LUCENE-5666: add SortedSetFieldSource

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5666@1594211 13f79535-47bb-0310-9956-ffa450edef68

lucene/queries/src/java/org/apache/lucene/queries/function/docvalues/DocTermsIndexDocValues.java

@@ -44,12 +44,12 @@ public abstract class DocTermsIndexDocValues extends FunctionValues {
   protected final CharsRef spareChars = new CharsRef();
 
   public DocTermsIndexDocValues(ValueSource vs, AtomicReaderContext context, String field) throws IOException {
-    try {
-      termsIndex = DocValues.getSorted(context.reader(), field);
-    } catch (RuntimeException e) {
-      throw new DocTermsIndexException(field, e);
-    }
+    this(vs, open(context, field));
+  }
+  
+  protected DocTermsIndexDocValues(ValueSource vs, SortedDocValues termsIndex) {
     this.vs = vs;
+    this.termsIndex = termsIndex;
   }
 
   protected abstract String toTerm(String readableValue);
@@ -162,6 +162,15 @@ public abstract class DocTermsIndexDocValues extends FunctionValues {
     };
   }
 
+  // TODO: why?
+  static SortedDocValues open(AtomicReaderContext context, String field) throws IOException {
+    try {
+      return DocValues.getSorted(context.reader(), field);
+    } catch (RuntimeException e) {
+      throw new DocTermsIndexException(field, e);
+    }
+  }
+  
   /**
    * Custom Exception to be thrown when the DocTermsIndex for a field cannot be generated
    */

lucene/queries/src/java/org/apache/lucene/queries/function/valuesource/SortedSetFieldSource.java

@@ -0,0 +1,90 @@
+package org.apache.lucene.queries.function.valuesource;
+
+/*
+ * 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 java.util.Map;
+
+import org.apache.lucene.index.AtomicReaderContext;
+import org.apache.lucene.index.DocValues;
+import org.apache.lucene.index.SortedDocValues;
+import org.apache.lucene.index.SortedSetDocValues;
+import org.apache.lucene.queries.function.FunctionValues;
+import org.apache.lucene.queries.function.docvalues.DocTermsIndexDocValues;
+import org.apache.lucene.search.SortedSetSelector;
+
+/**
+ * Retrieves {@link FunctionValues} instances for multi-valued string based fields.
+ * <p>
+ * A SortedSetDocValues contains multiple values for a field, so this 
+ * technique "selects" a value as the representative value for the document.
+ * 
+ * @see SortedSetSelector
+ */
+public class SortedSetFieldSource extends FieldCacheSource {
+  protected final SortedSetSelector.Type selector;
+  
+  public SortedSetFieldSource(String field) {
+    this(field, SortedSetSelector.Type.MIN);
+  }
+  
+  public SortedSetFieldSource(String field, SortedSetSelector.Type selector) {
+    super(field);
+    this.selector = selector;
+  }
+
+  @Override
+  public FunctionValues getValues(Map context, AtomicReaderContext readerContext) throws IOException {
+    SortedSetDocValues sortedSet = DocValues.getSortedSet(readerContext.reader(), field);
+    SortedDocValues view = SortedSetSelector.wrap(sortedSet, selector);
+    return new DocTermsIndexDocValues(this, view) {
+      @Override
+      protected String toTerm(String readableValue) {
+        return readableValue;
+      }
+
+      @Override
+      public Object objectVal(int doc) {
+        return strVal(doc);
+      }
+    };
+  }
+  
+  @Override
+  public String description() {
+    return "sortedset(" + field + ",selector=" + selector + ')';
+  }
+
+  @Override
+  public int hashCode() {
+    final int prime = 31;
+    int result = super.hashCode();
+    result = prime * result + ((selector == null) ? 0 : selector.hashCode());
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) return true;
+    if (!super.equals(obj)) return false;
+    if (getClass() != obj.getClass()) return false;
+    SortedSetFieldSource other = (SortedSetFieldSource) obj;
+    if (selector != other.selector) return false;
+    return true;
+  }
+}

lucene/queries/src/test/org/apache/lucene/queries/function/TestSortedSetFieldSource.java

@@ -0,0 +1,61 @@
+package org.apache.lucene.queries.function;
+
+/*
+ * 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.util.Collections;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.SortedSetDocValuesField;
+import org.apache.lucene.index.AtomicReader;
+import org.apache.lucene.index.DirectoryReader;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.queries.function.valuesource.SortedSetFieldSource;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.LuceneTestCase.SuppressCodecs;
+
+@SuppressCodecs({"Lucene40", "Lucene41"}) // avoid codecs that don't support sortedset
+public class TestSortedSetFieldSource extends LuceneTestCase {
+  public void testSimple() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(TEST_VERSION_CURRENT, null));
+    Document doc = new Document();
+    doc.add(new SortedSetDocValuesField("value", new BytesRef("baz")));
+    doc.add(newStringField("id", "2", Field.Store.YES));
+    writer.addDocument(doc);
+    doc = new Document();
+    doc.add(new SortedSetDocValuesField("value", new BytesRef("foo")));
+    doc.add(new SortedSetDocValuesField("value", new BytesRef("bar")));
+    doc.add(newStringField("id", "1", Field.Store.YES));
+    writer.addDocument(doc);
+    writer.forceMerge(1);
+    writer.shutdown();
+
+    DirectoryReader ir = DirectoryReader.open(dir);
+    AtomicReader ar = getOnlySegmentReader(ir);
+    
+    ValueSource vs = new SortedSetFieldSource("value");
+    FunctionValues values = vs.getValues(Collections.emptyMap(), ar.getContext());
+    assertEquals("baz", values.strVal(0));
+    assertEquals("bar", values.strVal(1)); 
+    ir.close();
+    dir.close();
+  }
+}