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RavenDB NGram Search
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Analysis.Tokenattributes;
using Lucene.Net.Util;
using Raven.Abstractions.Indexing;
using Raven.Client.Linq;
using Raven.Database.Indexing;
using Xunit;
namespace Raven.Tests.Bugs
{
public class NGramSearch : RavenTest
{
public class Image
{
public string Id { get; set; }
public string Name { get; set; }
public ICollection<string> Users { get; set; }
public ICollection<string> Tags { get; set; }
}
public class NGramTokenFilter : TokenFilter
{
public static int DEFAULT_MIN_NGRAM_SIZE = 1;
public static int DEFAULT_MAX_NGRAM_SIZE = 2;
private int minGram, maxGram;
private char[] curTermBuffer;
private int curTermLength;
private int curGramSize;
private int curPos;
private int tokStart;
private TermAttribute termAtt;
private OffsetAttribute offsetAtt;
/**
* Creates NGramTokenFilter with given min and max n-grams.
* <param name="input"><see cref="TokenStream"/> holding the input to be tokenized</param>
* <param name="minGram">the smallest n-gram to generate</param>
* <param name="maxGram">the largest n-gram to generate</param>
*/
public NGramTokenFilter(TokenStream input, int minGram, int maxGram)
: base(input)
{
if (minGram < 1)
{
throw new System.ArgumentException("minGram must be greater than zero");
}
if (minGram > maxGram)
{
throw new System.ArgumentException("minGram must not be greater than maxGram");
}
this.minGram = minGram;
this.maxGram = maxGram;
this.termAtt = (TermAttribute)AddAttribute(typeof(TermAttribute));
this.offsetAtt = (OffsetAttribute)AddAttribute(typeof(OffsetAttribute));
}
/**
* Creates NGramTokenFilter with default min and max n-grams.
* <param name="input"><see cref="TokenStream"/> holding the input to be tokenized</param>
*/
public NGramTokenFilter(TokenStream input)
: this(input, DEFAULT_MIN_NGRAM_SIZE, DEFAULT_MAX_NGRAM_SIZE)
{
}
/** Returns the next token in the stream, or null at EOS. */
public override bool IncrementToken()
{
while (true)
{
if (curTermBuffer == null)
{
if (!input.IncrementToken())
{
return false;
}
else
{
curTermBuffer = (char[])termAtt.TermBuffer().Clone();
curTermLength = termAtt.TermLength();
curGramSize = minGram;
curPos = 0;
tokStart = offsetAtt.StartOffset();
}
}
while (curGramSize <= maxGram)
{
while (curPos + curGramSize <= curTermLength)
{ // while there is input
ClearAttributes();
termAtt.SetTermBuffer(curTermBuffer, curPos, curGramSize);
offsetAtt.SetOffset(tokStart + curPos, tokStart + curPos + curGramSize);
curPos++;
return true;
}
curGramSize++; // increase n-gram size
curPos = 0;
}
curTermBuffer = null;
}
}
/** @deprecated Will be removed in Lucene 3.0. This method is final, as it should
* not be overridden. Delegates to the backwards compatibility layer. */
[System.Obsolete("Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.")]
public override Token Next(Token reusableToken)
{
return base.Next(reusableToken);
}
/** @deprecated Will be removed in Lucene 3.0. This method is final, as it should
* not be overridden. Delegates to the backwards compatibility layer. */
[System.Obsolete("Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.")]
public override Token Next()
{
return base.Next();
}
public override void Reset()
{
base.Reset();
curTermBuffer = null;
}
}
[NotForQuerying]
public class NGramAnalyzer : Analyzer
{
public override TokenStream TokenStream(string fieldName, TextReader reader)
{
var tokenizer = new StandardTokenizer(Version.LUCENE_29, reader);
tokenizer.SetMaxTokenLength(255);
TokenStream filter = new StandardFilter(tokenizer);
filter = new LowerCaseFilter(filter);
filter = new StopFilter(false,filter, StandardAnalyzer.STOP_WORDS_SET);
return new NGramTokenFilter(filter, 2, 6);
}
}
[Fact]
public void Can_search_inner_words()
{
using (var store = NewDocumentStore())
{
using (var session = store.OpenSession())
{
session.Store(new FullTextSearchOnTags.Image { Id = "1", Name = "Great Photo buddy" });
session.Store(new FullTextSearchOnTags.Image { Id = "2", Name = "Nice Photo of the sky" });
session.SaveChanges();
}
store.DatabaseCommands.PutIndex("test", new IndexDefinition
{
Map = "from doc in docs.Images select new { doc.Name }",
Indexes =
{
{"Name", FieldIndexing.Analyzed}
},
Analyzers =
{
{"Name", typeof (NGramAnalyzer).AssemblyQualifiedName}
}
});
using (var session = store.OpenSession())
{
var images = session.Query<FullTextSearchOnTags.Image>("test")
.Customize(x => x.WaitForNonStaleResults())
.OrderBy(x => x.Name)
.Search(x => x.Name, "phot")
.ToList();
WaitForUserToContinueTheTest(store);
Assert.NotEmpty(images);
}
}
}
}
}
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