expose a static for full precision scores

Author: vigyasharma

lucene/core/src/java/org/apache/lucene/search/DoubleValuesSource.java

@@ -273,14 +273,6 @@ public static DoubleValues similarityToQueryVector(
    */
   public static DoubleValues similarityToQueryVector(
       LeafReaderContext ctx, float[] queryVector, String vectorField) throws IOException {
-    if (ctx.reader().getFieldInfos().fieldInfo(vectorField).getVectorEncoding()
-        != VectorEncoding.FLOAT32) {
-      throw new IllegalArgumentException(
-          "Field "
-              + vectorField
-              + " does not have the expected vector encoding: "
-              + VectorEncoding.FLOAT32);
-    }
     return new FloatVectorSimilarityValuesSource(queryVector, vectorField).getValues(ctx, null);
   }
 

lucene/core/src/java/org/apache/lucene/search/FloatVectorSimilarityValuesSource.java

@@ -24,6 +24,7 @@
 import org.apache.lucene.index.FloatVectorValues;
 import org.apache.lucene.index.KnnVectorValues;
 import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.index.VectorEncoding;
 import org.apache.lucene.index.VectorSimilarityFunction;
 
 /**
@@ -32,6 +33,11 @@
  */
 class FloatVectorSimilarityValuesSource extends VectorSimilarityValuesSource {
 
+  public static DoubleValues fullPrecisionScores(
+      LeafReaderContext ctx, float[] queryVector, String vectorField) throws IOException {
+    return new FloatVectorSimilarityValuesSource(queryVector, vectorField, true).getValues(ctx, null);
+  }
+
   private final float[] queryVector;
   private final boolean useFullPrecision;
 
@@ -69,8 +75,15 @@ public VectorScorer getScorer(LeafReaderContext ctx) throws IOException {
       FloatVectorValues.checkField(ctx.reader(), fieldName);
       return null;
     }
+
     final FieldInfo fi = ctx.reader().getFieldInfos().fieldInfo(fieldName);
-    final VectorSimilarityFunction vectorSimilarityFunction = fi.getVectorSimilarityFunction();
+    if (fi.getVectorEncoding() != VectorEncoding.FLOAT32) {
+      throw new IllegalArgumentException(
+          "Field "
+              + fieldName
+              + " does not have the expected vector encoding: "
+              + VectorEncoding.FLOAT32);
+    }
     if (fi.getVectorDimension() != queryVector.length) {
       throw new IllegalArgumentException(
           "Query vector dimension does not match field dimension: "
@@ -79,12 +92,12 @@ public VectorScorer getScorer(LeafReaderContext ctx) throws IOException {
               + fi.getVectorDimension());
     }
 
+    // default vector scorer
     if (useFullPrecision == false) {
-      // use default VectorScorer for configured reader
       return vectorValues.scorer(queryVector);
     }
 
-    // return a full precision vector scorer
+    final VectorSimilarityFunction vectorSimilarityFunction = fi.getVectorSimilarityFunction();
     return new VectorScorer() {
       final KnnVectorValues.DocIndexIterator iterator = vectorValues.iterator();
 

lucene/core/src/test/org/apache/lucene/search/TestQuantizedVectorSimilarityValueSource.java

@@ -145,16 +145,11 @@ public void testFullPrecisionVectorSimilarityDVS() throws Exception {
       }
 
       float[] queryVector = TestVectorUtil.randomVector(VECTOR_DIMENSION);
-      FloatVectorSimilarityValuesSource fpSimValueSource =
-          new FloatVectorSimilarityValuesSource(queryVector, KNN_FIELD, true);
-      FloatVectorSimilarityValuesSource quantizedSimValueSource =
-          new FloatVectorSimilarityValuesSource(queryVector, KNN_FIELD);
-
       try (IndexReader reader = DirectoryReader.open(dir)) {
         FieldExistsQuery query = new FieldExistsQuery(KNN_FIELD);
         for (LeafReaderContext ctx : reader.leaves()) {
-          DoubleValues fpSimValues = fpSimValueSource.getValues(ctx, null);
-          DoubleValues quantizedSimValues = quantizedSimValueSource.getValues(ctx, null);
+          DoubleValues fpSimValues = FloatVectorSimilarityValuesSource.fullPrecisionScores(ctx, queryVector, KNN_FIELD);
+          DoubleValues quantizedSimValues = DoubleValuesSource.similarityToQueryVector(ctx, queryVector, KNN_FIELD);
           // validate when segment has no vectors
           if (fpSimValues == DoubleValues.EMPTY || quantizedSimValues == DoubleValues.EMPTY) {
             assertEquals(fpSimValues, quantizedSimValues);