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extract parse_pat_range_starting_with_lit

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This commit is contained in:
Mazdak Farrokhzad 2019-08-12 09:01:08 +02:00
parent e6f980f9b8
commit 49740b792d
1 changed files with 21 additions and 20 deletions
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41
src/libsyntax/parse/parser/pat.rs
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@ -202,26 +202,10 @@ impl<'a> Parser<'a> {
} else {
// Try to parse everything else as literal with optional minus
match self.parse_literal_maybe_minus() {
Ok(begin) => {
let op_span = self.token.span;
if self.check(&token::DotDot) || self.check(&token::DotDotEq) ||
self.check(&token::DotDotDot) {
let (end_kind, form) = if self.eat(&token::DotDotDot) {
(RangeEnd::Included(RangeSyntax::DotDotDot), "...")
} else if self.eat(&token::DotDotEq) {
(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
} else if self.eat(&token::DotDot) {
(RangeEnd::Excluded, "..")
} else {
panic!("impossible case: we already matched \
on a range-operator token")
};
let end = self.parse_pat_range_end_opt(&begin, form)?;
PatKind::Range(begin, end, respan(op_span, end_kind))
} else {
PatKind::Lit(begin)
}
}
Ok(begin) if self.check(&token::DotDot) || self.check(&token::DotDotEq)
|| self.check(&token::DotDotDot)
=> self.parse_pat_range_starting_with_lit(begin)?,
Ok(begin) => PatKind::Lit(begin),
Err(mut err) => {
self.cancel(&mut err);
let expected = expected.unwrap_or("pattern");
@ -360,6 +344,23 @@ impl<'a> Parser<'a> {
Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
}
/// Parse a range pattern `$literal $form $end?` where `$form = ".." | "..." | "..=" ;`.
/// The `$path` has already been parsed and the next token is the `$form`.
fn parse_pat_range_starting_with_lit(&mut self, begin: P<Expr>) -> PResult<'a, PatKind> {
let op_span = self.token.span;
let (end_kind, form) = if self.eat(&token::DotDotDot) {
(RangeEnd::Included(RangeSyntax::DotDotDot), "...")
} else if self.eat(&token::DotDotEq) {
(RangeEnd::Included(RangeSyntax::DotDotEq), "..=")
} else if self.eat(&token::DotDot) {
(RangeEnd::Excluded, "..")
} else {
panic!("impossible case: we already matched on a range-operator token")
};
let end = self.parse_pat_range_end_opt(&begin, form)?;
Ok(PatKind::Range(begin, end, respan(op_span, end_kind)))
}
// Helper function to decide whether to parse as ident binding
// or to try to do something more complex like range patterns.
fn parse_as_ident(&mut self) -> bool {