Struct NumericType 

#[repr(C)]
pub struct NumericType {
    exponents: [i32; 7],
    percent_hint: Optional<NumericBaseType>,
    non_zero_count: u8,
    non_zero_except_percent_count: u8,
}

https://drafts.css-houdini.org/css-typed-om-1/#numeric-typing

The spec models the per-base-type exponents as an ordered map keyed by base type. We use a fixed-size array indexed by NumericBaseType instead. A missing entry in the spec’s map and a zero entry are observably equivalent for every operation the spec defines (comparisons and iteration only consider non-zero entries), so the array representation is simpler, avoids allocations, and produces the same results.

non_zero_count and non_zero_except_percent_count are derived fields maintained in sync with exponents, allowing O(1) type compatibility checks. They fit without padding into the 2 bytes following percent_hint, so the struct remains 32 bytes.

Fields

exponents: [i32; 7]

percent_hint: Optional<NumericBaseType>

non_zero_count: u8

non_zero_except_percent_count: u8

Implementations

impl NumericType

fn empty() -> Self

fn with_base_type(base_type: NumericBaseType) -> Self

Constructs a numeric type from a single base type.

Keep Gecko’s StyleNumericType::WithBaseType() in sync with this implementation.

pub fn number() -> Self

A numeric type whose exponent map is empty.

pub fn percent() -> Self

A numeric type whose percent exponent is 1.

pub fn length() -> Self

A numeric type whose length exponent is 1.

pub fn angle() -> Self

A numeric type whose angle exponent is 1.

pub fn time() -> Self

A numeric type whose time exponent is 1.

pub fn frequency() -> Self

A numeric type whose frequency exponent is 1.

pub fn resolution() -> Self

A numeric type whose resolution exponent is 1.

pub fn flex() -> Self

A numeric type whose flex exponent is 1.

pub fn try_from_unit(unit: &str) -> Result<Self, ()>

https://drafts.css-houdini.org/css-typed-om-1/#create-a-type-from-a-string

pub fn from_unit_unchecked(unit: &str) -> Self

Creates a numeric type from a previously validated unit string.

fn exponent(&self, base_type: NumericBaseType) -> i32

fn set_exponent(&mut self, base_type: NumericBaseType, new_value: i32)

fn add_exponent(&mut self, base_type: NumericBaseType, delta: i32)

fn apply_percent_hint(&mut self, hint: NumericBaseType)

https://drafts.css-houdini.org/css-typed-om-1/#apply-the-percent-hint

fn add_two_types(type1: &NumericType, type2: &NumericType) -> Result<Self, ()>

https://drafts.css-houdini.org/css-typed-om-1/#cssnumericvalue-add-two-types

The algorithm has some complexity and uses branches rather than numbered sub-steps, so the implementation below quotes spec text inline. This is more verbose than usual, but should help map each branch back to the spec when reviewing or debugging.

fn multiply_two_types( type1: &NumericType, type2: &NumericType, ) -> Result<Self, ()>

https://drafts.css-houdini.org/css-typed-om-1/#cssnumericvalue-multiply-two-types

Spec text is quoted inline to make each step easy to map back to the algorithm during review.

fn combine_types<'a, I>( types: I, combine: fn(&NumericType, &NumericType) -> Result<NumericType, ()>, ) -> Result<Self, ()>

where I: Iterator<Item = &'a NumericType>,

pub fn add_types<'a, I>(types: I) -> Result<Self, ()>

where I: Iterator<Item = &'a NumericType>,

Applies the add two types algorithm repeatedly across a sequence of numeric types, returning the combined type.

pub fn multiply_types<'a, I>(types: I) -> Result<Self, ()>

where I: Iterator<Item = &'a NumericType>,

Applies the multiply two types algorithm repeatedly across a sequence of numeric types, returning the combined type.

Trait Implementations

impl Clone for NumericType

fn clone(&self) -> NumericType

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for NumericType

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

Formats the value using the given formatter.