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use crate::token::{Id, Index};
use crate::Error;
use std::collections::HashMap;
#[derive(Default)]
pub struct Namespace<'a> {
names: HashMap<Id<'a>, u32>,
count: u32,
}
impl<'a> Namespace<'a> {
pub fn register(&mut self, name: Option<Id<'a>>, desc: &str) -> Result<u32, Error> {
let index = self.alloc();
if let Some(name) = name {
if let Some(_prev) = self.names.insert(name, index) {
return Err(Error::new(
name.span(),
format!("duplicate {} identifier", desc),
));
}
}
Ok(index)
}
pub fn alloc(&mut self) -> u32 {
let index = self.count;
self.count += 1;
index
}
pub fn register_specific(&mut self, name: Id<'a>, index: u32, desc: &str) -> Result<(), Error> {
if let Some(_prev) = self.names.insert(name, index) {
return Err(Error::new(
name.span(),
format!(
"duplicate identifier: duplicate {desc} named `{}`",
name.name()
),
));
}
Ok(())
}
pub fn resolve(&self, idx: &mut Index<'a>, desc: &str) -> Result<u32, Error> {
let id = match idx {
Index::Num(n, _) => return Ok(*n),
Index::Id(id) => id,
};
if let Some(&n) = self.names.get(id) {
*idx = Index::Num(n, id.span());
return Ok(n);
}
Err(resolve_error(*id, desc))
}
}
pub fn resolve_error(id: Id<'_>, ns: &str) -> Error {
assert!(
!id.is_gensym(),
"symbol generated by `wast` itself cannot be resolved {:?}",
id
);
Error::new(
id.span(),
format!("unknown {ns}: failed to find name `${}`", id.name()),
)
}