datefilter.java

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package org.apache.lucene.search;

/* ====================================================================
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 *
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 * reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
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import java.util.BitSet;
import java.util.Date;
import java.io.IOException;

import org.apache.lucene.document.DateField;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.IndexReader;

/** A Filter that restricts search results to a range of time.

   <p>For this to work, documents must have been indexed with a {@link
   DateField}.  */

public final class DateFilter extends Filter {
  String field;

  String start = DateField.MIN_DATE_STRING();
  String end = DateField.MAX_DATE_STRING();

  private DateFilter(String f) {
    field = f;
  }

  /** Constructs a filter for field <code>f</code> matching dates between
    <code>from</code> and <code>to</code>. */
  public DateFilter(String f, Date from, Date to) {
    field = f;
    start = DateField.dateToString(from);
    end = DateField.dateToString(to);
  }
  /** Constructs a filter for field <code>f</code> matching times between
    <code>from</code> and <code>to</code>. */
  public DateFilter(String f, long from, long to) {
    field = f;
    start = DateField.timeToString(from);
    end = DateField.timeToString(to);
  }

  /** Constructs a filter for field <code>f</code> matching dates before
    <code>date</code>. */
  public static DateFilter Before(String field, Date date) {
    DateFilter result = new DateFilter(field);
    result.end = DateField.dateToString(date);
    return result;
  }
  /** Constructs a filter for field <code>f</code> matching times before
    <code>time</code>. */
  public static DateFilter Before(String field, long time) {
    DateFilter result = new DateFilter(field);
    result.end = DateField.timeToString(time);
    return result;
  }

  /** Constructs a filter for field <code>f</code> matching dates after
    <code>date</code>. */
  public static DateFilter After(String field, Date date) {
    DateFilter result = new DateFilter(field);
    result.start = DateField.dateToString(date);
    return result;
  }
  /** Constructs a filter for field <code>f</code> matching times after
    <code>time</code>. */
  public static DateFilter After(String field, long time) {
    DateFilter result = new DateFilter(field);
    result.start = DateField.timeToString(time);
    return result;
  }

  /** Returns a BitSet with true for documents which should be permitted in
    search results, and false for those that should not. */
  final public BitSet bits(IndexReader reader) throws IOException {
    BitSet bits = new BitSet(reader.maxDoc());
    TermEnum enum = reader.terms(new Term(field, start));
    TermDocs termDocs = reader.termDocs();
    if (enum.term() == null)
	return bits;

    try {
      Term stop = new Term(field, end);
      while (enum.term().compareTo(stop) <= 0) {
	termDocs.seek(enum.term());
	try {
	  while (termDocs.next())
	    bits.set(termDocs.doc());
	} finally {
	  termDocs.close();
	}
	if (!enum.next()) {
	  break;
	}
      }
    } finally {
      enum.close();
    }
    return bits;
  }

  public final String toString() {
    StringBuffer buffer = new StringBuffer();
    buffer.append(field);
    buffer.append(":");
    buffer.append(DateField.stringToDate(start).toString());
    buffer.append("-");
    buffer.append(DateField.stringToDate(end).toString());
    return buffer.toString();
  }
}