lidavidm commented on code in PR #86: URL: https://github.com/apache/iceberg-cpp/pull/86#discussion_r2055474145
########## test/formatter_test.cc: ########## @@ -0,0 +1,163 @@ +/* + * 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/formatter.h" + +#include <format> +#include <map> +#include <memory> +#include <string> +#include <unordered_map> +#include <vector> + +#include <gtest/gtest.h> + +#include "iceberg/statistics_file.h" + +namespace iceberg { + +// Tests for the std::format specializations +TEST(FormatterTest, VectorFormat) { + std::vector<int> empty; + EXPECT_EQ("[]", std::format("{}", empty)); + + std::vector<int> nums = {1, 2, 3, 4, 5}; + EXPECT_EQ("[1, 2, 3, 4, 5]", std::format("{}", nums)); + + std::vector<std::string> names = {"Alice", "Bob", "Charlie"}; + EXPECT_EQ("[Alice, Bob, Charlie]", std::format("{}", names)); +} + +TEST(FormatterTest, MapFormat) { + std::map<std::string, int> empty; + EXPECT_EQ("{}", std::format("{}", empty)); + + std::map<std::string, int> ages = {{"Alice", 30}, {"Bob", 25}, {"Charlie", 35}}; + EXPECT_EQ("{Alice: 30, Bob: 25, Charlie: 35}", std::format("{}", ages)); +} + +TEST(FormatterTest, UnorderedMapFormat) { + std::unordered_map<std::string, double> empty; + EXPECT_EQ("{}", std::format("{}", empty)); + + std::unordered_map<std::string, double> scores = { + {"Alice", 95.5}, {"Bob", 87.0}, {"Charlie", 92.3}}; + std::string str = std::format("{}", scores); + EXPECT_TRUE(str.find("Alice: 95.5") != std::string::npos); + EXPECT_TRUE(str.find("Bob: 87") != std::string::npos); + EXPECT_TRUE(str.find("Charlie: 92.3") != std::string::npos); +} + +TEST(FormatterTest, NestedContainersFormat) { + std::vector<std::map<std::string, int>> nested = {{{"a", 1}, {"b", 2}}, + {{"c", 3}, {"d", 4}}}; + + EXPECT_EQ("[{a: 1, b: 2}, {c: 3, d: 4}]", std::format("{}", nested)); + + std::map<std::string, std::vector<int>> nested_map = { + {"primes", {2, 3, 5, 7, 11}}, {"fibonacci", {1, 1, 2, 3, 5, 8, 13}}}; + std::string result = std::format("{}", nested_map); + EXPECT_TRUE(result.find("primes") != std::string::npos); Review Comment: Note that you can do `EXPECT_THAT(result, testing::HasSubstr("primes"));` which will also give a much better error on failure ########## src/iceberg/util/formatter.h: ########## @@ -40,3 +43,102 @@ struct std::formatter<Derived> : std::formatter<std::string_view> { return std::formatter<string_view>::format(obj.ToString(), ctx); } }; + +/// \brief std::formatter specialization for std::vector +template <typename T> +struct std::formatter<std::vector<T>> : std::formatter<std::string_view> { Review Comment: FWIW, I _think_ the "idiomatic" way is supposed to be `std::format::join` and ranges. I wonder if specializing on std types may come back to bite us later. Example: https://stackoverflow.com/a/77993463 ########## src/iceberg/util/formatter.h: ########## @@ -40,3 +43,102 @@ struct std::formatter<Derived> : std::formatter<std::string_view> { return std::formatter<string_view>::format(obj.ToString(), ctx); } }; + +/// \brief std::formatter specialization for std::vector +template <typename T> +struct std::formatter<std::vector<T>> : std::formatter<std::string_view> { + template <class FormatContext> + auto format(const std::vector<T>& vec, FormatContext& ctx) const { + std::string result = "["; + + bool first = true; + for (const auto& item : vec) { + if (!first) { + std::format_to(std::back_inserter(result), ", "); + } + if constexpr (requires { *item; }) { + if (item) { + std::format_to(std::back_inserter(result), "{}", *item); + } else { + std::format_to(std::back_inserter(result), "null"); + } + } else { + std::format_to(std::back_inserter(result), "{}", item); + } + first = false; + } + + std::format_to(std::back_inserter(result), "]"); + return std::formatter<std::string_view>::format(result, ctx); + } +}; + +/// \brief Helper template for formatting map-like containers +template <typename MapType> +std::string FormatMap(const MapType& map) { + std::string result = "{"; + + bool first = true; + for (const auto& [key, value] : map) { + if (!first) { + std::format_to(std::back_inserter(result), ", "); + } + + // Format key (handle if it's a smart pointer) + if constexpr (requires { *key; }) { Review Comment: Won't this also fire on something like `std::optional` that might be undesirable? ########## src/iceberg/util/formatter.h: ########## @@ -40,3 +43,102 @@ struct std::formatter<Derived> : std::formatter<std::string_view> { return std::formatter<string_view>::format(obj.ToString(), ctx); } }; + +/// \brief std::formatter specialization for std::vector +template <typename T> +struct std::formatter<std::vector<T>> : std::formatter<std::string_view> { Review Comment: Or another example, albeit C++23: https://stackoverflow.com/a/71196142 -- This is an automated message from the Apache Git Service. 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