Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/mbe/src/parser.rs')
| -rw-r--r-- | crates/mbe/src/parser.rs | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs index 2efe318f61..b55edf4a5e 100644 --- a/crates/mbe/src/parser.rs +++ b/crates/mbe/src/parser.rs @@ -84,6 +84,10 @@ pub(crate) enum Op { // FIXME: `usize`` once we drop support for 1.76 depth: Option<usize>, }, + Concat { + elements: Box<[ConcatMetaVarExprElem]>, + span: Span, + }, Repeat { tokens: MetaTemplate, kind: RepeatKind, @@ -98,6 +102,18 @@ pub(crate) enum Op { Ident(tt::Ident<Span>), } +#[derive(Clone, Debug, PartialEq, Eq)] +pub(crate) enum ConcatMetaVarExprElem { + /// There is NO preceding dollar sign, which means that this identifier should be interpreted + /// as a literal. + Ident(tt::Ident<Span>), + /// There is a preceding dollar sign, which means that this identifier should be expanded + /// and interpreted as a variable. + Var(tt::Ident<Span>), + /// For example, a number or a string. + Literal(tt::Literal<Span>), +} + #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub(crate) enum RepeatKind { ZeroOrMore, @@ -384,6 +400,32 @@ fn parse_metavar_expr(src: &mut TtIter<'_, Span>) -> Result<Op, ()> { let depth = if try_eat_comma(&mut args) { Some(parse_depth(&mut args)?) } else { None }; Op::Count { name: ident.sym.clone(), depth } } + s if sym::concat == *s => { + let mut elements = Vec::new(); + while let Some(next) = args.peek_n(0) { + let element = if let tt::TokenTree::Leaf(tt::Leaf::Literal(lit)) = next { + args.next().expect("already peeked"); + ConcatMetaVarExprElem::Literal(lit.clone()) + } else { + let is_var = try_eat_dollar(&mut args); + let ident = args.expect_ident_or_underscore()?.clone(); + + if is_var { + ConcatMetaVarExprElem::Var(ident) + } else { + ConcatMetaVarExprElem::Ident(ident) + } + }; + elements.push(element); + if args.peek_n(0).is_some() { + args.expect_comma()?; + } + } + if elements.len() < 2 { + return Err(()); + } + Op::Concat { elements: elements.into_boxed_slice(), span: func.span } + } _ => return Err(()), }; @@ -414,3 +456,11 @@ fn try_eat_comma(src: &mut TtIter<'_, Span>) -> bool { } false } + +fn try_eat_dollar(src: &mut TtIter<'_, Span>) -> bool { + if let Some(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: '$', .. }))) = src.peek_n(0) { + let _ = src.next(); + return true; + } + false +} |