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use super::{COMPONENT_SORT, CORE_MODULE_SORT, CORE_SORT, CORE_TYPE_SORT, TYPE_SORT};
use crate::{
encode_section, ComponentExportKind, ComponentSection, ComponentSectionId, Encode, ExportKind,
};
/// Represents the kinds of outer aliasable items in a component.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ComponentOuterAliasKind {
/// The alias is to a core module.
CoreModule,
/// The alias is to a core type.
CoreType,
/// The alias is to a type.
Type,
/// The alias is to a component.
Component,
}
impl Encode for ComponentOuterAliasKind {
fn encode(&self, sink: &mut Vec<u8>) {
match self {
Self::CoreModule => {
sink.push(CORE_SORT);
sink.push(CORE_MODULE_SORT);
}
Self::CoreType => {
sink.push(CORE_SORT);
sink.push(CORE_TYPE_SORT);
}
Self::Type => sink.push(TYPE_SORT),
Self::Component => sink.push(COMPONENT_SORT),
}
}
}
/// An encoder for the alias section of WebAssembly component.
///
/// # Example
///
/// ```rust
/// use wasm_encoder::{Component, Alias, ComponentAliasSection, ComponentExportKind, ComponentOuterAliasKind};
///
/// let mut aliases = ComponentAliasSection::new();
/// aliases.alias(Alias::InstanceExport { instance: 0, kind: ComponentExportKind::Func, name: "f" });
/// aliases.alias(Alias::Outer { count: 0, kind: ComponentOuterAliasKind::Type, index: 1 });
///
/// let mut component = Component::new();
/// component.section(&aliases);
///
/// let bytes = component.finish();
/// ```
#[derive(Clone, Debug, Default)]
pub struct ComponentAliasSection {
bytes: Vec<u8>,
num_added: u32,
}
/// Different forms of aliases that can be inserted into a
/// [`ComponentAliasSection`].
#[derive(Copy, Clone, Debug)]
pub enum Alias<'a> {
/// An alias of a component instance export.
InstanceExport {
/// The index of the component instance that's being aliased from.
instance: u32,
/// The kind of item that's being extracted from the component
/// instance.
kind: ComponentExportKind,
/// The name of the export that's being aliased.
name: &'a str,
},
/// Same as `InstanceExport`, but for core instances.
#[allow(missing_docs)]
CoreInstanceExport {
instance: u32,
kind: ExportKind,
name: &'a str,
},
/// Aliasing an item from an outer component.
Outer {
/// The kind of item being aliased, either a type or a component.
kind: ComponentOuterAliasKind,
/// Number of levels "up" to go to lookup the index within. Level 0 is
/// the current scope and level 1 is the enclosing scope, and so on.
count: u32,
/// The index of the item to alias within the scope referenced by
/// `count`.
index: u32,
},
}
impl ComponentAliasSection {
/// Create a new alias section encoder.
pub fn new() -> Self {
Self::default()
}
/// The number of aliases in the section.
pub fn len(&self) -> u32 {
self.num_added
}
/// Determines if the section is empty.
pub fn is_empty(&self) -> bool {
self.num_added == 0
}
/// Define an alias to a component instance's export.
pub fn alias(&mut self, alias: Alias<'_>) -> &mut Self {
alias.encode(&mut self.bytes);
self.num_added += 1;
self
}
}
impl Encode for ComponentAliasSection {
fn encode(&self, sink: &mut Vec<u8>) {
encode_section(sink, self.num_added, &self.bytes);
}
}
impl ComponentSection for ComponentAliasSection {
fn id(&self) -> u8 {
ComponentSectionId::Alias.into()
}
}
impl Encode for Alias<'_> {
fn encode(&self, sink: &mut Vec<u8>) {
match self {
Alias::InstanceExport {
instance,
kind,
name,
} => {
kind.encode(sink);
sink.push(0x00);
instance.encode(sink);
name.encode(sink);
}
Alias::CoreInstanceExport {
instance,
kind,
name,
} => {
sink.push(CORE_SORT);
kind.encode(sink);
sink.push(0x01);
instance.encode(sink);
name.encode(sink);
}
Alias::Outer { kind, count, index } => {
kind.encode(sink);
sink.push(0x02);
count.encode(sink);
index.encode(sink);
}
}
}
}