gty404 commented on code in PR #77: URL: https://github.com/apache/iceberg-cpp/pull/77#discussion_r2048079083
########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { Review Comment: There are three possible approaches to organizing type information: 1. Scalar holds built-in types independently, and StructLike does not rely on StructType. 2. Scalar does not contain any type information, and its type is inferred from the associated StructType within StructLike. 3. Both Scalar and StructType carry type information, resulting in some redundancy. I have chosen the first approach. Which one would you prefer? ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; + + /// Visit methods for complex types + virtual void visitStruct(const StructScalar& value) = 0; + virtual void visitArray(const ArrayScalar& value) = 0; +}; + +/** + * @brief Represents a scalar that holds a primitive value. + * @tparam T The type of the primitive value. + */ +template <typename T> +class ICEBERG_EXPORT PrimitiveScalar : public Scalar { + public: + /** + * @brief Constructs a PrimitiveScalar from an optional value. + * @param value The optional primitive value. + */ + explicit PrimitiveScalar(std::optional<T> value) : value_(std::move(value)) {} + + bool IsNull() const override { return !value_.has_value(); } + + /** + * @brief Gets the actual value held by the scalar. + * @return Reference to the value. + * @note Behavior is undefined if the scalar is null. + */ + const T& value() const { return *value_; } + + /** + * @brief (Deprecated) Type-specific accessor for raw value. + * @tparam U Must match T. + * @return Reference to the value if types match. + * @throws std::bad_cast if U does not match T. + */ + template <typename U> + const U& as() const { + if constexpr (std::is_same_v<T, U>) return *value_; + throw std::bad_cast(); + } + + std::shared_ptr<Scalar> clone() const override { + return std::make_shared<PrimitiveScalar<T>>(value_); + } + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visit(*value_); + } + } + + private: + std::optional<T> value_; +}; + +// Aliases for common primitive scalar types +using Int32Scalar = PrimitiveScalar<int32_t>; +using Int64Scalar = PrimitiveScalar<int64_t>; +using DoubleScalar = PrimitiveScalar<double>; +using StringScalar = PrimitiveScalar<std::string>; +using BoolScalar = PrimitiveScalar<bool>; + +/** + * @brief Base class for scalars that contain a vector of child Scalars. + * @tparam Derived The concrete subclass type (CRTP). + */ +template <typename Derived> +class VectorScalarBase : public Scalar { Review Comment: It is a bit strange because the type information is all in StructLike, with StructScalar/ArrayScalar both being a group of Scalar members and there is not much difference. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; + + /// Visit methods for complex types + virtual void visitStruct(const StructScalar& value) = 0; + virtual void visitArray(const ArrayScalar& value) = 0; +}; + +/** + * @brief Represents a scalar that holds a primitive value. + * @tparam T The type of the primitive value. + */ +template <typename T> +class ICEBERG_EXPORT PrimitiveScalar : public Scalar { + public: + /** + * @brief Constructs a PrimitiveScalar from an optional value. + * @param value The optional primitive value. + */ + explicit PrimitiveScalar(std::optional<T> value) : value_(std::move(value)) {} + + bool IsNull() const override { return !value_.has_value(); } + + /** + * @brief Gets the actual value held by the scalar. + * @return Reference to the value. + * @note Behavior is undefined if the scalar is null. + */ + const T& value() const { return *value_; } + + /** + * @brief (Deprecated) Type-specific accessor for raw value. + * @tparam U Must match T. + * @return Reference to the value if types match. + * @throws std::bad_cast if U does not match T. + */ + template <typename U> + const U& as() const { + if constexpr (std::is_same_v<T, U>) return *value_; + throw std::bad_cast(); + } + + std::shared_ptr<Scalar> clone() const override { + return std::make_shared<PrimitiveScalar<T>>(value_); + } + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visit(*value_); + } + } + + private: + std::optional<T> value_; +}; + +// Aliases for common primitive scalar types Review Comment: I think it should be specialized. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; Review Comment: In the Scalar class, `is_null` can be a member variable, or the `IsNull` interface can be implemented by subclasses, where subclasses might use `optional` or `pointer` to determine if it is null. Here, the second option was chosen; I actually don't have a strong preference. `StructScalar` also uses the `is_null` field, so it might be more appropriate to directly make `is_null` a member variable of Scalar. I'll make a modification. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; Review Comment:  The PrimitiveScalar::Accept method directly uses value, and using PrimitiveScalar is also acceptable. I will make some modifications. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; Review Comment: Thanks, I will modify it. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; + + /// Visit methods for complex types + virtual void visitStruct(const StructScalar& value) = 0; + virtual void visitArray(const ArrayScalar& value) = 0; +}; + +/** + * @brief Represents a scalar that holds a primitive value. + * @tparam T The type of the primitive value. + */ +template <typename T> +class ICEBERG_EXPORT PrimitiveScalar : public Scalar { + public: + /** + * @brief Constructs a PrimitiveScalar from an optional value. + * @param value The optional primitive value. + */ + explicit PrimitiveScalar(std::optional<T> value) : value_(std::move(value)) {} + + bool IsNull() const override { return !value_.has_value(); } + + /** + * @brief Gets the actual value held by the scalar. + * @return Reference to the value. + * @note Behavior is undefined if the scalar is null. + */ + const T& value() const { return *value_; } + + /** + * @brief (Deprecated) Type-specific accessor for raw value. + * @tparam U Must match T. + * @return Reference to the value if types match. + * @throws std::bad_cast if U does not match T. + */ + template <typename U> + const U& as() const { + if constexpr (std::is_same_v<T, U>) return *value_; + throw std::bad_cast(); + } + + std::shared_ptr<Scalar> clone() const override { + return std::make_shared<PrimitiveScalar<T>>(value_); + } + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visit(*value_); + } + } + + private: + std::optional<T> value_; +}; + +// Aliases for common primitive scalar types +using Int32Scalar = PrimitiveScalar<int32_t>; +using Int64Scalar = PrimitiveScalar<int64_t>; +using DoubleScalar = PrimitiveScalar<double>; +using StringScalar = PrimitiveScalar<std::string>; +using BoolScalar = PrimitiveScalar<bool>; + +/** + * @brief Base class for scalars that contain a vector of child Scalars. + * @tparam Derived The concrete subclass type (CRTP). + */ +template <typename Derived> +class VectorScalarBase : public Scalar { + public: + /** + * @brief Constructs a VectorScalarBase. + * @param values Child scalar values. + * @param is_null Whether the entire scalar is null. + */ + explicit VectorScalarBase(std::vector<std::shared_ptr<Scalar>> values, + bool is_null = false) + : values_(std::move(values)), is_null_(is_null) {} + + /** + * @brief Gets the child scalar values. + * @return Vector of shared pointers to child Scalars. + */ + const std::vector<std::shared_ptr<Scalar>>& value() const { return values_; } + + bool IsNull() const override { return is_null_; } + + std::shared_ptr<Scalar> clone() const override { + std::vector<std::shared_ptr<Scalar>> cloned; + for (const auto& v : values_) { + cloned.push_back(v->clone()); + } + return std::make_shared<Derived>(std::move(cloned), is_null_); + } + + protected: + std::vector<std::shared_ptr<Scalar>> values_; + bool is_null_; +}; + +/** + * @brief Represents a struct-like scalar (tuple of fields). + */ +class StructScalar : public VectorScalarBase<StructScalar> { + public: + using VectorScalarBase::VectorScalarBase; + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visitStruct(*this); + } + } +}; + +/** + * @brief Represents an array-like scalar (list of values). + */ +class ArrayScalar : public VectorScalarBase<ArrayScalar> { Review Comment: Currently, I haven't thought of a good design, perhaps map can still be used, and Scalar needs to add interfaces for hash and equality judgment? ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; + + /// Visit methods for complex types + virtual void visitStruct(const StructScalar& value) = 0; + virtual void visitArray(const ArrayScalar& value) = 0; +}; + +/** + * @brief Represents a scalar that holds a primitive value. + * @tparam T The type of the primitive value. + */ +template <typename T> +class ICEBERG_EXPORT PrimitiveScalar : public Scalar { + public: + /** + * @brief Constructs a PrimitiveScalar from an optional value. + * @param value The optional primitive value. + */ + explicit PrimitiveScalar(std::optional<T> value) : value_(std::move(value)) {} + + bool IsNull() const override { return !value_.has_value(); } + + /** + * @brief Gets the actual value held by the scalar. + * @return Reference to the value. + * @note Behavior is undefined if the scalar is null. + */ + const T& value() const { return *value_; } + + /** + * @brief (Deprecated) Type-specific accessor for raw value. + * @tparam U Must match T. + * @return Reference to the value if types match. + * @throws std::bad_cast if U does not match T. + */ + template <typename U> + const U& as() const { + if constexpr (std::is_same_v<T, U>) return *value_; + throw std::bad_cast(); + } + + std::shared_ptr<Scalar> clone() const override { + return std::make_shared<PrimitiveScalar<T>>(value_); + } + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visit(*value_); + } + } + + private: + std::optional<T> value_; +}; + +// Aliases for common primitive scalar types +using Int32Scalar = PrimitiveScalar<int32_t>; +using Int64Scalar = PrimitiveScalar<int64_t>; +using DoubleScalar = PrimitiveScalar<double>; +using StringScalar = PrimitiveScalar<std::string>; +using BoolScalar = PrimitiveScalar<bool>; + +/** + * @brief Base class for scalars that contain a vector of child Scalars. + * @tparam Derived The concrete subclass type (CRTP). + */ +template <typename Derived> +class VectorScalarBase : public Scalar { + public: + /** + * @brief Constructs a VectorScalarBase. + * @param values Child scalar values. + * @param is_null Whether the entire scalar is null. + */ + explicit VectorScalarBase(std::vector<std::shared_ptr<Scalar>> values, + bool is_null = false) + : values_(std::move(values)), is_null_(is_null) {} + + /** + * @brief Gets the child scalar values. + * @return Vector of shared pointers to child Scalars. + */ + const std::vector<std::shared_ptr<Scalar>>& value() const { return values_; } + + bool IsNull() const override { return is_null_; } + + std::shared_ptr<Scalar> clone() const override { + std::vector<std::shared_ptr<Scalar>> cloned; + for (const auto& v : values_) { + cloned.push_back(v->clone()); + } + return std::make_shared<Derived>(std::move(cloned), is_null_); + } + + protected: + std::vector<std::shared_ptr<Scalar>> values_; + bool is_null_; +}; + +/** + * @brief Represents a struct-like scalar (tuple of fields). + */ +class StructScalar : public VectorScalarBase<StructScalar> { + public: + using VectorScalarBase::VectorScalarBase; + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visitStruct(*this); + } + } +}; + +/** + * @brief Represents an array-like scalar (list of values). + */ +class ArrayScalar : public VectorScalarBase<ArrayScalar> { + public: + using VectorScalarBase::VectorScalarBase; + + void accept(ScalarVisitor& visitor) const override { + if (IsNull()) { + visitor.visitNull(); + } else { + visitor.visitArray(*this); + } + } +}; + +/** + * @brief Abstract interface for structured field access. + */ +class ICEBERG_EXPORT StructLike { Review Comment: StructLike has a StructType, while StructScalar does not have one, I think this should depend on the discussion result regarding whether a Scalar should have its own type information. ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; Review Comment: Good suggestion, visit I will modify it to accept Scalar types as input ########## src/iceberg/struct_like.h: ########## @@ -0,0 +1,278 @@ +/* + * 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 + +#include <string> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" +#include "iceberg/type.h" + +namespace iceberg { + +class Scalar; +class StructScalar; +class ArrayScalar; +class ScalarVisitor; +class StructLike; +class StructLikeVisitor; +/** + * @brief Base class representing a generic scalar value. + */ +class ICEBERG_EXPORT Scalar { + public: + virtual ~Scalar() = default; + + /** + * @brief Checks if the scalar represents a null value. + * @return true if the value is null, false otherwise. + */ + virtual bool IsNull() const = 0; + + /** + * @brief Casts the scalar to a specific derived type. + * @tparam T The target derived Scalar type. + * @return Reference to the casted value. + * @throws std::bad_cast if the cast fails. + */ + template <typename T> + const T& as() const { + auto ptr = dynamic_cast<const T*>(this); + if (!ptr) throw std::bad_cast(); + return *ptr; + } + + /** + * @brief Creates a deep copy of the scalar. + * @return A shared pointer to the cloned scalar. + */ + virtual std::shared_ptr<Scalar> clone() const = 0; + + /** + * @brief Accepts a visitor for dispatching based on scalar type. + * @param visitor The visitor to accept. + */ + virtual void accept(ScalarVisitor& visitor) const = 0; +}; + +/** + * @brief Visitor interface for Scalar, supporting type-dispatched operations. + */ +class ICEBERG_EXPORT ScalarVisitor { + public: + virtual ~ScalarVisitor() = default; + + /// Visit methods for primitive types + virtual void visit(int32_t value) = 0; + virtual void visit(int64_t value) = 0; + virtual void visit(float value) = 0; + virtual void visit(double value) = 0; + virtual void visit(bool value) = 0; + virtual void visit(const std::string& value) = 0; + + /** + * @brief Called when visiting a null scalar. + */ + virtual void visitNull() = 0; + + /// Visit methods for complex types + virtual void visitStruct(const StructScalar& value) = 0; + virtual void visitArray(const ArrayScalar& value) = 0; +}; + +/** + * @brief Represents a scalar that holds a primitive value. + * @tparam T The type of the primitive value. + */ +template <typename T> +class ICEBERG_EXPORT PrimitiveScalar : public Scalar { + public: + /** + * @brief Constructs a PrimitiveScalar from an optional value. + * @param value The optional primitive value. + */ + explicit PrimitiveScalar(std::optional<T> value) : value_(std::move(value)) {} + + bool IsNull() const override { return !value_.has_value(); } + + /** + * @brief Gets the actual value held by the scalar. + * @return Reference to the value. + * @note Behavior is undefined if the scalar is null. + */ + const T& value() const { return *value_; } Review Comment: Good suggestion, I will modify here -- This is an automated message from the Apache Git Service. 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