rustc_builtin_macros/
pattern_type.rs

1use rustc_ast::tokenstream::TokenStream;
2use rustc_ast::{AnonConst, DUMMY_NODE_ID, Ty, TyPat, TyPatKind, ast, token};
3use rustc_errors::PResult;
4use rustc_expand::base::{self, DummyResult, ExpandResult, ExtCtxt, MacroExpanderResult};
5use rustc_parse::exp;
6use rustc_parse::parser::{CommaRecoveryMode, RecoverColon, RecoverComma};
7use rustc_span::Span;
8
9pub(crate) fn expand<'cx>(
10    cx: &'cx mut ExtCtxt<'_>,
11    sp: Span,
12    tts: TokenStream,
13) -> MacroExpanderResult<'cx> {
14    let (ty, pat) = match parse_pat_ty(cx, tts) {
15        Ok(parsed) => parsed,
16        Err(err) => {
17            return ExpandResult::Ready(DummyResult::any(sp, err.emit()));
18        }
19    };
20
21    ExpandResult::Ready(base::MacEager::ty(cx.ty(sp, ast::TyKind::Pat(ty, pat))))
22}
23
24fn parse_pat_ty<'a>(
25    cx: &mut ExtCtxt<'a>,
26    stream: TokenStream,
27) -> PResult<'a, (Box<Ty>, Box<TyPat>)> {
28    let mut parser = cx.new_parser_from_tts(stream);
29
30    let ty = parser.parse_ty()?;
31    parser.expect_keyword(exp!(Is))?;
32
33    let start = parser.token.span;
34    let pat = if parser.eat(exp!(Bang)) {
35        parser.expect_keyword(exp!(Null))?;
36        ty_pat(TyPatKind::NotNull, start.to(parser.token.span))
37    } else {
38        pat_to_ty_pat(
39            cx,
40            parser.parse_pat_no_top_guard(
41                None,
42                RecoverComma::No,
43                RecoverColon::No,
44                CommaRecoveryMode::EitherTupleOrPipe,
45            )?,
46        )
47    };
48
49    if parser.token != token::Eof {
50        parser.unexpected()?;
51    }
52
53    Ok((ty, Box::new(pat)))
54}
55
56fn ty_pat(kind: TyPatKind, span: Span) -> TyPat {
57    TyPat { id: DUMMY_NODE_ID, kind, span, tokens: None }
58}
59
60fn pat_to_ty_pat(cx: &mut ExtCtxt<'_>, pat: ast::Pat) -> TyPat {
61    let kind = match pat.kind {
62        ast::PatKind::Range(start, end, include_end) => TyPatKind::Range(
63            start.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
64            end.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
65            include_end,
66        ),
67        ast::PatKind::Or(variants) => {
68            TyPatKind::Or(variants.into_iter().map(|pat| pat_to_ty_pat(cx, pat)).collect())
69        }
70        ast::PatKind::Err(guar) => TyPatKind::Err(guar),
71        _ => TyPatKind::Err(cx.dcx().span_err(pat.span, "pattern not supported in pattern types")),
72    };
73    ty_pat(kind, pat.span)
74}
rustc_builtin_macros/pattern_type.rs

rustc_builtin_macros/
pattern_type.rs
