RandomAccessAndFilter.java

package com.browseengine.bobo.facets.filter;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;

import com.browseengine.bobo.api.BoboSegmentReader;
import com.browseengine.bobo.docidset.AndDocIdSet;
import com.browseengine.bobo.docidset.RandomAccessDocIdSet;

public class RandomAccessAndFilter extends RandomAccessFilter {
  protected List<RandomAccessFilter> _filters;

  public RandomAccessAndFilter(List<RandomAccessFilter> filters) {
    _filters = filters;
  }

  @Override
  public double getFacetSelectivity(BoboSegmentReader reader) {
    double selectivity = Double.MAX_VALUE;
    for (RandomAccessFilter filter : _filters) {
      double curSelectivity = filter.getFacetSelectivity(reader);
      if (selectivity > curSelectivity) {
        selectivity = curSelectivity;
      }
    }
    if (selectivity > 0.999) {
      selectivity = 1.0;
    }
    return selectivity;
  }

  @Override
  public RandomAccessDocIdSet getRandomAccessDocIdSet(BoboSegmentReader reader) throws IOException {
    if (_filters.size() == 1) {
      return _filters.get(0).getRandomAccessDocIdSet(reader);
    } else {
      List<DocIdSet> list = new ArrayList<DocIdSet>(_filters.size());
      List<RandomAccessDocIdSet> randomAccessList = new ArrayList<RandomAccessDocIdSet>(
          _filters.size());
      for (RandomAccessFilter f : _filters) {
        RandomAccessDocIdSet s = f.getRandomAccessDocIdSet(reader);
        list.add(s);
        randomAccessList.add(s);
      }
      final RandomAccessDocIdSet[] randomAccessDocIdSets = randomAccessList
          .toArray(new RandomAccessDocIdSet[randomAccessList.size()]);
      final DocIdSet andDocIdSet = new AndDocIdSet(list);
      return new RandomAccessDocIdSet() {
        @Override
        public boolean get(int docId) {
          for (RandomAccessDocIdSet s : randomAccessDocIdSets) {
            if (!s.get(docId)) return false;
          }
          return true;
        }

        @Override
        public DocIdSetIterator iterator() throws IOException {
          return andDocIdSet.iterator();
        }
      };
    }
  }
}