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|
//! Proc Macro Expander stub
use base_db::{CrateId, ProcMacroExpansionError, ProcMacroId, ProcMacroKind};
use stdx::never;
use crate::{db::ExpandDatabase, tt, ExpandError, ExpandResult};
#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
pub struct ProcMacroExpander {
proc_macro_id: ProcMacroId,
}
const DUMMY_ID: u32 = !0;
impl ProcMacroExpander {
pub fn new(proc_macro_id: ProcMacroId) -> Self {
assert_ne!(proc_macro_id.0, DUMMY_ID);
Self { proc_macro_id }
}
pub fn dummy() -> Self {
Self { proc_macro_id: ProcMacroId(DUMMY_ID) }
}
pub fn is_dummy(&self) -> bool {
self.proc_macro_id.0 == DUMMY_ID
}
pub fn expand(
self,
db: &dyn ExpandDatabase,
def_crate: CrateId,
calling_crate: CrateId,
tt: &tt::Subtree,
attr_arg: Option<&tt::Subtree>,
) -> ExpandResult<tt::Subtree> {
match self.proc_macro_id {
ProcMacroId(DUMMY_ID) => {
ExpandResult::new(tt::Subtree::empty(), ExpandError::UnresolvedProcMacro(def_crate))
}
ProcMacroId(id) => {
let proc_macros = db.proc_macros();
let proc_macros = match proc_macros.get(&def_crate) {
Some(Ok(proc_macros)) => proc_macros,
Some(Err(_)) | None => {
never!("Non-dummy expander even though there are no proc macros");
return ExpandResult::new(
tt::Subtree::empty(),
ExpandError::other("Internal error"),
);
}
};
let proc_macro = match proc_macros.get(id 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
);
return ExpandResult::new(
tt::Subtree::empty(),
ExpandError::other("Internal error"),
);
}
};
let krate_graph = db.crate_graph();
// 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)) }
}
ProcMacroExpansionError::System(text)
| ProcMacroExpansionError::Panic(text) => {
ExpandResult::new(tt::Subtree::empty(), ExpandError::other(text))
}
},
}
}
}
}
}
|
