Struct Priority 

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

A candidate priority: a positive integer up to 2^31 − 1 (RFC 8839 §5.1).

The bound is the type’s whole reason for existing. RFC 8445 §6.1.2.3 combines two priorities into a pair priority as 2^32*MIN(G,D) + 2*MAX(G,D) + (G>D?1:0). With both operands at 2^31 − 1 that comes to 2^63 − 2: the G > D term is zero when the two are equal, so the 2^63 − 1 upper bound is approached and never reached, and every in-range pair therefore has half a u64 of headroom.

Carry an unchecked u32 from the wire into the same expression and the headroom is spent. The overflow is not one step past the bound — the arithmetic is still exact at 4294967294 — but 4294967295 on both sides, the ten-digit value 1*10DIGIT admits, comes to 2^64 + 2^32 − 2 and wraps. In a release build it wraps silently, reordering the checklist that the arithmetic exists to order. the_priority_bound_is_what_keeps_the_pair_priority_in_a_u64 asserts both halves of this.

Implementations

impl Priority

pub const MAX: Self

The largest priority RFC 8839 §5.1 permits.

pub const MIN: Self

The smallest. §5.1 says “positive”, so zero is not a priority.

pub fn new(value: u32) -> Option<Self>

The priority with this value, if it is in range.

pub fn parse(text: &str) -> Option<Self>

Read a priority production.

1*10DIGIT admits ten digits, so 4294967295 is well-formed text that is not a legal priority. It is read wide and then range-checked, so that an out-of-range value is rejected as out of range rather than silently truncated to something plausible.

pub fn get(self) -> u32

The value.

Trait Implementations

impl Clone for Priority

fn clone(&self) -> Priority

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Priority

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

Formats the value using the given formatter.

impl Display for Priority

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

Formats the value using the given formatter.

impl Hash for Priority

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 Ord for Priority

fn cmp(&self, other: &Priority) -> 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 Priority

fn eq(&self, other: &Priority) -> 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 PartialOrd for Priority

fn partial_cmp(&self, other: &Priority) -> 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 Copy for Priority

impl Eq for Priority

impl StructuralPartialEq for Priority