Struct BitIndex 

pub struct BitIndex(/* private fields */);

A value a BitSet can actually hold: non-negative, and small enough that the word vector backing it stays a real allocation.

This is the only route from a user-supplied Int to a bit position (RT-07), so the range check happens where the value enters, once. A negative member and one whose word vector the host could not serve are both unrepresentable rather than merely unreached.

Implementations

impl BitIndex

pub const MAX: i64

The largest member a BitSet accepts: 2^32 - 1, whose word vector is 512 MiB. A cap rather than “anything a usize holds”, for the same reason GridExtent::MAX_CELLS is one — a Vec request the host cannot serve is not an error the process survives.

pub const MAX_WORDS: usize

The most words a BitSet can ever hold, which is MAX/64 + 1.

This bound is what lets generated code omit the range test (ADR-118 part 2). bs.contains(x) inline is word = (x as u64) >> 6; if word >= words.len() { false } else { … }, with no separate check that x is a member BitIndex::new would accept — because for every i64 outside 0..=MAX the unsigned shift already lands at or above this number, and the word count never reaches it:

• x < 0 → x as u64 >= 2^63 → word >= 2^57;
• x > MAX → x as u64 >= 2^32 → word >= 2^26 == MAX_WORDS;
• and BitSetPayload::insert resizes to word + 1 for a BitIndex, so words.len() <= MAX_WORDS always.

So word >= words.len() subsumes the range test, exactly, for every value of the type. the_word_probe_generated_code_emits_answers_contains is that claim checked against contains rather than argued, in the module that owns the range — small_int’s the_unsigned_range_test_generated_code_emits_answers_index_of in its second place.

pub const fn new(value: i64) -> Option<BitIndex>

The bit value names, or None if it is negative or above MAX.

Trait Implementations

impl Clone for BitIndex

fn clone(&self) -> BitIndex

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for BitIndex

impl Debug for BitIndex

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

Formats the value using the given formatter.

impl Eq for BitIndex

impl Ord for BitIndex

fn cmp(&self, other: &BitIndex) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for BitIndex

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for BitIndex

fn partial_cmp(&self, other: &BitIndex) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for BitIndex