Github user hvanhovell commented on a diff in the pull request: https://github.com/apache/spark/pull/13969#discussion_r70075370 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Reflect.scala --- @@ -0,0 +1,170 @@ +/* + * 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.spark.sql.catalyst.expressions + +import java.lang.reflect.Method + +import scala.util.Try + +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.analysis.TypeCheckResult +import org.apache.spark.sql.catalyst.analysis.TypeCheckResult.{TypeCheckFailure, TypeCheckSuccess} +import org.apache.spark.sql.catalyst.expressions.codegen.CodegenFallback +import org.apache.spark.sql.types._ +import org.apache.spark.unsafe.types.UTF8String +import org.apache.spark.util.Utils + +/** + * An expression that invokes a method on a class via reflection. + * + * @param children the first element should be a literal string for the class name, + * and the second element should be a literal string for the method name, + * and the remaining are input arguments to the Java method. + */ +// scalastyle:off line.size.limit +@ExpressionDescription( + usage = "_FUNC_(class,method[,arg1[,arg2..]]) calls method with reflection", + extended = "> SELECT _FUNC_('java.util.UUID', 'randomUUID');\nc33fb387-8500-4bfa-81d2-6e0e3e930df2") +// scalastyle:on line.size.limit +case class Reflect(children: Seq[Expression]) + extends Expression with CodegenFallback { + + override def prettyName: String = "reflect" + + override def checkInputDataTypes(): TypeCheckResult = { + if (children.size < 2) { + TypeCheckFailure("requires at least two arguments") + } else if (!children.take(2).forall(e => e.dataType == StringType && e.foldable)) { + // The first two arguments must be string type. + TypeCheckFailure("first two arguments should be string literals") + } else if (!classExists) { + TypeCheckFailure(s"class $className not found") + } else if (method == null) { + TypeCheckFailure(s"cannot find a method that matches the argument types in $className") + } else { + TypeCheckSuccess + } + } + + override def deterministic: Boolean = false + override def nullable: Boolean = true + override val dataType: DataType = StringType + + override def eval(input: InternalRow): Any = { + var i = 0 + while (i < argExprs.length) { + buffer(i) = argExprs(i).eval(input).asInstanceOf[Object] + // Convert if necessary. Based on the types defined in typeMapping, string is the only + // type that needs conversion. + if (buffer(i).isInstanceOf[UTF8String]) { --- End diff -- What about timestamp/date/decimals/arrays/maps?
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