Struct IndexKey 

pub struct IndexKey { /* private fields */ }

A bit-packed multi-index key.

A key carries the width it was built for, and the storage arm is a function of that width, so two keys are equal exactly when they were built for the same width and hold the same bits. Arms wider than 128 bits are boxed so a narrow key does not pay the footprint of the widest arm.

The contents are deliberately opaque. A key can only be produced by FlatIndexer::encode or KeyBuilder::finish, both of which establish that its value occupies exactly width_bits bits. KeyBuilder::push relies on that invariant to place a sub-key without masking or truncation, and it is not one a caller could be asked to maintain by hand.

Examples

use tensor4all_core::index_key::FlatIndexer;
let indexer = FlatIndexer::try_new(&[2, 2]).unwrap();
let a = indexer.encode(&[1, 0]).unwrap();
let b = indexer.encode(&[0, 1]).unwrap();
assert_ne!(a, b);
assert_eq!(a, indexer.encode(&[1, 0]).unwrap());
assert_eq!(a.width_bits(), 2);

Implementations

impl IndexKey

pub fn width_bits(&self) -> u64

The width this key was built for, in bits.

This is what KeyBuilder::push consumes, so a sub-key can never be appended under a width that disagrees with its contents.

Examples

use tensor4all_core::index_key::FlatIndexer;
let indexer = FlatIndexer::try_new(&[3, 4]).unwrap();
assert_eq!(indexer.width_bits(), 4);
assert_eq!(indexer.encode(&[2, 3]).unwrap().width_bits(), 4);

Trait Implementations

impl Clone for IndexKey

fn clone(&self) -> IndexKey

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IndexKey

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

Formats the value using the given formatter.

impl Eq for IndexKey

impl Hash for IndexKey

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for IndexKey

fn eq(&self, other: &IndexKey) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for IndexKey