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use crate::subtree_source::SubtreeTokenSource;
use ra_parser::{FragmentKind, TokenSource, TreeSink};
use ra_syntax::SyntaxKind;
use tt::buffer::{Cursor, TokenBuffer};
struct OffsetTokenSink<'a> {
cursor: Cursor<'a>,
error: bool,
}
impl<'a> OffsetTokenSink<'a> {
pub fn collect(&self, begin: Cursor<'a>) -> Vec<&'a tt::TokenTree> {
if !self.cursor.is_root() {
return vec![];
}
let mut curr = begin;
let mut res = vec![];
while self.cursor != curr {
if let Some(token) = curr.token_tree() {
res.push(token);
}
curr = curr.bump();
}
res
}
}
impl<'a> TreeSink for OffsetTokenSink<'a> {
fn token(&mut self, _kind: SyntaxKind, n_tokens: u8) {
for _ in 0..n_tokens {
self.cursor = self.cursor.bump_subtree();
}
}
fn start_node(&mut self, _kind: SyntaxKind) {}
fn finish_node(&mut self) {}
fn error(&mut self, _error: ra_parser::ParseError) {
self.error = true;
}
}
pub(crate) struct Parser<'a> {
subtree: &'a tt::Subtree,
cur_pos: &'a mut usize,
}
impl<'a> Parser<'a> {
pub fn new(cur_pos: &'a mut usize, subtree: &'a tt::Subtree) -> Parser<'a> {
Parser { cur_pos, subtree }
}
pub fn parse_fragment(self, fragment_kind: FragmentKind) -> Option<tt::TokenTree> {
self.parse(|token_source, tree_skink| {
ra_parser::parse_fragment(token_source, tree_skink, fragment_kind)
})
}
fn parse<F>(self, f: F) -> Option<tt::TokenTree>
where
F: FnOnce(&mut dyn TokenSource, &mut dyn TreeSink),
{
let buffer = TokenBuffer::new(&self.subtree.token_trees[*self.cur_pos..]);
let mut src = SubtreeTokenSource::new(&buffer);
let mut sink = OffsetTokenSink { cursor: buffer.begin(), error: false };
f(&mut src, &mut sink);
let r = self.finish(buffer.begin(), &mut sink);
if sink.error {
return None;
}
r
}
fn finish(self, begin: Cursor, sink: &mut OffsetTokenSink) -> Option<tt::TokenTree> {
let res = sink.collect(begin);
*self.cur_pos += res.len();
match res.len() {
0 => None,
1 => Some(res[0].clone()),
_ => Some(tt::TokenTree::Subtree(tt::Subtree {
delimiter: tt::Delimiter::None,
token_trees: res.into_iter().cloned().collect(),
})),
}
}
}
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