twalthr commented on a change in pull request #8062: [FLINK-11884][table] Implement expression resolution on top of new Expressions URL: https://github.com/apache/flink/pull/8062#discussion_r275273674
########## File path: flink-table/flink-table-planner/src/main/java/org/apache/flink/table/operations/SortOperationFactory.java ########## @@ -0,0 +1,118 @@ +/* + * 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.flink.table.operations; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.api.ValidationException; +import org.apache.flink.table.expressions.ApiExpressionDefaultVisitor; +import org.apache.flink.table.expressions.CallExpression; +import org.apache.flink.table.expressions.Expression; +import org.apache.flink.table.expressions.ExpressionBridge; +import org.apache.flink.table.expressions.PlannerExpression; +import org.apache.flink.table.plan.logical.Limit; +import org.apache.flink.table.plan.logical.LogicalNode; +import org.apache.flink.table.plan.logical.Sort; + +import java.util.List; +import java.util.stream.Collectors; + +import static java.util.Collections.singletonList; +import static org.apache.flink.table.expressions.BuiltInFunctionDefinitions.ORDERING; +import static org.apache.flink.table.expressions.BuiltInFunctionDefinitions.ORDER_ASC; + +/** + * Utility class for creating a valid {@link Sort} operation. + */ +@Internal +public class SortOperationFactory { + + private final boolean isStreaming; + private final ExpressionBridge<PlannerExpression> expressionBridge; + private final OrderWrapper orderWrapper = new OrderWrapper(); + + public SortOperationFactory( + ExpressionBridge<PlannerExpression> expressionBridge, + boolean isStreaming) { + this.expressionBridge = expressionBridge; + this.isStreaming = isStreaming; + } + + /** + * Creates a valid {@link Sort} operation. + * + * <p><b>NOTE:</b> if the collation is not explicitly specified for any expression, it is wrapped in a + * default ascending order + * + * @param orders expressions describing order, + * @param child relational expression on top of which to apply the sort operation + * @return valid sort operation + */ + public Sort createSort(List<Expression> orders, TableOperation child) { + failIfStreaming(); + + List<PlannerExpression> convertedOrders = orders.stream() + .map(f -> f.accept(orderWrapper)) + .map(expressionBridge::bridge) + .collect(Collectors.toList()); + return new Sort(convertedOrders, (LogicalNode) child); + } + + /** + * Creates a valid {@link Limit} operation. + * + * @param offset offset to start from + * @param fetch number of records to fetch + * @return valid limit operation + */ + public Limit createLimit(int offset, int fetch, TableOperation child) { + failIfStreaming(); + + if (!(child instanceof Sort)) { + throw new ValidationException("Limit operator must be preceded by an OrderBy operator."); Review comment: nit: rename exception to "A limit operation must be preceded by a sort operation."? The case class names are not valid anymore and were misleading anyway. ---------------------------------------------------------------- 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 With regards, Apache Git Services
