SOLR-12221: Add valueAt Stream Evaluator

solr/solrj/src/java/org/apache/solr/client/solrj/io/Lang.java

@@ -233,6 +233,7 @@ public class Lang {
         .withFunctionName("linfnorm", LInfNormEvaluator.class)
         .withFunctionName("matrixMult", MatrixMultiplyEvaluator.class)
         .withFunctionName("bicubicSpline", BicubicSplineEvaluator.class)
+        .withFunctionName("valueAt", ValueAtEvaluator.class)
 
             // Boolean Stream Evaluators
 

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

@@ -0,0 +1,74 @@
+/*
+ * 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.util.List;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class ValueAtEvaluator extends RecursiveObjectEvaluator implements ManyValueWorker {
+  protected static final long serialVersionUID = 1L;
+
+  public ValueAtEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  @Override
+  public Object doWork(Object... values) throws IOException {
+    if(values[0] instanceof List) {
+
+      List<Number> c = (List<Number>) values[0];
+      int index = -1;
+      if(values.length == 2) {
+        index = ((Number)values[1]).intValue();
+        if(index >= c.size()) {
+          throw new IOException("Index out of bounds: "+index);
+        }
+      } else {
+        throw new IOException("The valueAt function expects an array and array index as parameters.");
+      }
+      return c.get(index);
+
+    } else if(values[0] instanceof Matrix) {
+
+      Matrix c = (Matrix) values[0];
+      double[][] data = c.getData();
+      int row = -1;
+      int col = -1;
+      if(values.length == 3) {
+        row = ((Number)values[1]).intValue();
+        if(row >= data.length) {
+          throw new IOException("Row index out of bounds: "+row);
+        }
+
+        col = ((Number)values[2]).intValue();
+        if(col >= data[0].length) {
+          throw new IOException("Column index out of bounds: "+col);
+        }
+
+      } else {
+        throw new IOException("The valueAt function expects a matrix and row and column indexes");
+      }
+      return data[row][col];
+    } else {
+      throw new IOException("The valueAt function expects a numeric array or matrix as the first parameter");
+    }
+
+  }
+}

solr/solrj/src/test/org/apache/solr/client/solrj/io/TestLang.java

@@ -68,7 +68,7 @@ public class TestLang extends LuceneTestCase {
        TemporalEvaluatorEpoch.FUNCTION_NAME, TemporalEvaluatorWeek.FUNCTION_NAME, TemporalEvaluatorQuarter.FUNCTION_NAME,
        TemporalEvaluatorDayOfQuarter.FUNCTION_NAME, "abs", "add", "div", "mult", "sub", "log", "pow",
       "mod", "ceil", "floor", "sin", "asin", "sinh", "cos", "acos", "cosh", "tan", "atan", "tanh", "round", "sqrt",
-      "cbrt", "coalesce", "uuid", "if", "convert"};
+      "cbrt", "coalesce", "uuid", "if", "convert", "valueAt"};
 
   @Test
   public void testLang() {
@@ -85,7 +85,7 @@ public class TestLang extends LuceneTestCase {
       assertTrue("Testing function:"+func, registeredFunctions.containsKey(func));
     }
 
-    //Check that ech function that is registered is expected.
+    //Check that each function that is registered is expected.
     Set<String> keys = registeredFunctions.keySet();
     for(String key : keys) {
       assertTrue("Testing key:"+key, functions.contains(key));

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

@@ -2354,6 +2354,31 @@ public class MathExpressionTest extends SolrCloudTestCase {
     }
   }
 
+
+  @Test
+  public void testValueAt() throws Exception {
+    String cexpr = "let(echo=true, " +
+        "               b=array(1,2,3,4), " +
+        "               c=matrix(array(5,6,7), " +
+        "                        array(8,9,10)), " +
+        "               d=valueAt(b, 3)," +
+        "               e=valueAt(c, 1, 0))";
+    ModifiableSolrParams paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", cexpr);
+    paramsLoc.set("qt", "/stream");
+    String url = cluster.getJettySolrRunners().get(0).getBaseUrl().toString()+"/"+COLLECTIONORALIAS;
+    TupleStream solrStream = new SolrStream(url, paramsLoc);
+    StreamContext context = new StreamContext();
+    solrStream.setStreamContext(context);
+    List<Tuple> tuples = getTuples(solrStream);
+    assertTrue(tuples.size() == 1);
+    Number value1 = (Number)tuples.get(0).get("d");
+    Number value2 = (Number)tuples.get(0).get("e");
+    assertEquals(value1.intValue(), 4);
+    assertEquals(value2.intValue(), 8);
+  }
+
+
   @Test
   public void testBetaDistribution() throws Exception {
     String cexpr = "let(a=sample(betaDistribution(1, 5), 50000), b=hist(a, 11), c=col(b, N))";