Struct BitmaskV 

pub struct BitmaskV<'a> {
    pub bitmask: &'a Bitmask,
    pub offset: usize,
    /* private fields */
}

BitmaskView

Zero-copy, bounds-checked window over a Bitmask.

Fields

• bitmask: borrowed reference to the backing Bitmask.
• offset: start bit position in the parent mask.
• len: number of bits in the view.

Behaviour

• All indexing is relative to the view’s start.
• All accesses are in-bounds (panics if violated).
• No allocation or buffer copying occurs when creating or slicing views.

Example

use minarrow::Bitmask;
use minarrow::BitmaskV;

let mask = Bitmask::from_bools(&[true, false, true, true, false]);
let view = BitmaskV::new(&mask, 1, 3); // window: false, true, true

assert_eq!(view.len(), 3);
assert!(!view.get(0));
assert!(view.get(1));
assert!(view.get(2));

Fields

bitmask: &'a Bitmask

The outer bitmask that this view is derived from - we retain a reference to it. Importantly, this is the full bitmask - not the view, and thus should not be accessed as though it were the view subset.

offset: usize

The index offset from 0 that for where this view starts from the outer bitmask

Implementations

impl<'a> BitmaskV<'a>

pub fn new(bitmask: &'a Bitmask, offset: usize, len: usize) -> Self

Construct a view over bitmask[offset..offset+len).

pub fn len(&self) -> usize

Returns the length (number of bits) in the view.

pub fn is_empty(&self) -> bool

Returns true if the view is empty.

pub fn get(&self, i: usize) -> bool

Returns the value at logical index i within the view.

pub unsafe fn get_unchecked(&self, i: usize) -> bool

Returns the value at logical index i within the view, skipping the bounds check.

Element-wise kernels read a flagged null_mask (valid) bit per row, so the checked get costs a comparison in the innermost loop. This is the unchecked counterpart for loops that have already established i < len.

Safety

i must be less than the view’s length.

pub fn as_bytes_window(&self) -> (&[u8], usize, usize)

Returns a slice of the bitmask’s bytes Due to the booleans being bitpacked in a u8, the slice retains:
Pos 0: Buffer: The bitpacked u8 buffer.
Pos 1: Offset: Bit offset indicating where it starts in that byte.
Pos 2: Length: Logical length in bits of the slice

pub fn to_bitmask(&self) -> Bitmask

Returns an owned Bitmask for the window.

If the view covers the entire backing bitmask, returns a clone of the underlying Bitmask (cheap for Shared storage; a byte memcpy for Owned storage). Otherwise falls back to bit-by-bit slice_clone, which has to honour bit alignment across the window boundary.

pub fn iter_set(&self) -> impl Iterator<Item = usize> + '_

Returns an iterator over all set bits (indices relative to the window).

The scan walks the backing mask one 64-bit word at a time from the window’s bit offset, so a word with no set bits costs a single comparison and each set bit is located through a trailing-zeros count.

pub fn iter_cleared(&self) -> impl Iterator<Item = usize> + '_

Returns an iterator over all cleared bits (indices relative to the window).

The scan walks the backing mask one 64-bit word at a time from the window’s bit offset, so a fully valid word costs a single comparison and each null is located through a trailing-zeros count.

pub fn count_ones(&self) -> usize

Counts number of set bits in the view.

pub fn count_zeros(&self) -> usize

Counts number of cleared bits in the view.

pub fn all_set(&self) -> bool

Returns true if all bits in the view are set.

pub fn all_unset(&self) -> bool

Returns true if all bits in the view are cleared.

pub fn has_cleared(&self) -> bool

Returns true if any bit in the view is cleared.

pub fn any_set(&self) -> bool

Returns true if any bit in the view is set.

pub fn slice(&self, offset: usize, len: usize) -> Self

Slices the view further by logical offset and len (relative to this window).

pub fn end(&self) -> usize

Returns the exclusive end row index of the window (relative to bitmask).

pub fn as_tuple(&self) -> BitmaskVT<'a>

Returns the underlying window as a tuple: (&Bitmask, offset, len).

Trait Implementations

impl<'a> Clone for BitmaskV<'a>

fn clone(&self) -> BitmaskV<'a>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for BitmaskV<'a>

impl<'a> Debug for BitmaskV<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> Display for BitmaskV<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> From<&'a Array> for BitmaskV<'a>

Extract the boolean data from an Array. Panics if not a BooleanArray variant.

fn from(arr: &'a Array) -> Self

Converts to this type from the input type.

impl<'a> From<&'a ArrayV> for BitmaskV<'a>

Available on crate feature views only.

Extract the boolean data from an ArrayV, preserving the view’s offset and length. Panics if the underlying array is not a BooleanArray variant.

fn from(av: &'a ArrayV) -> Self

Converts to this type from the input type.

impl<'a> From<&'a Bitmask> for BitmaskV<'a>

View over the full bitmask with zero offset.

fn from(bitmask: &'a Bitmask) -> Self

Converts to this type from the input type.

impl<'a, T> From<&'a BooleanArray<T>> for BitmaskV<'a>

View over a BooleanArray’s data bitmask with zero offset.

fn from(arr: &'a BooleanArray<T>) -> Self

Converts to this type from the input type.

impl<'a> From<BitmaskV<'a>> for Value

Available on crate feature views only.

Wrap a BitmaskV as Value::ArrayView of a BooleanArray. The bitmask data is taken as the BooleanArray’s data; null_mask is None since BitmaskV carries no separate null mask.

fn from(v: BitmaskV<'a>) -> Self

Converts to this type from the input type.

impl<'a> Index<usize> for BitmaskV<'a>

fn index(&self, index: usize) -> &Self::Output

Returns a reference to a constant true or false value depending on the bit at index.

Note: This does not return a reference into the underlying bitmask storage. The reference points to a compiler-promoted static constant, so its address is unrelated to the internal buffer. Use Self::get if you need the value directly.

type Output = bool

The returned type after indexing.

impl<'a> PartialEq for BitmaskV<'a>

fn eq(&self, other: &BitmaskV<'a>) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<'a> Shape for BitmaskV<'a>

fn shape(&self) -> ShapeDim

Returns arbitrary Shape dimension for any data shape

fn shape_1d(&self) -> usize

Returns the first dimension shape

fn shape_2d(&self) -> (usize, usize)

Returns the first and second dimension shapes

fn shape_3d(&self) -> (usize, usize, usize)

Returns the first, second and third dimension shapes

fn shape_4d(&self) -> (usize, usize, usize, usize)

Returns the first, second, third and fourth dimension shapes

impl<'a> StructuralPartialEq for BitmaskV<'a>

impl<'a> TryFrom<&'a Value> for BitmaskV<'a>

Available on crate feature views only.

Borrow a Value as a windowed BitmaskV over its boolean data.

The view borrows the Value, so the Value must outlive it. An ArrayView preserves the inner view’s offset and length. An owned Array windows the whole boolean column.

type Error = MinarrowError

The type returned in the event of a conversion error.

fn try_from(v: &'a Value) -> Result<Self, Self::Error>

Performs the conversion.