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parser: extract eat_or_separator.

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This commit is contained in:
Mazdak Farrokhzad 2019-08-18 18:13:19 +02:00
parent a4a34ab62d
commit 7b59b4f14d
1 changed files with 28 additions and 30 deletions
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58
src/libsyntax/parse/parser/pat.rs
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@ -29,27 +29,10 @@ impl<'a> Parser<'a> {
loop {
pats.push(self.parse_top_level_pat()?);
if self.token == token::OrOr {
self.ban_unexpected_or_or();
self.bump();
} else if self.eat(&token::BinOp(token::Or)) {
// This is a No-op. Continue the loop to parse the next
// pattern.
} else {
if !self.eat_or_separator() {
return Ok(pats);
}
};
}
fn ban_unexpected_or_or(&mut self) {
self.struct_span_err(self.token.span, "unexpected token `||` after pattern")
.span_suggestion(
self.token.span,
"use a single `|` to specify multiple patterns",
"|".to_owned(),
Applicability::MachineApplicable
)
.emit();
}
}
/// A wrapper around `parse_pat` with some special error handling for the
@ -127,17 +110,7 @@ impl<'a> Parser<'a> {
let lo = first_pat.span;
let mut pats = vec![first_pat];
loop {
if self.token == token::OrOr {
// Found `||`; Recover and pretend we parsed `|`.
self.ban_unexpected_or_or();
self.bump();
} else if self.eat(&token::BinOp(token::Or)) {
// Found `|`. Working towards a proper or-pattern.
} else {
break;
}
while self.eat_or_separator() {
let pat = self.parse_pat(expected)?;
self.maybe_recover_unexpected_comma(pat.span, top_level)?;
pats.push(pat);
@ -152,6 +125,31 @@ impl<'a> Parser<'a> {
Ok(self.mk_pat(or_pattern_span, PatKind::Or(pats)))
}
/// Eat the or-pattern `|` separator.
/// If instead a `||` token is encountered, recover and pretend we parsed `|`.
fn eat_or_separator(&mut self) -> bool {
match self.token.kind {
token::OrOr => {
// Found `||`; Recover and pretend we parsed `|`.
self.ban_unexpected_or_or();
self.bump();
true
}
_ => self.eat(&token::BinOp(token::Or)),
}
}
fn ban_unexpected_or_or(&mut self) {
self.struct_span_err(self.token.span, "unexpected token `||` after pattern")
.span_suggestion(
self.token.span,
"use a single `|` to specify multiple patterns",
"|".to_owned(),
Applicability::MachineApplicable
)
.emit();
}
/// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
/// allowed).
fn parse_pat_with_range_pat(