package org.apache.lucene.queries;
/*
* 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 java.io.IOException;
import org.apache.lucene.index.AtomicReader;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.search.BitsFilteredDocIdSet;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Filter;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.FixedBitSet;
/**
* <p>
* Allows multiple {@link Filter}s to be chained.
* Logical operations such as <b>NOT</b> and <b>XOR</b>
* are applied between filters. One operation can be used
* for all filters, or a specific operation can be declared
* for each filter.
* </p>
* <p>
* Order in which filters are called depends on
* the position of the filter in the chain. It's probably
* more efficient to place the most restrictive filters
* /least computationally-intensive filters first.
* </p>
*/
public class ChainedFilter extends Filter {
public static final int OR = 0;
public static final int AND = 1;
public static final int ANDNOT = 2;
public static final int XOR = 3;
/**
* Logical operation when none is declared. Defaults to OR.
*/
public static final int DEFAULT = OR;
/**
* The filter chain
*/
private Filter[] chain = null;
private int[] logicArray;
private int logic = -1;
/**
* Ctor.
*
* @param chain The chain of filters
*/
public ChainedFilter(Filter[] chain) {
this.chain = chain;
}
/**
* Ctor.
*
* @param chain The chain of filters
* @param logicArray Logical operations to apply between filters
*/
public ChainedFilter(Filter[] chain, int[] logicArray) {
this.chain = chain;
this.logicArray = logicArray;
}
/**
* Ctor.
*
* @param chain The chain of filters
* @param logic Logical operation to apply to ALL filters
*/
public ChainedFilter(Filter[] chain, int logic) {
this.chain = chain;
this.logic = logic;
}
/**
* {@link Filter#getDocIdSet}.
*/
@Override
public DocIdSet getDocIdSet(AtomicReaderContext context, Bits acceptDocs) throws IOException {
int[] index = new int[1]; // use array as reference to modifiable int;
index[0] = 0; // an object attribute would not be thread safe.
if (logic != -1) {
return BitsFilteredDocIdSet.wrap(getDocIdSet(context, logic, index), acceptDocs);
} else if (logicArray != null) {
return BitsFilteredDocIdSet.wrap(getDocIdSet(context, logicArray, index), acceptDocs);
}
return BitsFilteredDocIdSet.wrap(getDocIdSet(context, DEFAULT, index), acceptDocs);
}
private DocIdSetIterator getDISI(Filter filter, AtomicReaderContext context)
throws IOException {
// we dont pass acceptDocs, we will filter at the end using an additional filter
DocIdSet docIdSet = filter.getDocIdSet(context, null);
if (docIdSet == null) {
return DocIdSetIterator.empty();
} else {
DocIdSetIterator iter = docIdSet.iterator();
if (iter == null) {
return DocIdSetIterator.empty();
} else {
return iter;
}
}
}
private FixedBitSet initialResult(AtomicReaderContext context, int logic, int[] index)
throws IOException {
AtomicReader reader = context.reader();
FixedBitSet result = new FixedBitSet(reader.maxDoc());
if (logic == AND) {
result.or(getDISI(chain[index[0]], context));
++index[0];
} else if (logic == ANDNOT) {
result.or(getDISI(chain[index[0]], context));
result.flip(0, reader.maxDoc()); // NOTE: may set bits for deleted docs.
++index[0];
}
return result;
}
/**
* Delegates to each filter in the chain.
*
* @param context AtomicReaderContext
* @param logic Logical operation
* @return DocIdSet
*/
private DocIdSet getDocIdSet(AtomicReaderContext context, int logic, int[] index)
throws IOException {
FixedBitSet result = initialResult(context, logic, index);
for (; index[0] < chain.length; index[0]++) {
// we dont pass acceptDocs, we will filter at the end using an additional filter
doChain(result, logic, chain[index[0]].getDocIdSet(context, null));
}
return result;
}
/**
* Delegates to each filter in the chain.
*
* @param context AtomicReaderContext
* @param logic Logical operation
* @return DocIdSet
*/
private DocIdSet getDocIdSet(AtomicReaderContext context, int[] logic, int[] index)
throws IOException {
if (logic.length != chain.length) {
throw new IllegalArgumentException("Invalid number of elements in logic array");
}
FixedBitSet result = initialResult(context, logic[0], index);
for (; index[0] < chain.length; index[0]++) {
// we dont pass acceptDocs, we will filter at the end using an additional filter
doChain(result, logic[index[0]], chain[index[0]].getDocIdSet(context, null));
}
return result;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("ChainedFilter: [");
for (Filter aChain : chain) {
sb.append(aChain);
sb.append(' ');
}
sb.append(']');
return sb.toString();
}
private void doChain(FixedBitSet result, int logic, DocIdSet dis) throws IOException {
if (dis instanceof FixedBitSet) {
// optimized case for FixedBitSets
switch (logic) {
case OR:
result.or((FixedBitSet) dis);
break;
case AND:
result.and((FixedBitSet) dis);
break;
case ANDNOT:
result.andNot((FixedBitSet) dis);
break;
case XOR:
result.xor((FixedBitSet) dis);
break;
default:
doChain(result, DEFAULT, dis);
break;
}
} else {
DocIdSetIterator disi;
if (dis == null) {
disi = DocIdSetIterator.empty();
} else {
disi = dis.iterator();
if (disi == null) {
disi = DocIdSetIterator.empty();
}
}
switch (logic) {
case OR:
result.or(disi);
break;
case AND:
result.and(disi);
break;
case ANDNOT:
result.andNot(disi);
break;
case XOR:
result.xor(disi);
break;
default:
doChain(result, DEFAULT, dis);
break;
}
}
}
}