net.conquiris.lucene.search.NegatingFilter.java Source code

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Here is the source code for net.conquiris.lucene.search.NegatingFilter.java

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/*
 * Copyright (C) the original author or authors.
 *
 * Licensed 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 net.conquiris.lucene.search;

import static com.google.common.base.Preconditions.checkNotNull;

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.FixedBitSet;

/**
 * A wrapping filter that negates the provided one.
 * @author Andres Rodriguez
 */
final class NegatingFilter extends Filter {
    /** Serial UID. */
    private static final long serialVersionUID = 3218934851787738661L;

    /** Wrapped filter. */
    private final Filter filter;

    /**
     * Constructor.
     * @param filter Filter to cache results of.
     */
    NegatingFilter(Filter filter) {
        this.filter = checkNotNull(filter, "The filter to negate must be provided");
    }

    @Override
    public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
        final int n = reader.maxDoc();
        final FixedBitSet bits = new FixedBitSet(reader.maxDoc());
        final DocIdSet set = filter.getDocIdSet(reader);
        if (set == null || set == DocIdSet.EMPTY_DOCIDSET) {
            bits.set(0, n);
        } else {
            DocIdSetIterator i = set.iterator();
            if (i == null) {
                bits.set(0, n);
            } else {
                bits.or(i);
                bits.flip(0, n);
            }
        }
        return bits;
    }
}