org.apache.lucene.search.SortedNumericSelector.java Source code

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Here is the source code for org.apache.lucene.search.SortedNumericSelector.java

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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;

import java.io.IOException;

import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.FilterNumericDocValues;
import org.apache.lucene.index.NumericDocValues;
import org.apache.lucene.index.SortedNumericDocValues;
import org.apache.lucene.util.NumericUtils;

/** 
 * Selects a value from the document's list to use as the representative value 
 * <p>
 * This provides a NumericDocValues view over the SortedNumeric, for use with sorting,
 * expressions, function queries, etc.
 */
public class SortedNumericSelector {

    /** 
     * Type of selection to perform.
     */
    public enum Type {
        /** 
         * Selects the minimum value in the set 
         */
        MIN,
        /** 
         * Selects the maximum value in the set 
         */
        MAX,
        // TODO: we could do MEDIAN in constant time (at most 2 lookups)
    }

    /** 
     * Wraps a multi-valued SortedNumericDocValues as a single-valued view, using the specified selector 
     * and numericType.
     */
    public static NumericDocValues wrap(SortedNumericDocValues sortedNumeric, Type selector,
            SortField.Type numericType) {
        if (numericType != SortField.Type.INT && numericType != SortField.Type.LONG
                && numericType != SortField.Type.FLOAT && numericType != SortField.Type.DOUBLE) {
            throw new IllegalArgumentException("numericType must be a numeric type");
        }
        final NumericDocValues view;
        NumericDocValues singleton = DocValues.unwrapSingleton(sortedNumeric);
        if (singleton != null) {
            // it's actually single-valued in practice, but indexed as multi-valued,
            // so just sort on the underlying single-valued dv directly.
            // regardless of selector type, this optimization is safe!
            view = singleton;
        } else {
            switch (selector) {
            case MIN:
                view = new MinValue(sortedNumeric);
                break;
            case MAX:
                view = new MaxValue(sortedNumeric);
                break;
            default:
                throw new AssertionError();
            }
        }
        // undo the numericutils sortability
        switch (numericType) {
        case FLOAT:
            return new FilterNumericDocValues(view) {
                @Override
                public long longValue() throws IOException {
                    return NumericUtils.sortableFloatBits((int) in.longValue());
                }
            };
        case DOUBLE:
            return new FilterNumericDocValues(view) {
                @Override
                public long longValue() throws IOException {
                    return NumericUtils.sortableDoubleBits(in.longValue());
                }
            };
        default:
            return view;
        }
    }

    /** Wraps a SortedNumericDocValues and returns the first value (min) */
    static class MinValue extends NumericDocValues {
        final SortedNumericDocValues in;
        private long value;

        MinValue(SortedNumericDocValues in) {
            this.in = in;
        }

        @Override
        public int docID() {
            return in.docID();
        }

        @Override
        public int nextDoc() throws IOException {
            int docID = in.nextDoc();
            if (docID != NO_MORE_DOCS) {
                value = in.nextValue();
            }
            return docID;
        }

        @Override
        public int advance(int target) throws IOException {
            int docID = in.advance(target);
            if (docID != NO_MORE_DOCS) {
                value = in.nextValue();
            }
            return docID;
        }

        @Override
        public boolean advanceExact(int target) throws IOException {
            if (in.advanceExact(target)) {
                value = in.nextValue();
                return true;
            }
            return false;
        }

        @Override
        public long cost() {
            return in.cost();
        }

        @Override
        public long longValue() {
            return value;
        }
    }

    /** Wraps a SortedNumericDocValues and returns the last value (max) */
    static class MaxValue extends NumericDocValues {
        final SortedNumericDocValues in;
        private long value;

        MaxValue(SortedNumericDocValues in) {
            this.in = in;
        }

        @Override
        public int docID() {
            return in.docID();
        }

        private void setValue() throws IOException {
            int count = in.docValueCount();
            for (int i = 0; i < count; i++) {
                value = in.nextValue();
            }
        }

        @Override
        public int nextDoc() throws IOException {
            int docID = in.nextDoc();
            if (docID != NO_MORE_DOCS) {
                setValue();
            }
            return docID;
        }

        @Override
        public int advance(int target) throws IOException {
            int docID = in.advance(target);
            if (docID != NO_MORE_DOCS) {
                setValue();
            }
            return docID;
        }

        @Override
        public boolean advanceExact(int target) throws IOException {
            if (in.advanceExact(target)) {
                setValue();
                return true;
            }
            return false;
        }

        @Override
        public long cost() {
            return in.cost();
        }

        @Override
        public long longValue() {
            return value;
        }
    }
}