zhjwpku commented on code in PR #402: URL: https://github.com/apache/iceberg-cpp/pull/402#discussion_r2607111515
########## src/iceberg/expression/residual_evaluator.h: ########## @@ -0,0 +1,93 @@ +/* + * 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. + */ + +#pragma once + +/// \file iceberg/expression/residual_evaluator.h +/// Residual evaluator for finding residual expressions after partition evaluation. + +#include <memory> + +#include "iceberg/iceberg_export.h" +#include "iceberg/partition_spec.h" +#include "iceberg/result.h" +#include "iceberg/type_fwd.h" + +namespace iceberg { + +class Expression; +class StructLike; + +/// \brief Finds the residuals for an Expression using the partitions in the given +/// PartitionSpec. +/// +/// A residual expression is made by partially evaluating an expression using partition +/// values. For example, if a table is partitioned by day(utc_timestamp) and is read +/// with a filter expression utc_timestamp >= a and utc_timestamp <= b, then there are +/// 4 possible residual expressions for the partition data, d: +/// +/// - If d > day(a) and d < day(b), the residual is always true +/// - If d == day(a) and d != day(b), the residual is utc_timestamp >= a +/// - If d == day(b) and d != day(a), the residual is utc_timestamp <= b +/// - If d == day(a) == day(b), the residual is utc_timestamp >= a and utc_timestamp <= b +/// +/// Partition data is passed using StructLike. Residuals are returned by ResidualFor(). +class ICEBERG_EXPORT ResidualEvaluator { + public: + /// \brief Return a residual evaluator for an unpartitioned PartitionSpec. + /// + /// \param expr An expression + /// \return A residual evaluator that always returns the expression + static Result<std::unique_ptr<ResidualEvaluator>> Unpartitioned( + std::shared_ptr<Expression> expr); + + /// \brief Return a residual evaluator for a PartitionSpec and Expression. + /// + /// \param spec A partition spec + /// \param schema The schema to bind expressions against + /// \param expr An expression + /// \param case_sensitive Whether field name matching is case-sensitive + /// \return A residual evaluator for the expression + static Result<std::unique_ptr<ResidualEvaluator>> Make( + const std::shared_ptr<PartitionSpec>& spec, const std::shared_ptr<Schema>& schema, + std::shared_ptr<Expression> expr, bool case_sensitive = true); + + ~ResidualEvaluator(); + + /// \brief Returns a residual expression for the given partition values. + /// + /// \param partition_data Partition data values + /// \return The residual of this evaluator's expression from the partition values + virtual Result<std::shared_ptr<Expression>> ResidualFor( + const StructLike& partition_data) const; + + protected: + ResidualEvaluator(std::shared_ptr<Expression> expr, + const std::shared_ptr<PartitionSpec>& spec, + const std::shared_ptr<Schema>& schema, bool case_sensitive); Review Comment: Changed to const ref -- 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]
