bendns' repos / rust-analyzer
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.rs57
1 files changed, 57 insertions, 0 deletions
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs
index 2d2dbd8994..03d0cbee8b 100644
--- a/crates/mbe/src/tt_iter.rs
+++ b/crates/mbe/src/tt_iter.rs
@@ -146,6 +146,63 @@ impl<'a> TtIter<'a> {
ExpandResult { value: res, err }
}
+ pub(crate) fn expect_fragment2(
+ &mut self,
+ entry_point: parser::PrefixEntryPoint,
+ ) -> ExpandResult<Option<tt::TokenTree>> {
+ let buffer = TokenBuffer::from_tokens(self.inner.as_slice());
+ let parser_input = to_parser_input(&buffer);
+ let tree_traversal = entry_point.parse(&parser_input);
+
+ 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::Enter { .. } | parser::Step::Exit => (),
+ parser::Step::Error { .. } => error = true,
+ }
+ }
+
+ let mut err = if !cursor.is_root() || error {
+ Some(err!("expected {:?}", entry_point))
+ } else {
+ None
+ };
+
+ let mut curr = buffer.begin();
+ let mut res = vec![];
+
+ if cursor.is_root() {
+ while curr != cursor {
+ if let Some(token) = curr.token_tree() {
+ res.push(token);
+ }
+ curr = curr.bump();
+ }
+ }
+ self.inner = self.inner.as_slice()[res.len()..].iter();
+ if res.is_empty() && err.is_none() {
+ err = Some(err!("no tokens consumed"));
+ }
+ let res = match res.len() {
+ 1 => Some(res[0].cloned()),
+ 0 => None,
+ _ => Some(tt::TokenTree::Subtree(tt::Subtree {
+ delimiter: None,
+ token_trees: res.into_iter().map(|it| it.cloned()).collect(),
+ })),
+ };
+ ExpandResult { value: res, err }
+ }
+
pub(crate) fn peek_n(&self, n: usize) -> Option<&tt::TokenTree> {
self.inner.as_slice().get(n)
}