SpanOrQuery.java

package org.apache.lucene.search.spans;


/**
 * Copyright 2004 The Apache Software Foundation
 *
 * 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.
 */
import java.io.IOException;
import java.util.List;
import java.util.Collection;
import java.util.ArrayList;
import java.util.Iterator;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.util.PriorityQueue;

/** Matches the union of its clauses.*/
public class SpanOrQuery extends SpanQuery 
{
  private List clauses;
  private String field;

  /** Construct a SpanOrQuery merging the provided clauses. */
  public SpanOrQuery(SpanQuery[] clauses) 
  {
    // copy clauses array into an ArrayList
    this.clauses = new ArrayList(clauses.length);
    for (int i = 0; i < clauses.length; i++) 
    {
      SpanQuery clause = clauses[i];
      if (i == 0) { // check field
        field = clause.getField();
      }
      else if (!clause.getField().equals(field)) {
        throw new IllegalArgumentException("Clauses must have same field.");
      }
      this.clauses.add(clause);
    }
  }

  /** Return the clauses whose spans are matched. */
  public SpanQuery[] getClauses() {
    return (SpanQuery[])clauses.toArray(new SpanQuery[clauses.size()]);
  }

  public String getField() {
    return field;
  }

  public Collection getTerms() 
  {
    Collection terms = new ArrayList();
    Iterator i = clauses.iterator();
    while (i.hasNext()) {
      SpanQuery clause = (SpanQuery)i.next();
      terms.addAll(clause.getTerms());
    }
    return terms;
  }

  public Query[] getSubQueries() {
    return (Query[])clauses.toArray(new Query[clauses.size()]);
  }

  public Query rewrite(IndexReader reader)
    throws IOException 
  {
    List newClauses = new ArrayList(clauses.size());
    boolean anyChanged = false;
    for (Iterator i = clauses.iterator(); i.hasNext();) {
      SpanQuery clause = (SpanQuery)i.next();
      SpanQuery rewrittenClause = (SpanQuery)clause.rewrite(reader);
      newClauses.add(rewrittenClause);
      if (clause != rewrittenClause)
        anyChanged = true;
    }

    if (!anyChanged)
      return this;

    SpanOrQuery clone = (SpanOrQuery)this.clone();
    clone.clauses = newClauses;
    return clone;
  }

  public String toString(String field) 
  {
    StringBuffer buffer = new StringBuffer();
    buffer.append("spanOr([");
    Iterator i = clauses.iterator();
    while (i.hasNext()) 
    {
      SpanQuery clause = (SpanQuery)i.next();
      buffer.append(clause.toString(field));
      if (i.hasNext()) {
        buffer.append(", ");
      }
    }
    buffer.append("])");
    return buffer.toString();
  }

  private class SpanQueue extends PriorityQueue 
  {
    public SpanQueue(int size) {
      initialize(size);
    }

    protected final boolean lessThan(Object o1, Object o2) 
    {
      Spans spans1 = (Spans)o1;
      Spans spans2 = (Spans)o2;
      if (spans1.doc() == spans2.doc()) 
      {
        if (spans1.start() == spans2.start()) 
        {
          if (spans1.score() == spans2.score()) {
            return spans1.end() < spans2.end();
          }
          else {
            return spans1.score() > spans2.score();
          }
        }
        else {
          return spans1.start() < spans2.start();
        }
      }
      else {
        return spans1.doc() < spans2.doc();
      }
    }
  }

  public Spans getSpans(final IndexReader reader, final Searcher searcher)
    throws IOException 
  {
    if (clauses.size() == 1) // optimize 1-clause case
      return ((SpanQuery)clauses.get(0)).getSpans(reader, searcher);

    return new Spans() 
    {
      private List all = new ArrayList(clauses.size());
      private SpanQueue queue = new SpanQueue(clauses.size());
      
      {
        Iterator i = clauses.iterator();
        while (i.hasNext()) { // initialize all
          all.add(((SpanQuery)i.next()).getSpans(reader, searcher));
        }
      }

      private boolean firstTime = true;

      public boolean next()
        throws IOException 
      {
        if (firstTime) { // first time -- initialize
          for (int i = 0; i < all.size(); i++) 
        {
            Spans spans = (Spans)all.get(i);
            if (spans.next()) { // move to first entry
              queue.put(spans); // build queue
            }
            else {
              all.remove(i--);
            }
          }
          firstTime = false;
          return queue.size() != 0;
        }

        if (queue.size() == 0) { // all done
          return false;
        }

        if (top().next()) { // move to next
          queue.adjustTop();
          return true;
        }

        all.remove(queue.pop()); // exhausted a clause

        return queue.size() != 0;
      }

      private Spans top() {
        return (Spans)queue.top();
      }

      public boolean skipTo(int target)
        throws IOException 
      {
        if (firstTime) 
        {
          for (int i = 0; i < all.size(); i++) 
          {
            Spans spans = (Spans)all.get(i);
            if (spans.skipTo(target)) { // skip each spans in all
              queue.put(spans); // build queue
            }
            else {
              all.remove(i--);
            }
          }
          firstTime = false;
        }
        else {
          while (queue.size() != 0 && top().doc() < target) 
          {
            if (top().skipTo(target)) {
              queue.adjustTop();
            }
            else {
              all.remove(queue.pop());
            }
          }
        }

        return queue.size() != 0;
      }

      public int doc() {
        return top().doc();
      }

      public int start() {
        return top().start();
      }

      public int end() {
        return top().end();
      }

      public float score() {
        return top().score() * getBoost();
      }

      public String toString() {
        return "spans(" + SpanOrQuery.this + ")@" +
               (firstTime ? "START"
                : (queue.size() > 0 ? (doc() + ":" + start() + "-" + end())
                   : "END"));
      }

      public Explanation explain()
        throws IOException 
      {
        if (getBoost() == 1.0f)
          return top().explain();

        Explanation result = new Explanation(0,
                                             "weight(" + toString() +
                                             "), product of:");

        Explanation boostExpl = new Explanation(getBoost(), "boost");
        result.addDetail(boostExpl);

        Explanation inclExpl = top().explain();
        result.addDetail(inclExpl);

        result.setValue(boostExpl.getValue() * inclExpl.getValue());
        return result;
      }
    };
  }
}