90 lines
3.3 KiB
Rust
90 lines
3.3 KiB
Rust
//! Proc Macro Expander stub
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use base_db::{CrateId, ProcMacroExpansionError, ProcMacroId, ProcMacroKind};
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use stdx::never;
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use crate::{db::ExpandDatabase, tt, ExpandError, ExpandResult};
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#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
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pub struct ProcMacroExpander {
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proc_macro_id: ProcMacroId,
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}
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const DUMMY_ID: u32 = !0;
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impl ProcMacroExpander {
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pub fn new(proc_macro_id: ProcMacroId) -> Self {
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assert_ne!(proc_macro_id.0, DUMMY_ID);
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Self { proc_macro_id }
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}
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pub fn dummy() -> Self {
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Self { proc_macro_id: ProcMacroId(DUMMY_ID) }
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}
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pub fn is_dummy(&self) -> bool {
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self.proc_macro_id.0 == DUMMY_ID
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}
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pub fn expand(
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self,
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db: &dyn ExpandDatabase,
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def_crate: CrateId,
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calling_crate: CrateId,
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tt: &tt::Subtree,
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attr_arg: Option<&tt::Subtree>,
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) -> ExpandResult<tt::Subtree> {
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match self.proc_macro_id {
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ProcMacroId(DUMMY_ID) => {
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ExpandResult::new(tt::Subtree::empty(), ExpandError::UnresolvedProcMacro(def_crate))
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}
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ProcMacroId(id) => {
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let proc_macros = db.proc_macros();
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let proc_macros = match proc_macros.get(&def_crate) {
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Some(Ok(proc_macros)) => proc_macros,
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Some(Err(_)) | None => {
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never!("Non-dummy expander even though there are no proc macros");
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return ExpandResult::new(
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tt::Subtree::empty(),
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ExpandError::other("Internal error"),
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);
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}
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};
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let proc_macro = match proc_macros.get(id as usize) {
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Some(proc_macro) => proc_macro,
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None => {
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never!(
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"Proc macro index out of bounds: the length is {} but the index is {}",
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proc_macros.len(),
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id
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);
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return ExpandResult::new(
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tt::Subtree::empty(),
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ExpandError::other("Internal error"),
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);
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}
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};
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let krate_graph = db.crate_graph();
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// Proc macros have access to the environment variables of the invoking crate.
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let env = &krate_graph[calling_crate].env;
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match proc_macro.expander.expand(tt, attr_arg, env) {
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Ok(t) => ExpandResult::ok(t),
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Err(err) => match err {
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// Don't discard the item in case something unexpected happened while expanding attributes
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ProcMacroExpansionError::System(text)
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if proc_macro.kind == ProcMacroKind::Attr =>
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{
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ExpandResult { value: tt.clone(), err: Some(ExpandError::other(text)) }
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}
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ProcMacroExpansionError::System(text)
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| ProcMacroExpansionError::Panic(text) => {
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ExpandResult::new(tt::Subtree::empty(), ExpandError::other(text))
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}
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},
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}
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}
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}
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}
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}
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