Readability: Import Lucene.Net.Search.Similarites.SimilarityBase statically, where appropriate

[NightOwl888]

In several code files in Lucene.Net.Search.Similarities the Log2 method is imported directly in Java so it doesn't have to be qualified.

import static org.apache.lucene.search.similarities.SimilarityBase.log2;

public class BasicModelG extends BasicModel {
  
  /** Sole constructor: parameter-free */
  public BasicModelG() {}

  @Override
  public final float score(BasicStats stats, float tfn) {
    // just like in BE, approximation only holds true when F << N, so we use lambda = F / (N + F)
    double F = stats.getTotalTermFreq() + 1;
    double N = stats.getNumberOfDocuments();
    double lambda = F / (N + F);
    // -log(1 / (lambda + 1)) -> log(lambda + 1)
    return (float)(log2(lambda + 1) + tfn * log2((1 + lambda) / lambda));
  }

  @Override
  public String toString() {
    return "G";
  }
}

However, in .NET we are fully qualifying as SimilarityBase.Log2(), which reduces readability and doesn't align well with the original code.

    public class BasicModelG : BasicModel
    {
        /// <summary>
        /// Sole constructor: parameter-free </summary>
        public BasicModelG()
        {
        }

        public override sealed float Score(BasicStats stats, float tfn)
        {
            // just like in BE, approximation only holds true when F << N, so we use lambda = F / (N + F)
            double F = stats.TotalTermFreq + 1;
            double N = stats.NumberOfDocuments;
            double lambda = F / (N + F);
            // -log(1 / (lambda + 1)) -> log(lambda + 1)
            return (float)(SimilarityBase.Log2(lambda + 1) + tfn * SimilarityBase.Log2((1 + lambda) / lambda));
        }

        public override string ToString()
        {
            return "G";
        }
    }

To fix this, we should import the static members of SimilarityBase in every class where it is used. Add the following line at the top of the file above the namespace declaration.

using static Lucene.Net.Search.Similarities.SimilarityBase;

Then we can remove the qualifying statements for Log2().

    public class BasicModelG : BasicModel
    {
        /// <summary>
        /// Sole constructor: parameter-free </summary>
        public BasicModelG()
        {
        }

        public override sealed float Score(BasicStats stats, float tfn)
        {
            // just like in BE, approximation only holds true when F << N, so we use lambda = F / (N + F)
            double F = stats.TotalTermFreq + 1;
            double N = stats.NumberOfDocuments;
            double lambda = F / (N + F);
            // -log(1 / (lambda + 1)) -> log(lambda + 1)
            return (float)(Log2(lambda + 1) + tfn * Log2((1 + lambda) / lambda));
        }

        public override string ToString()
        {
            return "G";
        }
    }

We should do this in all classes in Lucene.Net.Search.Similarities namespace that use the SimilarityBase.Log2() method.