Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/mbe/src/tt_iter.rs')
| -rw-r--r-- | crates/mbe/src/tt_iter.rs | 208 |
1 files changed, 0 insertions, 208 deletions
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs deleted file mode 100644 index 9c7d7af7b1..0000000000 --- a/crates/mbe/src/tt_iter.rs +++ /dev/null @@ -1,208 +0,0 @@ -//! A "Parser" structure for token trees. We use this when parsing a declarative -//! macro definition into a list of patterns and templates. - -use core::fmt; - -use smallvec::{smallvec, SmallVec}; -use syntax::SyntaxKind; - -use crate::{to_parser_input::to_parser_input, ExpandError, ExpandResult}; - -#[derive(Debug, Clone)] -pub(crate) struct TtIter<'a, S> { - pub(crate) inner: std::slice::Iter<'a, tt::TokenTree<S>>, -} - -impl<'a, S: Copy> TtIter<'a, S> { - pub(crate) fn new(subtree: &'a tt::Subtree<S>) -> TtIter<'a, S> { - TtIter { inner: subtree.token_trees.iter() } - } - - pub(crate) fn expect_char(&mut self, char: char) -> Result<(), ()> { - match self.next() { - Some(&tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c, .. }))) if c == char => { - Ok(()) - } - _ => Err(()), - } - } - - pub(crate) fn expect_any_char(&mut self, chars: &[char]) -> Result<(), ()> { - match self.next() { - Some(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c, .. }))) - if chars.contains(c) => - { - Ok(()) - } - _ => Err(()), - } - } - - pub(crate) fn expect_subtree(&mut self) -> Result<&'a tt::Subtree<S>, ()> { - match self.next() { - Some(tt::TokenTree::Subtree(it)) => Ok(it), - _ => Err(()), - } - } - - pub(crate) fn expect_leaf(&mut self) -> Result<&'a tt::Leaf<S>, ()> { - match self.next() { - Some(tt::TokenTree::Leaf(it)) => Ok(it), - _ => Err(()), - } - } - - pub(crate) fn expect_dollar(&mut self) -> Result<(), ()> { - match self.expect_leaf()? { - tt::Leaf::Punct(tt::Punct { char: '$', .. }) => Ok(()), - _ => Err(()), - } - } - - pub(crate) fn expect_ident(&mut self) -> Result<&'a tt::Ident<S>, ()> { - match self.expect_leaf()? { - tt::Leaf::Ident(it) if it.text != "_" => Ok(it), - _ => Err(()), - } - } - - pub(crate) fn expect_ident_or_underscore(&mut self) -> Result<&'a tt::Ident<S>, ()> { - match self.expect_leaf()? { - tt::Leaf::Ident(it) => Ok(it), - _ => Err(()), - } - } - - pub(crate) fn expect_literal(&mut self) -> Result<&'a tt::Leaf<S>, ()> { - let it = self.expect_leaf()?; - match it { - tt::Leaf::Literal(_) => Ok(it), - tt::Leaf::Ident(ident) if ident.text == "true" || ident.text == "false" => Ok(it), - _ => Err(()), - } - } - - pub(crate) fn expect_single_punct(&mut self) -> Result<&'a tt::Punct<S>, ()> { - match self.expect_leaf()? { - tt::Leaf::Punct(it) => Ok(it), - _ => Err(()), - } - } - - /// Returns consecutive `Punct`s that can be glued together. - /// - /// This method currently may return a single quotation, which is part of lifetime ident and - /// conceptually not a punct in the context of mbe. Callers should handle this. - pub(crate) fn expect_glued_punct(&mut self) -> Result<SmallVec<[tt::Punct<S>; 3]>, ()> { - let tt::TokenTree::Leaf(tt::Leaf::Punct(first)) = self.next().ok_or(())?.clone() else { - return Err(()); - }; - - if first.spacing == tt::Spacing::Alone { - return Ok(smallvec![first]); - } - - let (second, third) = match (self.peek_n(0), self.peek_n(1)) { - ( - Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p2))), - Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p3))), - ) if p2.spacing == tt::Spacing::Joint => (p2, Some(p3)), - (Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p2))), _) => (p2, None), - _ => return Ok(smallvec![first]), - }; - - match (first.char, second.char, third.map(|it| it.char)) { - ('.', '.', Some('.' | '=')) | ('<', '<', Some('=')) | ('>', '>', Some('=')) => { - let _ = self.next().unwrap(); - let _ = self.next().unwrap(); - Ok(smallvec![first, *second, *third.unwrap()]) - } - ('-' | '!' | '*' | '/' | '&' | '%' | '^' | '+' | '<' | '=' | '>' | '|', '=', _) - | ('-' | '=' | '>', '>', _) - | ('<', '-', _) - | (':', ':', _) - | ('.', '.', _) - | ('&', '&', _) - | ('<', '<', _) - | ('|', '|', _) => { - let _ = self.next().unwrap(); - Ok(smallvec![first, *second]) - } - _ => Ok(smallvec![first]), - } - } - pub(crate) fn peek_n(&self, n: usize) -> Option<&'a tt::TokenTree<S>> { - self.inner.as_slice().get(n) - } -} - -impl<'a, S: Copy + fmt::Debug> TtIter<'a, S> { - pub(crate) fn expect_fragment( - &mut self, - entry_point: parser::PrefixEntryPoint, - edition: parser::Edition, - ) -> ExpandResult<Option<tt::TokenTree<S>>> { - let buffer = tt::buffer::TokenBuffer::from_tokens(self.inner.as_slice()); - let parser_input = to_parser_input(&buffer); - let tree_traversal = entry_point.parse(&parser_input, edition); - let mut cursor = buffer.begin(); - let mut error = false; - for step in tree_traversal.iter() { - match step { - parser::Step::Token { kind, mut n_input_tokens } => { - if kind == SyntaxKind::LIFETIME_IDENT { - n_input_tokens = 2; - } - for _ in 0..n_input_tokens { - cursor = cursor.bump_subtree(); - } - } - parser::Step::FloatSplit { .. } => { - // FIXME: We need to split the tree properly here, but mutating the token trees - // in the buffer is somewhat tricky to pull off. - cursor = cursor.bump_subtree(); - } - parser::Step::Enter { .. } | parser::Step::Exit => (), - parser::Step::Error { .. } => error = true, - } - } - - let err = if error || !cursor.is_root() { - Some(ExpandError::binding_error(format!("expected {entry_point:?}"))) - } else { - None - }; - - let mut curr = buffer.begin(); - let mut res = vec![]; - - while curr != cursor { - let Some(token) = curr.token_tree() else { break }; - res.push(token.cloned()); - curr = curr.bump(); - } - - self.inner = self.inner.as_slice()[res.len()..].iter(); - let res = match &*res { - [] | [_] => res.pop(), - [first, ..] => Some(tt::TokenTree::Subtree(tt::Subtree { - delimiter: tt::Delimiter::invisible_spanned(first.first_span()), - token_trees: res.into_boxed_slice(), - })), - }; - ExpandResult { value: res, err } - } -} - -impl<'a, S> Iterator for TtIter<'a, S> { - type Item = &'a tt::TokenTree<S>; - fn next(&mut self) -> Option<Self::Item> { - self.inner.next() - } - - fn size_hint(&self) -> (usize, Option<usize>) { - self.inner.size_hint() - } -} - -impl<S> std::iter::ExactSizeIterator for TtIter<'_, S> {} |