Jefffrey commented on code in PR #10172:
URL: https://github.com/apache/arrow-rs/pull/10172#discussion_r3456819931
##########
parquet/src/util/bit_util.rs:
##########
@@ -52,17 +50,29 @@ pub unsafe trait FromBytes: Sized {
/// directly converted from a u64 value. Types like Int96, ByteArray,
/// and FixedLenByteArray that cannot be represented in 64 bits do not
/// implement this trait.
-pub trait FromBitpacked: FromBytes {
+pub trait FromBitpacked {
+ /// The maximum number of bits that are allowed to be converted to this
type.
+ /// This is at most the size of the type in bits, but could be less, for
example
+ /// for the boolean type.
+ const BIT_CAPACITY: usize;
+ /// How many values are converted by one call to `unpack_batch`.
+ const BATCH_SIZE: usize;
/// Convert directly from a u64 value by truncation, avoiding byte slice
copies.
fn from_u64(v: u64) -> Self;
+
+ /// Converts multiple bitpacked values from `input` to `output`.
+ /// The `output` slice needs to have space for at least `BATCH_SIZE`
elements,
+ /// otherwise this method will panic.
+ fn unpack_batch(input: &[u8], output: &mut [Self], num_bits: usize)
+ where
+ Self: Sized;
}
macro_rules! from_le_bytes {
($($ty: ty),*) => {
$(
// SAFETY: this macro is used for types for which all bit patterns are
valid.
Review Comment:
```suggestion
```
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