srowen commented on a change in pull request #26728: [SPARK-30012][CORE][SQL] Change classes extending scala collection classes to work with 2.13 URL: https://github.com/apache/spark/pull/26728#discussion_r352932329
########## File path: sql/catalyst/src/main/scala-2.13/org/apache/spark/sql/catalyst/expressions/ExpressionSet.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 scala.collection.mutable +import scala.collection.mutable.ArrayBuffer + +object ExpressionSet { + /** Constructs a new [[ExpressionSet]] by applying [[Canonicalize]] to `expressions`. */ + def apply(expressions: TraversableOnce[Expression]): ExpressionSet = { + val set = new ExpressionSet() + expressions.foreach(set.add) + set + } +} + +/** + * A [[Set]] where membership is determined based on determinacy and a canonical representation of + * an [[Expression]] (i.e. one that attempts to ignore cosmetic differences). + * See [[Canonicalize]] for more details. + * + * Internally this set uses the canonical representation, but keeps also track of the original + * expressions to ease debugging. Since different expressions can share the same canonical + * representation, this means that operations that extract expressions from this set are only + * guaranteed to see at least one such expression. For example: + * + * {{{ + * val set = ExpressionSet(a + 1, 1 + a) + * + * set.iterator => Iterator(a + 1) + * set.contains(a + 1) => true + * set.contains(1 + a) => true + * set.contains(a + 2) => false + * }}} + * + * For non-deterministic expressions, they are always considered as not contained in the [[Set]]. + * On adding a non-deterministic expression, simply append it to the original expressions. + * This is consistent with how we define `semanticEquals` between two expressions. + */ +class ExpressionSet protected( + protected val baseSet: mutable.Set[Expression] = new mutable.HashSet, + protected val originals: mutable.Buffer[Expression] = new ArrayBuffer) + extends Set[Expression] { + + // Note: this class supports Scala 2.13. A parallel source tree has a 2.12 implementation. + + protected def add(e: Expression): Unit = { + if (!e.deterministic) { + originals += e + } else if (!baseSet.contains(e.canonicalized) ) { + baseSet.add(e.canonicalized) + originals += e + } + } + + override def contains(elem: Expression): Boolean = baseSet.contains(elem.canonicalized) + + override def incl(elem: Expression): ExpressionSet = { + val newSet = new ExpressionSet(baseSet.clone(), originals.clone()) + newSet.add(elem) + newSet + } + Review comment: It still exists in 2.13, it just can't be overridden. It's an alias for `concat`: `@inline final def ++ (that: collection.IterableOnce[A]): C = concat(that)` The methods the collection has to implement in 2.13 to support addition are different, like `incl`. ---------------------------------------------------------------- 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]
