From 2aa4a82499d4becd2284cdb482213d541b8804dd Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 16:29:10 +0200 Subject: Adding upstream version 86.0.1. Signed-off-by: Daniel Baumann --- third_party/rust/const_fn/src/iter.rs | 39 +++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 third_party/rust/const_fn/src/iter.rs (limited to 'third_party/rust/const_fn/src/iter.rs') diff --git a/third_party/rust/const_fn/src/iter.rs b/third_party/rust/const_fn/src/iter.rs new file mode 100644 index 0000000000..f998dce4d6 --- /dev/null +++ b/third_party/rust/const_fn/src/iter.rs @@ -0,0 +1,39 @@ +// Based on https://github.com/dtolnay/proc-macro-hack/blob/0.5.18/src/iter.rs + +use proc_macro::{token_stream, Delimiter, TokenStream, TokenTree}; + +pub(crate) struct TokenIter { + stack: Vec, + peeked: Option, +} + +impl TokenIter { + pub(crate) fn new(tokens: TokenStream) -> Self { + Self { stack: vec![tokens.into_iter()], peeked: None } + } + + pub(crate) fn peek(&mut self) -> Option<&TokenTree> { + self.peeked = self.next(); + self.peeked.as_ref() + } +} + +impl Iterator for TokenIter { + type Item = TokenTree; + + fn next(&mut self) -> Option { + if let Some(tt) = self.peeked.take() { + return Some(tt); + } + loop { + let top = self.stack.last_mut()?; + match top.next() { + None => drop(self.stack.pop()), + Some(TokenTree::Group(ref group)) if group.delimiter() == Delimiter::None => { + self.stack.push(group.stream().into_iter()); + } + Some(tt) => return Some(tt), + } + } + } +} -- cgit v1.2.3