Struct Component

#[non_exhaustive]
pub struct Component<'a> {
    pub span: Span,
    pub id: Option<Id<'a>>,
    pub name: Option<NameAnnotation<'a>>,
    pub kind: ComponentKind<'a>,
}

Available on crate feature component-model only.

A parsed WebAssembly component module.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

span: Span

Where this component was defined

id: Option<Id<'a>>

An optional identifier this component is known by

name: Option<NameAnnotation<'a>>

An optional @name annotation for this component

kind: ComponentKind<'a>

What kind of component this was parsed as.

Implementations

impl<'a> Component<'a>

pub fn resolve(&mut self) -> Result<(), Error>

Performs a name resolution pass on this Component, resolving all symbolic names to indices.

The WAT format contains a number of shorthands to make it easier to write, such as inline exports, inline imports, inline type definitions, etc. Additionally it allows using symbolic names such as $foo instead of using indices. This module will postprocess an AST to remove all of this syntactic sugar, preparing the AST for binary emission. This is where expansion and name resolution happens.

This function will mutate the AST of this Component and replace all Index arguments with Index::Num. This will also expand inline exports/imports listed on fields and handle various other shorthands of the text format.

If successful the AST was modified to be ready for binary encoding.

Errors

If an error happens during resolution, such a name resolution error or items are found in the wrong order, then an error is returned.

pub fn encode(&mut self) -> Result<Vec<u8>, Error>

Encodes this Component to its binary form.

This function will take the textual representation in Component and perform all steps necessary to convert it to a binary WebAssembly component, suitable for writing to a *.wasm file. This function may internally modify the Component, for example:

• Name resolution is performed to ensure that Index::Id isn’t present anywhere in the AST.

• Inline shorthands such as imports/exports/types are all expanded to be dedicated fields of the component.

• Component fields may be shuffled around to preserve index ordering from expansions.

After all of this expansion has happened the component will be converted to its binary form and returned as a Vec<u8>. This is then suitable to hand off to other wasm runtimes and such.

Errors

This function can return an error for name resolution errors and other expansion-related errors.

Trait Implementations

impl<'a> Debug for Component<'a>

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

Formats the value using the given formatter.

impl<'a> Parse<'a> for Component<'a>

fn parse(parser: Parser<'a>) -> Result<Self>

Attempts to parse Self from parser, returning an error if it could not be parsed.