SOLR-10743: Add sequence StreamEvaluator

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

@@ -186,6 +186,7 @@ public class StreamHandler extends RequestHandlerBase implements SolrCoreAware,
       .withFunctionName("empiricalDistribution", EmpiricalDistributionEvaluator.class)
       .withFunctionName("describe", DescribeEvaluator.class)
       .withFunctionName("finddelay", FindDelayEvaluator.class)
+      .withFunctionName("sequence", SequenceEvaluator.class)
 
       // metrics
          .withFunctionName("min", MinMetric.class)

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

@@ -0,0 +1,72 @@
+/*
+ * 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.ArrayList;
+import java.util.List;
+
+import org.apache.commons.math3.util.MathArrays;
+import org.apache.solr.client.solrj.io.Tuple;
+import org.apache.solr.client.solrj.io.stream.expr.Explanation;
+import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType;
+import org.apache.solr.client.solrj.io.stream.expr.Expressible;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
+import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionParameter;
+import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
+
+public class SequenceEvaluator extends ComplexEvaluator implements Expressible {
+
+  private static final long serialVersionUID = 1;
+
+  public SequenceEvaluator(StreamExpression expression, StreamFactory factory) throws IOException {
+    super(expression, factory);
+  }
+
+  public List<Number> evaluate(Tuple tuple) throws IOException {
+    StreamEvaluator sizeEval = subEvaluators.get(0);
+    StreamEvaluator startEval = subEvaluators.get(1);
+    StreamEvaluator strideEval = subEvaluators.get(2);
+
+    Number sizeNum = (Number)sizeEval.evaluate(tuple);
+    Number startNum = (Number)startEval.evaluate(tuple);
+    Number strideNum = (Number)strideEval.evaluate(tuple);
+
+    int[] sequence = MathArrays.sequence(sizeNum.intValue(), startNum.intValue(), strideNum.intValue());
+    List<Number> numbers = new ArrayList(sequence.length);
+    for(int i : sequence) {
+      numbers.add(i);
+    }
+
+    return numbers;
+  }
+
+  @Override
+  public StreamExpressionParameter toExpression(StreamFactory factory) throws IOException {
+    StreamExpression expression = new StreamExpression(factory.getFunctionName(getClass()));
+    return expression;
+  }
+
+  @Override
+  public Explanation toExplanation(StreamFactory factory) throws IOException {
+    return new Explanation(nodeId.toString())
+        .withExpressionType(ExpressionType.EVALUATOR)
+        .withFunctionName(factory.getFunctionName(getClass()))
+        .withImplementingClass(getClass().getName())
+        .withExpression(toExpression(factory).toString());
+  }
+}

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

@@ -5206,6 +5206,59 @@ public class StreamExpressionTest extends SolrCloudTestCase {
   }
 
 
+  @Test
+  public void testSequence() throws Exception {
+    String expr = "tuple(seq=sequence(20, 0, 1))";
+    ModifiableSolrParams paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", expr);
+    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);
+    List<Number> sequence = (List<Number>)tuples.get(0).get("seq");
+    assertTrue(sequence.size() == 20);
+    for(int i=0; i<sequence.size(); i++) {
+      assertTrue(sequence.get(i).intValue() == i);
+    }
+
+    //Change the size, stride
+    expr = "tuple(seq=sequence(100, 0, 4))";
+    paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", expr);
+    paramsLoc.set("qt", "/stream");
+
+    solrStream = new SolrStream(url, paramsLoc);
+    tuples = getTuples(solrStream);
+    assertTrue(tuples.size() == 1);
+    sequence = (List<Number>)tuples.get(0).get("seq");
+    assertTrue(sequence.size() == 100);
+    for(int i=0; i<sequence.size(); i++) {
+      assertTrue(sequence.get(i).intValue() == (i*4));
+    }
+
+    //Change the start
+    expr = "tuple(seq=sequence(100, 10, 1))";
+    paramsLoc = new ModifiableSolrParams();
+    paramsLoc.set("expr", expr);
+    paramsLoc.set("qt", "/stream");
+
+    solrStream = new SolrStream(url, paramsLoc);
+    tuples = getTuples(solrStream);
+    assertTrue(tuples.size() == 1);
+    sequence = (List<Number>)tuples.get(0).get("seq");
+    assertTrue(sequence.size() == 100);
+    for(int i=0; i<sequence.size(); i++) {
+      assertTrue(sequence.get(i).intValue() == (i+10));
+    }
+  }
+
+
+
   @Test
   public void testEvalStream() throws Exception {
     UpdateRequest updateRequest = new UpdateRequest();