package org.apache.lucene.queries.function;
/*
* 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.
*/
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.search.FieldComparator;
import org.apache.lucene.search.FieldComparatorSource;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.SortField;
import java.io.IOException;
import java.util.IdentityHashMap;
import java.util.Map;
/**
* Instantiates {@link FunctionValues} for a particular reader.
* <br>
* Often used when creating a {@link FunctionQuery}.
*
*
*/
public abstract class ValueSource {
/**
* Gets the values for this reader and the context that was previously
* passed to createWeight()
*/
public abstract FunctionValues getValues(Map context, AtomicReaderContext readerContext) throws IOException;
@Override
public abstract boolean equals(Object o);
@Override
public abstract int hashCode();
/**
* description of field, used in explain()
*/
public abstract String description();
@Override
public String toString() {
return description();
}
/**
* Implementations should propagate createWeight to sub-ValueSources which can optionally store
* weight info in the context. The context object will be passed to getValues()
* where this info can be retrieved.
*/
public void createWeight(Map context, IndexSearcher searcher) throws IOException {
}
/**
* Returns a new non-threadsafe context map.
*/
public static Map newContext(IndexSearcher searcher) {
Map context = new IdentityHashMap();
context.put("searcher", searcher);
return context;
}
//
// Sorting by function
//
/**
* EXPERIMENTAL: This method is subject to change.
* <p>
* Get the SortField for this ValueSource. Uses the {@link #getValues(java.util.Map, AtomicReaderContext)}
* to populate the SortField.
*
* @param reverse true if this is a reverse sort.
* @return The {@link org.apache.lucene.search.SortField} for the ValueSource
*/
public SortField getSortField(boolean reverse) {
return new ValueSourceSortField(reverse);
}
class ValueSourceSortField extends SortField {
public ValueSourceSortField(boolean reverse) {
super(description(), SortField.Type.REWRITEABLE, reverse);
}
@Override
public SortField rewrite(IndexSearcher searcher) throws IOException {
Map context = newContext(searcher);
createWeight(context, searcher);
return new SortField(getField(), new ValueSourceComparatorSource(context), getReverse());
}
}
class ValueSourceComparatorSource extends FieldComparatorSource {
private final Map context;
public ValueSourceComparatorSource(Map context) {
this.context = context;
}
@Override
public FieldComparator<Double> newComparator(String fieldname, int numHits,
int sortPos, boolean reversed) throws IOException {
return new ValueSourceComparator(context, numHits);
}
}
/**
* Implement a {@link org.apache.lucene.search.FieldComparator} that works
* off of the {@link FunctionValues} for a ValueSource
* instead of the normal Lucene FieldComparator that works off of a FieldCache.
*/
class ValueSourceComparator extends FieldComparator<Double> {
private final double[] values;
private FunctionValues docVals;
private double bottom;
private final Map fcontext;
ValueSourceComparator(Map fcontext, int numHits) {
this.fcontext = fcontext;
values = new double[numHits];
}
@Override
public int compare(int slot1, int slot2) {
return Double.compare(values[slot1], values[slot2]);
}
@Override
public int compareBottom(int doc) {
return Double.compare(bottom, docVals.doubleVal(doc));
}
@Override
public void copy(int slot, int doc) {
values[slot] = docVals.doubleVal(doc);
}
@Override
public FieldComparator setNextReader(AtomicReaderContext context) throws IOException {
docVals = getValues(fcontext, context);
return this;
}
@Override
public void setBottom(final int bottom) {
this.bottom = values[bottom];
}
@Override
public Double value(int slot) {
return values[slot];
}
@Override
public int compareDocToValue(int doc, Double valueObj) {
final double value = valueObj;
final double docValue = docVals.doubleVal(doc);
return Double.compare(docValue, value);
}
}
}