LUCENE-4250: fix trap in PayloadFunction explain API

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1365837 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -63,6 +63,10 @@ API Changes
   at all. If you want to tweak things like positionIncrementGap and offsetGap,
   analyze the field with KeywordTokenizer instead.  (Grant Ingersoll, Robert Muir)
 
+* LUCENE-4250: Pass fieldName to the PayloadFunction explain method, so it
+  parallels with docScore and the default implementation is correct.
+  (Robert Muir)
+
 Optimizations
 
 * LUCENE-4171: Performance improvements to Packed64.

lucene/core/src/java/org/apache/lucene/search/payloads/AveragePayloadFunction.java

@@ -1,6 +1,5 @@
 package org.apache.lucene.search.payloads;
 
-import org.apache.lucene.search.Explanation;
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
@@ -36,14 +35,6 @@ public class AveragePayloadFunction extends PayloadFunction{
   public float docScore(int docId, String field, int numPayloadsSeen, float payloadScore) {
     return numPayloadsSeen > 0 ? (payloadScore / numPayloadsSeen) : 1;
   }
-  @Override
-  public Explanation explain(int doc, int numPayloadsSeen, float payloadScore) {
-      Explanation payloadBoost = new Explanation();
-      float avgPayloadScore = (numPayloadsSeen > 0 ? (payloadScore / numPayloadsSeen) : 1);
-      payloadBoost.setValue(avgPayloadScore);
-      payloadBoost.setDescription("AveragePayloadFunction(...)");
-      return payloadBoost;
-  } 
 
   @Override
   public int hashCode() {

lucene/core/src/java/org/apache/lucene/search/payloads/MaxPayloadFunction.java

@@ -1,6 +1,5 @@
 package org.apache.lucene.search.payloads;
 
-import org.apache.lucene.search.Explanation;
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
@@ -40,14 +39,6 @@ public class MaxPayloadFunction extends PayloadFunction {
     return numPayloadsSeen > 0 ? payloadScore : 1;
   }
   
-  @Override
-  public Explanation explain(int doc, int numPayloadsSeen, float payloadScore) {
-	    Explanation expl = new Explanation();
-	    float maxPayloadScore = (numPayloadsSeen > 0 ? payloadScore : 1);
-	    expl.setValue(maxPayloadScore);
-	    expl.setDescription("MaxPayloadFunction(...)");
-	    return expl;
-	  } 
   @Override
   public int hashCode() {
     final int prime = 31;

lucene/core/src/java/org/apache/lucene/search/payloads/MinPayloadFunction.java

@@ -1,6 +1,5 @@
 package org.apache.lucene.search.payloads;
 
-import org.apache.lucene.search.Explanation;
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
@@ -38,14 +37,6 @@ public class MinPayloadFunction extends PayloadFunction {
     return numPayloadsSeen > 0 ? payloadScore : 1;
   }
   
-  @Override
-  public Explanation explain(int doc, int numPayloadsSeen, float payloadScore) {
-	  Explanation expl = new Explanation();
-	  float minPayloadScore = (numPayloadsSeen > 0 ? payloadScore : 1);
-	  expl.setValue(minPayloadScore);
-	  expl.setDescription("MinPayloadFunction(...)");
-	  return expl;
-  }  
   @Override
   public int hashCode() {
     final int prime = 31;

lucene/core/src/java/org/apache/lucene/search/payloads/PayloadFunction.java

@@ -55,10 +55,10 @@ public abstract class PayloadFunction {
    */
   public abstract float docScore(int docId, String field, int numPayloadsSeen, float payloadScore);
   
-  public Explanation explain(int docId, int numPayloadsSeen, float payloadScore){
+  public Explanation explain(int docId, String field, int numPayloadsSeen, float payloadScore){
 	  Explanation result = new Explanation();
-	  result.setDescription("Unimpl Payload Function Explain");
+	  result.setDescription(getClass().getSimpleName() + ".docScore()");
-	  result.setValue(1);
+	  result.setValue(docScore(docId, field, numPayloadsSeen, payloadScore));
 	  return result;
   };
   

lucene/core/src/java/org/apache/lucene/search/payloads/PayloadNearQuery.java

@@ -167,8 +167,9 @@ public class PayloadNearQuery extends SpanNearQuery {
           Explanation scoreExplanation = docScorer.explain(doc, new Explanation(freq, "phraseFreq=" + freq));
           expl.addDetail(scoreExplanation);
           expl.setValue(scoreExplanation.getValue());
+          String field = ((SpanQuery)getQuery()).getField();
           // now the payloads part
-          Explanation payloadExpl = function.explain(doc, scorer.payloadsSeen, scorer.payloadScore);
+          Explanation payloadExpl = function.explain(doc, field, scorer.payloadsSeen, scorer.payloadScore);
           // combined
           ComplexExplanation result = new ComplexExplanation();
           result.addDetail(expl);

lucene/core/src/java/org/apache/lucene/search/payloads/PayloadTermQuery.java

@@ -28,6 +28,7 @@ import org.apache.lucene.search.ComplexExplanation;
 import org.apache.lucene.search.similarities.DefaultSimilarity;
 import org.apache.lucene.search.similarities.Similarity;
 import org.apache.lucene.search.similarities.Similarity.SloppySimScorer;
+import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.search.spans.TermSpans;
 import org.apache.lucene.search.spans.SpanTermQuery;
 import org.apache.lucene.search.spans.SpanWeight;
@@ -190,7 +191,8 @@ public class PayloadTermQuery extends SpanTermQuery {
           // whether to load the payload or not
           // GSI: I suppose we could toString the payload, but I don't think that
           // would be a good idea
-          Explanation payloadExpl = function.explain(doc, scorer.payloadsSeen, scorer.payloadScore);
+          String field = ((SpanQuery)getQuery()).getField();
+          Explanation payloadExpl = function.explain(doc, field, scorer.payloadsSeen, scorer.payloadScore);
           payloadExpl.setValue(scorer.getPayloadScore());
           // combined
           ComplexExplanation result = new ComplexExplanation();