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use crate::ast::{self, kw};
use crate::parser::{Parse, Parser, Result};
/// A WebAssembly tag directive, part of the exception handling proposal.
#[derive(Debug)]
pub struct Tag<'a> {
/// Where this tag was defined
pub span: ast::Span,
/// An optional name by which to refer to this tag in name resolution.
pub id: Option<ast::Id<'a>>,
/// An optional name for this function stored in the custom `name` section.
pub name: Option<ast::NameAnnotation<'a>>,
/// Optional export directives for this tag.
pub exports: ast::InlineExport<'a>,
/// The type of tag that is defined.
pub ty: TagType<'a>,
/// What kind of tag this is defined as.
pub kind: TagKind<'a>,
}
/// Listing of various types of tags that can be defined in a wasm module.
#[derive(Clone, Debug)]
pub enum TagType<'a> {
/// An exception tag, where the payload is the type signature of the tag
/// (constructor parameters, etc).
Exception(ast::TypeUse<'a, ast::FunctionType<'a>>),
}
/// Different kinds of tags that can be defined in a module.
#[derive(Debug)]
pub enum TagKind<'a> {
/// An tag which is actually defined as an import, such as:
///
/// ```text
/// (tag (type 0) (import "foo" "bar"))
/// ```
Import(ast::InlineImport<'a>),
/// A tag defined inline in the module itself
Inline(),
}
impl<'a> Parse<'a> for Tag<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
let span = parser.parse::<kw::tag>()?.0;
let id = parser.parse()?;
let name = parser.parse()?;
let exports = parser.parse()?;
let (ty, kind) = if let Some(import) = parser.parse()? {
(parser.parse()?, TagKind::Import(import))
} else {
(parser.parse()?, TagKind::Inline())
};
Ok(Tag {
span,
id,
name,
exports,
ty,
kind,
})
}
}
impl<'a> Parse<'a> for TagType<'a> {
fn parse(parser: Parser<'a>) -> Result<Self> {
Ok(TagType::Exception(parser.parse()?))
}
}