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Remove a loop in ext::tt::transcribe.

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This commit is contained in:
Jeffrey Seyfried 2017-01-26 09:37:25 +00:00
parent be760566cf
commit d09e512158
1 changed files with 23 additions and 32 deletions
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55
src/libsyntax/ext/tt/transcribe.rs
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@ -151,43 +151,34 @@ fn lockstep_iter_size(t: &TokenTree, r: &TtReader) -> LockstepIterSize {
/// EFFECT: advances the reader's token field
fn tt_next_token(r: &mut TtReader, prev_span: Span) -> Option<TokenTree> {
loop {
let should_pop = if let Some(frame) = r.stack.last() {
if frame.idx < frame.forest.len() {
break;
}
!frame.dotdotdoted || *r.repeat_idx.last().unwrap() == *r.repeat_len.last().unwrap() - 1
} else {
return None;
let frame = match r.stack.last() {
Some(frame) => frame.clone(),
None => return None,
};
/* done with this set; pop or repeat? */
if should_pop {
let prev = r.stack.pop().unwrap();
if let Some(frame) = r.stack.last_mut() {
frame.idx += 1;
if frame.idx == frame.forest.len() {
if frame.dotdotdoted &&
*r.repeat_idx.last().unwrap() == *r.repeat_len.last().unwrap() - 1 {
*r.repeat_idx.last_mut().unwrap() += 1;
r.stack.last_mut().unwrap().idx = 0;
if let Some(tk) = r.stack.last().unwrap().sep.clone() {
return Some(TokenTree::Token(prev_span, tk)); // repeat same span, I guess
}
} else {
return None;
}
if prev.dotdotdoted {
r.repeat_idx.pop();
r.repeat_len.pop();
}
} else { /* repeat */
*r.repeat_idx.last_mut().unwrap() += 1;
r.stack.last_mut().unwrap().idx = 0;
if let Some(tk) = r.stack.last().unwrap().sep.clone() {
return Some(TokenTree::Token(prev_span, tk)); // repeat same span, I guess
r.stack.pop();
match r.stack.last_mut() {
Some(frame) => frame.idx += 1,
None => return None,
}
if frame.dotdotdoted {
r.repeat_idx.pop();
r.repeat_len.pop();
}
}
continue
}
}
loop { /* because it's easiest, this handles `TokenTree::Delimited` not starting
with a `TokenTree::Token`, even though it won't happen */
let t = {
let frame = r.stack.last().unwrap();
// FIXME(pcwalton): Bad copy.
frame.forest.get_tt(frame.idx)
};
match t {
match frame.forest.get_tt(frame.idx) {
TokenTree::Sequence(sp, seq) => {
// FIXME(pcwalton): Bad copy.
match lockstep_iter_size(&TokenTree::Sequence(sp, seq.clone()),