Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/14656#discussion_r75222985
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveTableValuedFunctions.scala
---
@@ -0,0 +1,121 @@
+/*
+ * 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.analysis
+
+import org.apache.spark.{SparkConf, SparkContext}
+import org.apache.spark.sql.catalyst.expressions.Expression
+import org.apache.spark.sql.catalyst.plans._
+import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Range}
+import org.apache.spark.sql.catalyst.rules._
+import org.apache.spark.sql.types.{DataType, IntegerType, LongType}
+
+/**
+ * Rule that resolves table-valued function references.
+ */
+object ResolveTableValuedFunctions extends Rule[LogicalPlan] {
+ private lazy val defaultParallelism =
+ SparkContext.getOrCreate(new SparkConf(false)).defaultParallelism
+
+ /**
+ * List of argument names and their types, used to declare a function.
+ */
+ private case class ArgumentList(args: (String, DataType)*) {
+ /**
+ * Try to cast the expressions to satisfy the expected types of this
argument list. If there
+ * are any types that cannot be casted, then None is returned.
+ */
+ def implicitCast(values: Seq[Expression]): Option[Seq[Expression]] = {
+ if (args.length == values.length) {
+ val casted = values.zip(args).map { case (value, (_,
expectedType)) =>
+ TypeCoercion.ImplicitTypeCasts.implicitCast(value, expectedType)
+ }
+ if (casted.forall(_.isDefined)) {
+ return Some(casted.map(_.get))
+ }
+ }
+ None
+ }
+
+ override def toString: String = {
+ args.map { a =>
+ s"${a._1}: ${a._2.typeName}"
+ }.mkString(", ")
+ }
+ }
+
+ /**
+ * A TVF maps argument lists to resolver functions that accept those
arguments. Using a map
+ * here allows for function overloading.
+ */
+ private type TVF = Map[ArgumentList, Seq[Any] => LogicalPlan]
+
+ /**
+ * TVF builder.
+ */
+ private def tvf(args: (String, DataType)*)(pf: PartialFunction[Seq[Any],
LogicalPlan])
+ : (ArgumentList, Seq[Any] => LogicalPlan) = (ArgumentList(args: _*),
pf)
+
+ /**
+ * Internal registry of table-valued functions.
+ */
+ private val builtinFunctions: Map[String, TVF] = Map(
+ "range" -> Map(
+ /* range(end) */
+ tvf("end" -> LongType) { case Seq(end: Long) =>
+ Range(0, end, 1, defaultParallelism)
+ },
+
+ /* range(start, end) */
+ tvf("start" -> LongType, "end" -> LongType) { case Seq(start: Long,
end: Long) =>
+ Range(start, end, 1, defaultParallelism)
+ },
+
+ /* range(start, end, step) */
+ tvf("start" -> LongType, "end" -> LongType, "step" -> LongType) {
+ case Seq(start: Long, end: Long, step: Long) =>
+ Range(start, end, step, defaultParallelism)
--- End diff --
Nit Style: Weird indentation.
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