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 pat = pat_to_ty_pat(
34        cx,
35        *parser.parse_pat_no_top_guard(
36            None,
37            RecoverComma::No,
38            RecoverColon::No,
39            CommaRecoveryMode::EitherTupleOrPipe,
40        )?,
41    );
42
43    if parser.token != token::Eof {
44        parser.unexpected()?;
45    }
46
47    Ok((ty, pat))
48}
49
50fn ty_pat(kind: TyPatKind, span: Span) -> Box<TyPat> {
51    Box::new(TyPat { id: DUMMY_NODE_ID, kind, span, tokens: None })
52}
53
54fn pat_to_ty_pat(cx: &mut ExtCtxt<'_>, pat: ast::Pat) -> Box<TyPat> {
55    let kind = match pat.kind {
56        ast::PatKind::Range(start, end, include_end) => TyPatKind::Range(
57            start.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
58            end.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
59            include_end,
60        ),
61        ast::PatKind::Or(variants) => {
62            TyPatKind::Or(variants.into_iter().map(|pat| pat_to_ty_pat(cx, *pat)).collect())
63        }
64        ast::PatKind::Err(guar) => TyPatKind::Err(guar),
65        _ => TyPatKind::Err(cx.dcx().span_err(pat.span, "pattern not supported in pattern types")),
66    };
67    ty_pat(kind, pat.span)
68}
rustc_builtin_macros/pattern_type.rs

rustc_builtin_macros/
pattern_type.rs
