package org.apache.lucene.misc;
/**
* 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.IndexReader;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Filter;
import org.apache.lucene.util.OpenBitSet;
import org.apache.lucene.util.OpenBitSetDISI;
import org.apache.lucene.util.SortedVIntList;
/**
* <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 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}.
*/
public DocIdSet getDocIdSet(IndexReader reader) 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 getDocIdSet(reader, logic, index);
else if (logicArray != null)
return getDocIdSet(reader, logicArray, index);
else
return getDocIdSet(reader, DEFAULT, index);
}
private DocIdSetIterator getDISI(Filter filter, IndexReader reader)
throws IOException {
DocIdSet docIdSet = filter.getDocIdSet(reader);
if (docIdSet == null) {
return DocIdSet.EMPTY_DOCIDSET.iterator();
} else {
DocIdSetIterator iter = docIdSet.iterator();
if (iter == null) {
return DocIdSet.EMPTY_DOCIDSET.iterator();
} else {
return iter;
}
}
}
private OpenBitSetDISI initialResult(IndexReader reader, int logic, int[] index)
throws IOException
{
OpenBitSetDISI result;
/**
* First AND operation takes place against a completely false
* bitset and will always return zero results.
*/
if (logic == AND)
{
result = new OpenBitSetDISI(getDISI(chain[index[0]], reader), reader.maxDoc());
++index[0];
}
else if (logic == ANDNOT)
{
result = new OpenBitSetDISI(getDISI(chain[index[0]], reader), reader.maxDoc());
result.flip(0,reader.maxDoc()); // NOTE: may set bits for deleted docs.
++index[0];
}
else
{
result = new OpenBitSetDISI(reader.maxDoc());
}
return result;
}
// TODO: in 3.0, instead of removing this deprecated
// method, make it a no-op and mark it final
/** Provide a SortedVIntList when it is definitely
* smaller than an OpenBitSet
* @deprecated Either use CachingWrapperFilter, or
* switch to a different DocIdSet implementation yourself. */
protected DocIdSet finalResult(OpenBitSetDISI result, int maxDocs) {
return (result.cardinality() < (maxDocs / 9))
? (DocIdSet) new SortedVIntList(result)
: (DocIdSet) result;
}
/**
* Delegates to each filter in the chain.
* @param reader IndexReader
* @param logic Logical operation
* @return DocIdSet
*/
private DocIdSet getDocIdSet(IndexReader reader, int logic, int[] index)
throws IOException
{
OpenBitSetDISI result = initialResult(reader, logic, index);
for (; index[0] < chain.length; index[0]++)
{
doChain(result, logic, chain[index[0]].getDocIdSet(reader));
}
return finalResult(result, reader.maxDoc());
}
/**
* Delegates to each filter in the chain.
* @param reader IndexReader
* @param logic Logical operation
* @return DocIdSet
*/
private DocIdSet getDocIdSet(IndexReader reader, int[] logic, int[] index)
throws IOException
{
if (logic.length != chain.length)
throw new IllegalArgumentException("Invalid number of elements in logic array");
OpenBitSetDISI result = initialResult(reader, logic[0], index);
for (; index[0] < chain.length; index[0]++)
{
doChain(result, logic[index[0]], chain[index[0]].getDocIdSet(reader));
}
return finalResult(result, reader.maxDoc());
}
public String toString()
{
StringBuffer sb = new StringBuffer();
sb.append("ChainedFilter: [");
for (int i = 0; i < chain.length; i++)
{
sb.append(chain[i]);
sb.append(' ');
}
sb.append(']');
return sb.toString();
}
private void doChain(OpenBitSetDISI result, int logic, DocIdSet dis)
throws IOException {
if (dis instanceof OpenBitSet) {
// optimized case for OpenBitSets
switch (logic) {
case OR:
result.or((OpenBitSet) dis);
break;
case AND:
result.and((OpenBitSet) dis);
break;
case ANDNOT:
result.andNot((OpenBitSet) dis);
break;
case XOR:
result.xor((OpenBitSet) dis);
break;
default:
doChain(result, DEFAULT, dis);
break;
}
} else {
DocIdSetIterator disi;
if (dis == null) {
disi = DocIdSet.EMPTY_DOCIDSET.iterator();
} else {
disi = dis.iterator();
if (disi == null) {
disi = DocIdSet.EMPTY_DOCIDSET.iterator();
}
}
switch (logic) {
case OR:
result.inPlaceOr(disi);
break;
case AND:
result.inPlaceAnd(disi);
break;
case ANDNOT:
result.inPlaceNot(disi);
break;
case XOR:
result.inPlaceXor(disi);
break;
default:
doChain(result, DEFAULT, dis);
break;
}
}
}
}