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use crate::{encode_section, ComponentSection, ComponentSectionId, Encode};
/// Represents options for canonical function definitions.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CanonicalOption {
/// The string types in the function signature are UTF-8 encoded.
UTF8,
/// The string types in the function signature are UTF-16 encoded.
UTF16,
/// The string types in the function signature are compact UTF-16 encoded.
CompactUTF16,
/// The memory to use if the lifting or lowering of a function requires memory access.
///
/// The value is an index to a core memory.
Memory(u32),
/// The realloc function to use if the lifting or lowering of a function requires memory
/// allocation.
///
/// The value is an index to a core function of type `(func (param i32 i32 i32 i32) (result i32))`.
Realloc(u32),
/// The post-return function to use if the lifting of a function requires
/// cleanup after the function returns.
PostReturn(u32),
}
impl Encode for CanonicalOption {
fn encode(&self, sink: &mut Vec<u8>) {
match self {
Self::UTF8 => sink.push(0x00),
Self::UTF16 => sink.push(0x01),
Self::CompactUTF16 => sink.push(0x02),
Self::Memory(idx) => {
sink.push(0x03);
idx.encode(sink);
}
Self::Realloc(idx) => {
sink.push(0x04);
idx.encode(sink);
}
Self::PostReturn(idx) => {
sink.push(0x05);
idx.encode(sink);
}
}
}
}
/// An encoder for the canonical function section of WebAssembly components.
///
/// # Example
///
/// ```
/// use wasm_encoder::{Component, CanonicalFunctionSection, CanonicalOption};
///
/// let mut functions = CanonicalFunctionSection::new();
/// functions.lift(0, 0, [CanonicalOption::UTF8]);
///
/// let mut component = Component::new();
/// component.section(&functions);
///
/// let bytes = component.finish();
/// ```
#[derive(Clone, Debug, Default)]
pub struct CanonicalFunctionSection {
bytes: Vec<u8>,
num_added: u32,
}
impl CanonicalFunctionSection {
/// Construct a new component function section encoder.
pub fn new() -> Self {
Self::default()
}
/// The number of functions 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 a function that will lift a core WebAssembly function to the canonical ABI.
pub fn lift<O>(&mut self, core_func_index: u32, type_index: u32, options: O) -> &mut Self
where
O: IntoIterator<Item = CanonicalOption>,
O::IntoIter: ExactSizeIterator,
{
let options = options.into_iter();
self.bytes.push(0x00);
self.bytes.push(0x00);
core_func_index.encode(&mut self.bytes);
options.len().encode(&mut self.bytes);
for option in options {
option.encode(&mut self.bytes);
}
type_index.encode(&mut self.bytes);
self.num_added += 1;
self
}
/// Define a function that will lower a canonical ABI function to a core WebAssembly function.
pub fn lower<O>(&mut self, func_index: u32, options: O) -> &mut Self
where
O: IntoIterator<Item = CanonicalOption>,
O::IntoIter: ExactSizeIterator,
{
let options = options.into_iter();
self.bytes.push(0x01);
self.bytes.push(0x00);
func_index.encode(&mut self.bytes);
options.len().encode(&mut self.bytes);
for option in options {
option.encode(&mut self.bytes);
}
self.num_added += 1;
self
}
/// Defines a function which will create an owned handle to the resource
/// specified by `ty_index`.
pub fn resource_new(&mut self, ty_index: u32) -> &mut Self {
self.bytes.push(0x02);
ty_index.encode(&mut self.bytes);
self.num_added += 1;
self
}
/// Defines a function which will drop the specified type of handle.
pub fn resource_drop(&mut self, ty_index: u32) -> &mut Self {
self.bytes.push(0x03);
ty_index.encode(&mut self.bytes);
self.num_added += 1;
self
}
/// Defines a function which will return the representation of the specified
/// resource type.
pub fn resource_rep(&mut self, ty_index: u32) -> &mut Self {
self.bytes.push(0x04);
ty_index.encode(&mut self.bytes);
self.num_added += 1;
self
}
}
impl Encode for CanonicalFunctionSection {
fn encode(&self, sink: &mut Vec<u8>) {
encode_section(sink, self.num_added, &self.bytes);
}
}
impl ComponentSection for CanonicalFunctionSection {
fn id(&self) -> u8 {
ComponentSectionId::CanonicalFunction.into()
}
}