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fix: implicit discard in list patterns

This commit is contained in:
rvcas 2022-11-24 09:54:13 -05:00 committed by Lucas
parent a70ebb5c32
commit ba8855add9
1 changed files with 31 additions and 10 deletions
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41
crates/lang/src/parser.rs
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@ -1061,19 +1061,40 @@ pub fn pattern_parser() -> impl Parser<Token, ast::UntypedPattern, Error = Parse
just(Token::LeftSquare)
.ignore_then(r.clone().separated_by(just(Token::Comma)))
.then(choice((
just(Token::Comma).ignore_then(
just(Token::DotDot)
.ignore_then(r.clone())
.map(Box::new)
.or_not(),
),
just(Token::Comma)
.ignore_then(just(Token::DotDot).ignore_then(r.clone().or_not()).or_not()),
just(Token::Comma).ignored().or_not().map(|_| None),
)))
.then_ignore(just(Token::RightSquare))
.map_with_span(|(elements, tail), span| ast::UntypedPattern::List {
location: span,
elements,
tail,
.validate(|(elements, tail), span: Span, _emit| {
let tail = match tail {
// There is a tail and it has a Pattern::Var or Pattern::Discard
Some(Some(
pat @ (ast::UntypedPattern::Var { .. }
| ast::UntypedPattern::Discard { .. }),
)) => Some(pat),
Some(Some(pat)) => {
// use emit
// return parse_error(ParseErrorType::InvalidTailPattern, pat.location())
Some(pat)
}
// There is a tail but it has no content, implicit discard
Some(None) => Some(ast::UntypedPattern::Discard {
location: Span {
start: span.end - 1,
end: span.end,
},
name: "_".to_string(),
}),
// No tail specified
None => None,
};
ast::UntypedPattern::List {
location: span,
elements,
tail: tail.map(Box::new),
}
}),
))
.then(