self.parse_pat_with_range_pat(true, expected)
}
- /// Parses patterns, separated by '|' s.
- pub(super) fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
- // Allow a '|' before the pats (RFC 1925 + RFC 2530)
- self.eat(&token::BinOp(token::Or));
+ // FIXME(or_patterns, Centril | dlrobertson):
+ // remove this and use `parse_top_pat` everywhere it is used instead.
+ pub(super) fn parse_top_pat_unpack(&mut self, gate_or: bool) -> PResult<'a, Vec<P<Pat>>> {
+ self.parse_top_pat(gate_or)
+ .map(|pat| pat.and_then(|pat| match pat.node {
+ PatKind::Or(pats) => pats,
+ node => vec![self.mk_pat(pat.span, node)],
+ }))
+ }
+
+ /// Entry point to the main pattern parser.
+ /// Corresponds to `top_pat` in RFC 2535 and allows or-pattern at the top level.
+ pub(super) fn parse_top_pat(&mut self, gate_or: bool) -> PResult<'a, P<Pat>> {
+ // Allow a '|' before the pats (RFCs 1925, 2530, and 2535).
+ if self.eat_or_separator() && gate_or {
+ self.sess.gated_spans.or_patterns.borrow_mut().push(self.prev_span);
+ }
+
+ self.parse_pat_with_or(None, gate_or, true)
+ }
+
+ pub(super) fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
+ let pat = self.parse_pat(None)?;
+ self.maybe_recover_unexpected_comma(pat.span, true)?;
+ Ok(pat)
+ }
+
+ /// Parses a pattern, that may be a or-pattern (e.g. `Foo | Bar` in `Some(Foo | Bar)`).
+ /// Corresponds to `pat<allow_top_alt>` in RFC 2535.
+ fn parse_pat_with_or(
+ &mut self,
+ expected: Expected,
+ gate_or: bool,
+ top_level: bool
+ ) -> PResult<'a, P<Pat>> {
+ // Parse the first pattern.
+ let first_pat = self.parse_pat(expected)?;
+ self.maybe_recover_unexpected_comma(first_pat.span, top_level)?;
+
+ // If the next token is not a `|`,
+ // this is not an or-pattern and we should exit here.
+ if !self.check(&token::BinOp(token::Or)) && self.token != token::OrOr {
+ return Ok(first_pat)
+ }
+
+ let lo = first_pat.span;
+ let mut pats = vec![first_pat];
+ while self.eat_or_separator() {
+ let pat = self.parse_pat(expected)?;
+ self.maybe_recover_unexpected_comma(pat.span, top_level)?;
+ pats.push(pat);
+ }
+ let or_pattern_span = lo.to(self.prev_span);
+
+ // Feature gate the or-pattern if instructed:
+ if gate_or {
+ self.sess.gated_spans.or_patterns.borrow_mut().push(or_pattern_span);
+ }
- let mut pats = Vec::new();
- loop {
- pats.push(self.parse_top_level_pat()?);
+ Ok(self.mk_pat(or_pattern_span, PatKind::Or(pats)))
+ }
- if self.token == token::OrOr {
+ /// 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();
- } else if self.eat(&token::BinOp(token::Or)) {
- // This is a No-op. Continue the loop to parse the next
- // pattern.
- } else {
- return Ok(pats);
+ true
}
- };
+ _ => self.eat(&token::BinOp(token::Or)),
+ }
}
+ /// We have parsed `||` instead of `|`. Error and suggest `|` instead.
fn ban_unexpected_or_or(&mut self) {
self.struct_span_err(self.token.span, "unexpected token `||` after pattern")
.span_suggestion(
.emit();
}
- /// A wrapper around `parse_pat` with some special error handling for the
- /// "top-level" patterns in a match arm, `for` loop, `let`, &c. (in contrast
- /// to subpatterns within such).
- pub(super) fn parse_top_level_pat(&mut self) -> PResult<'a, P<Pat>> {
- let pat = self.parse_pat(None)?;
- if self.token == token::Comma {
- // An unexpected comma after a top-level pattern is a clue that the
- // user (perhaps more accustomed to some other language) forgot the
- // parentheses in what should have been a tuple pattern; return a
- // suggestion-enhanced error here rather than choking on the comma
- // later.
- let comma_span = self.token.span;
- self.bump();
- if let Err(mut err) = self.skip_pat_list() {
- // We didn't expect this to work anyway; we just wanted
- // to advance to the end of the comma-sequence so we know
- // the span to suggest parenthesizing
- err.cancel();
- }
- let seq_span = pat.span.to(self.prev_span);
- let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
- if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
- err.span_suggestion(
- seq_span,
- "try adding parentheses to match on a tuple..",
- format!("({})", seq_snippet),
- Applicability::MachineApplicable
- ).span_suggestion(
- seq_span,
- "..or a vertical bar to match on multiple alternatives",
- format!("{}", seq_snippet.replace(",", " |")),
- Applicability::MachineApplicable
- );
- }
- return Err(err);
+ /// Some special error handling for the "top-level" patterns in a match arm,
+ /// `for` loop, `let`, &c. (in contrast to subpatterns within such).
+ fn maybe_recover_unexpected_comma(&mut self, lo: Span, top_level: bool) -> PResult<'a, ()> {
+ if !top_level || self.token != token::Comma {
+ return Ok(());
}
- Ok(pat)
+
+ // An unexpected comma after a top-level pattern is a clue that the
+ // user (perhaps more accustomed to some other language) forgot the
+ // parentheses in what should have been a tuple pattern; return a
+ // suggestion-enhanced error here rather than choking on the comma later.
+ let comma_span = self.token.span;
+ self.bump();
+ if let Err(mut err) = self.skip_pat_list() {
+ // We didn't expect this to work anyway; we just wanted to advance to the
+ // end of the comma-sequence so we know the span to suggest parenthesizing.
+ err.cancel();
+ }
+ let seq_span = lo.to(self.prev_span);
+ let mut err = self.struct_span_err(comma_span, "unexpected `,` in pattern");
+ if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
+ err.span_suggestion(
+ seq_span,
+ "try adding parentheses to match on a tuple..",
+ format!("({})", seq_snippet),
+ Applicability::MachineApplicable
+ )
+ .span_suggestion(
+ seq_span,
+ "..or a vertical bar to match on multiple alternatives",
+ format!("{}", seq_snippet.replace(",", " |")),
+ Applicability::MachineApplicable
+ );
+ }
+ Err(err)
}
/// Parse and throw away a parentesized comma separated
Ok(())
}
- /// Parses a pattern, that may be a or-pattern (e.g. `Some(Foo | Bar)`).
- fn parse_pat_with_or(&mut self, expected: Expected, gate_or: bool) -> PResult<'a, P<Pat>> {
- // Parse the first pattern.
- let first_pat = self.parse_pat(expected)?;
-
- // If the next token is not a `|`,
- // this is not an or-pattern and we should exit here.
- if !self.check(&token::BinOp(token::Or)) {
- return Ok(first_pat)
- }
-
- let lo = first_pat.span;
-
- let mut pats = vec![first_pat];
-
- while self.eat(&token::BinOp(token::Or)) {
- pats.push(self.parse_pat_with_range_pat(true, expected)?);
- }
-
- let or_pattern_span = lo.to(self.prev_span);
-
- // Feature gate the or-pattern if instructed:
- if gate_or {
- self.sess.gated_spans.or_patterns.borrow_mut().push(or_pattern_span);
- }
-
- Ok(self.mk_pat(or_pattern_span, PatKind::Or(pats)))
- }
-
/// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
/// allowed).
fn parse_pat_with_range_pat(
// Parse `[pat, pat,...]` as a slice pattern.
let (pats, _) = self.parse_delim_comma_seq(
token::Bracket,
- |p| p.parse_pat_with_or(None, true),
+ |p| p.parse_pat_with_or(None, true, false),
)?;
PatKind::Slice(pats)
}
/// Parse a tuple or parenthesis pattern.
fn parse_pat_tuple_or_parens(&mut self) -> PResult<'a, PatKind> {
let (fields, trailing_comma) = self.parse_paren_comma_seq(|p| {
- p.parse_pat_with_or(None, true)
+ p.parse_pat_with_or(None, true, false)
})?;
// Here, `(pat,)` is a tuple pattern.
err.span_label(self.token.span, msg);
return Err(err);
}
- let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or(None, true))?;
+ let (fields, _) = self.parse_paren_comma_seq(|p| p.parse_pat_with_or(None, true, false))?;
Ok(PatKind::TupleStruct(path, fields))
}
// Parsing a pattern of the form "fieldname: pat"
let fieldname = self.parse_field_name()?;
self.bump();
- let pat = self.parse_pat_with_or(None, true)?;
+ let pat = self.parse_pat_with_or(None, true, false)?;
hi = pat.span;
(pat, fieldname, false)
} else {
projects / rust.git / blobdiff