Struct StreamingIntData 

pub struct StreamingIntData<F: Fn(usize, &mut [i32]) -> usize> {
    len: usize,
    reader: F,
    cache: RefCell<BTreeMap<usize, Vec<i32>>>,
    chunk_size: usize,
}

Streaming data adaptor for ALTREP integer (i32) vectors.

Elements are loaded on-demand via a reader closure in fixed-size chunks. Chunks are cached in a BTreeMap for repeated access.

Reader Contract

The reader F(start, buf) -> count fills buf with elements starting at index start and returns the number of elements actually written.

Example

use miniextendr_api::altrep_data::StreamingIntData;

let data = StreamingIntData::new(1000, 64, |start, buf| {
    let count = buf.len().min(1000 - start);
    for (i, slot) in buf[..count].iter_mut().enumerate() {
        *slot = (start + i) as i32;
    }
    count
});

Fields

len: usize

reader: F

cache: RefCell<BTreeMap<usize, Vec<i32>>>

chunk_size: usize

Implementations

impl<F: Fn(usize, &mut [i32]) -> usize> StreamingIntData<F>

pub fn new(len: usize, chunk_size: usize, reader: F) -> Self

Create a new streaming integer data source.

• len: total number of elements
• chunk_size: number of elements per cache chunk
• reader: closure that fills a buffer starting at a given index

fn ensure_chunk(&self, chunk_idx: usize)

Load a chunk into the cache if not already present.

Trait Implementations

impl<F: Fn(usize, &mut [i32]) -> usize> AltIntegerData for StreamingIntData<F>

fn elt(&self, i: usize) -> i32

Get the integer element at index i.

fn get_region(&self, start: usize, len: usize, buf: &mut [i32]) -> usize

Optional: bulk read into buffer. Returns number of elements read.

fn as_slice(&self) -> Option<&[i32]>

Optional: return a pointer to contiguous data if available. Default returns None (no contiguous backing).

fn is_sorted(&self) -> Option<Sortedness>

Optional: sortedness hint. Default is unknown.

fn no_na(&self) -> Option<bool>

Optional: does this vector contain any NA values?

fn sum(&self, _na_rm: bool) -> Option<i64>

Optional: optimized sum. Default returns None (use R’s default).

fn min(&self, _na_rm: bool) -> Option<i32>

Optional: optimized min. Default returns None (use R’s default).

fn max(&self, _na_rm: bool) -> Option<i32>

Optional: optimized max. Default returns None (use R’s default).

impl<F: Fn(usize, &mut [i32]) -> usize> AltrepLen for StreamingIntData<F>

fn len(&self) -> usize

Returns the length of this ALTREP vector.

fn is_empty(&self) -> bool

Returns true if the vector is empty.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.