vegarsti commented on code in PR #8589: URL: https://github.com/apache/arrow-rs/pull/8589#discussion_r2462624454
########## arrow-cast/src/cast/run_array.rs: ########## @@ -0,0 +1,262 @@ +use crate::cast::*; +use arrow_ord::partition::partition; + +/// Attempts to cast a Run-End Encoded array to another type, handling both REE-to-REE +/// and REE-to-other type conversions with proper validation and error handling. +/// +/// # Arguments +/// * `array` - The input Run-End Encoded array to be cast +/// * `to_type` - The target data type for the casting operation +/// * `cast_options` - Options controlling the casting behavior (e.g., safe vs unsafe) +/// +/// # Returns +/// A `Result` containing the new `ArrayRef` or an `ArrowError` if casting fails +/// +/// # Behavior +/// This function handles two main casting scenarios: +/// +/// ## Case 1: REE-to-REE Casting +/// When casting to another Run-End Encoded type: +/// - Casts both the `values` and `run_ends` to their target types +/// - Validates that run-end casting only allows upcasts (Int16→Int32, Int16→Int64, Int32→Int64) +/// - Preserves the REE structure while updating both fields +/// - Returns a new `RunArray` with the appropriate run-end type (Int16, Int32, or Int64) +/// +/// ## Case 2: REE-to-Other Casting +/// When casting to a non-REE type: +/// - Expands the REE array to its logical form by unpacking all values +/// - Applies the target type casting to the expanded array +/// - Returns a regular array of the target type (e.g., StringArray, Int64Array) +/// +/// # Error Handling, error occurs if: +/// - the input array is not a Run-End Encoded array +/// - run-end downcasting would cause overflow +/// - the target run-end type is unsupported +/// - Propagates errors from underlying casting operations +/// +/// # Safety Considerations +/// - Run-end casting uses `safe: false` to prevent silent overflow Review Comment: 17f4f6f ########## arrow-cast/src/cast/run_array.rs: ########## @@ -0,0 +1,262 @@ +use crate::cast::*; +use arrow_ord::partition::partition; + +/// Attempts to cast a Run-End Encoded array to another type, handling both REE-to-REE +/// and REE-to-other type conversions with proper validation and error handling. +/// +/// # Arguments +/// * `array` - The input Run-End Encoded array to be cast +/// * `to_type` - The target data type for the casting operation +/// * `cast_options` - Options controlling the casting behavior (e.g., safe vs unsafe) +/// +/// # Returns +/// A `Result` containing the new `ArrayRef` or an `ArrowError` if casting fails +/// +/// # Behavior +/// This function handles two main casting scenarios: +/// +/// ## Case 1: REE-to-REE Casting +/// When casting to another Run-End Encoded type: +/// - Casts both the `values` and `run_ends` to their target types +/// - Validates that run-end casting only allows upcasts (Int16→Int32, Int16→Int64, Int32→Int64) +/// - Preserves the REE structure while updating both fields +/// - Returns a new `RunArray` with the appropriate run-end type (Int16, Int32, or Int64) +/// +/// ## Case 2: REE-to-Other Casting +/// When casting to a non-REE type: +/// - Expands the REE array to its logical form by unpacking all values +/// - Applies the target type casting to the expanded array +/// - Returns a regular array of the target type (e.g., StringArray, Int64Array) +/// +/// # Error Handling, error occurs if: +/// - the input array is not a Run-End Encoded array +/// - run-end downcasting would cause overflow +/// - the target run-end type is unsupported +/// - Propagates errors from underlying casting operations +/// +/// # Safety Considerations +/// - Run-end casting uses `safe: false` to prevent silent overflow +/// - Only upcasts are allowed for run-ends to maintain valid REE structure +/// - Unpacking preserves null values and array length +/// - Type validation ensures only supported run-end types (Int16, Int32, Int64) Review Comment: 17f4f6f ########## arrow-cast/src/cast/run_array.rs: ########## @@ -0,0 +1,262 @@ +use crate::cast::*; +use arrow_ord::partition::partition; + +/// Attempts to cast a Run-End Encoded array to another type, handling both REE-to-REE +/// and REE-to-other type conversions with proper validation and error handling. +/// +/// # Arguments +/// * `array` - The input Run-End Encoded array to be cast +/// * `to_type` - The target data type for the casting operation +/// * `cast_options` - Options controlling the casting behavior (e.g., safe vs unsafe) +/// +/// # Returns +/// A `Result` containing the new `ArrayRef` or an `ArrowError` if casting fails +/// +/// # Behavior +/// This function handles two main casting scenarios: +/// +/// ## Case 1: REE-to-REE Casting +/// When casting to another Run-End Encoded type: +/// - Casts both the `values` and `run_ends` to their target types +/// - Validates that run-end casting only allows upcasts (Int16→Int32, Int16→Int64, Int32→Int64) +/// - Preserves the REE structure while updating both fields +/// - Returns a new `RunArray` with the appropriate run-end type (Int16, Int32, or Int64) +/// +/// ## Case 2: REE-to-Other Casting +/// When casting to a non-REE type: +/// - Expands the REE array to its logical form by unpacking all values +/// - Applies the target type casting to the expanded array +/// - Returns a regular array of the target type (e.g., StringArray, Int64Array) +/// +/// # Error Handling, error occurs if: +/// - the input array is not a Run-End Encoded array +/// - run-end downcasting would cause overflow +/// - the target run-end type is unsupported +/// - Propagates errors from underlying casting operations +/// +/// # Safety Considerations +/// - Run-end casting uses `safe: false` to prevent silent overflow +/// - Only upcasts are allowed for run-ends to maintain valid REE structure +/// - Unpacking preserves null values and array length +/// - Type validation ensures only supported run-end types (Int16, Int32, Int64) +/// +/// # Performance Notes +/// - REE-to-REE casting is efficient as it operates on the compressed structure +/// - REE-to-other casting requires full unpacking, which may be expensive for large arrays +/// - Run-end validation adds minimal overhead for safety Review Comment: 17f4f6f -- This is an automated message from the Apache Git Service. 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