cloud-fan commented on a change in pull request #30134: URL: https://github.com/apache/spark/pull/30134#discussion_r511926874
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/AliasHelper.scala ########## @@ -0,0 +1,100 @@ +/* + * 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 org.apache.spark.sql.catalyst.analysis.MultiAlias +import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression +import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Project} + +/** + * Helper methods for collecting and replacing aliases. + */ +trait AliasHelper { + + protected def getAliasMap(plan: Project): AttributeMap[Alias] = { + // Create a map of Aliases to their values from the child projection. + // e.g., 'SELECT a + b AS c, d ...' produces Map(c -> Alias(a + b, c)). + getAliasMap(plan.projectList) + } + + protected def getAliasMap(plan: Aggregate): AttributeMap[Alias] = { + // Find all the aliased expressions in the aggregate list that don't include any actual + // AggregateExpression or PythonUDF, and create a map from the alias to the expression + val aliasMap = plan.aggregateExpressions.collect { + case a: Alias if a.child.find(e => e.isInstanceOf[AggregateExpression] || + PythonUDF.isGroupedAggPandasUDF(e)).isEmpty => + (a.toAttribute, a) + } + AttributeMap(aliasMap) + } + + protected def getAliasMap(exprs: Seq[NamedExpression]): AttributeMap[Alias] = { + // Create a map of Aliases to their values from the child projection. + // e.g., 'SELECT a + b AS c, d ...' produces Map(c -> Alias(a + b, c)). + AttributeMap(exprs.collect { case a: Alias => (a.toAttribute, a) }) + } + + /** + * Replace all attributes, that reference an alias, with the aliased expression + */ + protected def replaceAlias( + expr: Expression, Review comment: nit: 4 space indentation ---------------------------------------------------------------- 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: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org