SOLR-10257: Add logarithm StreamEvaluator

solr/core/src/java/org/apache/solr/handler/StreamHandler.java

@@ -42,6 +42,7 @@ import org.apache.solr.client.solrj.io.eval.IfThenElseEvaluator;
 import org.apache.solr.client.solrj.io.eval.LessThanEqualToEvaluator;
 import org.apache.solr.client.solrj.io.eval.LessThanEvaluator;
 import org.apache.solr.client.solrj.io.eval.MultiplyEvaluator;
+import org.apache.solr.client.solrj.io.eval.NaturalLogEvaluator;
 import org.apache.solr.client.solrj.io.eval.NotEvaluator;
 import org.apache.solr.client.solrj.io.eval.OrEvaluator;
 import org.apache.solr.client.solrj.io.eval.RawValueEvaluator;
@@ -197,7 +198,7 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
       .withFunctionName("div", DivideEvaluator.class)
       .withFunctionName("mult", MultiplyEvaluator.class)
       .withFunctionName("sub", SubtractEvaluator.class)
-      
+      .withFunctionName("log", NaturalLogEvaluator.class)
       // Conditional Stream Evaluators
       .withFunctionName("if", IfThenElseEvaluator.class)
       ;

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

@@ -0,0 +1,60 @@
+/*
+ * 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.eval;
+
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Locale;
+
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class NaturalLogEvaluator extends NumberEvaluator {
+  protected static final long serialVersionUID = 1L;
+
+  public NaturalLogEvaluator(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()));
+    }
+  }
+
+  @Override
+  public Number evaluate(Tuple tuple) throws IOException {
+
+    List<BigDecimal> results = evaluateAll(tuple);
+
+    // we're still doing these checks because if we ever add an array-flatten evaluator,
+    // one found in the constructor could become != 1
+    if(1 != results.size()){
+      throw new IOException(String.format(Locale.ROOT,"%s(...) only works with a 1 value but %d were provided", constructingFactory.getFunctionName(getClass()), results.size()));
+    }
+
+    if(null == results.get(0)){
+      return null;
+    }
+
+    return Math.log(results.get(0).doubleValue());
+  }
+
+}

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

@@ -0,0 +1,98 @@
+/*
+ * 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.Map;
+
+import junit.framework.Assert;
+
+import org.apache.commons.collections.map.HashedMap;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.eval.AddEvaluator;
+import org.apache.solr.client.solrj.io.eval.NaturalLogEvaluator;
+import org.apache.solr.client.solrj.io.eval.StreamEvaluator;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+import org.junit.Test;
+
+public class NaturalLogEvaluatorTest extends LuceneTestCase {
+
+  StreamFactory factory;
+  Map<String, Object> values;
+
+  public NaturalLogEvaluatorTest() {
+    super();
+
+    factory = new StreamFactory()
+        .withFunctionName("log", NaturalLogEvaluator.class).withFunctionName("add", AddEvaluator.class);
+    values = new HashedMap();
+  }
+
+  @Test
+  public void logOneField() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("log(a)");
+    Object result;
+
+    values.clear();
+    values.put("a", 100);
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Double);
+    Assert.assertTrue(result.equals(Math.log(100)));
+
+  }
+
+  @Test
+  public void logNestedField() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("log(add(50,50))");
+    Object result;
+
+    values.clear();
+    result = evaluator.evaluate(new Tuple(values));
+    Assert.assertTrue(result instanceof Double);
+    Assert.assertTrue(result.equals(Math.log(100)));
+
+  }
+
+  @Test(expected = IOException.class)
+  public void logNoField() throws Exception{
+    factory.constructEvaluator("log()");
+  }
+
+  @Test(expected = IOException.class)
+  public void logTwoFields() throws Exception{
+    factory.constructEvaluator("log(a,b)");
+  }
+
+  @Test
+  public void logNoValue() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("log(a)");
+
+    values.clear();
+    Object result = evaluator.evaluate(new Tuple(values));
+    assertNull(result);
+  }
+  @Test
+  public void logNullValue() throws Exception{
+    StreamEvaluator evaluator = factory.constructEvaluator("log(a)");
+
+    values.clear();
+    values.put("a", null);
+    Object result = evaluator.evaluate(new Tuple(values));
+    assertNull(result);
+  }
+}