Struct StreamingRealData 

pub struct StreamingRealData<F: Fn(usize, &mut [f64]) -> usize> {
    len: usize,
    reader: F,
    cache: RefCell<BTreeMap<usize, Vec<f64>>>,
    chunk_size: usize,
}

Streaming ALTREP for real (f64) 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::StreamingRealData;

let data = StreamingRealData::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 f64 * 0.1;
    }
    count
});

Fields

len: usize

reader: F

cache: RefCell<BTreeMap<usize, Vec<f64>>>

chunk_size: usize

Implementations

impl<F: Fn(usize, &mut [f64]) -> usize> StreamingRealData<F>

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

Create a new streaming real 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 [f64]) -> usize + 'static> AltReal for StreamingRealData<F>

const HAS_ELT: bool = true

Set to true to register elt.

const HAS_GET_REGION: bool = true

Set to true to register get_region.

fn elt(x: SEXP, i: R_xlen_t) -> f64

Get element at index.

fn get_region( x: SEXP, start: R_xlen_t, len: R_xlen_t, buf: &mut [f64], ) -> R_xlen_t

Bulk read elements into buffer.

const HAS_IS_SORTED: bool = false

Set to true to register is_sorted.

fn is_sorted(_x: SEXP) -> i32

Sortedness hint.

const HAS_NO_NA: bool = false

Set to true to register no_na.

fn no_na(_x: SEXP) -> i32

NA-free hint.

const HAS_SUM: bool = false

Set to true to register sum.

fn sum(_x: SEXP, _narm: bool) -> SEXP

Optimized sum.

const HAS_MIN: bool = false

Set to true to register min.

fn min(_x: SEXP, _narm: bool) -> SEXP

Optimized min.

const HAS_MAX: bool = false

Set to true to register max.

fn max(_x: SEXP, _narm: bool) -> SEXP

Optimized max.

impl<F: Fn(usize, &mut [f64]) -> usize> AltRealData for StreamingRealData<F>

fn elt(&self, i: usize) -> f64

Get the real element at index i.

fn get_region(&self, start: usize, len: usize, buf: &mut [f64]) -> usize

Optional: bulk read into buffer (clamped to available data).

fn as_slice(&self) -> Option<&[f64]>

Optional: return a pointer to contiguous data if available.

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

Optional: sortedness hint.

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

Optional: does this vector contain any NA values?

fn sum(&self, _na_rm: bool) -> Option<f64>

Optional: optimized sum.

fn min(&self, _na_rm: bool) -> Option<f64>

Optional: optimized min.

fn max(&self, _na_rm: bool) -> Option<f64>

Optional: optimized max.

impl<F: Fn(usize, &mut [f64]) -> usize + 'static> AltVec for StreamingRealData<F>

const HAS_DATAPTR: bool = false

Set to true to register dataptr.

fn dataptr(_x: SEXP, _writable: bool) -> *mut c_void

Get raw data pointer.

const HAS_DATAPTR_OR_NULL: bool = false

Set to true to register dataptr_or_null.

fn dataptr_or_null(_x: SEXP) -> *const c_void

Get data pointer without forcing materialization.

const HAS_EXTRACT_SUBSET: bool = false

Set to true to register extract_subset.

fn extract_subset(_x: SEXP, _indx: SEXP, _call: SEXP) -> SEXP

Optimized subsetting.

impl<F: Fn(usize, &mut [f64]) -> usize + 'static> Altrep for StreamingRealData<F>

fn length(x: SEXP) -> R_xlen_t

Returns the length of the ALTREP vector. This is REQUIRED - R cannot determine vector length without it.

const GUARD: AltrepGuard = AltrepGuard::RUnwind

The guard mode for all ALTREP trampolines on this type.

const HAS_SERIALIZED_STATE: bool = false

Set to true to register serialized_state.

fn serialized_state(_x: SEXP) -> SEXP

Return serialization state.

const HAS_UNSERIALIZE: bool = false

Set to true to register unserialize.

fn unserialize(_class: SEXP, _state: SEXP) -> SEXP

Reconstruct ALTREP from serialized state.

const HAS_UNSERIALIZE_EX: bool = false

Set to true to register unserialize_ex.

fn unserialize_ex( _class: SEXP, _state: SEXP, _attr: SEXP, _objf: i32, _levs: i32, ) -> SEXP

Extended unserialization with attributes.

const HAS_DUPLICATE: bool = false

Set to true to register duplicate.

fn duplicate(_x: SEXP, _deep: bool) -> SEXP

Duplicate the ALTREP object.

const HAS_DUPLICATE_EX: bool = false

Set to true to register duplicate_ex.

fn duplicate_ex(_x: SEXP, _deep: bool) -> SEXP

Extended duplication.

const HAS_COERCE: bool = false

Set to true to register coerce.

fn coerce(_x: SEXP, _to_type: SEXPTYPE) -> SEXP

Coerce to another type.

const HAS_INSPECT: bool = false

Set to true to register inspect.

fn inspect( _x: SEXP, _pre: i32, _deep: i32, _pvec: i32, _inspect_subtree: Option<unsafe extern "C-unwind" fn(SEXP, i32, i32, i32)>, ) -> bool

Custom inspection for .Internal(inspect()).

impl<F: Fn(usize, &mut [f64]) -> usize> AltrepLen for StreamingRealData<F>

fn len(&self) -> usize

Returns the length of this ALTREP vector.

fn is_empty(&self) -> bool

Returns true if the vector is empty.

impl<F: Fn(usize, &mut [f64]) -> usize + 'static> InferBase for StreamingRealData<F>

const BASE: RBase = crate::altrep::RBase::Real

The inferred R base type.

unsafe fn make_class( class_name: *const i8, pkg_name: *const i8, ) -> R_altrep_class_t

Create the ALTREP class handle.

unsafe fn install_methods(cls: R_altrep_class_t)

Install ALTREP methods on the class.

impl<F: Fn(usize, &mut [f64]) -> usize + 'static> TypedExternal for StreamingRealData<F>

const TYPE_NAME: &'static str = "StreamingRealData"

The type name as a static string (for debugging and display)

const TYPE_NAME_CSTR: &'static [u8] = b"StreamingRealData\0"

The type name as a null-terminated C string (for R tag display)

const TYPE_ID_CSTR: &'static [u8] = b"miniextendr_api::altrep::StreamingRealData\0"

Namespaced type ID as a null-terminated C string (for type checking).