Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/spark/pull/13969#discussion_r69706643
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/JavaMethodReflect.scala
---
@@ -0,0 +1,153 @@
+/*
+ * 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 JavaMethodReflect(children: Seq[Expression])
+ extends Expression with CodegenFallback {
+ import JavaMethodReflect._
+
+ 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 (method == null) {
+ TypeCheckFailure("cannot find a method that matches the argument
types")
+ } 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]) {
+ buffer(i) = buffer(i).toString
+ }
+ i += 1
+ }
+ UTF8String.fromString(String.valueOf(method.invoke(obj, buffer : _*)))
+ }
+
+ @transient private lazy val argExprs: Array[Expression] =
children.drop(2).toArray
+
+ /** Name of the class -- this has to be called after we verify children
has at least two exprs. */
+ @transient private lazy val className =
children(0).eval(null).asInstanceOf[UTF8String].toString
+
+ /** The reflection method. */
+ @transient lazy val method: Method = {
+ val methodName =
children(1).eval(null).asInstanceOf[UTF8String].toString
+ findMethod(className, methodName, argExprs.map(_.dataType)).orNull
+ }
+
+ /** If the class has a no-arg ctor, instantiate the object. Otherwise,
obj is null. */
+ @transient private lazy val obj: Object =
instantiate(className).orNull.asInstanceOf[Object]
+
+ /** A temporary buffer used to hold intermediate results returned by
children. */
+ @transient private lazy val buffer = new Array[Object](argExprs.length)
+}
+
+object JavaMethodReflect {
+ /** Mapping from Spark's type to acceptable JVM types. */
+ val typeMapping = Map[DataType, Seq[Class[_]]](
+ BooleanType -> Seq(classOf[java.lang.Boolean], classOf[Boolean]),
+ ByteType -> Seq(classOf[java.lang.Byte], classOf[Byte]),
+ ShortType -> Seq(classOf[java.lang.Short], classOf[Short]),
+ IntegerType -> Seq(classOf[java.lang.Integer], classOf[Int]),
+ LongType -> Seq(classOf[java.lang.Long], classOf[Long]),
+ FloatType -> Seq(classOf[java.lang.Float], classOf[Float]),
+ DoubleType -> Seq(classOf[java.lang.Double], classOf[Double]),
+ StringType -> Seq(classOf[String])
+ )
+
+ /**
+ * Finds a Java method using reflection that matches the given argument
types,
+ * and whose return type is string.
+ *
+ * The types sequence must be the valid types defined in [[typeMapping]].
+ *
+ * This is made public for unit testing.
+ */
+ def findMethod(className: String, methodName: String, argTypes:
Seq[DataType]): Option[Method] = {
+ val clazz: Class[_] = Utils.classForName(className)
--- End diff --
Otherwise, None?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
