Copilot commented on code in PR #905: URL: https://github.com/apache/iceberg-cpp/pull/905#discussion_r3921668889
########## src/iceberg/util/iterator.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/util/iterator.h +/// \brief Pull-based iterator interface for fallible, lazily produced values. + +#include <deque> +#include <optional> +#include <type_traits> +#include <utility> +#include <vector> + +#include "iceberg/result.h" +#include "iceberg/util/macros.h" Review Comment: This header includes iceberg/util/macros.h but does not use any of the macros; keeping it increases transitive includes for a public header (and pulls in exception.h). Consider dropping it to reduce compile-time and coupling. ########## src/iceberg/util/iterator.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/util/iterator.h +/// \brief Pull-based iterator interface for fallible, lazily produced values. + +#include <deque> +#include <optional> +#include <type_traits> +#include <utility> +#include <vector> + +#include "iceberg/result.h" +#include "iceberg/util/macros.h" + +namespace iceberg { + +/// \brief A pull-based iterator whose reads may fail. +/// +/// Iterator implementations own any resources needed to produce values. Destroying an +/// iterator releases those resources, including when iteration stops before reaching the +/// end. Iterators are not thread-safe unless an implementation explicitly says otherwise. +/// +/// \tparam T Value returned by the iterator. +template <typename T> +class Iterator { + public: + virtual ~Iterator() = default; + + Iterator() = default; + Iterator(const Iterator&) = delete; + Iterator& operator=(const Iterator&) = delete; + + /// \brief Return the next value, or std::nullopt when the iterator is exhausted. + virtual Result<std::optional<T>> Next() = 0; + + /// \brief Consume the remaining values into a vector. + Result<std::vector<T>> ToVector() { + if constexpr (!std::is_move_constructible_v<T>) { + static_assert(std::is_copy_constructible_v<T>, + "Iterator::ToVector requires T to be move- or copy-constructible"); + + // A vector cannot grow portably when T has an explicitly deleted move + // constructor. Stage copy-only values in a deque, then use vector's + // forward-range constructor to allocate the final storage once. Review Comment: The comment claims std::vector cannot grow when T has a deleted move constructor, but std::vector can still grow by copying when T is copy-constructible. If the intent is to avoid repeated copies during reallocations, the comment should say that explicitly to avoid misleading readers about portability. ########## src/iceberg/test/iterator_test.cc: ########## @@ -0,0 +1,117 @@ +/* + * 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. + */ + +#include "iceberg/util/iterator.h" + +#include <memory> +#include <optional> +#include <type_traits> +#include <vector> + +#include <gtest/gtest.h> + +#include "iceberg/test/matchers.h" + +namespace iceberg { +namespace { + +class CopyOnly { + public: + explicit CopyOnly(int value) : value_(value) {} + + CopyOnly(const CopyOnly&) = default; + CopyOnly& operator=(const CopyOnly&) = default; + CopyOnly(CopyOnly&&) = delete; + CopyOnly& operator=(CopyOnly&&) = delete; + + int value() const { return value_; } + + private: + int value_; +}; + +static_assert(std::is_copy_constructible_v<CopyOnly>); +static_assert(!std::is_move_constructible_v<CopyOnly>); + +class CopyOnlyIterator final : public Iterator<CopyOnly> { + public: + Result<std::optional<CopyOnly>> Next() override { + if (next_ == 3) { + return Result<std::optional<CopyOnly>>(std::in_place, std::nullopt); + } + return Result<std::optional<CopyOnly>>(std::in_place, std::in_place, next_++); + } + + private: + int next_ = 0; +}; + +class MoveOnlyIterator final : public Iterator<std::unique_ptr<int>> { + public: + Result<std::optional<std::unique_ptr<int>>> Next() override { + if (next_ == 3) { + return Result<std::optional<std::unique_ptr<int>>>(std::in_place, + std::nullopt); + } + return Result<std::optional<std::unique_ptr<int>>>( + std::in_place, std::in_place, std::make_unique<int>(next_++)); + } + + private: + int next_ = 0; +}; + +class FailingIterator final : public Iterator<int> { + public: + Result<std::optional<int>> Next() override { return Invalid("iteration failed"); } +}; + +TEST(IteratorTest, ToVectorSupportsCopyOnlyValues) { + CopyOnlyIterator iterator; + + ICEBERG_UNWRAP_OR_FAIL(auto values, iterator.ToVector()); + + ASSERT_EQ(values.size(), 3); + EXPECT_EQ(values[0].value(), 0); + EXPECT_EQ(values[1].value(), 1); + EXPECT_EQ(values[2].value(), 2); +} + +TEST(IteratorTest, ToVectorSupportsMoveOnlyValues) { + MoveOnlyIterator iterator; + + ICEBERG_UNWRAP_OR_FAIL(auto values, iterator.ToVector()); + + ASSERT_EQ(values.size(), 3); + EXPECT_EQ(*values[0], 0); + EXPECT_EQ(*values[1], 1); + EXPECT_EQ(*values[2], 2); +} + +TEST(IteratorTest, ToVectorPropagatesErrors) { + FailingIterator iterator; + + auto result = iterator.ToVector(); + + EXPECT_THAT(result, IsError(ErrorKind::kInvalid)); + EXPECT_THAT(result, HasErrorMessage("iteration failed")); +} Review Comment: The tests cover immediate failure, but the PR description also mentions preserving errors when collecting remaining values. Add a test where the iterator yields at least one value, then fails, and ToVector() is called after partial consumption to ensure the error still propagates. -- 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]
