content: /**
   * 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.solr.search.function;
  
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.search.*;
  import org.apache.solr.common.SolrException;
  import org.apache.solr.search.SolrSortField;
  
  import java.io.IOException;
  import java.io.Serializable;
  import java.util.IdentityHashMap;
  import java.util.Map;
  import java.util.Collections;
  
  /**
   * Instantiates {@link org.apache.solr.search.function.DocValues} for a particular reader.
   * <br>
   * Often used when creating a {@link FunctionQuery}.
   *
   * @version $Id: ValueSource.java 1140724 2011-06-28 17:00:20Z yonik $
   */
  public abstract class ValueSource implements Serializable {
  
    @Deprecated
    public DocValues getValues(IndexReader reader) throws IOException {
      return getValues(null, reader);
    }
  
    /**
     * Gets the values for this reader and the context that was previously
     * passed to createWeight()
     */
    public DocValues getValues(Map context, IndexReader reader) throws IOException {
      return getValues(reader);
    }
  
    @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, Searcher searcher) throws IOException {
    }
  
    /**
     * Returns a new non-threadsafe context map.
     */
    public static Map newContext() {
      return new IdentityHashMap();
    }
  
    //
    // Sorting by function
    //
  
    /**
     * EXPERIMENTAL: This method is subject to change.
     * <br>WARNING: Sorted function queries are not currently weighted.
     * <p>
     * Get the SortField for this ValueSource.  Uses the {@link #getValues(java.util.Map, IndexReader)}
     * to populate the SortField.
     *
     * @param reverse true if this is a reverse sort.
     * @return The {@link org.apache.lucene.search.SortField} for the ValueSource
     * @throws IOException if there was a problem reading the values.
     */
    public SortField getSortField(boolean reverse) throws IOException {
      return new ValueSourceSortField(reverse);
    }
  
    private static FieldComparatorSource dummyComparator = new FieldComparatorSource() {
      @Override
      public FieldComparator newComparator(String fieldname, int numHits, int sortPos, boolean reversed) throws IOException {
        throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "Unweighted use of sort " + fieldname);
      }
    };
  
    class ValueSourceSortField extends SortField implements SolrSortField {
      public ValueSourceSortField(boolean reverse) {
        super(description(), dummyComparator, reverse);
      }
  
      public SortField weight(IndexSearcher searcher) throws IOException {
        Map context = newContext();
        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 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 org.apache.solr.search.function.DocValues} 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 DocValues docVals;
      private double bottom;
      private Map fcontext;
  
      ValueSourceComparator(Map fcontext, int numHits) {
        this.fcontext = fcontext;
        values = new double[numHits];
      }
  
      @Override
      public int compare(int slot1, int slot2) {
        final double v1 = values[slot1];
        final double v2 = values[slot2];
        if (v1 > v2) {
          return 1;
        } else if (v1 < v2) {
          return -1;
        } else {
          return 0;
        }
  
      }
  
      @Override
      public int compareBottom(int doc) {
        final double v2 = docVals.doubleVal(doc);
        if (bottom > v2) {
          return 1;
        } else if (bottom < v2) {
          return -1;
        } else {
          return 0;
        }
      }
  
      @Override
      public void copy(int slot, int doc) {
        values[slot] = docVals.doubleVal(doc);
      }
  
      @Override
      public void setNextReader(IndexReader reader, int docBase) throws IOException {
        docVals = getValues(fcontext, reader);
      }
  
      @Override
      public void setBottom(final int bottom) {
        this.bottom = values[bottom];
      }
  
      @Override
      public Double value(int slot) {
        return values[slot];
      }
      
      @Override
      public double docValue(int doc) {
        return docVals.doubleVal(doc);
      }
    }
  }
  
  
  
  