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simplify

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This commit is contained in:
Aleksey Kladov 2021-12-27 16:28:54 +03:00
parent 369001615f
commit 8e7fc7be65
5 changed files with 27 additions and 104 deletions
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59
crates/mbe/src/tt_iter.rs
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@ -1,7 +1,7 @@
//! A "Parser" structure for token trees. We use this when parsing a declarative
//! macro definition into a list of patterns and templates.
use crate::{to_parser_input::to_parser_input, ExpandError, ExpandResult, ParserEntryPoint};
use crate::{to_parser_input::to_parser_input, ExpandError, ExpandResult};
use syntax::SyntaxKind;
use tt::buffer::TokenBuffer;
@ -90,63 +90,6 @@ impl<'a> TtIter<'a> {
}
pub(crate) fn expect_fragment(
&mut self,
entry_point: ParserEntryPoint,
) -> ExpandResult<Option<tt::TokenTree>> {
let buffer = TokenBuffer::from_tokens(self.inner.as_slice());
let parser_input = to_parser_input(&buffer);
let tree_traversal = parser::parse(&parser_input, entry_point);
let mut cursor = buffer.begin();
let mut error = false;
for step in tree_traversal.iter() {
match step {
parser::Step::Token { kind, mut n_input_tokens } => {
if kind == SyntaxKind::LIFETIME_IDENT {
n_input_tokens = 2;
}
for _ in 0..n_input_tokens {
cursor = cursor.bump_subtree();
}
}
parser::Step::Enter { .. } | parser::Step::Exit => (),
parser::Step::Error { .. } => error = true,
}
}
let mut err = if !cursor.is_root() || error {
Some(err!("expected {:?}", entry_point))
} else {
None
};
let mut curr = buffer.begin();
let mut res = vec![];
if cursor.is_root() {
while curr != cursor {
if let Some(token) = curr.token_tree() {
res.push(token);
}
curr = curr.bump();
}
}
self.inner = self.inner.as_slice()[res.len()..].iter();
if res.is_empty() && err.is_none() {
err = Some(err!("no tokens consumed"));
}
let res = match res.len() {
1 => Some(res[0].cloned()),
0 => None,
_ => Some(tt::TokenTree::Subtree(tt::Subtree {
delimiter: None,
token_trees: res.into_iter().map(|it| it.cloned()).collect(),
})),
};
ExpandResult { value: res, err }
}
pub(crate) fn expect_fragment2(
&mut self,
entry_point: parser::PrefixEntryPoint,
) -> ExpandResult<Option<tt::TokenTree>> {