rdblue commented on a change in pull request #24117: [SPARK-27181][SQL]: Add public transform API URL: https://github.com/apache/spark/pull/24117#discussion_r270567384
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalog/v2/expressions/expressions.scala ########## @@ -0,0 +1,194 @@ +/* + * 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.catalog.v2.expressions + +import org.apache.spark.sql.AnalysisException +import org.apache.spark.sql.catalyst +import org.apache.spark.sql.catalyst.catalog.BucketSpec +import org.apache.spark.sql.catalyst.parser.CatalystSqlParser +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.types.{DataType, IntegerType, StringType} + +/** + * Helper methods for working with the logical expressions API. + * + * Factory methods can be used when referencing the logical expression nodes is ambiguous because + * logical and internal expressions are used. + */ +private[sql] object LogicalExpressions { + // a generic parser that is only used for parsing multi-part field names. + // because this is only used for field names, the SQL conf passed in does not matter. + private lazy val parser = new CatalystSqlParser(SQLConf.get) + + def fromPartitionColumns(columns: String*): Array[IdentityTransform] = + columns.map(identity).toArray + + def fromBucketSpec(spec: BucketSpec): BucketTransform = { + if (spec.sortColumnNames.nonEmpty) { + throw new AnalysisException( + s"Cannot convert bucketing with sort columns to a transform: $spec") + } + + bucket(spec.numBuckets, spec.bucketColumnNames: _*) + } + + implicit class TransformHelper(transforms: Seq[Transform]) { + def asPartitionColumns: Seq[String] = { + val (idTransforms, nonIdTransforms) = transforms.partition(_.isInstanceOf[IdentityTransform]) + + if (nonIdTransforms.nonEmpty) { + throw new AnalysisException("Transforms cannot be converted to partition columns: " + + nonIdTransforms.map(_.describe).mkString(", ")) + } + + idTransforms.map(_.asInstanceOf[IdentityTransform]).map(_.reference.describe) + } + } + + def literal[T](value: T): LiteralValue[T] = { + val internalLit = catalyst.expressions.Literal(value) + literal(value, internalLit.dataType) + } + + def literal[T](value: T, dataType: DataType): LiteralValue[T] = LiteralValue(value, dataType) + + def reference(name: String): NamedReference = + FieldReference(parser.parseMultipartIdentifier(name).toArray) + + def apply(name: String, arguments: Array[Expression]): Transform = ApplyTransform(name, arguments) + + def apply(name: String, arguments: Expression*): Transform = ApplyTransform(name, arguments) + + def bucket(numBuckets: Int, columns: Array[String]): BucketTransform = + BucketTransform(literal(numBuckets, IntegerType), columns.map(reference)) + + def bucket(numBuckets: Int, columns: String*): BucketTransform = + BucketTransform(literal(numBuckets, IntegerType), columns.map(reference)) + + def identity(column: String): IdentityTransform = IdentityTransform(reference(column)) + + def year(column: String): YearTransform = YearTransform(reference(column)) + + def month(column: String): MonthTransform = MonthTransform(reference(column)) + + def date(column: String): DateTransform = DateTransform(reference(column)) + + def dateHour(column: String): DateHourTransform = DateHourTransform(reference(column)) +} + +/** + * Base class for simple transforms of a single column. + */ +private[sql] abstract class SingleColumnTransform(ref: NamedReference) extends Transform { + + def reference: NamedReference = ref + + override lazy val references: Array[NamedReference] = Array(ref) + + override lazy val arguments: Array[Expression] = Array(ref) + + override lazy val describe: String = name + "(" + reference.describe + ")" + + override def toString: String = describe +} + +private[sql] final case class BucketTransform( + numBuckets: Literal[Int], + columns: Seq[NamedReference]) extends Transform { + + override lazy val name: String = "bucket" + + override lazy val references: Array[NamedReference] = { + arguments + .filter(_.isInstanceOf[NamedReference]) + .map(_.asInstanceOf[NamedReference]) + } + + override lazy val arguments: Array[Expression] = numBuckets +: columns.toArray + + override lazy val describe: String = s"bucket(${arguments.map(_.describe).mkString(", ")})" + + override def toString: String = describe +} + +private[sql] final case class ApplyTransform( + name: String, + args: Seq[Expression]) extends Transform { + + override lazy val arguments: Array[Expression] = args.toArray + + override lazy val references: Array[NamedReference] = { + arguments + .filter(_.isInstanceOf[NamedReference]) + .map(_.asInstanceOf[NamedReference]) + } + + override lazy val describe: String = s"$name(${arguments.map(_.describe).mkString(", ")})" + + override def toString: String = describe +} + +private[sql] final case class IdentityTransform( + ref: NamedReference) extends SingleColumnTransform(ref) { + override lazy val name: String = "identity" + override lazy val describe: String = ref.describe Review comment: Please be more clear. Why is using a `lazy val` an abuse? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
