/// <summary>
/// Constructor for enumeration of all terms from specified <c>reader</c> which share a prefix of
/// length <paramref name="prefixLength"/> with <paramref name="term"/> and which have a fuzzy similarity >
/// <paramref name="minSimilarity"/>.
/// <para/>
/// After calling the constructor the enumeration is already pointing to the first
/// valid term if such a term exists.
/// </summary>
/// <param name="terms"> Delivers terms. </param>
/// <param name="atts"> <see cref="AttributeSource"/> created by the rewrite method of <see cref="MultiTermQuery"/>
/// thats contains information about competitive boosts during rewrite. It is also used
/// to cache DFAs between segment transitions. </param>
/// <param name="term"> Pattern term. </param>
/// <param name="minSimilarity"> Minimum required similarity for terms from the reader. Pass an integer value
/// representing edit distance. Passing a fraction is deprecated. </param>
/// <param name="prefixLength"> Length of required common prefix. Default value is 0. </param>
/// <param name="transpositions"> Transpositions </param>
/// <exception cref="IOException"> if there is a low-level IO error </exception>
public FuzzyTermsEnum(Terms terms, AttributeSource atts, Term term, float minSimilarity, int prefixLength, bool transpositions)
{
InitializeInstanceFields();
if (minSimilarity >= 1.0f && minSimilarity != (int)minSimilarity)
{
throw new ArgumentException("fractional edit distances are not allowed");
}
if (minSimilarity < 0.0f)
{
throw new ArgumentException("minimumSimilarity cannot be less than 0");
}
if (prefixLength < 0)
{
throw new ArgumentException("prefixLength cannot be less than 0");
}
this.m_terms = terms;
this.term = term;
// convert the string into a utf32 int[] representation for fast comparisons
string utf16 = term.Text();
this.m_termText = new int[utf16.CodePointCount(0, utf16.Length)];
for (int cp, i = 0, j = 0; i < utf16.Length; i += Character.CharCount(cp))
{
m_termText[j++] = cp = utf16.CodePointAt(i);
}
this.m_termLength = m_termText.Length;
this.dfaAtt = atts.AddAttribute <ILevenshteinAutomataAttribute>();
//The prefix could be longer than the word.
//It's kind of silly though. It means we must match the entire word.
this.m_realPrefixLength = prefixLength > m_termLength ? m_termLength : prefixLength;
// if minSimilarity >= 1, we treat it as number of edits
if (minSimilarity >= 1f)
{
this.m_minSimilarity = 0; // just driven by number of edits
m_maxEdits = (int)minSimilarity;
m_raw = true;
}
else
{
this.m_minSimilarity = minSimilarity;
// calculate the maximum k edits for this similarity
m_maxEdits = InitialMaxDistance(this.m_minSimilarity, m_termLength);
m_raw = false;
}
if (transpositions && m_maxEdits > LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE)
{
throw new NotSupportedException("with transpositions enabled, distances > " + LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE + " are not supported ");
}
this.transpositions = transpositions;
this.m_scaleFactor = 1.0f / (1.0f - this.m_minSimilarity);
this.maxBoostAtt = atts.AddAttribute <IMaxNonCompetitiveBoostAttribute>();
bottom = maxBoostAtt.MaxNonCompetitiveBoost;
bottomTerm = maxBoostAtt.CompetitiveTerm;
BottomChanged(null, true);
}
/// <summary>
/// Constructor for enumeration of all terms from specified <code>reader</code> which share a prefix of
/// length <code>prefixLength</code> with <code>term</code> and which have a fuzzy similarity >
/// <code>minSimilarity</code>.
/// <p>
/// After calling the constructor the enumeration is already pointing to the first
/// valid term if such a term exists.
/// </summary>
/// <param name="terms"> Delivers terms. </param>
/// <param name="atts"> <seealso cref="AttributeSource"/> created by the rewrite method of <seealso cref="MultiTermQuery"/>
/// thats contains information about competitive boosts during rewrite. It is also used
/// to cache DFAs between segment transitions. </param>
/// <param name="term"> Pattern term. </param>
/// <param name="minSimilarity"> Minimum required similarity for terms from the reader. Pass an integer value
/// representing edit distance. Passing a fraction is deprecated. </param>
/// <param name="prefixLength"> Length of required common prefix. Default value is 0. </param>
/// <exception cref="IOException"> if there is a low-level IO error </exception>
public FuzzyTermsEnum(Terms terms, AttributeSource atts, Term term, float minSimilarity, int prefixLength, bool transpositions)
{
if (!InstanceFieldsInitialized)
{
InitializeInstanceFields();
InstanceFieldsInitialized = true;
}
if (minSimilarity >= 1.0f && minSimilarity != (int)minSimilarity)
{
throw new System.ArgumentException("fractional edit distances are not allowed");
}
if (minSimilarity < 0.0f)
{
throw new System.ArgumentException("minimumSimilarity cannot be less than 0");
}
if (prefixLength < 0)
{
throw new System.ArgumentException("prefixLength cannot be less than 0");
}
this.Terms = terms;
this.Term_Renamed = term;
// convert the string into a utf32 int[] representation for fast comparisons
string utf16 = term.Text();
//LUCENE TO-DO
//this.TermText = new int[utf16.codePointCount(0, utf16.Length)];
this.TermText = new int[utf16.Length];
for (int cp, i = 0, j = 0; i < utf16.Length; i += Character.CharCount(cp))
{
TermText[j++] = cp = Character.CodePointAt(utf16, i);
}
this.TermLength = TermText.Length;
this.DfaAtt = atts.AddAttribute<ILevenshteinAutomataAttribute>();
//The prefix could be longer than the word.
//It's kind of silly though. It means we must match the entire word.
this.RealPrefixLength = prefixLength > TermLength ? TermLength : prefixLength;
// if minSimilarity >= 1, we treat it as number of edits
if (minSimilarity >= 1f)
{
this.MinSimilarity_Renamed = 0; // just driven by number of edits
MaxEdits = (int)minSimilarity;
Raw = true;
}
else
{
this.MinSimilarity_Renamed = minSimilarity;
// calculate the maximum k edits for this similarity
MaxEdits = InitialMaxDistance(this.MinSimilarity_Renamed, TermLength);
Raw = false;
}
if (transpositions && MaxEdits > LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE)
{
throw new System.NotSupportedException("with transpositions enabled, distances > " + LevenshteinAutomata.MAXIMUM_SUPPORTED_DISTANCE + " are not supported ");
}
this.Transpositions = transpositions;
this.Scale_factor = 1.0f / (1.0f - this.MinSimilarity_Renamed);
this.MaxBoostAtt = atts.AddAttribute<IMaxNonCompetitiveBoostAttribute>();
Bottom = MaxBoostAtt.MaxNonCompetitiveBoost;
BottomTerm = MaxBoostAtt.CompetitiveTerm;
BottomChanged(null, true);
}
