Struct Selector

pub struct Selector { /* private fields */ }

The selector of an ink! dispatchable.

Note

This is equal to the first four bytes of the BLAKE-2 256 hash of a function’s name.

Implementations

impl Selector

pub fn compute(input: &[u8]) -> Self

Computes the BLAKE-2 256-bit based selector from the given input bytes.

pub fn compose<'a, T>(trait_prefix: T, fn_name: String) -> Self

where T: Into<Option<TraitPrefix<'a>>>,

Note

• trait_prefix is None when computing the selector of ink! constructors and messages in inherent implementation blocks.
• trait_prefix is Some when computing the selector of ink! constructors and messages in trait implementation blocks. In this case the namespace is either the full path of the trait definition gained by Rust’s module_path! macro by default or it is customized by manual application of the #[ink(namespace = "my_namespace")] ink! attribute. In the example my_namespace concatenated with :: and the identifier of the trait definition would then be part of the provided trait_prefix parameter.
• fn_ident refers to the ink! constructor or message identifier.

Inherent Implementation Blocks

For inherent implementation blocks, when trait_prefix is None the composed selector is computed as follows:

1. Apply BLAKE2 256-bit hash H on the bytes of the ASCII representation of the fn_ident identifier.
2. The first 4 bytes of H make up the selector.

Trait Implementation Blocks

For trait implementation blocks, when trait_prefix is Some((namespace, trait_ident)) the composed selector is computed as follows:

1. Compute the ASCII byte representation of fn_ident and call it F.
2. Compute the ASCII byte representation of namespace and call it N.
3. Compute the ASCII byte representation of trait_ident and call it T.
4. Concatenate N, T and F using :: as separator and call it C.
5. Apply the BLAKE2 256-bit hash H of C.
6. The first 4 bytes of H make up the selector.

pub fn to_bytes(&self) -> [u8; 4]

Returns the underlying four bytes.

pub fn into_be_u32(self) -> u32

Returns the big-endian u32 representation of the selector bytes.

pub fn hex_lits(self) -> [LitInt; 4]

Returns the 4 bytes that make up the selector as hex encoded bytes.

Trait Implementations

impl Clone for Selector

fn clone(&self) -> Selector

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Selector

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

Formats the value using the given formatter.

impl From<[u8; 4]> for Selector

fn from(bytes: [u8; 4]) -> Self

Converts to this type from the input type.

impl Hash for Selector

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 Selector

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

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

fn partial_cmp(&self, other: &Selector) -> 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 Selector

impl Eq for Selector

impl StructuralPartialEq for Selector