[ARROW-229] [C++] Implement safe casts for primitive types

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.7.0
• Component/s: C++
• External issue URL: https://github.com/apache/arrow/issues/15574
• Assignee: Wes McKinney
• Reporter: Uwe Korn
• Created: 26/Jun/16 09:49
• Updated: 11/Jan/23 07:07
• Resolved: 07/Sep/17 17:00

Description

In some situations, you want to cast the data in a PrimitiveArray to a different (but similar) data type, e.g. from uint32_t to int32_t or uint32_t to uint8_t. This can either be done by reinterpreting the data or needs to involve a copy if the size of the underlying type changes. There is already an implementation for this in parquet-cpp that could be pulled out into Arrow: https://github.com/apache/parquet-cpp/blob/9a0407e684c0a6299d0e6ab98c11c1162915c0ee/src/parquet/arrow/writer.cc#L71

Issue Links

• Is contained by: ARROW-1492 [C++] Type casting function kernel suite
• is depended upon by: ARROW-1156 [Python] pyarrow.Array.from_pandas should take a type parameter
• is related to: ARROW-1481 [C++] Expose type casts as generic callable object that can write into pre-allocated memory