Upgrade rust/crates/proc-macro-hack to 0.5.16
Test: None
Change-Id: If211fb7376a0bee11173aac2e3681e0b785e1eb0
diff --git a/src/iter.rs b/src/iter.rs
new file mode 100644
index 0000000..722013c
--- /dev/null
+++ b/src/iter.rs
@@ -0,0 +1,42 @@
+use proc_macro::{token_stream, Delimiter, TokenStream, TokenTree};
+
+pub type Iter<'a> = &'a mut IterImpl;
+
+pub struct IterImpl {
+ stack: Vec<token_stream::IntoIter>,
+ peeked: Option<TokenTree>,
+}
+
+pub fn new(tokens: TokenStream) -> IterImpl {
+ IterImpl {
+ stack: vec![tokens.into_iter()],
+ peeked: None,
+ }
+}
+
+impl IterImpl {
+ pub fn peek(&mut self) -> Option<&TokenTree> {
+ self.peeked = self.next();
+ self.peeked.as_ref()
+ }
+}
+
+impl Iterator for IterImpl {
+ type Item = TokenTree;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ 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),
+ }
+ }
+ }
+}