Struct wasmtime::StructType

pub struct StructType { /* private fields */ }

Available on crate feature runtime only.

The type of a WebAssembly struct.

WebAssembly structs are a static, fixed-length, ordered sequence of fields. Fields are named by index, not an identifier. Each field is mutable or constant and stores unpacked Vals or packed 8-/16-bit integers.

Subtyping and Equality

StructType does not implement Eq, because reference types have a subtyping relationship, and so 99.99% of the time you actually want to check whether one type matches (i.e. is a subtype of) another type. You can use the StructType::matches method to perform these types of checks. If, however, you are in that 0.01% scenario where you need to check precise equality between types, you can use the StructType::eq method.

Implementations

impl StructType

pub fn new( engine: &Engine, fields: impl IntoIterator<Item = FieldType> ) -> Result<Self>

Construct a new StructType with the given field types.

This StructType will be final and without a supertype.

The result will be associated with the given engine, and attempts to use it with other engines will panic (for example, checking whether it is a subtype of another struct type that is associated with a different engine).

Returns an error if the number of fields exceeds the implementation limit.

Panics

Panics if any given field type is not associated with the given engine.

pub fn with_finality_and_supertype( engine: &Engine, finality: Finality, supertype: Option<&Self>, fields: impl IntoIterator<Item = FieldType> ) -> Result<Self>

Construct a new StructType with the given finality, supertype, and fields.

The result will be associated with the given engine, and attempts to use it with other engines will panic (for example, checking whether it is a subtype of another struct type that is associated with a different engine).

Returns an error if the number of fields exceeds the implementation limit, if the supertype is final, or if this type does not match the supertype.

Panics

Panics if any given field type is not associated with the given engine.

pub fn engine(&self) -> &Engine

Get the engine that this struct type is associated with.

pub fn finality(&self) -> Finality

Get the finality of this struct type.

pub fn supertype(&self) -> Option<Self>

Get the supertype of this struct type, if any.

pub fn field(&self, i: usize) -> Option<FieldType>

Get the ith field type.

Returns None if i is out of bounds.

pub fn fields(&self) -> impl ExactSizeIterator<Item = FieldType> + '_

Returns the list of field types for this function.

pub fn matches(&self, other: &StructType) -> bool

Does this struct type match the other struct type?

That is, is this function type a subtype of the other struct type?

Panics

Panics if either type is associated with a different engine from the other.

pub fn eq(a: &StructType, b: &StructType) -> bool

Is struct type a precisely equal to struct type b?

Returns false even if a is a subtype of b or vice versa, if they are not exactly the same struct type.

Panics

Panics if either type is associated with a different engine from the other.

Trait Implementations

impl Clone for StructType

fn clone(&self) -> StructType

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for StructType

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

Formats the value using the given formatter.

impl From<StructType> for HeapType

fn from(s: StructType) -> Self

Converts to this type from the input type.

impl Hash for StructType

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.