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 | 56 |
1 files changed, 35 insertions, 21 deletions
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs index 351c359b73..fad905e97f 100644 --- a/crates/mbe/src/parser.rs +++ b/crates/mbe/src/parser.rs @@ -1,7 +1,7 @@ //! Parser recognizes special macro syntax, `$var` and `$(repeat)*`, in token //! trees. -use smallvec::SmallVec; +use smallvec::{smallvec, SmallVec}; use syntax::SmolStr; use crate::{tt_iter::TtIter, ParseError}; @@ -39,7 +39,7 @@ impl MetaTemplate { let mut src = TtIter::new(tt); let mut res = Vec::new(); - while let Some(first) = src.next() { + while let Some(first) = src.peek_n(0) { let op = next_op(first, &mut src, mode)?; res.push(op); } @@ -54,8 +54,10 @@ pub(crate) enum Op { Ignore { name: SmolStr, id: tt::TokenId }, Index { depth: u32 }, Repeat { tokens: MetaTemplate, kind: RepeatKind, separator: Option<Separator> }, - Leaf(tt::Leaf), Subtree { tokens: MetaTemplate, delimiter: Option<tt::Delimiter> }, + Literal(tt::Literal), + Punct(SmallVec<[tt::Punct; 3]>), + Ident(tt::Ident), } #[derive(Copy, Clone, Debug, PartialEq, Eq)] @@ -108,28 +110,23 @@ impl PartialEq for Separator { } } -impl Separator { - pub(crate) fn tt_count(&self) -> usize { - match self { - Separator::Literal(_) => 1, - Separator::Ident(_) => 1, - Separator::Puncts(it) => it.len(), - } - } -} - #[derive(Clone, Copy)] enum Mode { Pattern, Template, } -fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Result<Op, ParseError> { - let res = match first { - tt::TokenTree::Leaf(leaf @ tt::Leaf::Punct(tt::Punct { char: '$', .. })) => { +fn next_op( + first_peeked: &tt::TokenTree, + src: &mut TtIter<'_>, + mode: Mode, +) -> Result<Op, ParseError> { + let res = match first_peeked { + tt::TokenTree::Leaf(tt::Leaf::Punct(p @ tt::Punct { char: '$', .. })) => { + src.next().expect("first token already peeked"); // Note that the '$' itself is a valid token inside macro_rules. let second = match src.next() { - None => return Ok(Op::Leaf(leaf.clone())), + None => return Ok(Op::Punct(smallvec![p.clone()])), Some(it) => it, }; match second { @@ -160,7 +157,7 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul tt::TokenTree::Leaf(leaf) => match leaf { tt::Leaf::Ident(ident) if ident.text == "crate" => { // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path. - Op::Leaf(tt::Leaf::from(tt::Ident { text: "$crate".into(), id: ident.id })) + Op::Ident(tt::Ident { text: "$crate".into(), id: ident.id }) } tt::Leaf::Ident(ident) => { let kind = eat_fragment_kind(src, mode)?; @@ -180,7 +177,7 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul "`$$` is not allowed on the pattern side", )) } - Mode::Template => Op::Leaf(tt::Leaf::Punct(*punct)), + Mode::Template => Op::Punct(smallvec![*punct]), }, tt::Leaf::Punct(_) | tt::Leaf::Literal(_) => { return Err(ParseError::expected("expected ident")) @@ -188,8 +185,25 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul }, } } - tt::TokenTree::Leaf(tt) => Op::Leaf(tt.clone()), + + tt::TokenTree::Leaf(tt::Leaf::Literal(it)) => { + src.next().expect("first token already peeked"); + Op::Literal(it.clone()) + } + + tt::TokenTree::Leaf(tt::Leaf::Ident(it)) => { + src.next().expect("first token already peeked"); + Op::Ident(it.clone()) + } + + tt::TokenTree::Leaf(tt::Leaf::Punct(_)) => { + // There's at least one punct so this shouldn't fail. + let puncts = src.expect_glued_punct().unwrap(); + Op::Punct(puncts) + } + tt::TokenTree::Subtree(subtree) => { + src.next().expect("first token already peeked"); let tokens = MetaTemplate::parse(subtree, mode)?; Op::Subtree { tokens, delimiter: subtree.delimiter } } @@ -259,7 +273,7 @@ fn parse_repeat(src: &mut TtIter<'_>) -> Result<(Option<Separator>, RepeatKind), _ => return Err(ParseError::InvalidRepeat), }, }; - return Ok((has_sep.then(|| separator), repeat_kind)); + return Ok((has_sep.then_some(separator), repeat_kind)); } } } |