SOLR-10882: LengthEvaluator now supports collections of any type

solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/LengthEvaluator.java

@@ -17,7 +17,8 @@
 package org.apache.solr.client.solrj.io.eval;
 
 import java.io.IOException;
-import java.util.List;
+import java.util.Collection;
+import java.util.Locale;
 
 import org.apache.solr.client.solrj.io.Tuple;
 import org.apache.solr.client.solrj.io.stream.expr.Explanation;
@@ -33,12 +34,26 @@ public class LengthEvaluator extends ComplexEvaluator implements Expressible {
 
   public LengthEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
     super(expression, factory);
+    
+    if(1 != subEvaluators.size()){
+      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting one value but found %d",expression,subEvaluators.size()));
+    }
   }
 
   public Number evaluate(Tuple tuple) throws IOException {
-    StreamEvaluator colEval1 = subEvaluators.get(0);
-    List<Number> numbers = (List<Number>)colEval1.evaluate(tuple);
-    return numbers.size();
+    
+    Object result = subEvaluators.get(0).evaluate(tuple);
+    
+    if(null == result){
+      throw new IOException(String.format(Locale.ROOT, "Unable to find %s(...) because the value is null", constructingFactory.getFunctionName(getClass())));
+    }
+    
+    if(result instanceof Collection<?>){
+      // Cause other evaluators expect Long instead of Integer
+      return new Long(((Collection<?>)result).size());
+    }
+    
+    throw new IOException(String.format(Locale.ROOT, "Unable to find %s(...) because the value is not a collection, instead a %s was found", constructingFactory.getFunctionName(getClass()), result.getClass().getSimpleName()));
   }
 
   @Override

solr/solrj/src/test/org/apache/solr/client/solrj/io/stream/eval/LengthEvaluatorTest.java

@@ -0,0 +1,119 @@
+/*
+ * 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.
+ */
+package org.apache.solr.client.solrj.io.stream.eval;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.eval.LengthEvaluator;
+import org.apache.solr.client.solrj.io.eval.SequenceEvaluator;
+import org.apache.solr.client.solrj.io.eval.StreamEvaluator;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+import org.junit.Test;
+
+import junit.framework.Assert;
+
+public class LengthEvaluatorTest extends LuceneTestCase {
+
+  StreamFactory factory;
+  Map<String, Object> values;
+  
+  public LengthEvaluatorTest() {
+    super();
+    
+    factory = new StreamFactory()
+      .withFunctionName("length", LengthEvaluator.class)
+      .withFunctionName("sequence", SequenceEvaluator.class);
+    values = new HashMap<String,Object>();
+  }
+    
+  @Test
+  public void lengthField() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("length(a)");
+    Object result;
+    
+    values.clear();
+    values.put("a", new ArrayList<Integer>(){{ add(1); add(2); add(4); }});
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Long);
+    Assert.assertEquals(3L, result);
+    
+    values.clear();
+    values.put("a", new ArrayList<String>(){{ add("a"); add("b"); }});
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Long);
+    Assert.assertEquals(2L, result);
+    
+    values.clear();
+    values.put("a", new ArrayList<String>(){{ }});
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Long);
+    Assert.assertEquals(0L, result);    
+  }
+
+  @Test
+  public void lengthEvaluator() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("length(sequence(3,4,10))");
+    Object result;
+    
+    values.clear();
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Long);
+    Assert.assertEquals(3L, result);    
+  }
+  
+  @Test(expected = IOException.class)
+  public void lengthValueNotCollection() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("length(a)");
+    
+    values.clear();
+    values.put("a", "foo");
+    evaluator.evaluate(new Tuple(values));    
+  }
+  
+  @Test(expected = IOException.class)
+  public void lengthNoField() throws Exception{
+    factory.constructEvaluator("length()");
+  }
+  
+  @Test(expected = IOException.class)
+  public void lengthTwoFields() throws Exception{
+    factory.constructEvaluator("length(a,b)");
+  }
+  
+  @Test(expected = IOException.class)
+  public void lengthNoValue() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("length(a)");
+    
+    values.clear();
+    Object result = evaluator.evaluate(new Tuple(values));
+    assertNull(result);
+  }
+  @Test(expected = IOException.class)
+  public void lengthNullValue() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("length(a)");
+    
+    values.clear();
+    values.put("a", null);
+    Object result = evaluator.evaluate(new Tuple(values));
+    assertNull(result);
+  }
+}