Lucene.Net/Document/DateField.cs

   1 using System;
   2 using System.Text;
   3 using Lucene.Net.Util;
   4
   5 namespace Lucene.Net.Documents
   6 {
   7         /* ====================================================================
   8          * The Apache Software License, Version 1.1
   9          *
  10          * Copyright (c) 2001 The Apache Software Foundation.  All rights
  11          * reserved.
  12          *
  13          * Redistribution and use in source and binary forms, with or without
  14          * modification, are permitted provided that the following conditions
  15          * are met:
  16          *
  17          * 1. Redistributions of source code must retain the above copyright
  18          *    notice, this list of conditions and the following disclaimer.
  19          *
  20          * 2. Redistributions in binary form must reproduce the above copyright
  21          *    notice, this list of conditions and the following disclaimer in
  22          *    the documentation and/or other materials provided with the
  23          *    distribution.
  24          *
  25          * 3. The end-user documentation included with the redistribution,
  26          *    if any, must include the following acknowledgment:
  27          *       "This product includes software developed by the
  28          *        Apache Software Foundation (http://www.apache.org/)."
  29          *    Alternately, this acknowledgment may appear in the software itself,
  30          *    if and wherever such third-party acknowledgments normally appear.
  31          *
  32          * 4. The names "Apache" and "Apache Software Foundation" and
  33          *    "Apache Lucene" must not be used to endorse or promote products
  34          *    derived from this software without prior written permission. For
  35          *    written permission, please contact apache@apache.org.
  36          *
  37          * 5. Products derived from this software may not be called "Apache",
  38          *    "Apache Lucene", nor may "Apache" appear in their name, without
  39          *    prior written permission of the Apache Software Foundation.
  40          *
  41          * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  42          * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  43          * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  44          * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  45          * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  46          * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  47          * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  48          * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  49          * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  50          * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  51          * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52          * SUCH DAMAGE.
  53          * ====================================================================
  54          *
  55          * This software consists of voluntary contributions made by many
  56          * individuals on behalf of the Apache Software Foundation.  For more
  57          * information on the Apache Software Foundation, please see
  58          * <http://www.apache.org/>.
  59          */
  60
  61         /// <summary>
  62         /// Provides support for converting dates to strings and vice-versa.
  63         /// The strings are structured so that lexicographic sorting orders by date.
  64         /// This makes them suitable for use as field values and search terms.
  65         /// <P>
  66         /// Note: currenly dates before 1970 cannot be used, and therefore cannot be
  67         /// indexed.</P>
  68         /// </summary>
  69         public class DateField
  70         {
  71                 private DateField() {}
  72
  73                 /// <summary>
  74                 /// make date strings long enough to last a millenium
  75                 /// </summary>
  76                 private static int DATE_LEN = Lucene.Net.Util.Number.ToString(
  77                         1000L*365*24*60*60*1000,
  78                         Lucene.Net.Util.Number.MAX_RADIX).Length;
  79
  80                 public static String MIN_DATE_STRING()
  81                 {
  82                         return TimeToString(0);
  83                 }
  84
  85                 public static String MAX_DATE_STRING()
  86                 {
  87                         char[] buffer = new char[DATE_LEN];
  88                         char c = 'F';
  89                         for (int i = 0 ; i < DATE_LEN; i++)
  90                                 buffer[i] = c;
  91                         return new string(buffer);
  92                 }
  93
  94                 /// <summary>
  95                 /// Converts a Date to a string suitable for indexing.
  96                 /// This method will throw a Exception if the date specified in the
  97                 /// method argument is before 1970.
  98                 /// </summary>
  99                 /// <param name="date"></param>
 100                 /// <returns></returns>
 101                 public static String DateToString(DateTime date)
 102                 {
 103                         return TimeToString(Date.GetTime(date));
 104                 }
 105
 106                 /// <summary>
 107                 /// Converts a millisecond time to a string suitable for indexing.
 108                 /// This method will throw a Exception if the time specified in the
 109                 /// method argument is negative, that is, before 1970.
 110                 /// </summary>
 111                 /// <param name="time"></param>
 112                 /// <returns></returns>
 113                 public static String TimeToString(long time)
 114                 {
 115                         if (time < 0)
 116                                 throw new Exception("time too early");
 117
 118                         string s = Lucene.Net.Util.Number.ToString(
 119                                 time, Lucene.Net.Util.Number.MAX_RADIX
 120                         );
 121
 122                         if (s.Length > DATE_LEN)
 123                                 throw new Exception("time too late");
 124
 125                         while (s.Length < DATE_LEN)
 126                                 s = "0" + s;                              // pad with leading zeros
 127
 128                         // Pad with leading zeros
 129                         if (s.Length < DATE_LEN)
 130                         {
 131                                 StringBuilder sb = new StringBuilder(s);
 132                                 while (sb.Length < DATE_LEN)
 133                                         sb.Insert(0, 0);
 134                                 s = sb.ToString();
 135                         }
 136
 137                         return s;
 138                 }
 139
 140                 /// <summary>
 141                 /// Converts a string-encoded date into a millisecond time.
 142                 /// </summary>
 143                 /// <param name="s"></param>
 144                 /// <returns></returns>
 145                 public static long StringToTime(String s)
 146                 {
 147                         return Lucene.Net.Util.Number.Parse(s, Lucene.Net.Util.Number.MAX_RADIX);
 148                 }
 149
 150                 /// <summary>
 151                 /// Converts a string-encoded date into a Date object.
 152                 /// </summary>
 153                 /// <param name="s"></param>
 154                 /// <returns></returns>
 155                 public static DateTime StringToDate(String s)
 156                 {
 157                         long ticks = StringToTime(s) * TimeSpan.TicksPerMillisecond;
 158                         DateTime date = new DateTime(ticks);
 159                         date = date.Add(TimeZone.CurrentTimeZone.GetUtcOffset(date));
 160                         date = date.AddYears(1969);
 161                         return date;
 162                 }
 163         }
 164 }