/// <summary>
/// Creates NGramTokenFilter with given min and max n-grams. </summary>
/// <param name="version"> Lucene version to enable correct position increments.
/// See <a href="#version">above</a> for details. </param>
/// <param name="input"> <seealso 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(Version version, TokenStream input, int minGram, int maxGram) : base(new CodepointCountFilter(version, input, minGram, int.MaxValue))
{
this.version = version;
this.charUtils = version.onOrAfter(Version.LUCENE_44) ? CharacterUtils.getInstance(version) : CharacterUtils.Java4Instance;
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;
if (version.onOrAfter(Version.LUCENE_44))
{
posIncAtt = addAttribute(typeof(PositionIncrementAttribute));
posLenAtt = addAttribute(typeof(PositionLengthAttribute));
}
else
{
posIncAtt = new PositionIncrementAttributeAnonymousInnerClassHelper(this);
posLenAtt = new PositionLengthAttributeAnonymousInnerClassHelper(this);
}
}
/// <summary>
/// Creates NGramTokenFilter with given min and max n-grams. </summary>
/// <param name="version"> Lucene version to enable correct position increments.
/// See <a href="#version">above</a> for details. </param>
/// <param name="input"> <seealso 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(Version version, TokenStream input, int minGram, int maxGram) : base(new CodepointCountFilter(version, input, minGram, int.MaxValue))
{
this.version = version;
this.charUtils = version.onOrAfter(Version.LUCENE_44) ? CharacterUtils.getInstance(version) : CharacterUtils.Java4Instance;
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;
if (version.onOrAfter(Version.LUCENE_44))
{
posIncAtt = addAttribute(typeof(PositionIncrementAttribute));
posLenAtt = addAttribute(typeof(PositionLengthAttribute));
}
else
{
posIncAtt = new PositionIncrementAttributeAnonymousInnerClassHelper(this);
posLenAtt = new PositionLengthAttributeAnonymousInnerClassHelper(this);
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: public void testRandom() throws Exception
public virtual void testRandom()
{
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final int alphabetSize = org.apache.lucene.util.TestUtil.nextInt(random(), 2, 7);
int alphabetSize = TestUtil.Next(random(), 2, 7);
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final int docLen = atLeast(3000);
int docLen = atLeast(3000);
//final int docLen = 50;
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String document = getRandomString('a', alphabetSize, docLen);
string document = getRandomString('a', alphabetSize, docLen);
if (VERBOSE)
{
Console.WriteLine("TEST: doc=" + document);
}
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final int numSyn = atLeast(5);
int numSyn = atLeast(5);
//final int numSyn = 2;
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final java.util.Map<String,OneSyn> synMap = new java.util.HashMap<>();
IDictionary<string, OneSyn> synMap = new Dictionary<string, OneSyn>();
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final java.util.List<OneSyn> syns = new java.util.ArrayList<>();
IList<OneSyn> syns = new List<OneSyn>();
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final boolean dedup = random().nextBoolean();
bool dedup = random().nextBoolean();
if (VERBOSE)
{
Console.WriteLine(" dedup=" + dedup);
}
b = new SynonymMap.Builder(dedup);
for (int synIDX = 0;synIDX < numSyn;synIDX++)
{
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String synIn = getRandomString('a', alphabetSize, org.apache.lucene.util.TestUtil.nextInt(random(), 1, 5)).trim();
string synIn = getRandomString('a', alphabetSize, TestUtil.Next(random(), 1, 5)).Trim();
OneSyn s = synMap[synIn];
if (s == null)
{
s = new OneSyn();
s.@in = synIn;
syns.Add(s);
s.@out = new List<>();
synMap[synIn] = s;
s.keepOrig = random().nextBoolean();
}
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String synOut = getRandomString('0', 10, org.apache.lucene.util.TestUtil.nextInt(random(), 1, 5)).trim();
string synOut = getRandomString('0', 10, TestUtil.Next(random(), 1, 5)).Trim();
[email protected](synOut);
add(synIn, synOut, s.keepOrig);
if (VERBOSE)
{
Console.WriteLine(" syns[" + synIDX + "] = " + s.@in + " -> " + s.@out + " keepOrig=" + s.keepOrig);
}
}
tokensIn = new MockTokenizer(new StringReader("a"), MockTokenizer.WHITESPACE, true);
tokensIn.reset();
assertTrue(tokensIn.incrementToken());
assertFalse(tokensIn.incrementToken());
tokensIn.end();
tokensIn.close();
tokensOut = new SynonymFilter(tokensIn, b.build(), true);
termAtt = tokensOut.addAttribute(typeof(CharTermAttribute));
posIncrAtt = tokensOut.addAttribute(typeof(PositionIncrementAttribute));
posLenAtt = tokensOut.addAttribute(typeof(PositionLengthAttribute));
offsetAtt = tokensOut.addAttribute(typeof(OffsetAttribute));
if (dedup)
{
pruneDups(syns);
}
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String expected = slowSynMatcher(document, syns, 5);
string expected = slowSynMatcher(document, syns, 5);
if (VERBOSE)
{
Console.WriteLine("TEST: expected=" + expected);
}
verify(document, expected);
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: public void testOutputHangsOffEnd() throws Exception
public virtual void testOutputHangsOffEnd()
{
b = new SynonymMap.Builder(true);
const bool keepOrig = false;
// b hangs off the end (no input token under it):
add("a", "a b", keepOrig);
tokensIn = new MockTokenizer(new StringReader("a"), MockTokenizer.WHITESPACE, true);
tokensIn.reset();
assertTrue(tokensIn.incrementToken());
assertFalse(tokensIn.incrementToken());
tokensIn.end();
tokensIn.close();
tokensOut = new SynonymFilter(tokensIn, b.build(), true);
termAtt = tokensOut.addAttribute(typeof(CharTermAttribute));
posIncrAtt = tokensOut.addAttribute(typeof(PositionIncrementAttribute));
offsetAtt = tokensOut.addAttribute(typeof(OffsetAttribute));
posLenAtt = tokensOut.addAttribute(typeof(PositionLengthAttribute));
// Make sure endOffset inherits from previous input token:
verify("a", "a b:1");
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: public void testBasic2() throws Exception
public virtual void testBasic2()
{
b = new SynonymMap.Builder(true);
const bool keepOrig = false;
add("aaa", "aaaa1 aaaa2 aaaa3", keepOrig);
add("bbb", "bbbb1 bbbb2", keepOrig);
tokensIn = new MockTokenizer(new StringReader("a"), MockTokenizer.WHITESPACE, true);
tokensIn.reset();
assertTrue(tokensIn.incrementToken());
assertFalse(tokensIn.incrementToken());
tokensIn.end();
tokensIn.close();
tokensOut = new SynonymFilter(tokensIn, b.build(), true);
termAtt = tokensOut.addAttribute(typeof(CharTermAttribute));
posIncrAtt = tokensOut.addAttribute(typeof(PositionIncrementAttribute));
posLenAtt = tokensOut.addAttribute(typeof(PositionLengthAttribute));
offsetAtt = tokensOut.addAttribute(typeof(OffsetAttribute));
if (keepOrig)
{
verify("xyzzy bbb pot of gold", "xyzzy bbb/bbbb1 pot/bbbb2 of gold");
verify("xyzzy aaa pot of gold", "xyzzy aaa/aaaa1 pot/aaaa2 of/aaaa3 gold");
}
else
{
verify("xyzzy bbb pot of gold", "xyzzy bbbb1 pot/bbbb2 of gold");
verify("xyzzy aaa pot of gold", "xyzzy aaaa1 pot/aaaa2 of/aaaa3 gold");
}
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: public void testBasic() throws Exception
public virtual void testBasic()
{
b = new SynonymMap.Builder(true);
add("a", "foo", true);
add("a b", "bar fee", true);
add("b c", "dog collar", true);
add("c d", "dog harness holder extras", true);
add("m c e", "dog barks loudly", false);
add("i j k", "feep", true);
add("e f", "foo bar", false);
add("e f", "baz bee", false);
add("z", "boo", false);
add("y", "bee", true);
tokensIn = new MockTokenizer(new StringReader("a"), MockTokenizer.WHITESPACE, true);
tokensIn.reset();
assertTrue(tokensIn.incrementToken());
assertFalse(tokensIn.incrementToken());
tokensIn.end();
tokensIn.close();
tokensOut = new SynonymFilter(tokensIn, b.build(), true);
termAtt = tokensOut.addAttribute(typeof(CharTermAttribute));
posIncrAtt = tokensOut.addAttribute(typeof(PositionIncrementAttribute));
posLenAtt = tokensOut.addAttribute(typeof(PositionLengthAttribute));
offsetAtt = tokensOut.addAttribute(typeof(OffsetAttribute));
verify("a b c", "a/bar b/fee c");
// syn output extends beyond input tokens
verify("x a b c d", "x a/bar b/fee c/dog d/harness holder extras");
verify("a b a", "a/bar b/fee a/foo");
// outputs that add to one another:
verify("c d c d", "c/dog d/harness c/holder/dog d/extras/harness holder extras");
// two outputs for same input
verify("e f", "foo/baz bar/bee");
// verify multi-word / single-output offsets:
verify("g i j k g", "g i/feep:7_3 j k g");
// mixed keepOrig true/false:
verify("a m c e x", "a/foo dog barks loudly x");
verify("c d m c e x", "c/dog d/harness holder/dog extras/barks loudly x");
assertTrue(tokensOut.CaptureCount > 0);
// no captureStates when no syns matched
verify("p q r s t", "p q r s t");
assertEquals(0, tokensOut.CaptureCount);
// no captureStates when only single-input syns, w/ no
// lookahead needed, matched
verify("p q z y t", "p q boo y/bee t");
assertEquals(0, tokensOut.CaptureCount);
}
/// <summary>
/// Retrieve suggestions.
/// </summary>
public virtual IList <LookupResult> Lookup(string key, HashSet <BytesRef> contexts, int num)
{
if (contexts != null)
{
throw new System.ArgumentException("this suggester doesn't support contexts");
}
TokenStream ts = queryAnalyzer.TokenStream("", key.ToString());
try
{
TermToBytesRefAttribute termBytesAtt = ts.AddAttribute <TermToBytesRefAttribute>();
OffsetAttribute offsetAtt = ts.AddAttribute <OffsetAttribute>();
PositionLengthAttribute posLenAtt = ts.AddAttribute <PositionLengthAttribute>();
PositionIncrementAttribute posIncAtt = ts.AddAttribute <PositionIncrementAttribute>();
ts.Reset();
var lastTokens = new BytesRef[grams];
//System.out.println("lookup: key='" + key + "'");
// Run full analysis, but save only the
// last 1gram, last 2gram, etc.:
BytesRef tokenBytes = termBytesAtt.BytesRef;
int maxEndOffset = -1;
bool sawRealToken = false;
while (ts.IncrementToken())
{
termBytesAtt.FillBytesRef();
sawRealToken |= tokenBytes.Length > 0;
// TODO: this is somewhat iffy; today, ShingleFilter
// sets posLen to the gram count; maybe we should make
// a separate dedicated att for this?
int gramCount = posLenAtt.PositionLength;
Debug.Assert(gramCount <= grams);
// Safety: make sure the recalculated count "agrees":
if (CountGrams(tokenBytes) != gramCount)
{
throw new System.ArgumentException("tokens must not contain separator byte; got token=" + tokenBytes + " but gramCount=" + gramCount + " does not match recalculated count=" + countGrams(tokenBytes));
}
maxEndOffset = Math.Max(maxEndOffset, offsetAtt.EndOffset());
lastTokens[gramCount - 1] = BytesRef.DeepCopyOf(tokenBytes);
}
ts.End();
if (!sawRealToken)
{
throw new System.ArgumentException("no tokens produced by analyzer, or the only tokens were empty strings");
}
// Carefully fill last tokens with _ tokens;
// ShingleFilter appraently won't emit "only hole"
// tokens:
int endPosInc = posIncAtt.PositionIncrement;
// Note this will also be true if input is the empty
// string (in which case we saw no tokens and
// maxEndOffset is still -1), which in fact works out OK
// because we fill the unigram with an empty BytesRef
// below:
bool lastTokenEnded = offsetAtt.EndOffset() > maxEndOffset || endPosInc > 0;
//System.out.println("maxEndOffset=" + maxEndOffset + " vs " + offsetAtt.endOffset());
if (lastTokenEnded)
{
//System.out.println(" lastTokenEnded");
// If user hit space after the last token, then
// "upgrade" all tokens. This way "foo " will suggest
// all bigrams starting w/ foo, and not any unigrams
// starting with "foo":
for (int i = grams - 1; i > 0; i--)
{
BytesRef token = lastTokens[i - 1];
if (token == null)
{
continue;
}
token.Grow(token.Length + 1);
token.Bytes[token.Length] = separator;
token.Length++;
lastTokens[i] = token;
}
lastTokens[0] = new BytesRef();
}
var arc = new FST.Arc <long?>();
var bytesReader = fst.BytesReader;
// Try highest order models first, and if they return
// results, return that; else, fallback:
double backoff = 1.0;
IList <LookupResult> results = new List <LookupResult>(num);
// We only add a given suffix once, from the highest
// order model that saw it; for subsequent lower order
// models we skip it:
var seen = new HashSet <BytesRef>();
for (int gram = grams - 1; gram >= 0; gram--)
{
BytesRef token = lastTokens[gram];
// Don't make unigram predictions from empty string:
if (token == null || (token.Length == 0 && key.Length > 0))
{
// Input didn't have enough tokens:
//System.out.println(" gram=" + gram + ": skip: not enough input");
continue;
}
if (endPosInc > 0 && gram <= endPosInc)
{
// Skip hole-only predictions; in theory we
// shouldn't have to do this, but we'd need to fix
// ShingleFilter to produce only-hole tokens:
//System.out.println(" break: only holes now");
break;
}
//System.out.println("try " + (gram+1) + " gram token=" + token.utf8ToString());
// TODO: we could add fuzziness here
// match the prefix portion exactly
//Pair<Long,BytesRef> prefixOutput = null;
long?prefixOutput = null;
prefixOutput = LookupPrefix(fst, bytesReader, token, arc);
//System.out.println(" prefixOutput=" + prefixOutput);
if (prefixOutput == null)
{
// This model never saw this prefix, e.g. the
// trigram model never saw context "purple mushroom"
backoff *= ALPHA;
continue;
}
// TODO: we could do this division at build time, and
// bake it into the FST?
// Denominator for computing scores from current
// model's predictions:
long contextCount = totTokens;
BytesRef lastTokenFragment = null;
for (int i = token.Length - 1; i >= 0; i--)
{
if (token.Bytes[token.Offset + i] == separator)
{
BytesRef context = new BytesRef(token.Bytes, token.Offset, i);
long? output = Util.Get(fst, Lucene.Net.Util.Fst.Util.ToIntsRef(context, new IntsRef()));
Debug.Assert(output != null);
contextCount = DecodeWeight(output);
lastTokenFragment = new BytesRef(token.Bytes, token.Offset + i + 1, token.Length - i - 1);
break;
}
}
BytesRef finalLastToken;
if (lastTokenFragment == null)
{
finalLastToken = BytesRef.DeepCopyOf(token);
}
else
{
finalLastToken = BytesRef.DeepCopyOf(lastTokenFragment);
}
Debug.Assert(finalLastToken.Offset == 0);
CharsRef spare = new CharsRef();
// complete top-N
Util.Fst.Util.TopResults <long?> completions = null;
try
{
// Because we store multiple models in one FST
// (1gram, 2gram, 3gram), we must restrict the
// search so that it only considers the current
// model. For highest order model, this is not
// necessary since all completions in the FST
// must be from this model, but for lower order
// models we have to filter out the higher order
// ones:
// Must do num+seen.size() for queue depth because we may
// reject up to seen.size() paths in acceptResult():
Util.Fst.Util.TopNSearcher <long?> searcher = new TopNSearcherAnonymousInnerClassHelper(this, fst, num, num + seen.Count, weightComparator, seen, finalLastToken);
// since this search is initialized with a single start node
// it is okay to start with an empty input path here
searcher.AddStartPaths(arc, prefixOutput, true, new IntsRef());
completions = searcher.Search();
Debug.Assert(completions.IsComplete);
}
catch (IOException bogus)
{
throw new Exception(bogus);
}
int prefixLength = token.Length;
BytesRef suffix = new BytesRef(8);
//System.out.println(" " + completions.length + " completions");
foreach (Util.Fst.Util.Result <long?> completion in completions)
{
token.Length = prefixLength;
// append suffix
Util.Fst.Util.ToBytesRef(completion.Input, suffix);
token.Append(suffix);
//System.out.println(" completion " + token.utf8ToString());
// Skip this path if a higher-order model already
// saw/predicted its last token:
BytesRef lastToken = token;
for (int i = token.Length - 1; i >= 0; i--)
{
if (token.Bytes[token.Offset + i] == separator)
{
Debug.Assert(token.Length - i - 1 > 0);
lastToken = new BytesRef(token.Bytes, token.Offset + i + 1, token.Length - i - 1);
break;
}
}
if (seen.Contains(lastToken))
{
//System.out.println(" skip dup " + lastToken.utf8ToString());
goto nextCompletionContinue;
}
seen.Add(BytesRef.DeepCopyOf(lastToken));
spare.Grow(token.Length);
UnicodeUtil.UTF8toUTF16(token, spare);
LookupResult result = new LookupResult(spare.ToString(), (long)(long.MaxValue * backoff * ((double)DecodeWeight(completion.Output)) / contextCount));
results.Add(result);
Debug.Assert(results.Count == seen.Count);
//System.out.println(" add result=" + result);
nextCompletionContinue :;
}
nextCompletionBreak :
backoff *= ALPHA;
}
results.Sort(new ComparatorAnonymousInnerClassHelper(this));
if (results.Count > num)
{
results.SubList(num, results.Count).Clear();
}
return(results);
}
finally
{
IOUtils.CloseWhileHandlingException(ts);
}
}
