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//! FIXME: write short doc here
#[derive(Debug, Clone)]
pub(crate) struct TtIter<'a> {
pub(crate) inner: std::slice::Iter<'a, tt::TokenTree>,
}
impl<'a> TtIter<'a> {
pub(crate) fn new(subtree: &'a tt::Subtree) -> TtIter<'a> {
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_subtree(&mut self) -> Result<&'a tt::Subtree, ()> {
match self.next() {
Some(tt::TokenTree::Subtree(it)) => Ok(it),
_ => Err(()),
}
}
pub(crate) fn expect_leaf(&mut self) -> Result<&'a tt::Leaf, ()> {
match self.next() {
Some(tt::TokenTree::Leaf(it)) => Ok(it),
_ => Err(()),
}
}
pub(crate) fn expect_ident(&mut self) -> Result<&'a tt::Ident, ()> {
match self.expect_leaf()? {
tt::Leaf::Ident(it) => Ok(it),
_ => Err(()),
}
}
pub(crate) fn expect_literal(&mut self) -> Result<&'a tt::Leaf, ()> {
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_punct(&mut self) -> Result<&'a tt::Punct, ()> {
match self.expect_leaf()? {
tt::Leaf::Punct(it) => Ok(it),
_ => Err(()),
}
}
pub(crate) fn peek_n(&self, n: usize) -> Option<&tt::TokenTree> {
self.inner.as_slice().get(n)
}
}
impl<'a> Iterator for TtIter<'a> {
type Item = &'a tt::TokenTree;
fn next(&mut self) -> Option<Self::Item> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<'a> std::iter::ExactSizeIterator for TtIter<'a> {}
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