beagled/Lucene.Net/Search/PhrasePositions.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 Lucene.Net.Index;
  19
  20 namespace Lucene.Net.Search
  21 {
  22
  23         sealed class PhrasePositions
  24         {
  25                 internal int doc; // current doc
  26                 internal int position; // position in doc
  27                 internal int count; // remaining pos in this doc
  28                 internal int offset; // position in phrase
  29                 internal TermPositions tp; // stream of positions
  30                 internal PhrasePositions next; // used to make lists
  31
  32                 internal PhrasePositions(TermPositions t, int o)
  33                 {
  34                         tp = t;
  35                         offset = o;
  36                 }
  37
  38                 internal bool Next()
  39                 {
  40                         // increments to next doc
  41                         if (!tp.Next())
  42                         {
  43                                 tp.Close(); // close stream
  44                                 doc = System.Int32.MaxValue; // sentinel value
  45                                 return false;
  46                         }
  47                         doc = tp.Doc();
  48                         position = 0;
  49                         return true;
  50                 }
  51
  52                 internal bool SkipTo(int target)
  53                 {
  54                         if (!tp.SkipTo(target))
  55                         {
  56                                 tp.Close(); // close stream
  57                                 doc = System.Int32.MaxValue; // sentinel value
  58                                 return false;
  59                         }
  60                         doc = tp.Doc();
  61                         position = 0;
  62                         return true;
  63                 }
  64
  65
  66                 internal void  FirstPosition()
  67                 {
  68                         count = tp.Freq(); // read first pos
  69                         NextPosition();
  70                 }
  71
  72                 internal bool NextPosition()
  73                 {
  74                         if (count-- > 0)
  75                         {
  76                                 // read subsequent pos's
  77                                 position = tp.NextPosition() - offset;
  78                                 return true;
  79                         }
  80                         else
  81                                 return false;
  82                 }
  83         }
  84 }