wgtmac commented on code in PR #61:
URL: https://github.com/apache/iceberg-cpp/pull/61#discussion_r2040668421
##########
src/iceberg/transform.h:
##########
@@ -56,16 +57,133 @@ enum class TransformType {
kVoid,
};
+/// \brief Get the relative transform name
+ICEBERG_EXPORT constexpr std::string_view TransformTypeToString(TransformType
type);
+
+/// \brief Represents a transform used in partitioning or sorting in Iceberg.
+///
+/// This class supports binding to a source type and instantiating the
corresponding
+/// TransformFunction, as well as serialization-friendly introspection.
+class ICEBERG_EXPORT Transform : public util::Formattable {
+ public:
+ /// \brief Returns a shared singleton instance of the Identity transform.
+ ///
+ /// This transform leaves values unchanged and is commonly used for direct
partitioning.
+ /// \return A shared pointer to the Identity transform.
+ static std::shared_ptr<Transform> Identity();
+
+ /// \brief Creates a shared instance of the Bucket transform.
+ ///
+ /// Buckets values using a hash modulo operation. Commonly used for
distributing data.
+ /// \param num_buckets The number of buckets.
+ /// \return A shared pointer to the Bucket transform.
+ static std::shared_ptr<Transform> Bucket(int32_t num_buckets);
+
+ /// \brief Creates a shared instance of the Truncate transform.
+ ///
+ /// Truncates values to a fixed width (e.g., for strings or binary data).
+ /// \param width The width to truncate to.
+ /// \return A shared pointer to the Truncate transform.
+ static std::shared_ptr<Transform> Truncate(int32_t width);
+
+ /// \brief Creates a shared singleton instance of the Year transform.
+ ///
+ /// Extracts the year portion from a date or timestamp.
+ /// \return A shared pointer to the Year transform.
+ static std::shared_ptr<Transform> Year();
+
+ /// \brief Creates a shared singleton instance of the Month transform.
+ ///
+ /// Extracts the month portion from a date or timestamp.
+ /// \return A shared pointer to the Month transform.
+ static std::shared_ptr<Transform> Month();
+
+ /// \brief Creates a shared singleton instance of the Day transform.
+ ///
+ /// Extracts the day portion from a date or timestamp.
+ /// \return A shared pointer to the Day transform.
+ static std::shared_ptr<Transform> Day();
+
+ /// \brief Creates a shared singleton instance of the Hour transform.
+ ///
+ /// Extracts the hour portion from a timestamp.
+ /// \return A shared pointer to the Hour transform.
+ static std::shared_ptr<Transform> Hour();
+
+ /// \brief Creates a shared singleton instance of the Void transform.
+ ///
+ /// Ignores values and always returns null. Useful for testing or special
cases.
+ /// \return A shared pointer to the Void transform.
+ static std::shared_ptr<Transform> Void();
+
+ /// \brief Returns the transform type.
+ TransformType transform_type() const;
+
+ /// \brief Binds this transform to a source type, returning a typed
TransformFunction.
+ ///
+ /// This creates a concrete transform implementation based on the transform
type and
+ /// parameter.
+ /// \param source_type The source column type to bind to.
+ /// \return A TransformFunction instance wrapped in `expected`, or an error
on failure.
+ expected<std::unique_ptr<TransformFunction>, Error> Bind(
Review Comment:
```suggestion
Result<std::unique_ptr<TransformFunction>> Bind(
```
nit: we can leave these as-is and fix all together in a separate PR.
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