beagled/Lucene.Net/Index/TermBuffer.cs

   1 /*
   2  * Copyright 2004 The Apache Software Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 using System;
  17 using IndexInput = Lucene.Net.Store.IndexInput;
  18 namespace Lucene.Net.Index
  19 {
  20
  21     sealed class TermBuffer : System.ICloneable
  22     {
  23         private static readonly char[] NO_CHARS = new char[0];
  24
  25         private System.String field;
  26         private char[] text = NO_CHARS;
  27         private int textLength;
  28         private Term term; // cached
  29
  30         public int CompareTo(TermBuffer other)
  31         {
  32             if ((System.Object) field == (System.Object) other.field)
  33                 // fields are interned
  34                 return CompareChars(text, textLength, other.text, other.textLength);
  35             else
  36                 return String.CompareOrdinal(field, other.field);
  37         }
  38
  39         private static int CompareChars(char[] v1, int len1, char[] v2, int len2)
  40         {
  41             int end = System.Math.Min(len1, len2);
  42             for (int k = 0; k < end; k++)
  43             {
  44                 char c1 = v1[k];
  45                 char c2 = v2[k];
  46                 if (c1 != c2)
  47                 {
  48                     return c1 - c2;
  49                 }
  50             }
  51             return len1 - len2;
  52         }
  53
  54         private void  SetTextLength(int newLength)
  55         {
  56             if (text.Length < newLength)
  57             {
  58                 char[] newText = new char[newLength];
  59                 Array.Copy(text, 0, newText, 0, textLength);
  60                 text = newText;
  61             }
  62             textLength = newLength;
  63         }
  64
  65         public void  Read(IndexInput input, FieldInfos fieldInfos)
  66         {
  67             this.term = null; // invalidate cache
  68             int start = input.ReadVInt();
  69             int length = input.ReadVInt();
  70             int totalLength = start + length;
  71             SetTextLength(totalLength);
  72             input.ReadChars(this.text, start, length);
  73             this.field = fieldInfos.FieldName(input.ReadVInt());
  74         }
  75
  76         public void  Set(Term term)
  77         {
  78             if (term == null)
  79             {
  80                 Reset();
  81                 return ;
  82             }
  83
  84             // copy text into the buffer
  85             SetTextLength(term.Text().Length);
  86                         text = term.Text().ToCharArray();
  87
  88             this.field = term.Field();
  89             this.term = term;
  90         }
  91
  92         public void  Set(TermBuffer other)
  93         {
  94             SetTextLength(other.textLength);
  95             Array.Copy(other.text, 0, text, 0, textLength);
  96
  97             this.field = other.field;
  98             this.term = other.term;
  99         }
 100
 101         public void  Reset()
 102         {
 103             this.field = null;
 104             this.textLength = 0;
 105             this.term = null;
 106         }
 107
 108         public Term ToTerm()
 109         {
 110             if (field == null)
 111                 // unset
 112                 return null;
 113
 114             if (term == null)
 115                 term = new Term(field, new System.String(text, 0, textLength), false);
 116
 117             return term;
 118         }
 119
 120         public System.Object Clone()
 121         {
 122             TermBuffer clone = null;
 123             try
 124             {
 125                 clone = (TermBuffer) base.MemberwiseClone();
 126             }
 127             catch (System.Exception e)
 128             {
 129             }
 130
 131             clone.text = new char[text.Length];
 132             Array.Copy(text, 0, clone.text, 0, textLength);
 133
 134             return clone;
 135         }
 136     }
 137 }