PartNumberAnalyzer.cs

using System.IO;
using Lucene.Net.Analysis;

namespace LuceneTest
{
  public class PartNumberAnalyzer : Analyzer
  {
    private const string SkipCharacters = " -/\\";

    #region Overrides of Analyzer

    public override TokenStream TokenStream(string fieldName, TextReader reader)
    {
      TokenStream result = new SkipCharTokenizer(reader, SkipCharacters);
      result = new LowerCaseFilter(result);
      return result;
    }

    #endregion
  }
}

SkipCharTokenizer.cs

using Lucene.Net.Analysis;

namespace LuceneTest
{
  public class SkipCharTokenizer : Tokenizer
  {
    private int _offset, _bufferIndex, _dataLen;
    private const int MaxWordLen = 255;
    private const int IoBufferSize = 1024;
    private readonly char[] _ioBuffer = new char[IoBufferSize];
    private readonly string _skipCharacters;

    public SkipCharTokenizer(System.IO.TextReader input, string skipCharacters)
      : base(input)
    {
      _skipCharacters = skipCharacters;
    }

    public override Token Next(Token token)
    {
      token.Clear();

      var length = 0;
      var start = _bufferIndex;
      var buffer = token.TermBuffer();

      while (true) {
        if (_bufferIndex >= _dataLen) {
          _offset += _dataLen;
          _dataLen = input.Read(_ioBuffer, 0, _ioBuffer.Length);
          if (_dataLen <= 0) {
            if (length > 0) {
              break;
            }

            return null;
          }
          _bufferIndex = 0;
        }

        var c = _ioBuffer[_bufferIndex++];
        if (_skipCharacters.IndexOf(c) != -1) {
          continue;
        }

        if (length == 0) {
          start = _offset + _bufferIndex - 1;
        }
        else if (length == buffer.Length) {
          buffer = token.ResizeTermBuffer(1 + length);
        }

        buffer[length++] = c;

        if (length == MaxWordLen) {
          break;
        }
      }

      token.SetTermLength(length);
      token.SetStartOffset(start);
      token.SetEndOffset(start + length);
      return token;
    }

    public override void Reset(System.IO.TextReader reader)
    {
      base.Reset(reader);
      _bufferIndex = 0;
      _offset = 0;
      _dataLen = 0;
    }
  }
}