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use super::*;
use std::convert::TryFrom;
/// An encoder for the tag section.
///
/// # Example
///
/// ```
/// use wasm_encoder::{Module, TagSection, TagType, TagKind};
///
/// let mut tags = TagSection::new();
/// tags.tag(TagType {
/// kind: TagKind::Exception,
/// func_type_idx: 0,
/// });
///
/// let mut module = Module::new();
/// module.section(&tags);
///
/// let wasm_bytes = module.finish();
/// ```
#[derive(Clone, Default, Debug)]
pub struct TagSection {
bytes: Vec<u8>,
num_added: u32,
}
impl TagSection {
/// Create a new tag section encoder.
pub fn new() -> Self {
Self::default()
}
/// How many tags have been defined inside this section so far?
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 tag.
pub fn tag(&mut self, tag_type: TagType) -> &mut Self {
tag_type.encode(&mut self.bytes);
self.num_added += 1;
self
}
}
impl Section for TagSection {
fn id(&self) -> u8 {
SectionId::Tag.into()
}
fn encode<S>(&self, sink: &mut S)
where
S: Extend<u8>,
{
let num_added = encoders::u32(self.num_added);
let n = num_added.len();
sink.extend(
encoders::u32(u32::try_from(n + self.bytes.len()).unwrap())
.chain(num_added)
.chain(self.bytes.iter().copied()),
);
}
}
#[allow(missing_docs)]
#[repr(u8)]
#[derive(Clone, Copy, Debug)]
pub enum TagKind {
Exception = 0x0,
}
/// A tag's type.
#[derive(Clone, Copy, Debug)]
pub struct TagType {
/// The kind of tag
pub kind: TagKind,
/// The function type this tag uses
pub func_type_idx: u32,
}
impl TagType {
pub(crate) fn encode(&self, bytes: &mut Vec<u8>) {
bytes.push(self.kind as u8);
bytes.extend(encoders::u32(self.func_type_idx));
}
}