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//! Proc Macro Expander stub
use base_db::{CrateId, ProcMacroExpansionError, ProcMacroId, ProcMacroKind};
use stdx::never;
use crate::{db::AstDatabase, tt, ExpandError, ExpandResult};
#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
pub struct ProcMacroExpander {
krate: CrateId,
proc_macro_id: Option<ProcMacroId>,
}
impl ProcMacroExpander {
pub fn new(krate: CrateId, proc_macro_id: ProcMacroId) -> Self {
Self { krate, proc_macro_id: Some(proc_macro_id) }
}
pub fn dummy(krate: CrateId) -> Self {
// FIXME: Should store the name for better errors
Self { krate, proc_macro_id: None }
}
pub fn is_dummy(&self) -> bool {
self.proc_macro_id.is_none()
}
pub fn expand(
self,
db: &dyn AstDatabase,
calling_crate: CrateId,
tt: &tt::Subtree,
attr_arg: Option<&tt::Subtree>,
) -> ExpandResult<tt::Subtree> {
match self.proc_macro_id {
Some(id) => {
let krate_graph = db.crate_graph();
let proc_macros = match &krate_graph[self.krate].proc_macro {
Ok(proc_macros) => proc_macros,
Err(_) => {
never!("Non-dummy expander even though there are no proc macros");
return ExpandResult::with_err(
tt::Subtree::empty(),
ExpandError::Other("Internal error".into()),
);
}
};
let proc_macro = match proc_macros.get(id.0 as usize) {
Some(proc_macro) => proc_macro,
None => {
never!(
"Proc macro index out of bounds: the length is {} but the index is {}",
proc_macros.len(),
id.0
);
return ExpandResult::with_err(
tt::Subtree::empty(),
ExpandError::Other("Internal error".into()),
);
}
};
// Proc macros have access to the environment variables of the invoking crate.
let env = &krate_graph[calling_crate].env;
match proc_macro.expander.expand(tt, attr_arg, env) {
Ok(t) => ExpandResult::ok(t),
Err(err) => match err {
// Don't discard the item in case something unexpected happened while expanding attributes
ProcMacroExpansionError::System(text)
if proc_macro.kind == ProcMacroKind::Attr =>
{
ExpandResult {
value: tt.clone(),
err: Some(ExpandError::Other(text.into())),
}
}
ProcMacroExpansionError::System(text)
| ProcMacroExpansionError::Panic(text) => ExpandResult::with_err(
tt::Subtree::empty(),
ExpandError::Other(text.into()),
),
},
}
}
None => ExpandResult::with_err(
tt::Subtree::empty(),
ExpandError::UnresolvedProcMacro(self.krate),
),
}
}
}
|
