wgtmac commented on code in PR #196:
URL: https://github.com/apache/iceberg-cpp/pull/196#discussion_r2303021854
##########
test/CMakeLists.txt:
##########
@@ -89,7 +89,8 @@ add_iceberg_test(util_test
formatter_test.cc
config_test.cc
visit_type_test.cc
- string_utils_test.cc)
+ string_utils_test.cc
+ endian_test.cc)
Review Comment:
Please sort them alphabetically.
##########
src/iceberg/util/endian.h:
##########
@@ -0,0 +1,135 @@
+/*
+ * 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 <bit>
+#include <concepts>
+#include <cstdint>
+
+/// \file iceberg/util/endian.h
+/// \brief Endianness conversion utilities
+
+namespace iceberg {
+
+/// \brief Concept for values that can be converted to/from another endian
format.
+template <typename T>
+concept EndianConvertible = std::is_arithmetic_v<T> && !std::same_as<T, bool>;
+
+/// \brief Convert a value to little-endian format.
+template <EndianConvertible T>
+constexpr T ToLittleEndian(T value) {
Review Comment:
There four functions are essentially same. Could we write our own `ByteSwap`
function and reuse it by those functions?
##########
src/iceberg/util/endian.h:
##########
@@ -0,0 +1,124 @@
+/*
+ * 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 <bit>
+#include <concepts>
+
+/// \file iceberg/util/endian.h
+/// \brief Endianness conversion utilities
+
+namespace iceberg {
+
+/// \brief Concept for values that can be converted to/from another endian
format.
+template <typename T>
+concept EndianConvertible = std::is_arithmetic_v<T> && !std::same_as<T, bool>;
Review Comment:
Why excluding `bool`?
##########
src/iceberg/util/endian.h:
##########
@@ -0,0 +1,125 @@
+/*
+ * 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 <bit>
+#include <concepts>
+#include <cstdint>
+
+/// \file iceberg/util/endian.h
+/// \brief Endianness conversion utilities
+
+namespace iceberg {
+
+/// \brief Concept for values that can be converted to/from another endian
format.
+template <typename T>
+concept EndianConvertible = std::is_arithmetic_v<T> && !std::same_as<T, bool>;
+
+/// \brief Convert a value to little-endian format.
+template <EndianConvertible T>
+constexpr T ToLittleEndian(T value) {
+ if constexpr (std::endian::native == std::endian::little || sizeof(T) <= 1) {
+ return value;
+ } else {
+ if constexpr (std::is_integral_v<T>) {
Review Comment:
```suggestion
} else if constexpr (std::is_integral_v<T>) {
```
Can we unnest the else branch?
##########
src/iceberg/util/endian.h:
##########
@@ -0,0 +1,135 @@
+/*
+ * 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 <bit>
+#include <concepts>
+#include <cstdint>
+
+/// \file iceberg/util/endian.h
+/// \brief Endianness conversion utilities
+
+namespace iceberg {
+
+/// \brief Concept for values that can be converted to/from another endian
format.
+template <typename T>
+concept EndianConvertible = std::is_arithmetic_v<T> && !std::same_as<T, bool>;
+
+/// \brief Convert a value to little-endian format.
+template <EndianConvertible T>
+constexpr T ToLittleEndian(T value) {
+ if constexpr (std::endian::native == std::endian::little || sizeof(T) <= 1) {
+ return value;
+ } else {
+ if constexpr (std::is_integral_v<T>) {
+ return std::byteswap(value);
+ } else if constexpr (std::is_floating_point_v<T>) {
+ // For floats, use the bit_cast -> byteswap -> bit_cast pattern.
+ // We only support 32-bit and 64-bit floats.
+ if constexpr (sizeof(T) == sizeof(uint32_t)) {
+ uint32_t int_representation = std::bit_cast<uint32_t>(value);
+ int_representation = std::byteswap(int_representation);
+ return std::bit_cast<T>(int_representation);
+ } else if constexpr (sizeof(T) == sizeof(uint64_t)) {
+ uint64_t int_representation = std::bit_cast<uint64_t>(value);
+ int_representation = std::byteswap(int_representation);
+ return std::bit_cast<T>(int_representation);
+ } else {
+ static_assert(false, "Unsupported floating-point size for endian
conversion.");
+ }
+ }
+ }
+}
+
+/// \brief Convert a value from little-endian format.
+template <EndianConvertible T>
+constexpr T FromLittleEndian(T value) {
+ if constexpr (std::endian::native == std::endian::little || sizeof(T) <= 1) {
+ return value;
+ } else {
+ if constexpr (std::is_integral_v<T>) {
+ return std::byteswap(value);
+ } else if constexpr (std::is_floating_point_v<T>) {
+ // For floats, use the bit_cast -> byteswap -> bit_cast pattern.
+ // We only support 32-bit and 64-bit floats.
+ if constexpr (sizeof(T) == sizeof(uint32_t)) {
+ uint32_t int_representation = std::bit_cast<uint32_t>(value);
+ int_representation = std::byteswap(int_representation);
+ return std::bit_cast<T>(int_representation);
Review Comment:
```suggestion
return
std::bit_cast<T>(std::byteswap(std::bit_cast<uint32_t>(value)));
```
We can use one-liner here.
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