vladimirg-db commented on code in PR #49029: URL: https://github.com/apache/spark/pull/49029#discussion_r1881081459
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/resolver/NameTarget.scala: ########## @@ -0,0 +1,81 @@ +/* + * 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.resolver + +import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute +import org.apache.spark.sql.catalyst.expressions.{Attribute, AttributeReference, Expression} +import org.apache.spark.sql.catalyst.util.StringUtils.orderSuggestedIdentifiersBySimilarity +import org.apache.spark.sql.errors.QueryCompilationErrors + +/** + * Class that represents results of name resolution or star expansion. It encapsulates: + * - `candidates` - A list of candidates that are possible matches for a given name. + * - `aliasName` - If the candidates size is 1 and it's type is `ExtractValue` (which means that + * it's a recursive type), then the `aliasName` should be the name with which the candidate is + * aliased. Otherwise, `aliasName` should be `None`. + * - `allAttributes` - A list of all attributes which is used to generate suggestions for + * unresolved column error. + * + * Example: + * + * - Attribute resolution: + * {{{ SELECT col1 FROM VALUES (1); }}} will have a [[NameTarget]] with a single candidate `col1`. + * `aliasName` would be `None` in this case because the column is not of recursive type. + * + * - Recursive attribute resolution: + * {{{ SELECT col1.col1 FROM VALUES(STRUCT(1,2), 3) }}} will have a [[NameTarget]] with a + * single candidate `col1` and an `aliasName` of `Some("col1")`. + */ +case class NameTarget( + candidates: Seq[Expression], + aliasName: Option[String] = None, + allAttributes: Seq[Attribute] = Seq.empty) { + + /** + * Picks a candidate from the list of candidates based on the given unresolved attribute. + * Its behavior is as follows (based on the number of candidates): + * + * - If there is only one candidate, it will be returned. + * + * - If there are multiple candidates, an ambiguous reference error will be thrown. + * + * - If there are no candidates, an unresolved column error will be thrown. + */ + def pickCandidate(unresolvedAttribute: UnresolvedAttribute): Expression = { + candidates match { + case Seq() => + throwUnresolvedColumnError(unresolvedAttribute) + case Seq(candidate) => + candidate + case _ => + throw QueryCompilationErrors.ambiguousReferenceError( + unresolvedAttribute.name, + candidates.collect { case attribute: AttributeReference => attribute } + ) + } + } + + private def throwUnresolvedColumnError(unresolvedAttribute: UnresolvedAttribute): Nothing = + throw QueryCompilationErrors.unresolvedColumnError( Review Comment: Yeah, we do that here: https://github.com/apache/spark/pull/49029/files#diff-40c128960e158dee79a7562850a925f25adc6f312cb43b9eeff2625fe5318fdfR226 -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
