beagled/Lucene.Net/Search/Regex/RegexTermEnum.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
  17 using System;
  18 using IndexReader = Lucene.Net.Index.IndexReader;
  19 using Term = Lucene.Net.Index.Term;
  20 using FilteredTermEnum = Lucene.Net.Search.FilteredTermEnum;
  21 using Pattern = System.Text.RegularExpressions.Regex;
  22
  23 namespace Lucene.Net.Search.Regex
  24 {
  25
  26         public class RegexTermEnum : FilteredTermEnum
  27         {
  28                 private System.String field = "";
  29                 private System.String pre = "";
  30                 internal bool endEnum = false;
  31                 private Pattern pattern;
  32
  33                 public RegexTermEnum(IndexReader reader, Term term) : base()
  34                 {
  35                         field = term.Field();
  36                         System.String text = term.Text();
  37
  38                         pattern = new Pattern(text);
  39
  40                         // Find the first regex character position, to find the
  41                         // maximum prefix to use for term enumeration
  42                         int index = 0;
  43                         while (index < text.Length)
  44                         {
  45                                 char c = text[index];
  46
  47                                 if (!System.Char.IsLetterOrDigit(c))
  48                                         break;
  49
  50                                 index++;
  51                         }
  52
  53                         pre = text.Substring(0, (index) - (0));
  54
  55                         SetEnum(reader.Terms(new Term(term.Field(), pre)));
  56                 }
  57
  58                 protected internal override bool TermCompare(Term term)
  59                 {
  60                         if ((System.Object) field == (System.Object) term.Field())
  61                         {
  62                                 System.String searchText = term.Text();
  63                                 if (searchText.StartsWith(pre))
  64                                 {
  65                     return pattern.Match(searchText).Success;
  66                                 }
  67                         }
  68                         endEnum = true;
  69                         return false;
  70                 }
  71
  72                 public override float Difference()
  73                 {
  74                         // TODO: adjust difference based on distance of searchTerm.text() and term().text()
  75                         return 1.0f;
  76                 }
  77
  78                 public override bool EndEnum()
  79                 {
  80                         return endEnum;
  81                 }
  82
  83                 public override void  Close()
  84                 {
  85                         base.Close();
  86                         field = null;
  87                 }
  88         }
  89 }