Fokko commented on code in PR #31: URL: https://github.com/apache/iceberg-cpp/pull/31#discussion_r1918197785
########## src/iceberg/type_fwd.h: ########## @@ -0,0 +1,55 @@ +/* + * 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/type_fwd.h +/// Forward declarations and enum definitions. + +namespace iceberg { + +/// \brief A data type. +/// +/// This is not a complete data type by itself because some types are nested +/// and/or parameterized. +enum class TypeId { Review Comment: I think we can go two ways; - Leave as is, and first go with everything in V2 since V3 is still not finalized (eg Variant support is still pending in Java, Geometry/Geography is still under discussion). - Add everything, and fail when a user tries to read a table with an unsupported type. I think I'll prefer the first one to make sure that we don't expand too much on the surface area. ########## src/iceberg/type.h: ########## @@ -0,0 +1,120 @@ +/* + * 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/type.h +/// Data types for Iceberg. + +#include <memory> +#include <span> +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/type_fwd.h" + +namespace iceberg { + +/// \brief Interface for a data type for a field. +class ICEBERG_EXPORT Type { + public: + virtual ~Type() = default; + + /// \brief Get the type ID. + [[nodiscard]] virtual TypeId type_id() const = 0; + + /// \brief Get a user-readable string representation of the type. + [[nodiscard]] virtual std::string ToString() const = 0; + + /// \brief Compare two types for equality. + [[nodiscard]] virtual bool Equals(const Type& other) const = 0; + + friend bool operator==(const Type& lhs, const Type& rhs) { return lhs.Equals(rhs); } + + friend bool operator!=(const Type& lhs, const Type& rhs) { return !(lhs == rhs); } +}; + +/// \brief A type combined with a name. +class ICEBERG_EXPORT Field { + public: + Field(int32_t field_id, std::string name, std::shared_ptr<Type> type, bool optional); + + static Field MakeOptional(int32_t field_id, std::string name, + std::shared_ptr<Type> type); + static Field MakeRequired(int32_t field_id, std::string name, + std::shared_ptr<Type> type); + + /// \brief Get the field ID. + [[nodiscard]] int32_t field_id() const; + + /// \brief Get the field name. + [[nodiscard]] std::string_view name() const; + + /// \brief Get the field type. + [[nodiscard]] const std::shared_ptr<Type>& type() const; + + /// \brief Get whether the field is optional. + [[nodiscard]] bool optional() const; + + /// \brief Get a user-readable string representation of the field. + [[nodiscard]] std::string ToString() const; + + /// \brief Compare two fields for equality. + [[nodiscard]] bool Equals(const Field& other) const; + + friend bool operator==(const Field& lhs, const Field& rhs) { return lhs.Equals(rhs); } + + friend bool operator!=(const Field& lhs, const Field& rhs) { return !(lhs == rhs); } +}; + +/// \brief A data type representing a boolean. +class ICEBERG_EXPORT BooleanType : public Type { Review Comment: In [PyIceberg](https://github.com/apache/iceberg-python/blob/f4caa3ac927c626eeba5d0408f80ddd9b95214e0/pyiceberg/types.py#L179)/[Java](https://github.com/apache/iceberg/blob/d96901b843395fe669f6bd4f618f8e5e46c0eed4/api/src/main/java/org/apache/iceberg/types/Type.java#L104) we add a `PrimitiveType` to the OOP hierarchy. This makes it a bit easier down the road, maybe also something to consider here. ########## src/iceberg/type.h: ########## @@ -0,0 +1,120 @@ +/* + * 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/type.h +/// Data types for Iceberg. + +#include <memory> +#include <span> +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/type_fwd.h" + +namespace iceberg { + +/// \brief Interface for a data type for a field. +class ICEBERG_EXPORT Type { + public: + virtual ~Type() = default; + + /// \brief Get the type ID. + [[nodiscard]] virtual TypeId type_id() const = 0; + + /// \brief Get a user-readable string representation of the type. + [[nodiscard]] virtual std::string ToString() const = 0; + + /// \brief Compare two types for equality. + [[nodiscard]] virtual bool Equals(const Type& other) const = 0; + + friend bool operator==(const Type& lhs, const Type& rhs) { return lhs.Equals(rhs); } + + friend bool operator!=(const Type& lhs, const Type& rhs) { return !(lhs == rhs); } +}; + +/// \brief A type combined with a name. +class ICEBERG_EXPORT Field { + public: + Field(int32_t field_id, std::string name, std::shared_ptr<Type> type, bool optional); + + static Field MakeOptional(int32_t field_id, std::string name, + std::shared_ptr<Type> type); + static Field MakeRequired(int32_t field_id, std::string name, + std::shared_ptr<Type> type); + + /// \brief Get the field ID. + [[nodiscard]] int32_t field_id() const; + + /// \brief Get the field name. + [[nodiscard]] std::string_view name() const; + + /// \brief Get the field type. + [[nodiscard]] const std::shared_ptr<Type>& type() const; + + /// \brief Get whether the field is optional. + [[nodiscard]] bool optional() const; + + /// \brief Get a user-readable string representation of the field. + [[nodiscard]] std::string ToString() const; + + /// \brief Compare two fields for equality. + [[nodiscard]] bool Equals(const Field& other) const; + + friend bool operator==(const Field& lhs, const Field& rhs) { return lhs.Equals(rhs); } + + friend bool operator!=(const Field& lhs, const Field& rhs) { return !(lhs == rhs); } +}; + +/// \brief A data type representing a boolean. +class ICEBERG_EXPORT BooleanType : public Type { + public: + BooleanType() = default; + ~BooleanType() = default; + + TypeId type_id() const override; + + std::string ToString() const override; + + bool Equals(const Type& other) const override; +}; + +/// \brief A data type representing a struct with nested fields. +class ICEBERG_EXPORT StructType : public Type { + public: + explicit StructType(std::vector<Field> fields); + + StructType() = default; + ~StructType() = default; + + [[nodiscard]] std::span<Field> fields() const; + + const Field& field(int i) const; + const Field& field(std::string_view name) const; Review Comment: I would add case-sensitive here as well ########## src/iceberg/schema.h: ########## @@ -0,0 +1,60 @@ +/* + * 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/schema.h +/// Schemas for Iceberg tables. + +#include <cstdint> +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/type.h" + +namespace iceberg { + +/// \brief A schema for a Table. +/// +/// A schema is a list of typed columns, along with a unique integer ID. A +/// Table may have different schemas over its lifetime due to schema +/// evolution. +class ICEBERG_EXPORT Schema : public StructType { Review Comment:  You can take inspiration from PyIceberg: - [`schema_to_pyarrow`](https://github.com/apache/iceberg-python/blob/f4caa3ac927c626eeba5d0408f80ddd9b95214e0/pyiceberg/io/pyarrow.py#L557) - [`pyarrow_to_schema`](https://github.com/apache/iceberg-python/blob/f4caa3ac927c626eeba5d0408f80ddd9b95214e0/pyiceberg/io/pyarrow.py#L905C5-L905C22) -- 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. 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