Struct FieldIdx

pub struct FieldIdx {
    private_use_as_methods_instead: u32,
}

The source-order index of a field in a variant.

This is how most code after type checking refers to fields, rather than using names (as names have hygiene complications and more complex lookup).

Particularly for repr(Rust) types, this may not be the same as layout order. (It is for repr(C) structs, however.)

For example, in the following types,

enum Demo1 {
   Variant0 { a: Never, b: i32 } = 100,
   Variant1 { c: u8, d: u64 } = 10,
}
struct Demo2 { e: u8, f: u16, g: u8 }

b is FieldIdx(1) in VariantIdx(0), d is FieldIdx(1) in VariantIdx(1), and f is FieldIdx(1) in VariantIdx(0).

Fields

private_use_as_methods_instead: u32

Implementations

impl FieldIdx

pub const MAX_AS_U32: u32 = 4_294_967_040u32

Maximum value the index can take, as a u32.

pub const MAX: FieldIdx = _

Maximum value the index can take.

pub const ZERO: FieldIdx = _

Zero value of the index.

pub const fn from_usize(value: usize) -> FieldIdx

Creates a new index from a given usize.

Panics

Will panic if value exceeds MAX.

pub const fn from_u32(value: u32) -> FieldIdx

Creates a new index from a given u32.

Panics

Will panic if value exceeds MAX.

pub const fn from_u16(value: u16) -> FieldIdx

Creates a new index from a given u16.

Panics

Will panic if value exceeds MAX.

pub const unsafe fn from_u32_unchecked(value: u32) -> FieldIdx

Creates a new index from a given u32.

Safety

The provided value must be less than or equal to the maximum value for the newtype. Providing a value outside this range is undefined due to layout restrictions.

Prefer using from_u32.

pub const fn index(self) -> usize

Extracts the value of this index as a usize.

pub const fn as_u32(self) -> u32

Extracts the value of this index as a u32.

pub const fn as_usize(self) -> usize

Extracts the value of this index as a usize.

Trait Implementations

impl Add<usize> for FieldIdx

type Output = FieldIdx

The resulting type after applying the + operator.

fn add(self, other: usize) -> FieldIdx

Performs the + operation.

impl Clone for FieldIdx

fn clone(&self) -> FieldIdx

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for FieldIdx

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

Formats the value using the given formatter.

impl<D> Decodable<D> for FieldIdx

where D: Decoder,

fn decode(d: &mut D) -> FieldIdx

impl<E> Encodable<E> for FieldIdx

where E: Encoder,

fn encode(&self, e: &mut E)

impl From<u32> for FieldIdx

fn from(value: u32) -> FieldIdx

Converts to this type from the input type.

impl From<usize> for FieldIdx

fn from(value: usize) -> FieldIdx

Converts to this type from the input type.

impl Hash for FieldIdx

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

where __H: Hasher,

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<__CTX> HashStable<__CTX> for FieldIdx

where __CTX: HashStableContext,

fn hash_stable( &self, __hcx: &mut __CTX, __hasher: &mut StableHasher<SipHasher128>, )

impl Idx for FieldIdx

fn new(value: usize) -> FieldIdx

fn index(self) -> usize

fn increment_by(&mut self, amount: usize)

fn plus(self, amount: usize) -> Self

impl Ord for FieldIdx

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

fn eq(&self, other: &FieldIdx) -> 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 FieldIdx

fn partial_cmp(&self, other: &FieldIdx) -> 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 Step for FieldIdx

fn steps_between(start: &FieldIdx, end: &FieldIdx) -> Option<usize>

🔬This is a nightly-only experimental API. (step_trait)

Returns the number of successor steps required to get from start to end.

fn forward_checked(start: FieldIdx, u: usize) -> Option<FieldIdx>

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the successor of self count times.

fn backward_checked(start: FieldIdx, u: usize) -> Option<FieldIdx>

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the predecessor of self count times.

fn forward(start: Self, count: usize) -> Self

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the successor of self count times.

unsafe fn forward_unchecked(start: Self, count: usize) -> Self

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the successor of self count times.

fn backward(start: Self, count: usize) -> Self

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the predecessor of self count times.

unsafe fn backward_unchecked(start: Self, count: usize) -> Self

🔬This is a nightly-only experimental API. (step_trait)

Returns the value that would be obtained by taking the predecessor of self count times.

impl Copy for FieldIdx

impl Eq for FieldIdx

impl StructuralPartialEq for FieldIdx

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 4 bytes