Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
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MatrixPermutationIterator.cs
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2  * Licensed to the Apache Software Foundation (ASF) under one or more
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17 
18 using System;
19 
20 namespace Lucene.Net.Analysis.Shingle.Matrix
21 {
23  {
24  private readonly Analysis.Shingle.Matrix.Matrix _enclosingInstance;
25 
26  private readonly int[] _columnRowCounters;
27 
28  public MatrixPermutationIterator(Analysis.Shingle.Matrix.Matrix enclosingInstance)
29  {
30  _enclosingInstance = enclosingInstance;
31  _columnRowCounters = new int[_enclosingInstance.Columns.Count];
32  }
33 
34  public bool HasNext()
35  {
36  var s = _columnRowCounters.Length;
37  var n = _enclosingInstance.Columns.Count;
38  return s != 0 && n >= s && _columnRowCounters[s - 1] < _enclosingInstance.Columns[s - 1].Rows.Count;
39  }
40 
41  public Row[] Next()
42  {
43  if (!HasNext())
44  throw new Exception("no more elements");
45 
46  var rows = new Row[_columnRowCounters.Length];
47 
48  for (int i = 0; i < _columnRowCounters.Length; i++)
49  {
50  rows[i] = _enclosingInstance.Columns[i].Rows[_columnRowCounters[i]];
51  }
52 
53  IncrementColumnRowCounters();
54 
55  return rows;
56  }
57 
58  private void IncrementColumnRowCounters()
59  {
60  for (int i = 0; i < _columnRowCounters.Length; i++)
61  {
62  _columnRowCounters[i]++;
63 
64  if (_columnRowCounters[i] != _enclosingInstance.Columns[i].Rows.Count ||
65  i >= _columnRowCounters.Length - 1)
66  break;
67 
68  _columnRowCounters[i] = 0;
69  }
70  }
71  }
72 }