use CastToObjectVectorProcessor for cast to string (#17148) (#17149)

processing/src/main/java/org/apache/druid/math/expr/vector/CastToStringVectorProcessor.java

@@ -1,52 +0,0 @@
-/*
- * 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.druid.math.expr.vector;
-
-import org.apache.druid.math.expr.Evals;
-import org.apache.druid.math.expr.Expr;
-import org.apache.druid.math.expr.ExpressionType;
-
-public final class CastToStringVectorProcessor extends CastToTypeVectorProcessor<Object[]>
-{
-  private final Object[] output;
-
-  public CastToStringVectorProcessor(ExprVectorProcessor<?> delegate, int maxVectorSize)
-  {
-    super(delegate);
-    this.output = new Object[maxVectorSize];
-  }
-
-  @Override
-  public ExprEvalVector<Object[]> evalVector(Expr.VectorInputBinding bindings)
-  {
-    ExprEvalVector<?> result = delegate.evalVector(bindings);
-    final Object[] objects = result.getObjectVector();
-    for (int i = 0; i < bindings.getCurrentVectorSize(); i++) {
-      output[i] = Evals.asString(objects[i]);
-    }
-    return new ExprEvalObjectVector(output, ExpressionType.STRING);
-  }
-
-  @Override
-  public ExpressionType getOutputType()
-  {
-    return ExpressionType.STRING;
-  }
-}

processing/src/main/java/org/apache/druid/math/expr/vector/CastToTypeVectorProcessor.java

@@ -42,9 +42,6 @@ public abstract class CastToTypeVectorProcessor<TOutput> implements ExprVectorPr
       caster = castInput;
     } else {
       switch (castToType.getType()) {
-        case STRING:
-          caster = new CastToStringVectorProcessor(castInput, maxVectorSize);
-          break;
         case LONG:
           caster = new CastToLongVectorProcessor(castInput);
           break;

processing/src/test/java/org/apache/druid/math/expr/VectorExprSanityTest.java

@@ -271,6 +271,16 @@ public class VectorExprSanityTest extends InitializedNullHandlingTest
     testExpression("array(s1, l2)", types);
   }
 
+  @Test
+  public void testCastArraysRoundTrip()
+  {
+    testExpression("cast(cast(s1, 'ARRAY<STRING>'), 'STRING')", types);
+    testExpression("cast(cast(d1, 'ARRAY<DOUBLE>'), 'DOUBLE')", types);
+    testExpression("cast(cast(d1, 'ARRAY<STRING>'), 'DOUBLE')", types);
+    testExpression("cast(cast(l1, 'ARRAY<LONG>'), 'LONG')", types);
+    testExpression("cast(cast(l1, 'ARRAY<STRING>'), 'LONG')", types);
+  }
+
   @Test
   public void testJsonFns()
   {