bjoernager/rust
bjoernager/rust
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Add LazyTokenStream.

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This commit is contained in:
Jeffrey Seyfried 2017-03-29 01:55:01 +00:00
parent e42836b208
commit 7d493bdd2a
13 changed files with 151 additions and 89 deletions
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45
src/libsyntax/tokenstream.rs
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@ -348,6 +348,10 @@ struct StreamCursor {
}
impl StreamCursor {
fn new(stream: RcSlice<TokenStream>) -> Self {
StreamCursor { stream: stream, index: 0, stack: Vec::new() }
}
fn next_as_stream(&mut self) -> Option<TokenStream> {
loop {
if self.index < self.stream.len() {
@ -355,10 +359,7 @@ impl StreamCursor {
let next = self.stream[self.index - 1].clone();
match next.kind {
TokenStreamKind::Tree(..) | TokenStreamKind::JointTree(..) => return Some(next),
TokenStreamKind::Stream(stream) => {
self.stack.push((mem::replace(&mut self.stream, stream),
mem::replace(&mut self.index, 0)));
}
TokenStreamKind::Stream(stream) => self.insert(stream),
TokenStreamKind::Empty => {}
}
} else if let Some((stream, index)) = self.stack.pop() {
@ -369,6 +370,11 @@ impl StreamCursor {
}
}
}
fn insert(&mut self, stream: RcSlice<TokenStream>) {
self.stack.push((mem::replace(&mut self.stream, stream),
mem::replace(&mut self.index, 0)));
}
}
impl Iterator for Cursor {
@ -388,9 +394,7 @@ impl Cursor {
TokenStreamKind::Empty => CursorKind::Empty,
TokenStreamKind::Tree(tree) => CursorKind::Tree(tree, false),
TokenStreamKind::JointTree(tree) => CursorKind::JointTree(tree, false),
TokenStreamKind::Stream(stream) => {
CursorKind::Stream(StreamCursor { stream: stream, index: 0, stack: Vec::new() })
}
TokenStreamKind::Stream(stream) => CursorKind::Stream(StreamCursor::new(stream)),
})
}
@ -408,13 +412,30 @@ impl Cursor {
Some(stream)
}
pub fn original_stream(self) -> TokenStream {
pub fn insert(&mut self, stream: TokenStream) {
match self.0 {
_ if stream.is_empty() => return,
CursorKind::Empty => *self = stream.trees(),
CursorKind::Tree(_, consumed) | CursorKind::JointTree(_, consumed) => {
*self = TokenStream::concat(vec![self.original_stream(), stream]).trees();
if consumed {
self.next();
}
}
CursorKind::Stream(ref mut cursor) => {
cursor.insert(ThinTokenStream::from(stream).0.unwrap());
}
}
}
pub fn original_stream(&self) -> TokenStream {
match self.0 {
CursorKind::Empty => TokenStream::empty(),
CursorKind::Tree(tree, _) => tree.into(),
CursorKind::JointTree(tree, _) => tree.joint(),
CursorKind::Stream(cursor) => TokenStream::concat_rc_slice({
cursor.stack.get(0).cloned().map(|(stream, _)| stream).unwrap_or(cursor.stream)
CursorKind::Tree(ref tree, _) => tree.clone().into(),
CursorKind::JointTree(ref tree, _) => tree.clone().joint(),
CursorKind::Stream(ref cursor) => TokenStream::concat_rc_slice({
cursor.stack.get(0).cloned().map(|(stream, _)| stream)
.unwrap_or(cursor.stream.clone())
}),
}
}