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