parent among its {@code children} using the configured
* {@code selection} type. */
public static SortedDocValues wrap(final SortedDocValues values, Type selection, BitSet parents, BitSet children) {
return new SortedDocValues() {
@Override
public int getOrd(int docID) {
assert parents.get(docID) : "this selector may only be used on parent documents";
if (docID == 0) {
// no children
return -1;
}
final int firstChild = parents.prevSetBit(docID - 1) + 1;
int ord = -1;
for (int child = children.nextSetBit(firstChild); child < docID; child = children.nextSetBit(child + 1)) {
final int childOrd = values.getOrd(child);
switch (selection) {
case MIN:
if (ord == -1) {
ord = childOrd;
} else if (childOrd != -1) {
ord = Math.min(ord, childOrd);
}
break;
case MAX:
ord = Math.max(ord, childOrd);
break;
default:
throw new AssertionError();
}
}
return ord;
}
@Override
public BytesRef lookupOrd(int ord) {
return values.lookupOrd(ord);
}
@Override
public int getValueCount() {
return values.getValueCount();
}
};
}
/** Wraps the provided {@link SortedNumericDocValues} in order to only select
* one value per parent among its {@code children} using the configured
* {@code selection} type. */
public static NumericDocValues wrap(SortedNumericDocValues sortedNumerics, Type selection, BitSet parents, BitSet children) {
NumericDocValues values;
switch (selection) {
case MIN:
values = SortedNumericSelector.wrap(sortedNumerics, SortedNumericSelector.Type.MIN, SortField.Type.LONG);
break;
case MAX:
values = SortedNumericSelector.wrap(sortedNumerics, SortedNumericSelector.Type.MAX, SortField.Type.LONG);
break;
default:
throw new AssertionError();
}
return wrap(values, DocValues.docsWithValue(sortedNumerics, parents.length()), selection, parents, children);
}
/** Wraps the provided {@link NumericDocValues} in order to only select
* one value per parent among its {@code children} using the configured
* {@code selection} type. */
public static NumericDocValues wrap(final NumericDocValues values, Bits docsWithValue, Type selection, BitSet parents, BitSet children) {
return new NumericDocValues() {
@Override
public long get(int docID) {
assert parents.get(docID) : "this selector may only be used on parent documents";
if (docID == 0) {
// no children
return 0;
}
final int firstChild = parents.prevSetBit(docID - 1) + 1;
long value = 0;
boolean hasValue = false;
for (int child = children.nextSetBit(firstChild); child < docID; child = children.nextSetBit(child + 1)) {
final long childValue = values.get(child);
final boolean childHasValue = value != 0 || docsWithValue.get(child);
if (hasValue == false) {
value = childValue;
hasValue = childHasValue;
} else if (childHasValue) {
switch (selection) {
case MIN:
value = Math.min(value, childValue);
break;
case MAX:
value = Math.max(value, childValue);
break;
default:
throw new AssertionError();
}
}
}
return value;
}
};
}
}
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