Index: lucene/src/test/org/apache/lucene/search/MockDFRSimilarity.java
===================================================================
--- lucene/src/test/org/apache/lucene/search/MockDFRSimilarity.java	(revision 0)
+++ lucene/src/test/org/apache/lucene/search/MockDFRSimilarity.java	(revision 0)
@@ -0,0 +1,173 @@
+package org.apache.lucene.search;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.index.FieldInvertState;
+import org.apache.lucene.index.IndexReader.ReaderContext;
+import org.apache.lucene.index.IndexReader.AtomicReaderContext;
+import org.apache.lucene.search.Explanation.IDFExplanation;
+import org.apache.lucene.util.ReaderUtil;
+import org.apache.lucene.util.TermContext;
+import org.apache.lucene.util.SmallFloat;
+
+/**
+ * DFR I(F)L2 model
+ * <ul>
+ *   <li> I(F) basic model: approximation of mixture of Poisson and inverse document frequency
+ *   <li> first normalization L: laplace's law of succession 
+ *   <li> second normalization H2: term frequency density is inversely related to the length
+ * <ul>
+ */
+public class MockDFRSimilarity extends Similarity {
+  private static final float c = 1f;
+  
+  /**
+   * Our normalization is log(1 + (c * avg_dl)/l)
+   * currently we put doclen into the boost byte (divided by boost) for simple quantization
+   * our decoder precomputes the full formula into the norm table
+   * 
+   * this is pretty crappy for doc/field boosting, but with a static schema you can boost per-field
+   * in your sim anyway (sorta dumb to bake into the index)
+   */
+  @Override
+  public float computeNorm(FieldInvertState state) {
+    final int numTerms = state.getLength() - state.getNumOverlap();
+    return numTerms / state.getBoost();
+  }
+  
+  /** Cache of decoded bytes. */
+  private static final float[] NORM_TABLE = new float[256];
+
+  static {
+    for (int i = 0; i < 256; i++) {
+      NORM_TABLE[i] = SmallFloat.byte315ToFloat((byte)i);
+    }
+  }
+  
+  @Override
+  public float decodeNormValue(byte b) {
+    return NORM_TABLE[b & 0xFF];
+  }
+
+  @Override
+  public byte encodeNormValue(float f) {
+    return SmallFloat.floatToByte315(f);
+  }
+
+  @Override
+  public float sloppyFreq(int distance) {
+    return 1.0f / (distance + 1);
+  }
+
+  // weight for a term as log( (maxDoc+1) / (totalTermFreq+0.5))
+  // nocommit: nuke IDFExplanation!
+  // nocommit: are we summing this in the right place for phrase estimation????
+  @Override
+  public IDFExplanation computeWeight(IndexSearcher searcher, String fieldName, TermContext... termStats) throws IOException {
+    float value = 0.0f;
+    final StringBuilder exp = new StringBuilder();
+
+    final int max = searcher.maxDoc();
+    
+    for (final TermContext stat : termStats ) {
+      final long F = stat.totalTermFreq();
+      value += Math.log((max + 1D)/(F + 0.5D));
+      exp.append(" ");
+      exp.append(F);
+    }
+    
+    final float idfValue = value;
+    return new IDFExplanation() {
+      @Override
+      public float getIdf() {
+        return idfValue;
+      }
+      @Override
+      public String explain() {
+        return exp.toString();
+      }
+    };
+  }
+
+  @Override
+  public ExactDocScorer exactDocScorer(Weight weight, String fieldName, AtomicReaderContext context) throws IOException {
+    byte[] norms = context.reader.norms(fieldName);
+    float avgdl = norms == null ? 0f : avgDocumentLength(fieldName, context);
+    return new ExactDFRDocScorer((float) Math.sqrt(weight.getValue()), norms, avgdl);
+  }
+
+  @Override
+  public SloppyDocScorer sloppyDocScorer(Weight weight, String fieldName, AtomicReaderContext context) throws IOException {
+    byte[] norms = context.reader.norms(fieldName);
+    float avgdl = norms == null ? 0f : avgDocumentLength(fieldName, context);
+    return new SloppyDFRDocScorer((float) Math.sqrt(weight.getValue()), norms, avgdl);
+  }
+  
+  private float avgDocumentLength(String field, ReaderContext context) throws IOException {
+    // nocommit: crap that we calc this over and over redundantly for each segment (we should just do it once in the weight, once its generalized)
+    context = ReaderUtil.getTopLevelContext(context);
+    long normsum = context.reader.getSumOfNorms(field);
+    long maxdoc = context.reader.maxDoc();
+    int avgnorm = (int) (normsum / (double) maxdoc);
+    return decodeNormValue((byte)avgnorm);
+  }
+
+  private class ExactDFRDocScorer extends ExactDocScorer {
+    private final float weightValue;
+    private final byte[] norms;
+    private final float avgdl;
+    
+    ExactDFRDocScorer(float weightValue, byte norms[], float avgdl) {
+      this.weightValue = weightValue;
+      this.norms = norms;
+      this.avgdl = avgdl;
+    }
+    
+    // todo: optimize
+    @Override
+    public float score(int doc, int freq) {
+      float norm2 = norms == null ? 1 : (float) Math.log(1F + (c * avgdl / decodeNormValue(norms[doc])));
+      float tfn = freq * norm2;
+      float norm = 1/(1F+tfn);
+      return tfn * weightValue * norm;
+    }
+  }
+  
+  private class SloppyDFRDocScorer extends SloppyDocScorer {
+    private final float weightValue;
+    private final byte[] norms;
+    private final float avgdl;
+    
+    SloppyDFRDocScorer(float weightValue, byte norms[], float avgdl) {
+      this.weightValue = weightValue;
+      this.norms = norms;
+      this.avgdl = avgdl;
+    }
+    
+    // todo: optimize
+    @Override
+    public float score(int doc, float freq) {
+      float norm2 = norms == null ? 1 : (float) Math.log(1 + (c * avgdl / decodeNormValue(norms[doc])));
+      float tfn = freq * norm2;
+      float norm = 1/(1+tfn);
+      return tfn * weightValue * norm;
+    }
+  }
+}

Property changes on: lucene\src\test\org\apache\lucene\search\MockDFRSimilarity.java
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Added: svn:eol-style
   + native

Index: lucene/src/test/org/apache/lucene/search/MockDFRSimilarityProvider.java
===================================================================
--- lucene/src/test/org/apache/lucene/search/MockDFRSimilarityProvider.java	(revision 0)
+++ lucene/src/test/org/apache/lucene/search/MockDFRSimilarityProvider.java	(revision 0)
@@ -0,0 +1,31 @@
+package org.apache.lucene.search;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class MockDFRSimilarityProvider extends DefaultSimilarityProvider {
+
+  private final Similarity impl = new MockDFRSimilarity();
+
+  public Similarity get(String field) {
+    return impl;
+  }
+
+  public float queryNorm(float sumOfSquaredWeights) {
+    return 1f;
+  }
+}

Property changes on: lucene\src\test\org\apache\lucene\search\MockDFRSimilarityProvider.java
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Added: svn:eol-style
   + native