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use crate::subtree_source::SubtreeTokenSource;
use ra_parser::{TokenSource, TreeSink};
use ra_syntax::{SyntaxKind};
struct OffsetTokenSink {
token_pos: usize,
}
impl TreeSink for OffsetTokenSink {
fn token(&mut self, _kind: SyntaxKind, n_tokens: u8) {
self.token_pos += n_tokens as usize;
}
fn start_node(&mut self, _kind: SyntaxKind) {}
fn finish_node(&mut self) {}
fn error(&mut self, _error: ra_parser::ParseError) {}
}
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_path(self) -> Option<tt::TokenTree> {
self.parse(ra_parser::parse_path)
}
fn parse<F>(self, f: F) -> Option<tt::TokenTree>
where
F: FnOnce(&dyn TokenSource, &mut dyn TreeSink),
{
let mut src = SubtreeTokenSource::new(self.subtree);
src.start_from_nth(*self.cur_pos);
let mut sink = OffsetTokenSink { token_pos: 0 };
f(&src, &mut sink);
self.finish(sink.token_pos, &mut src)
}
fn finish(self, parsed_token: usize, src: &mut SubtreeTokenSource) -> Option<tt::TokenTree> {
let res = src.bump_n(parsed_token);
*self.cur_pos += res.len();
let res: Vec<_> = res.into_iter().cloned().collect();
match res.len() {
0 => None,
1 => Some(res[0].clone()),
_ => Some(tt::TokenTree::Subtree(tt::Subtree {
delimiter: tt::Delimiter::None,
token_trees: res,
})),
}
}
}
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